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carnitine and L – carnitine

Posted on 23. Dec, 2011 by .

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L-Carnitine, a sub-type of Carnitine
Carnitine is a naturally occurring amino acid which plays a vital role in the metabolism of fat. It functions as a transporter of fatty acids into the mitochondria, the metabolic furnace of the cell.Carnitine is a substance that helps the body turn fat into energy. Your body makes it in the liver and kidneys and stores it in the skeletal muscles, heart, brain, and sperm
Carnitine plays a critical role in energy production. It transports long-chain fatty acids into the mitochondria so they can be oxidized (“burned”) to produce energy. It also transports the toxic compounds generated out of this cellular organelle to prevent their accumulation. Given these key functions, carnitine is concentrated in tissues like skeletal and cardiac muscle that utilize fatty acids as a dietary fuel
Usually, your body can make all the carnitine it needs. Some people, however, may not have enough carnitine because their bodies cannot make enough or can’ t transport it into tissues so it can be used. Some other conditions, such as angina or intermittent claudication, can also cause low levels of carnitine in the body, as can some medications.For genetic or medical reasons, some individuals (such as preterm infants), cannot make enough, so for them carnitine is a conditionally essential nutrient
Carnitine has been proposed as a treatment for many conditions because it acts as an antioxidant. Antioxidants fight harmful particles in the body known as free radicals, which damage cells and tamper with DNA. Antioxidants can neutralize free radicals and may reduce or help prevent some of the damage they cause.

Some of the conditions carnitine may help treat are serious. Serious diseases and conditions require conventional medical treatment, and you should talk to your health care provider before taking carnitine. For other conditions, such as fatigue or improving athletic performance, carnitine seems safe but may not help much.

L-carnitine was discovered in Russia, and one year later in Germany. The proper name, Carnitine, refers to the Latin origin, (carno, caris). Its structural formula was decoded in 1927, and its physiological significance was understood by the 1960’s. (http://www.hlthmall.com/l-carnitine.html) L-carnitine is synthesized in the liver and kidneys, from two essential amino acids, lysine and methionine. This synthesis requires the presence of vitamins niacin, B6, and iron. Most (98%) of the carnitine supply resides in the body’s muscle tissue. Approximately 80% of the amino acids our bodies need is endogenously synthesized, the remaining 20% are referred to as the essential amino acids. The supply of such aminos, like l-carnitine, must be supplemented exogenously. L-carnitine is available in the following food sources: red meat, diary products, avocado, and tempeh. Although a well balanced diet can provide approximately 75% of what the body is lacking, often conditions arise that make it difficult to obtain all the carnitine one needs.
It has been established that an adequate supply of l-carnitine is necessary for the maintenance of good health. L-carnitine transports long-chain fatty acids across the mitochondrial membrane to be metabolized. L-carnitine aids in the release of stored body fat, tryglycerides, into the bloodstream for energy. Tryglycerides are the major source for the production of energy in the heart and skeletal muscles. Access to l-carnitine is believed to increase energy levels for long-term aerobic activity. L-carnitine is also responsible for muscle contraction, regulation of protein balance and maintenance of a healthy heart. Research also suggests that an adequate supply of l-carnitine could be instrumental in the treatment of diabetes, chronic fatigue syndrome, kidney and liver disease.Since its involvement in the process of burning fats is of most importance to those interested in endurance and body fitness, it is this topic that will be focused upon.

THE ROLE OF L-CARNITINE: HOW DOES IT WORK?

Carnitine boosts energy by stimulating the body’s burning of tryglycerides as fuel, and sparing the supply of glycogen stored in the liver for heavier exertion. During exercise, the body will burn fat at a rate of 75-80% of maximum exertion, thus less glycogen from carbohydrates is burned. L-carnitine allows the body to burn more fat, save more glycogen, and ultimately boost stamina and endurance. By providing more fat to the muscles, carnitine makes accessible an otherwise unavailable energy source

FAT + OXYGEN + L-CARNITINE = ENERGY

Is this the recipe for success? According to proponents of L-Carnitine, it is the essential amino acid in the optimum fat burning process. They believe that carnitine is to the human body, what a turbo mechanism is to a car: both provide optimal fuel and performance. Minus L-carnitine, fatty acids would have a difficult time permeating the walls of the mitochondria. Energy, stored in carbohydrates and fats, is required to work the muscle. Carbohydrates are converted from glucose to glycogen, to be stored in liver and muscle cells. Eventually, the body turns to fat storage for energy, and possibly, with more ease in the presence of L-carnitine. This is where L-carnitine as a supplement enters. During high energy output, the supply of L-carnitine becomes exhausted. Is it possible to compensate for this decrease solely through metabolic processes and diet? Or is an additional carnitine supplement needed for the extra boost? Judging from the variety of carnitine products now on the market, apparently many believe an additional outside source proves beneficial.

L-carnitine supplements are used to increase L-carnitine levels in people whose natural level of L-carnitine is too low because they have a genetic disorder, are taking certain drugs (valproic acid for seizures), or because they are undergoing a medical procedure (hemodialysis for kidney disease) that uses up the body’s L-carnitine. It is also used as a replacement supplement in strict vegetarians, dieters, and low-weight or premature infants.

L-carnitine is used for conditions of the heart and blood vessels including heart-related chest pain, congestive heart failure (CHF), heart complications of a disease called diphtheria, heart attack, leg pain caused by circulation problems (intermittent claudication), and high cholesterol.

Some people use L-carnitine for muscle disorders associated with certain AIDS medications, difficulty fathering a child (male infertility), a brain development disorder called Rett syndrome, anorexia, chronic fatigue syndrome, diabetes, overactive thyroid, attention deficit-hyperactivity disorder (ADHD), leg ulcers, Lyme disease, and to improve athletic performance and endurance.

The body can convert L-carnitine to other amino acids called acetyl-L-carnitine and propionyl-L-carnitine. But, no one knows whether the benefits of carnitines are interchangeable. Until more is known, don’t substitute one form of carnitine for another.

When can a carnitine deficiency occur?

Two types of carnitine deficiency states exist. Primary carnitine deficiency is a genetic disorder of the cellular carnitine-transporter system that usually manifests itself by five years of age with symptoms of cardiomyopathy, skeletal-muscle weakness, and hypoglycemia. Secondary carnitine deficiencies may occur due to certain disorders (such as chronic renal failure) or under particular conditions (e.g., use of certain antibiotics) that reduce carnitine absorption or increase its excretion . There is scientific agreement on carnitine’s value as a prescription product for treating such deficiencies .

What are some current issues and controversies about carnitine?

Carnitine has been studied extensively because it is important to energy production and is a well-tolerated and generally safe therapeutic agent . Researchers prefer to use acetyl-L-carnitine in research studies because it is better absorbed from the small intestine than L-carnitine and more efficiently crosses the blood-brain barrier (i.e., gets into brain tissue) .

Athletic performance

Some athletes take carnitine to improve performance. However, twenty years of research finds no consistent evidence that carnitine supplements can improve exercise or physical performance in healthy subjects—at doses ranging from 2-6 grams/day administered for 1 to 28 days. (The total body content of carnitine is about 20 grams in a man weighing 155 pounds, almost all of it in the skeletal muscle .) For example, carnitine supplements do not appear to increase the body’s use of oxygen or improve metabolic status when exercising, nor do they necessarily increase the amount of carnitine in muscle.

Aging

A decline in mitochondrial function is thought to contribute to the aging process. Carnitine may be involved because its concentration in tissues declines with age and thereby reduces the integrity of the mitochondrial membrane
. Research in aged rats found supplementation with high doses of acetyl-L-carnitine and alpha-lipoic acid (an antioxidant) to reduce mitochondrial decay
. The animals also moved about more and improved their performance on memory-requiring tasks. At present there are no equivalent studies of this kind in humans. However, a meta-analysis of double-blind, placebo-controlled studies suggests that supplements of acetyl-L-carnitine may improve mental function and reduce deterioration in older adults with mild cognitive impairment and Alzheimer’s disease
. In these studies, subjects took 1.5-3.0 grams/day of acetyl-L-carnitine for 3-12 months.

Cardiovascular and peripheral-arterial disease
Several studies have examined supplemental carnitine in the management of cardiac ischemia (restriction of blood flow to the heart) and peripheral arterial disease (of which the most important symptom is poor circulation in the legs, known as intermittent claudication)
. Because levels of carnitine are low in the failing heart muscle, supplemental amounts might be beneficial to the organ by counteracting the toxic effects of free fatty acids and improving carbohydrate metabolism
. In short-term studies, carnitine has demonstrated anti-ischemic properties when given orally and by injection. A double-blind, placebo-controlled, multicenter clinical trial in Italy with patients who had suffered a first heart attack found that supplemental carnitine (given intravenously for five days, then 6 grams/day orally for one year) reduced heart failure and overall mortality
. The results were not conclusive but promising enough to justify a larger study whose results have not yet been reported

Claudication results from an inadequate supply of oxygen-rich blood to the legs and leads to an accumulation of acetylcarnitine in muscle due to its incomplete utilization. Patients with peripheral arterial disease who develop claudication have significant impairments in exercise performance and find it difficult to walk even short distances at a slow speed
. Two published randomized, controlled trials raise the possibility that carnitine may improve the performance of skeletal muscles in the leg. In one European multicenter clinical trial, subjects with moderate to severe claudication who were supplemented with L-carnitine (in the form of propionyl-L-carnitine at 2 grams/day for 12 months) significantly improved their maximal walking distance and perceived quality of life as compared to subjects receiving the placebo [21]red for 6 months in patients with disabling claudication to significantly improve walking distance and speed, reduce bodily pain, enhance physical function, and improve perceived health state as compared to controls.

Cancer

Fatigue resulting from chemotherapy, radiation treatment, and poor nutritional status is common in cancer patients
. They may also be deficient in carnitine
. In one study, treatment with carnitine supplements (4 grams/day for one week) ameliorated fatigue in most chemotherapy-treated subjects and restored normal blood levels of carnitine
. In another trial, terminal cancer patients supplemented with carnitine (doses ranged from 250 milligrams to 3 grams/day) experienced less fatigue and improved mood and quality of sleep
. In both studies, most subjects were carnitine deficient before taking the supplements.

Type 2 diabetes

Insulin resistance, which plays an important role in the development of type 2 diabetes, may be associated with a defect in fatty-acid oxidation in muscle. This raises the question as to whether mitochondrial dysfunction might be a factor in the development of the disease. Increased storage of fat in lean tissues has become a marker for insulin resistance . Early research suggests that supplementation with L-carnitine intravenously may improve insulin sensitivity in diabetics by decreasing fat levels in muscle and may lower glucose levels in the blood by more promptly increasing its oxidation in cells. A recent analysis of two multicenter clinical trials of subjects with either type 1 or type 2 diabetes found that treatment with acetyl-L-carnitine (3 grams/day orally) for one year provided significant relief of nerve pain and improved vibration perception in those with diabetic neuropathy. The treatment was most effective in subjects with type 2 diabetes of short duration.

HIV and AIDS

The human immunodeficiency virus (HIV) causes a decline in the number of lymphocytes (one type of white blood cell), resulting in acquired immunodeficiency syndrome (AIDS). HIV-infected individuals often accumulate fat in some areas of the body and lose fat in others and develop high levels of blood fats (hyperlipidemia) and insulin resistance, which together constitute the lipodystrophy syndrome. This syndrome may represent mitochondrial toxicity brought about by the HIV infection and the antiretroviral drugs used to treat it, and can induce a carnitine deficiency that limits mitochondrial fat metabolism . The molecular mechanisms by which this occurs are poorly understood. Preliminary research provides conflicting findings but suggests that supplementation with carnitine both intravenously and orally (at doses of 2-6 grams/day for weeks or months) in HIV-infected individuals may slow the death of lymphocytes (which in turn may slow HIV progression), reduce neuropathy , and favorably affect blood lipid levels .

End-stage renal disease and hemodialysis

Carnitine homeostasis (balance within the body) among individuals with renal diseases can be substantially impaired by several factors, particularly reduced synthesis and increased elimination of the compound by the kidneys as well as reduced intake from food due to poor appetite and consumption of fewer animal products . Many patients with end-stage renal disease, particularly those on hemodialysis, become carnitine insufficient. Carnitine blood levels and muscle stores are low, which may contribute to anemia, muscle weakness, fatigue, altered levels of blood fats, and heart disorders. Numerous studies suggest that high doses of supplemental carnitine (often injected) in patients on maintenance hemodialysis can correct some or all of these symptoms, though most involve small numbers of patients and are not double-blinded trials. A recent meta-analysis of these studies concludes that carnitine supplements may aid anemia management but not blood-lipid profiles, and that their effects on exercise capacity or heart stability are inconclusive .

Male infertility

Low sperm counts have been linked to low carnitine levels in men. Several studies suggest that L-carnitine supplements may increase sperm count and mobility.

Erectile Dysfunction

Preliminary studies suggest propionyl-L-carnitine may help improve male sexual function. One study found that carnitine improved the effectiveness of sidenafil (Viagra) in men with diabetes who had not previously responded to Viagra. In another study, a combination of propionyl-L-carnitine and acetyl-L-carnitine improved the effectiveness of Viagra in men who had erectile dysfunction after prostate surgery. More studies are needed.

Peyronie’s Disease

Peyronie’s disease is characterized by a curvature of the penis that leads to pain during an erection. One promising study compared acetyl-L-carnitine to the medication tamoxifen in 48 men with this condition. Acetyl-L-carnitine worked better than tamoxifen at reducing pain during sex and reducing the curve of the penis. Acetyl-L-carnitine also had fewer side effects than tamoxifen. More research is needed.

The carnitine content of seminal fluid is directly related to sperm count and motility , suggesting that the compound might be of value in treating male infertility. Several studies indicate that carnitine supplementation (2-3 grams/day for 3-4 months) may improve sperm quality, and one randomized, double-blind crossover trial found that 2 grams/day of carnitine taken for 2 months by 100 infertile men increased the concentration and both total and forward motility of their sperm . The reported benefits may relate to increased mitochondrial fatty-acid oxidation (providing more energy for sperm) and reduced cell death in the testes . However, a recent randomized controlled trial with 21 infertile men found that 3 grams/day of carnitine taken for 24 weeks produced no significant increases in sperm motility or total motile sperm counts as compared to placebo . Larger and more carefully designed studies are needed to evaluate carnitine’s potential value as an infertility therapy.

Are there health risks from too much carnitine?

At doses of approximately 3 grams/day, carnitine supplements may cause nausea, vomiting, abdominal cramps, diarrhea, and a “fishy” body odor . More rare side effects include muscle weakness in uremic patients and seizures in those with seizure disorders.

Carnitine and medication interaction

Carnitine interacts with pivalate-conjugated antibiotics such as pivampicillin that are used in the long-term prevention of urinary-tract infections . Chronic administration of these antibiotics increases the excretion of pivaloyl-carnitine, which can lead to carnitine depletion. However, while tissue carnitine levels may become low enough to limit fatty acid oxidation, no cases of illness due to deficiency have been described . Blood concentrations of carnitine may be reduced in children treated for convulsions with phenobarbital, valproic acid, phenytoin, or carbamazepine, but no clinical consequences have been shown .

Supplemental sources of carnitine

L-carnitine, acetyl-L-carnitine, and propionyl-L-carnitine are available over-the-counter as dietary supplements. Carnitine is often promoted as an aid for weight loss, to improve exercise performance, and to enhance a sense of well-being . It is also a drug approved by the Food and Drug Administration to treat primary and certain secondary carnitine-deficiency syndromes.

Carnitine intakes and healthful diets

Most people obtain sufficient carnitine because of the body’s natural production of the substance as well as from their diets. The Dietary Guidelines for Americans describes a healthy diet as one that:

* emphasizes a variety of fruits, vegetables, whole grains, and fat-free or low-fat milk and milk products;
* includes lean meats, poultry, fish, beans, eggs, and nuts;
* is low in saturated fats, trans fats, cholesterol, salt (sodium), and added sugars; and
* stays within your daily calorie needs.

Heart Conditions

* Angina — Some good evidence shows that carnitine can be used along with conventional treatment for stable angina. Several clinical trials show that L-carnitine and propionyl-L-carnitine can help reduce symptoms of angina and improve the ability of people with angina to exercise without chest pain. Do not self-treat chest pain with carnitine, however. See your health care provider for diagnosis and conventional treatment, and take carnitine only under your health care provider’s supervision.
* Heart attack — A few studies have found that carnitine may help when used with conventional medicines after a heart attack, but not all studies agree. Some small studies suggest that people who take L-carnitine supplements soon after a heart attack may be less likely to have another heart attack, die of heart disease, have chest pain and abnormal heart rhythms, or develop heart failure. However, other studies have shown no benefit. Treatment with oral carnitine may also improve muscle weakness. Carnitine should be used along with conventional medication under your health care provider supervision.
* Heart failure — A few small studies have suggested that carnitine (usually propionyl-L-carnitine) can help reduce symptoms of heart failure and improve exercise capacity in people with heart failure. However, more and larger studies are needed to know for sure.

Peripheral Vascular Disease

Decreased blood flow to the legs from atherosclerosis or hardening of the arteries — where plaque builds up in the arteries — often causes an aching or cramping pain in the legs while walking or exercising. This pain is called intermittent claudication, and the reduced blood flow to the legs is called peripheral vascular disease (PVD). Several studies show that carnitine can help reduce symptoms and increase the distance that people with intermittent claudication can walk. Most studies have used propionyl-L-carnitine. Scientists don’t know whether L-carnitine would work the same.

Diabetic Neuropathy

Diabetic neuropathy happens when high blood sugar levels damage nerves in the body, especially the arms, legs, and feet, causing pain and numbness. Some small preliminary studies suggest acetyl-L-carnitine may help reduce pain and increase feeling in affected nerves. It is also possible that carnitine can help nerves regenerate. More research is needed.

Exercise Performance

Although carnitine is often taken to boost exercise performance, there is no evidence it works.

Weight Loss

Although L-carnitine has been marketed as a weight loss supplement, there is no scientific evidence to show that it works. Some studies do show that oral carnitine reduces fat mass, increases muscle mass, and reduces fatigue, which may contribute to weight loss in some people.

Alzheimer’s Disease and Memory Impairment

The evidence is mixed as to whether carnitine is useful in treating Alzheimer’s disease. Several early studies showed that acetyl-L-carnitine, might help slow down the progression of Alzheimer’s disease, relieve depression related to senility and other forms of dementia, and improve memory in the elderly. But larger and better-designed studies found it didn’ t help at all. People should take carnitine for Alzheimer’s and other forms of dementia only under the supervision of their health care provider.

Kidney Disease and Dialysis

Because the kidneys make carnitine, kidney disease could lead to low levels of carnitine in the body. If you have kidney disease, your health care provider may prescribe carnitine — but you shouldn’ t take it without medical supervision.

Hyperthyroidism

Some research suggests that L-carnitine may help prevent or reduce symptoms of an overactive thyroid, such as insomnia, nervousness, heart palpitations, and tremors. In fact, in one study, a small group of people with hyperthyroidism saw these symptoms improve, and their body temperature become normal, when taking carnitine. But a larger, better-designed clinical trial is needed to see if carnitine really works. In addition, researchers think carnitine may work by blocking the action of thyroid hormone, which could be dangerous for people with low thyroid levels. Don’ t take carnitine for hyperthyroidism without your doctor’ s supervision.

Dietary Sources:

Red meat (particularly lamb) and dairy products are the main food sources of carnitine. It can also be found in fish, poultry, tempeh, wheat, asparagus, avocados, and peanut butter.
Available Forms:

Carnitine is available as a supplement in a variety of forms.

* L-carnitine: the most widely available and least expensive
* Acetyl-L-carnitine: Often used in studies for Alzheimer’s disease and other brain disorders
* Propionyl-L-carnitine: Often used in studies for heart disease and peripheral vascular disease

Avoid D-carnitine supplements. They interfere with the natural form of L-carnitine and may produce unwanted side effects.

In some cases, L-carnitine may be taken by prescription or given intravenously by a health care provider.
How to Take It:

Pediatric

Don’ t give carnitine supplements to a child without your child’s health care provider’s supervision. Your child’s health care provider should first make sure that the child has a carnitine deficiency.

Adult

Recommended doses of L-carnitine vary depending on the health condition being treated. The usual dose is between 1 – 3 g per day.
Precautions:

Because supplements may have side effects or interact with medications, you should take them only under the supervision of a knowledgeable health care provider.

Side effects are generally mild. High doses (5 or more grams per day) may cause diarrhea. Other rare side effects include increased appetite, body odor, and rash.

People with the following conditions should talk to their health care provider before taking carnitine:

* Peripheral vascular disease
* High blood pressure
* Liver disease from alcoholism (cirrhosis)
* Diabetes
* Kidney disease
* History of seizures

Possible Interactions:

If you are being treated with any of the following medications, you should not use carnitine without first talking to your health care provider.

AZT — In a laboratory study, L-carnitine supplements protected muscle tissue against toxic side effects from AZT, a medication used to treat HIV and AIDS. More studies are needed to know whether L-carnitine would have the same effect in people.

Doxorubicin — Treatment with L-carnitine may protect heart cells against the toxic side effects of doxorubicin, a chemotherapy medication used to treat cancer, without making the medication any less effective. Always talk to your oncologist before using any complementary or alternative therapy with chemotherapy.

Isotretinoin (Accutane) — Accutane, a strong medication used for severe acne, can cause liver problems, as measured by a blood test, as well as high cholesterol and muscle pain and weakness. These symptoms are like those seen with carnitine deficiency. Researchers in Greece showed that a large group of people who had side effects from Accutane got better when taking L-carnitine compared to those who took a placebo.

Thyroid hormone — Carnitine may stop thyroid hormone from getting into cells, and theoretically may make thyroid hormone replacement less effective. If you take thyroid replacement hormone, talk to your health care provider before taking carnitine.

Valproic acid (Depakote) — The anti-seizure medication valproic acid may lower blood levels of carnitine. Taking L-carnitine supplements may prevent any deficiency and may also reduce the side effects of valproic acid. However, taking carnitine may increase the risk of seizures in people with a history of seizures.
Alternative Names:

Acetyl-l-carnitine; L-carnitine

thank you and reference
http://www.webmd.com
http://www.vanderbilt.edu
http://www.carnitine.com
http://ods.od.nih.gov
http://www.umm.edu
http://www.nutritional-supplements-health-guide.com
http://www.drweil.com
http://www.naturalremedies.org/l-carnitine

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Fiber

Posted on 23. Dec, 2011 by .

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Fiber became a household word back in 1970s when Dr. Denis Burkitt, a man nicknamed the Fiber Man, and his colleagues made “the fiber hypothesis” that states that fiber can prevent certain diseases. Through their work in Africa, they discovered that diseases that were common in the Western cultures were not common there. These included heart attacks and high blood pressure (cardiovascular diseases), obesity and diabetes (metabolic disorders), intestinal problems (constipation, diverticulosis, diverticulitis, gallstones, appendicitis, hemorrhoids, polyps, and colon cancer), varicose veins and blood clots (deep vein thrombosis). The primary dietary difference was the high intake of fiber and low intake of refined carbohydrates in the African population. Burkitt also noted the emergence of these diseases in the United States and England after 1890 following the introduction of a new milling technique that removed fiber from whole grain flour to produce white flour.

While the exact mechanism by which fiber might prevent these diseases remained unknown, Burkitt made a discovery about the beneficial impact that fiber had on bowel movements and how that related to certain diseases. Burkitt noted that he was able to predict the number of a patient’s hospital visits from the size and frequency of their bowel movements. Those with high intakes of fiber had more frequent and bulky stools and had less illness. Burkitt proposed that fiber’s health benefits stemmed from its ability to increase stool bulk and speed up how quickly stool moves through the colon. Since these findings, controversy remains. A great deal of research has both supported and disputed what Burkitt had discovered.

What is fiber?

Fiber is a substance in plants. Dietary fiber is the kind you eat. It is in fruits, vegetables and grains. It is the part of the plant that your body can’t digest. Yet it is an important part of a healthy diet. It adds bulk to your diet and makes you feel full faster, helping you control your weight. Fiber helps digestion and helps prevent constipation.

You can get fiber from whole grains, beans, nuts, fruits and vegetables. You should add fiber to your diet slowly. Increasing dietary fiber too quickly can lead to gas, bloating and cramps.

A variety of definitions of fiber exist. In an attempt to develop one definition of fiber that everyone can use, the Food and Nutrition Board assembled a panel that came up with the following definitions:

* Dietary fiber consists of nondigestible carbohydrates and lignin that are intrinsic and intact in plants. This includes plant nonstarch polysaccharides (for example, cellulose, pectin, gums, hemicellulose, and fibers contained in oat and wheat bran), oligosaccharides, lignin, and some resistant starch.

* Functional fiber consists of isolated, nondigestible carbohydrates that have beneficial physiological effects in humans. This includes nondigestible plant (for example, resistant starch, pectin, and gums), chitin, chitosan, or commercially produced (for example, resistant starch, polydextrose, inulin, and indigestible dextrins) carbohydrates.

* Total fiber is the sum of dietary fiber and functional fiber. It’s not important to differentiate between which forms of each of these fibers you are getting in your diet. Your total fiber is what matters.

You may also hear fiber referred to as bulk or roughage. Call it what you want, but always remember that fiber is an essential part of everyone’s diet. While fiber does fall under the category of carbohydrates, in comparison, it does not provide the same number of calories, nor is it processed the way that other sources of carbohydrates are.

This difference can be seen among the two categories that fiber is divided into: soluble and insoluble.

* Soluble fiber dissolves in water to form a gel-like substance. Sources of soluble fiber are oats, legumes (beans, peas, and soybeans), apples, bananas, berries, barely, some vegetables, and psylluim.

* Insoluble fiber increases the movement of material through your digestive tract and increases your stool bulk. Sources of insoluble fiber are whole wheat foods, bran, nuts, seeds, and the skin of some fruits and vegetables.

Fiber for weight control

There is some evidence that “bulking up” could lead to slimming down. In a recent study of more than 1700 overweight and obese men and women, those with the highest fiber intake had the greatest weight loss over 24 months. Results from the Continuing Survey of Food Intakes by Individuals (CSFII) from 1994 -1996 also supported the relationship between a high-fiber intake and lower body weight. One of the reasons that fiber may have an impact on body weight is its ability to slow the movement of food through the intestines. The gel-like substance that soluble fibers form when they dissolve in water causes things to swell and move slower in the intestines. This increase in time that foods stay in the intestines has been shown to reduce hunger feelings and overall food intake. It has also been shown to decrease the number of calories that are actually absorbed from the ingested food. One study showed an increase in the number of calories that were excreted in the stools when high-fiber psyllium gum-based crackers were given in comparison to low-fiber crackers. Whenever fewer calories are taken in, or more are excreted, weight loss will generally occur

Fiber for controlling diabetes

A high-fiber diet may be just what the doctor ordered to get your blood sugars under control. Keeping our blood sugars stable is a goal that we would all benefit from. If you don’t have type 2 diabetes, this could be the way to prevent it. If you do have it, this could be the way to keep it under control. The best time to address type 2 diabetes is before it has developed. Research has shown that high-fiber diets can help prevent this form of diabetes. The most recent study on done on overweight and obese men and women without diabetes showed reductions in blood sugar and insulin with the use of a high soluble fiber supplement. A German clinical trial reported that eating fiber-enriched bread for only three days improved insulin sensitivity in overweight and obese women by 8%. If a diet intervention this small can have that great of an impact, you can imagine what years of following a high-fiber diet, filled with vegetables, fruits and whole grains would do. The good news for those with diabetes is that increasing your fiber now can also prevent long-term complications from diabetes. Soluble fiber has been found to produce significant reductions in blood sugar in 33 of 50 studies testing it. In clinical intervention trials ranging from two to 17 weeks, consumption of fiber was shown to decrease insulin requirements in people with type 2 diabetes. If you have ever had to inject yourself with insulin, you can appreciate how much easier and less painful it would be to increase your fiber intake to avoid the need for insulin injections.

Fiber for preventing heart disease

If we were to sit down and have a “heart to heart,” I would tell you that one of the best things that you could do on your own to protect your heart is to follow a high-fiber diet. Numerous studies have produced compelling evidence to support this. In a Harvard study of over 40,000 male health professionals, researchers found that a high total dietary fiber intake was linked to a 40% lower risk of coronary heart disease, compared to a low-fiber intake. Another study of over 31,000 California Seventh-day Adventists found a 44% reduced risk of nonfatal coronary heart disease and an 11% reduced risk of fatal coronary heart disease for those who ate whole wheat bread compared with those who ate white bread. One minor change in their diets provided a protective effect that could save their lives.

Another strong predictor of heart disease is abnormal blood cholesterol, LDL, and/or HDL levels. It appears that soluble fiber reduces the absorption of cholesterol in your intestines by binding with bile (which contains cholesterol) and dietary cholesterol so that the body excretes it. The oat bran and bean fiber intervention trials where dietary fiber supplementation was combined with a low-fat diet shows that reductions in total cholesterol levels ranged from 8-26%. Other studies have shown that 5 to 10 grams of soluble fiber a day decreases LDL cholesterol by about 5%. All of these benefits will occur regardless of changes in dietary fat. In a trial with low fat and low fat plus high fiber groups, the group consuming high fiber exhibited a greater average reduction (13%) in total cholesterol concentration than the low fat (9%) and the usual diet (7%) groups. It seems that you don’t have to change everything to gain something.

Fiber for bowel disorders

“Roughing” up your diet can be the key to healthier bowels. With the introduction of white flour came an increased prevalence of bowel disorders such as diverticulosis, diverticulitis, hemorrhoids, polyps, colon cancer, and irritable bowel syndrome (IBS). In Burkitt’s early research into this phenomenon, he made reference to the fact that the typical African stool specimen was large and soft, and that stool transit times were rapid, compared to the puny hard fecal deposits and slow transit times of Europeans. In one of his studies, they conducted elaborate experiments in which volunteers in England, India, and Africa had their bowel movements timed and their stools weighed. Among the results of the study: People living under primitive conditions, on diets high in insoluble fibers, passed from 2½ to 4½ times as much feces as sailors in the Royal Navy, and were relatively free of many of the diseases studied. Current research supports the early findings. Studies have shown that a high-fiber diet (particularly fruit and vegetable fiber) help to prevent diverticulosis and will decrease the risk of complications if you have it. Although the mechanism by which fiber may be protective against diverticulosis is unknown, several hypotheses have been proposed.

For example, some scientists report that fiber helps by decreasing transit time, increasing stool weight, and decreasing pressure within the colon. The same has been found for irritable bowel syndrome (IBS). The current guidelines for the treatment of IBS include following a high fiber diet. The bulk that fiber provides is thought to help prevent the painful spasms often associated with IBS and aid in comfortable regularity. There is still a great deal of debate about the role of fiber in preventing colon cancer. The studies that look for connections with people’s diets and their health have seen a trend in low-fiber diets and people with colon cancer. The studies that tried to intervene by putting people on high-fiber diets in order to prevent colon cancer or polyps did not find the same protective relationship. Burkitt’s work and a more recent study showed that a daily stool weight greater than 150 grams needs to be achieved for the protective affect against colon cancer. This was not taken into account in many of the studies and may be the reason the protective effect was not found.

Fiber for preventing or treating constipation

Fiber may just be the way to go when constipation is the problem. Although what constitutes constipation is not well established, diets that increase the number of bowel movements per day, improve the ease with which a stool is passed, or increase stool bulk are considered beneficial. Both soluble and insoluble fibers are necessary for regular bowel movements. Oftentimes, people use over-the-counter supplements to assist with regularity. Unfortunately, these supplements only provide soluble fiber. Studies support the benefits of the combination of soluble and insoluble fiber in alleviating constipation, but only with the consumption of an adequate fluid intake. High amounts of fiber, without fluids, can aggravate, rather then alleviate constipation. The way to go is to eat foods high in both soluble and insoluble fibers and drink lots of water to flush it down.

A high-fiber diet has many benefits, which include:

* Helps maintain bowel integrity and health. A high-fiber diet may lower your risk of developing hemorrhoids, and small pouches in your colon (diverticular disease). Some fiber is fermented in the colon. Researchers are looking at how this may play a role in preventing diseases of the colon.
* Lowers blood cholesterol levels. Soluble fiber found in beans, oats, flaxseed and oat bran may help lower total blood cholesterol levels by lowering low-density lipoprotein, or “bad,” cholesterol levels. Epidemiologic studies have shown that increased fiber in the diet can reduce blood pressure and inflammation, which is also protective to heart health.
* Helps control blood sugar levels. Fiber, particularly soluble fiber, can slow the absorption of sugar, which for people with diabetes can help improve blood sugar levels. A diet that includes insoluble fiber has been associated with a reduced risk of developing type 2 diabetes.
* Aids in weight loss. High-fiber foods generally require more chewing time, which gives your body time to register when you’re no longer hungry, so you’re less likely to overeat. Also, a high-fiber diet tends to make a meal feel larger and linger longer, so you stay full for a greater amount of time. And high-fiber diets also tend to be less “energy dense,” which means they have fewer calories for the same volume of food.
* Uncertain effect on colorectal cancer. Evidence that dietary fiber reduces colorectal cancer is mixed — some studies show benefit, some show nothing and some suggest increased risk. If you’re concerned about preventing colorectal cancer, adopt or stick with a colon cancer screening regimen. Regular testing for and removal of colon polyps can prevent colon cancer.

How Much Fiber?

The average American consumes 14 grams of dietary fiber a day, which is considerably less than the recommended level. The 2005 Dietary Guidelines for Americans recommends 14 grams of fiber per 1000 calories consumed. So, if you consume a 2,500 calorie diet, you should eat approximately 35 grams of fiber per day. Also, fiber intake may vary depending on age and gender.

While the 2005 Dietary Guidelines for Americans serves as a general guide to healthy eating, the Dietary Reference Intakes (DRIs) provide standard recommended amounts for nutrients. In 2002, the Food and Nutrition Board of the National Academy of Sciences Research Council issued DRIs for fiber (see Table 1). Previously, no national standardized recommendation existed. The new DRIs represent desirable intake levels established using the most recent scientific evidence available.
Table 2: Dietary Reference Intakes (DRI) for Fiber.

Age g/day Fiber

Children
1-3 years 19
4-8 years 25

Males
9-13 years 31
14-18 years 38
19-50 years 38
51+ years 30

Females
9-13 years 26
14-18 years 26
19-50 years 25
51+ years 21

Pregnancy
<18 years 28 18+ years 28 Lactation <18 years 29 18+ years 29 For many people, meeting the DRI for fiber may require changes in their eating habits. Eating several servings of whole grains, fruits, vegetables and dried beans each day is good way to boost fiber intake. Anyone with a chronic disease should consult a physician before greatly altering a diet. If you are not used to eating high fiber foods regularly, these changes should be made gradually to avoid problems with gas and diarrhea. Also, drink plenty of water to minimize intestinal gas. If problems with gas continue to be an issue, gas-reducing over-the-counter and prescription drugs are available. How can I get more fiber in my diet? The amount of fiber you should get from your diet each day depends on your age and sex. Men 50 years of age and younger should consume at least 38 grams of fiber per day, while men older than 50 years of age should aim for at least 30 grams of fiber daily. Women 50 years of age and younger should consume at least 25 grams of fiber per day, while women older than 50 years of age should aim for at least 21 grams of fiber daily. Try the following ideas to increase the fiber in your diet: * Eat at least 2 cups of fruits and 2 1/2 cups of vegetables each day. Fruits and vegetables that are high in fiber include: o Beans such as: + navy (1/2 cup = 9.5 grams), + kidney (1/2 cup = 8.2 grams), + pinto (1/2 cup = 7.7 grams), + black (1/2 cup = 7.5), + lima (1/2 = 6.6 grams), + white (1/2 cup = 6.3 grams) + great northern (1/2 cup = 6.2 grams). o Artichokes (1 artichoke = 6.5 grams) o Sweet potatoes (1 medium sweet potato = 4.8 grams) o Pears (I small pear = 4.4 grams) o Green peas (1/2 cup = 4.4 grams) o Berries such as raspberries (1/2 cup = 4.0 grams) and blackberries (1/2 cup = 3.8 grams) o Prunes (1/2 cup = 3.8 grams) o Figs and dates (1/4 cup = 3.6 grams) o Spinach (1/2 cup = 3.5 grams) o Apples (1 medium apple = 3.3 grams) o Oranges (I medium orange = 3.1 grams) * Replace refined white bread with whole-grain breads and cereals. Eat brown rice instead of white rice. Eat more of the following foods: o Bran muffins o Oatmeal o Bran or multiple-grain cereals, cooked or dry o Brown rice o Popcorn o 100% whole-wheat bread * When eating store-bought foods, check the nutrition information labels for the amounts of dietary fiber in each product. Aim for 5 grams of fiber per serving. o Add 1/4 cup of wheat bran (miller's bran) to foods such as cooked cereal, applesauce or meat loaf. o Eat beans each week. Start slowly When you first add fiber to your diet you may notice bloating, cramping or gas. But you can prevent this by making smaller changes in your diet over a period of time. Start with one of the changes listed above, then wait several days to a week before making another. If one change doesn't seem to work for you, try a different one. Be sure to drink more fluids when you increase the amount of fiber you eat. Liquids help your body digest fiber. Try to drink 8 glasses of no- or low-calorie beverages, such as water, unsweetened tea or diet soda each day. thank you and references http://www.ext.colostate.edu http://www.mayoclinic.com http://www.nlm.nih.gov http://www.medicinenet.com http://familydoctor.org http://www.whfoods.com http://www.webmd.com

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Vitamin K

Posted on 27. Dec, 2010 by .

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Vitamin K is a fat-soluble vitamin, so it is stored in the body’s fat tissue and liver. It is best known for its role in helping blood clot (coagulate) properly (the “K” comes from its German name, Koagulationsvitamin). Vitamin K is known as the clotting vitamin, because without it blood would not clot.Vitamin K also plays an important role in bone health.

It is rare to have a vitamin K deficiency, because in addition to being found in leafy green foods, the bacteria that are found in the intestines can make vitamin K. Sometimes taking antibiotics can kill the bacteria and lead to a mild deficiency. Vitamin K deficiency can lead to excessive bleeding (hemorrhage), which may begin as oozing from the gums or nose. Other circumstances that may lead to vitamin K deficiency include:

* Health problems that can prevent the absorption of vitamin K (such as gallbladder or biliary disease, which may alter the absorption of fat), cystic fibrosis, celiac disease, and Crohn’s disease
* Liver disease
* Use of blood-thinning medications (such as warfarin)
* Continuing hemodialysis
* Serious burns

Other conditions that benefit from vitamin K include:

Excessive Bleeding

Vitamin K is used to reduce the risk of bleeding in liver disease, malabsorption syndromes, or in association with long-term use of antibiotics.

In the U.S., Canada, Great Britain, and many other countries, all newborns receive vitamin K injections to prevent the possibility of hemorrhage (particularly in the brain) just after delivery. Babies are born without any bacteria in their intestines and do not get enough vitamin K from breast milk to tide them over until their bodies are able to make it. (However, if a mother eats lots of green vegetables on a daily basis, she can improve the amount of vitamin K in breast milk.) Even though vitamin K deficiency in newborns is very rare, it is dangerous enough to warrant these measures. Newborns at greatest risk for vitamin K deficiency are those who are born prematurely or whose mother had to take seizure medications during pregnancy. Mothers on seizure medications are often given oral vitamin K for 2 weeks prior to delivery.

Osteoporosis

Vitamin K is needed for proper use of calcium in bones. Higher vitamin K levels correspond to greater bone density, while low levels of vitamin K have been found in those with osteoporosis. There is increasing evidence that vitamin K improves bone health and reduces risk of bone fractures, particularly in postmenopausal women who are at risk for osteoporosis. In addition, studies of other groups (such as male and female athletes) have also shown bone enhancing benefits from vitamin K supplements.

Dietary Sources:

Foods that contain a significant amount of vitamin K include beef liver, green tea,soybeans, turnip greens, broccoli, kale, spinach, cauliflower,cabbage, asparagus, and dark green lettuce. Chlorophyll is the substance in plants that gives them their green color and provides vitamin K.Vitamin K is also made by the bacteria that line the gastrointestinal tract

Freezing foods may destroy vitamin K, but heating does not affect it.
Available Forms:

There are 3 forms of vitamin K:

* Vitamin K1 (phylloquinone, the natural version of K1 and phytonadione, the synthetic type of K1)
* Vitamin K2 (menaquinone)
* Vitamin K3 (menaphthone or menadione)

K1 and K3 are both available as part of multivitamin complexes or alone, in 5 mg tablets. These fat-soluble forms are an excellent source of vitamin K.

Water-soluble chlorophyll is the most common form of vitamin K found over the counter. It is available in tablet, capsule, and liquid forms.
How to Take It:

As with all supplements, check with a health care provider before taking vitamin K or giving it to a child.

People with vitamin K deficiencies related to malabsorption (such as gallbladder or biliary disease, cystic fibrosis, celiac disease, and Crohn’s disease) will benefit most from a multivitamin containing vitamin K, rather than an individual vitamin K supplement. In certain circumstances, your doctor may administer vitamin K by injection.

Daily intake for dietary vitamin K (according to the U.S. RDA) are listed below:

Pediatric

* Infants birth – 6 months: 2 mcg
* Infants 7 – 12 months: 2.5 mcg
* Children 1 – 3 years: 30 mcg
* Children 4 – 8 years: 55 mcg
* Children 9 – 13 years: 60 mcg
* Adolescents 14 – 18 years: 75 mcg

A single injection of vitamin K is also given at birth.

Adult

* Males 19 years and older: 120 mcg
* Females 19 years and older: 90 mcg
* Pregnant and breastfeeding females 14 – 18 years: 75 mcg
* Pregnant and breastfeeding females 19 years and older: 90 mcg

Precautions:

Because of the potential for side effects and interactions with medications, you should take dietary supplements only under the supervision of a knowledgeable health care provider.

At recommended doses, vitamin K has few side effects.

Vitamin K crosses the placenta and is also excreted in breast milk. Therefore, pregnant women and women who are breastfeeding should talk to their doctor before taking vitamin K supplements.

People with an rare metabolic condition called Glucose-6-phosphate dehydrogenase (G6PD) deficiency should avoid vitamin K.
Possible Interactions:

If you are currently being treated with any of the following medications, you should not take vitamin K without first talking to your health care provider.

Antibiotics — Antibiotics, particularly a class known as cephalosporins, reduce the absorption of vitamin K in the body. Long-term use (more than 10 days) of antibiotics may result in vitamin K deficiency because these drugs kill not only harmful bacteria but also beneficial, vitamin K-activating bacteria. This is not likely to occur in people who already have low levels of vitamin K or are at risk for deficiency (such as those who are malnourished, elderly, or taking warfarin). Cephalosporins include:

* Cefamandole (Mandol)
* Cefoperazone (Cefobid)
* Cefmetazole (Zefazone)
* Cefotetan (Cefotan)

Phenytoin (Dilantin) — Phenytoin interferes with the body’s ability to use vitamin K. Taking anticonvulsants (such as phenytoin) during pregnancy or while breastfeeding may deplete vitamin K in newborns.

Warfarin (Coumadin) — Vitamin K reduces the effects of the blood thinning medication warfarin, rendering the medication ineffective. You should not take vitamin K, or eat foods containing high amounts of vitamin K, while you are taking warfarin.

Orlistat (Xenical, Alli) and Olestra — Orlistat, a medication used for weight loss, and olestra, a substance added to certain food products, prevent the absorption of fat and can reduce the body’s absorption of fat-soluble vitamins. The Food and Drug Administration now requires that vitamin K and other fat-soluble vitamins (A, D, and E) be added to food products containing olestra. In addition, physicians who prescribe orlistat add a multivitamin with fat soluble vitamins to the regimen.

The fact that vitamin K is now added to olestra-containing foods is important to know if you should not be taking vitamin K (if you are on the blood thinner warfarin, for example).

Bile acid sequestrants — These medications, used to reduce cholesterol, reduce the overall absorption of dietary fats and may also reduce absorption of fat-soluble vitamins. If you take one of these drugs, your doctor may recommend a vitamin K supplement:

* Cholestyramine (Questran)
* Colestipol (Colestid)
* Colsevelam (Welchol)

How Vitamin K Deficiencies Occur

Human intake of vitamin K comes from two main sources – our diets and synthesis from intestinal bacteria. Vitamin K deficiencies can be caused by a variety of factors. These include:

* Not consuming enough vitamin K from one’s diet can contribute to a deficiency. Dietary vitamin K is highest in leafy green vegetables such as lettuce, kale, broccoli and collard greens. These are foods that many people don’t eat frequently.

* A diet with high intakes of salicylates can block vitamin K. Salicylates are found in foods such as nuts, fruits, spices and mints. Aspirin is a salicylate. Blocking vitamin K is why aspirin can “thin” the blood – it basically keeps blood from coagulating. This is why too much aspirin may be a factor in bleding related health issues such as epistaxis (nose bleeds), as well as brain and intestinal bleeding.
* Antibiotics can cause bleeding problems from vitamin K deficiencies. Antibiotics destroy not only harmful digestive tract bacteria, but also the beneficial intestinal bacteria that is needed to create vitamin K. In order to replace the beneficial intestinal bacteria after a course of antibiotics it is often recommended to eat yogurt with active cultures or have to take probiotic supplements containing acidophilus. In the U.S. You can usually get the supplements at most drug stores or health food stores. The refrigerated kind is often best because the cultures last the longest when they have been kept cold.

Replacing beneficial bacteria after antibiotics is standard conventional medical advice in many European countries, but does not seem to be common medical advice in the United States.

*Candida (systemic yeast) infections have been linked to vitamin K deficiencies. An overgrowth of candida albicans or other kinds of yeast can crowd out the helpful bacteria in the digestive tract that make vitamin K. People who eat a lot of sugary foods, an unusually high proportion of alkaline foods and/or take antibiotics tend to be at high risk for Candida infections.

*Malabsorption syndromes that prevent the proper absorption of nutrients can cause vitamin K deficiencies. Celiac disease, an intolerance to gluten, can cause deficiencies of a wide variety of nutrients, especially vitamin K. Crohn’s disease can also cause vitamin K and other deficiencies.

*Anticoagulants like Warfarin block the action of vitamin K. In turn, vitamin K blocks the action of anticoagulants. This is why people taking these types of medications have to limit how much vitamin K they get in their diet.

*High amounts of vitamin A and/or vitamin E can also block vitamin K. I get nosebleeds whenever I take a multivitamin or eat one of the popular nutrition bars, even if I choose one with vitamin K. I think it may be at least in part because the multivitamins and nutrition bars always contain high amounts of vitamin A and E–probably too much for someone like me who bleeds easily.

*The bacteria that synthesize vitamin K thrive in an acidic digestive environment. Antacids, if taken in sufficient quantity, may cause a vitamin K deficiency, as well as irritable bowel syndrome and various nutritional deficiencies, because they neutralize the hydrochloric acid in a person’s stomach. Hydrochloric acid is needed to digest food and create the acidic environment in which the beneficial bacteria thrive.

(For more information on this topic, see my section on Acidic Foods – Alkaline Foods.

*One study found vitamin K deficiencies to be common in male alcoholics. (Perhaps not coincidentally, children born with fetal alcohol syndrome share many overlapping borth defects linked to vitamin K deficiencies.)

*In rats, butylated hydroxytoluene (BHT), a food preservative, was shown in tests to induce vitamin K deficiencies. BHT is a common preservative. Many commercial cereal boxes are sprayed with BHT to extend the shelf life of the product.

Regular aspirin use may raise the risk of bleeding strokes in healthy people. A study from Oxford University found that large numbers of older people suffered from bleeding in the brain when they took aspirin or other antithrombotic drugs. Another study from the Wolfson Institute of Preventive Medicine in London found that aspirin use caused a risk of serious bleeding in men with high blood pressure.

Alternative Names:

Menadione; Menaphthone; Menaquinone; Phylloquinone

thank you and references

http://www.umm.edu
http://www.nlm.nih.gov/medlineplus/ency/article/002407.htm
http://www.ctds.info/vitamink.html

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vitamin C

Posted on 12. Nov, 2010 by .

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Vitamin C is an antioxidant. Antioxidants are substances that may protect your cells against the effects of free radicals. Free radicals are molecules produced when your body breaks down food, or by environmental exposures like tobacco smoke and radiation. Vitamin C is important for your skin, bones, and connective tissue. It promotes healing and helps the body absorb iron.

Vitamin C comes from fruits and vegetables. Good sources include citrus, red and green peppers, tomatoes, broccoli, and greens. Some juices and cereals have added vitamin C.

Some people may need extra vitamin C:

* Pregnant/breastfeeding women
* Smokers
* People recovering from surgery
* Burn victims

Vitamin C (ascorbic acid) is a water-soluble vitamin, which is necessary in the body to form collagen in bones, cartilage, muscle, and blood vessels and aids in the absorption of iron. Dietary sources of vitamin C include fruits and vegetables, particularly citrus fruits such as oranges.

Severe deficiency of vitamin C causes scurvy. Although rare, scurvy includes potentially severe consequences, and can cause sudden death. Patients with scurvy are treated with vitamin C and should be under medical supervision.

Many uses for vitamin C have been proposed, but few have been found to be beneficial in scientific studies. In particular, research in asthma, cancer, and diabetes remains inconclusive, and no benefits have been found in the prevention of cataracts or heart disease.

The use of vitamin C in the prevention/treatment of the common cold and respiratory infections remains controversial, with ongoing research. For cold prevention , more than 30 clinical trials including over 10,000 participants have examined the effects of taking daily vitamin C. Overall, no significant reduction in the risk of developing colds has been observed. In people who developed colds while taking vitamin C, no difference in severity of symptoms has been seen overall, although a very small significant reduction in the duration of colds has been reported (approximately 10% in adults and 15% in children). Notably, a subset of studies in people living in extreme circumstances, including soldiers in sub-arctic exercises, skiers, and marathon runners, have found a significant reduction in the risk of developing a cold by approximately 50%. This area merits additional study and may be of particular interest to elite athletes or military personnel.

For cold treatment , numerous studies have examined the effects of starting vitamin C after the onset of cold symptoms. So far, no significant benefits have been observed.

references and thank you

http://www.mayoclinic.com/health/vitamin-c/NS_patient-vitaminc
http://www.nlm.nih.gov/medlineplus/vitaminc.html

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vitamin A

Posted on 02. Nov, 2010 by .

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Vitamin A, also called retinol, helps your eyes adjust to light changes when you come in from outside and also helps keep your eyes, skin and mucous membranes moist. Vitamin A mostly comes from animal foods, but some plant-based foods supply beta-carotene, which your body then converts into Vitamin A. It also has antioxidant properties that neutralize free radicals in the body that cause tissue and cellular damage. Early information from scientific studies suggests that beta-carotene might help people who already have Coronary Artery Disease (CAD) (ref1) If you’re pregnant, you should avoid eating liver because of the amount of vitamin A it contains. (ref. 2)

Sources of Vitamin A

Top sources of vitamin A include:

• Beef liver

• Egg yolk

• Cheddar cheese

• Fortified milk

Top sources of beta-carotene include:

• Sweet potato

• Carrots

• Pumpkin

• Cantaloupe

• Broccoli

• Apricots

• Spinach and collard greens

Can You Have Too Much or Too Little?

Vitamin A deficiency is rare in the United States, but it can cause night blindness, eye inflammation, diarrhea and other problems. Overconsumption of vitamin A can cause nausea, irritability and blurred vision in its mild form. In addition, the palms of the hands and the bottoms of the feet can turn orange if a person has a high intake of Vitamin A. Vitamin A toxicity can cause growth retardation, hair loss and enlarged spleen and liver in its more severe form. Vitamin A overdose can also cause birth defects and has been linked to increased risk of bone fractures in some people.

Vitamin Storage

If you want to get the most vitamins possible from your food, refrigerate fresh produce, and keep milk and grains away from strong light. Vitamins are easily destroyed and washed out during food preparation and storage. If you take vitamin supplements, store them at room temperature in a dry place that’s free of moisture.(ref. 2)

Recommendations

The best way to get the daily requirement of essential vitamins is to eat a balanced diet that contains a variety of foods from the food guide pyramid.

The Food and Nutrition Board at the Institute of Medicine recommends the following:

Infants

  • 0 – 6 months: 400 micrograms per day (mcg/day)
  • 7 – 12 months: 500 mcg/day

Children

  • 1 – 3 years: 300 mcg/day
  • 4 – 8 years: 400 mcg/day
  • 9 – 13 years: 600 mcg/day

Adolescents and Adults

  • Males age 14 and older: 900 mcg/day
  • Females age 14 and older: 700 mcg/day

Specific recommendations depend on age, gender, and other factors (such as pregnancy). Women who are pregnant or producing breast milk (lactating) need higher amounts. Ask your doctor what dose is best for you.(ref.3)

references and thank you

1 http://www.eatwell.gov.uk/healthydiet/nutritionessentials/vitaminsandminerals/vitamina/

2 http://www.lifeclinic.com/focus/nutrition/vitamin-a.asp

3http://www.nlm.nih.gov/medlineplus/ency/article/002400.htm

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