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Vitamins & Supplements
Vitamins & Supplements Articles
Vitamin B12 is needed to produce an adequate amount of healthy red blood cells in the bone marrow. Vitamin B12 is available only in animal foods (meat and dairy products) or yeast extracts (such as brewer's yeast). Vitamin B12 deficiency is defined by low levels of stored B12 in the body that can result in anemia, a lower-than-normal number of red blood cells.
Vitamin B12 deficiency can develop for the following reasons:
Absence of intrinsic factor, also called pernicious anemia — Intrinsic factor is a protein secreted by cells of the stomach lining. Intrinsic factor attaches to vitamin B12 and takes it to the intestines to be absorbed. An absence of intrinsic factor is the most common cause of pernicious anemia. Absent intrinsic factor is often associated with a condition called atrophic gastritis, a thinning of the lining of the stomach. Atrophic gastritis is more common in elderly people of African-American or Northern-European descent. In these people, pernicious anemia develops at about age 60.
In children, decreased levels of intrinsic factor can be an inherited (genetic) condition. When this happens, low levels of intrinsic factor produce symptoms of juvenile pernicious anemia in patients younger than age 10.
Pernicious anemia occurs more commonly in people who already have diseases that are linked to immune-system abnormalities, such as Graves' disease, hypothyroidism (under-functioning thyroid gland), thyroiditis (inflammation of the thyroid), vitiligo and Addison's disease (adrenocortical insufficiency).
Tropical sprue is a digestive problem that occurs in the tropics and subtropics. People with tropical sprue do not absorb nutrients properly, especially vitamin B12 and folic acid.
Normal small intestines have fingerlike projections called villi that provide more surface area for nutrients to be absorbed. In people with tropical sprue, these villi are flattened, making absorption difficult.
Tropical sprue is rare except in a specific geographical zone. It occurs from about 30 degrees north of the equator to 30 degrees south of it. It is more common in certain countries within this tropical area, including India, Southeast Asian countries, Haiti, Cuba, Puerto Rico and the Dominican Republic. The condition afflicts residents of the affected countries as well as travelers, though usually it affects only travelers who stay for a month or longer.
The cause of tropical sprue has not been identified, but many experts suspect that an intestinal infection is to blame. When tropical sprue occurs, the lining of the small intestine is damaged so that it is unable to absorb nutrients efficiently.
Bacteria have a reputation for causing disease, so the idea of tossing down a few billion a day for your health might seem — literally and figuratively — hard to swallow. But a growing body of scientific evidence suggests that you can treat and even prevent some illnesses with foods and supplements containing certain kinds of live bacteria. Northern Europeans consume a lot of these beneficial microorganisms, called probiotics (from pro and biota, meaning "for life"), because of their tradition of eating foods fermented with bacteria, such as yogurt. Probiotic-laced beverages are also big business in Japan.
Some digestive disease specialists are recommending probiotic supplements for disorders that frustrate conventional medicine, such as irritable bowel syndrome. Since the mid-1990s, clinical studies suggest that probiotic therapy can help treat several gastrointestinal ills, delay the development of allergies in children, and treat and prevent vaginal and urinary infections in women.
When it comes to fighting high blood pressure, the average American diet delivers too much sodium and too little potassium. Eating to reverse this imbalance could prevent or control high blood pressure and translate into fewer heart attacks, strokes, and deaths from heart disease.
Normal body levels of potassium are important for muscle function. Potassium relaxes the walls of the blood vessels, lowering blood pressure and protecting against muscle cramping. A number of studies have shown an association between low potassium intake and increased blood pressure and higher risk of stroke. On the flip side, people who already have high blood pressure can significantly lower their systolic (top number) blood pressure by increasing their potassium intake when they choose to eat healthy foods.
Most Americans get barely half of the recommended amount of potassium — 4,700 milligrams (mg) a day. Fruits, vegetables, beans, and some seeds offer good ways to get more of it. Bananas (about 425 mg of potassium in a medium-sized one) are often held up as the poster child for potassium, but there are better sources.
By now, nearly everyone has heard of the health benefits of the omega-3 fats found in fish. The most persuasive studies show that they protect against the serious — and sometimes fatal — episodes of an irregular heart rhythm that can cause sudden death. Other research indicates that a diet rich in omega-3 fats may lower your risk for heart attack and stroke.
Farm-raised salmon is one of the better sources of omega-3s. A 6-ounce serving contains about 3½ grams which is much more than in other popular fish. There's no straight answer to whether farm-raised or wild salmon has more omega-3 fat—it depends on what they eat. Today about half of the salmon sold worldwide comes from fish farms.
Polychlorinated biphenyls (PCBs) are oily, synthetic chemicals that were used in electrical equipment and as additives to paint, plastics, and other products. Unfortunately, they're now found in today's farm-raised salmon. The federal government ordered industry to stop making them in the 1970s, but they still get freshly released into the environment from hazardous waste sites, leaks from old equipment, and incinerators. PCBs also stick to soil and sediment and can travel long distances through the air. They also "bioaccumulate" in fat, so concentrations tend to be higher in animals — like salmon and marine mammals like seals — that are further up the food chain. High doses kill fish, and PCBs have been linked to reproductive and immunological problems in several species of wildlife.
In December 2003, the U.S. Food and Drug Administration announced it was banning the sale of products containing ephedra. This announcement heralded the first time the agency has banned an herbal supplement. Its decision was based on extensive research involving more than 16,000 reports of adverse health effects from products containing ephedra. These studies clearly indicate that ephedra is dangerous. And it can kill. Roughly 155 deaths have been blamed on the amphetamine-like stimulant, including the 2003 death of 23-year-old Baltimore Orioles pitcher Steve Bechler.
Ephedra occurs naturally in the Chinese herb ma huang and contains ephedrine and pseudoephedrine, stimulants that can constrict blood vessels. In low doses, they act as decongestants, but in higher doses, they can raise blood pressure. The stimulant effect contributes to the herb's effectiveness as an appetite suppressant, especially when combined with caffeine, aspirin, or both. Its claims for promoting weight loss as well as for increasing energy and alertness led athletes and average gym goers alike to take ephedra products.
A variety of studies associate ephedra use with cardiovascular problems, including high blood pressure, palpitations, and heart attacks. Side effects of the herb include heart palpitations, nausea, and vomiting. More than 800 dangerous reactions have been reported - among them, heart attacks, strokes, seizures, and sudden death. Psychosis, insomnia, and heatstroke have also been reported.
After the death of Baltimore Orioles pitcher Steve Bechler more than 10 years ago, many questions arose about the safety of ephedra and the government's role in regulating the herb. Bechler died of heat stroke while taking ephedra, which occurs naturally in the Chinese herb ma huang. The speed-like drug contains the chemical ephedrine, an amphetamine-like compound closely related to adrenaline. Athletes and average people alike started taking ephedra when word started spreading about its ability to aid weight loss and increase energy and alertness.
But just because a supplement comes from natural sources doesn't make it safe. Ephedra can cause a quickened heartbeat and elevated blood pressure. Side effects include heart palpitations, nausea, and vomiting. More than 800 dangerous reactions have been reported with use of the herb. These include heart attacks, strokes, seizures, and sudden deaths. According to a study in the Annals of Internal Medicine, ephedra products make up only 1% of herbal supplement sales in the U.S., but they are responsible for 62% of herb-related reports to poison-control centers.
The authors of one analysis concluded that supplements containing ephedra and ephedrine trigger modest short-term weight loss (about 2 pounds per month more than placebo). But none of the 52 trials they looked at lasted more than six months, so there is no evidence to support ephedra use for long-term weight loss. And no studies were found that evaluated ephedra use for enhancing athletic performance. Data from 50 trials did show, however, that ephedra and ephedrine are associated with 2- to 3-fold increases in psychiatric symptoms (such as irritability and anxiety), autonomic symptoms (jitteriness, trouble sleeping), upset stomach, and heart palpitations.
In the mid-1990s, doctors at a clinic in Belgium treated 43 patients with end-stage kidney failure, requiring dialysis or transplant. Not surprisingly, these individuals had something in common in their medical histories. Between 1990 and 1992, each had used a Chinese herbal remedy in combination with two other drugs for weight loss. The herbal preparation supposedly contained Stephania tetrandra and Magnolia officinalis. But the sudden appearance of kidney failure in these patients, caused their doctors to suspect that the herb Aristolochia fangchi, which is poisonous to the kidneys, had unintentionally been substituted for S. tetrandra. The Chinese names for A. fangchi and S. tetrandra sound similar and the two are often confused. Analysis showed that the herbal remedy did, in fact, contain aristolochic acids, which are derived from A. fangchi. Aristolochic acids cause cancer in rats and mutations in bacteria and mammals.Reports of patients who had developed urothelial carcinoma (cancer of the tissues lining the bladder, ureter, and part of the kidney), as well as kidney failure related to the Chinese herbs, drew concern among the Belgian doctors. When one of their patients also developed this cancer, the doctors decided that all patients with end-stage kidney failure related to the use of Chinese herbs should be checked for cancer of these organs. By removing these organs, the doctors hoped to prevent cancer from developing in their patients. Thirty-nine of the 43 patients agreed to undergo the preventive surgery. Of these patients, 46% of them already had cancerous growths in the removed tissues. In addition, 19 of the remaining 21 patients had abnormal growths in the urinary system. The investigators also analyzed DNA samples taken from the kidneys and ureters of each patient. The DNA samples for every patient showed changes typically found after exposure to aristolochic acid. The researchers compared these results to analysis of DNA samples taken from eight patients with end-stage kidney failure unrelated to Chinese herbs. None of these control samples showed DNA changes formed by aristolochic acid.The doctors calculated the cumulative dose of the implicated herb and other treatments for each patient. They found that the risk of cancer was related to the cumulative dose of A. fangchi. Because many of the patients had also taken appetite suppressants as well as a diuretic, the doctors noted that these drugs might enhance the toxicity of aristolochic acid.This case study provides strong evidence suggesting a relationship between the Chinese herb A. fangchi and urothelial carcinoma. While a manufacturing mistake led to the introduction of this herb into an herbal preparation for weight loss, this study highlights the risks involved in taking herbal remedies. There is little control over the quality of herbal medicines. This means that the label on an herbal medicine may not accurately represent what is actually in the container, as was the case with S. tetrandra. Several countries have banned the use of herbs that contain aristolochic acid, yet Aristolochia is readily available in the United States in capsule form.In the United States, the FDA does not have the authority to assess the safety and efficacy of a dietary supplement before it reaches the shelves of stores. The agency is allowed to restrict a supplement only after it proves the substance is harmful as commonly consumed, but there is no adequate system for reporting serious side effects associated with these products. Furthermore, the FDA does not have any way of knowing which herbal remedies contain harmful substances such as aristolochic acid. The case of the Chinese herbal diet pill and its association with urothelial cancer is just one of a number of cases that demonstrate the need for greater oversight of dietary supplements and caution in the use of supplements on the part of consumers.