Vitamins Debunked

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Transcript of Vitamins Debunked

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Vitamin C megadosage

Consuming Vitamin C in doses well beyond the current Dietary Reference Intake

The WHO recommends a daily intake of 45 mg/day of vitamin C for healthy adults

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Side effect

Diarrhea◦Tolerable upper limit – 2g/d

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Uses of Vit C

Production of collagenPrevention of scurvyAntioxidantIn alternative medicine: commn cold,

cancer, polio

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Vitamin C and the common cold

200 mg to 2 grams per day ◦Reduces the duration, but not the incidence, of

the common cold by 8% for adults and 14% for children

◦Reduces the incidence by 50%in stressed adults, such as soldiers or athletes, in extreme cold environments

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Cochrane Review recommendation

Routine prophylaxis is not justifiedVitamin C could be useful for people exposed

to brief periods of severe physical exercise

◦While the prophylaxis trials have consistently shown that vitamin C reduces the duration and alleviates the symptoms of colds, this was not replicated in the few therapeutic trials that have been carried out. Further therapeutic RCTs are warranted.

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Vitamin C and heart disease

Clinical trials investigating the use of vitamin C in the prevention of coronary disease or strokes have produced equivocal results, with positive, negative and neutral outcomes. Issues with methodology, patient selection and study design make the results of the studies difficult to interpret.[10]

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Cancer

"we have to conclude that we still do not know whether Vitamin C has any clinically significant antitumor activity. Nor do we know which histological types of cancers, if any, are susceptible to this agent. Finally, we don't know what the recommended dose of Vitamin C is, if there is indeed such a dose, that can produce an anti-tumor response."

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Gout

In 2008, researchers established that higher vitamin C intake (diet or supplements) reduces serum uric acid levels and is associated with lower incidence of gout. The relative risk of gout was 45% lower for intakes of over 1500 mg/d.[23]

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While being harmless in most typical quantities, as with all substances to which the human body is exposed, vitamin C can still cause harm under certain conditions. In the medical community, these are known as contraindications.

As vitamin C enhances iron absorption for iron deficiency, iron overload may become an issue to people with rare iron-overload conditions, such as Beta (β) thalassemias and hemochromatosis.[citation needed]

A genetic condition that results in inadequate levels of the enzyme glucose-6-phosphate dehydrogenase (G6PD) can cause sufferers to develop hemolytic anemia after ingesting specific oxidizing substances (favism), such as very large dosages of vitamin C. Common, inexpensive tests exist to determine G6PD deficiency.[citation needed]

There is a longstanding belief among the mainstream medical community that vitamin C causes kidney stones, which seems based little on science.[28] Although some individual recent studies have found a relationship,[29] there is no clear relationship between excess ascorbic acid intake and kidney stone formation.[30]

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Side effects Blood levels of vitamin C remain steady at approximately 200 mg per

day. Although vitamin C can be well tolerated at doses well above the RDA recommendations, adverse effects can occur at doses above 3 grams per day though overload is unlikely. The common 'threshold' side effect of megadoses is diarrhea. Other possible adverse effects include increased oxalate excretion and kidney stones, increased uric acid excretion, systemic conditioning ("rebound scurvy"), preoxidant effects, iron overload, reduced absorption of vitamin B12 and copper, increased oxygen demand and acid erosion of the teeth.[31] In addition, one case has been noted of a woman who had received a kidney transplant followed by high-dose vitamin C and died soon afterwards as a result of calcium oxalate deposits that destroyed her new kidney. Her doctors concluded that high-dose vitamin C therapy should be avoided in patients with renal failure.[32]

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Conflicts with prescription drugs Pharmaceuticals designed to reduce stomach acid, such as

the proton pump inhibitors (PPIs), are among the most widely-sold drugs in the world. One PPI, omeprazole (Prilosec), has been found to lower the bioavailability of vitamin C by 12% after 28 days of treatment, independent of dietary intake. The probable mechanism of vitamin C reduction, intragastric pH elevated into alkalinity, would apply to all other PPI drugs, though not necessarily to doses of PPIs low enough to keep the stomach slightly acidic.[34] In another study, 40 mg/day of omeprazole lowered the fasting gastric vitamin C levels from 3.8 to 0.7 microg/mL.[35]

Aspirin may also inhibit the absorption of vitamin C.[36][37][38]

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In April 1998 the journal Nature reported pro-oxidant effects of excessive doses of vitamin C / ascorbic acid in healthy human volunteers.

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In June 2004, Duke University researchers reported an increased susceptibility to osteoarthritis in guinea pigs fed a diet high in vitamin C. However, a 2003 study at Umeå University in Sweden, found that "the plasma levels of vitamin C, retinol and uric acid were inversely correlated to variables related to rheumatoid arthritis disease activity."

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A speculated increased risk of kidney stones may be a side effect of taking vitamin C in larger than normal amounts (more than 1 gram). The potential mechanism of action is through the metabolism of vitamin C to dehydroascorbic acid, which is then metabolized to oxalic acid,[44] a known constituent of kidney stones. However, this oxalate issue is still controversial, with evidence being presented for[45] and against[46] the possibility of this side effect

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"Rebound scurvy" is a theoretical, never observed, condition that could occur when daily intake of vitamin C is rapidly reduced from a very large amount to a relatively low amount. Advocates suggest this is an exaggeration of the rebound effect which occurs because ascorbate-dependent enzyme reactions continue for 24–48 hours after intake is lowered, and use up vitamin C which is not being replenished

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Some writers have identified a risk of poor copper absorption from high doses of vitamin C. Ceruloplasmin levels seem specifically lowered by high vitamin C intake. In one study, 600 milligrams of vitamin C daily led to lower ceruloplasmin levels similar to those caused by copper deficiency.[48] In another, ceruloplasmin levels were significantly reduced

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Long term use of high-dose vitamin C supplements may be associated with increased incidence of age-related cataract in older women.

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Many multivitamins are formulated or labeled to differentiate consumer sectors, such as prenatal, children, mature or 50+, men's, women's, diabetic, or stress. Consumer multivitamin formulas are available as tablets, capsules, bulk powder, or liquid

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Modern multivitamin products roughly classify into RDA (recommended dietary allowance) centric multivitamins with or without iron, RDA centric multivitamin/multimineral formulas with or without iron, higher potency formulas with mostly above RDA components with or without iron, and more specialized formulas by condition, such as for diabetics or by less common components, such as diversified antioxidants, herbal extracts, or premium[clarification needed] vitamin and mineral forms

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the United States Food and Drug Administration allows a multivitamin to be called "high potency" if at least two-thirds of its nutrients have at least 100 percent of the DV. In practice, "high potency" usually means substantially increased vitamins C and B, with some other enhanced vitamin and mineral levels, though some minerals may still be much less than DV

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Some components are typically much lower than RDA amounts, often for cost reasons

Sometimes low content composition is for population subgroups, where the RDA would be inappropriate

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Basic commercial multivitamin supplement products often contain the following ingredients: vitamin C, B1, B2, B3, B6, folic acid (B9), B12, B5 (pantothenate), H (biotin), A, E, D3, K1, potassium iodide, cupric (sulfate anhydrous, picolinate, sulfate monohydrate, trioxide), selenomethionine, borate(s), zinc, calcium, magnesium, chromium, manganese, molybdenum, betacarotene, and iron

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Other formulas may include additional ingredients such as other carotenes (e.g. lutein, lycopene), higher than RDA amounts of B, C or E vitamins including gamma-tocopherol, "near" B vitamins (inositol, choline, PABA), trimethylglycine (anhydrous betaine), betaine hydrochloride, vitamin K2 as menaquinone-7, lecithin, citrus bioflavinoids or nutrient forms variously described as more easily absorbed.

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By supplementing the diet with additional vitamins and minerals, multivitamins can be a valuable tool for those with dietary imbalances or different nutritional needs.[6] People with dietary imbalances may include those on restrictive diets and those who cannot or will not eat a nutritious diet. Pregnant women and elderly adults have different nutritional needs than other adults, and a multivitamin may be indicated by a physician.

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In the 1999–2000 National Health and Nutrition Examination Survey, 52% of adults in the United States reported taking at least one dietary supplement in the last month and 35% reported regular use of multivitamin-multimineral supplements. Women versus men, older adults versus younger adults, non-Hispanic whites versus non-Hispanic blacks, and those with higher education levels versus lower education levels (among other categories) were more likely to take multivitamins. Individuals who use dietary supplements (including multivitamins) generally report higher dietary nutrient intakes and healthier diets. Additionally, adults with a history of prostate and breast cancers were more likely to use dietary and multivitamin supplements.[7]

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Various medications may adversely interact with multivitamins, and many people with medical conditions have special dietary needs. In particular, pregnant women should generally consult their doctors before taking any multivitamins: for example, either an excess or deficiency of vitamin A can cause birth defects.[8] Long-term use of beta-carotene, vitamin A, and vitamin E supplements may shorten life,[9][10] with the additional risk being particularly large in smokers.[citation needed] Many common brand supplements in the United States contain levels above the DRI/RDA amounts for some vitamins or minerals.

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Multivitamins in large quantities may pose a risk of an acute overdose, due to the toxicity of some components, principally iron. However, in contrast to iron tablets, which can be lethal to children,[14] toxicity from overdoses of multivitamins are very rare.[15] There appears to be little risk to supplement users of experiencing acute side effects due to excessive intakes of micronutrients.[16] There also are strict limits on the retinol content for vitamin A during pregnancies that are specifically addressed by prenatal formulas.

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There is a new gravitation in the United States towards the Mediterranean diet. This diet is based on the Mediterranean Diet Pyramid, created by Walter Willett in 1995.[20] In 2008, the Harvard School of Public Health updated Willett’s pyramid in a Nutrition Source article called “Food Pyramids: What Should You Really Eat?”. Included in this new pyramid, and the original pyramid, is a daily multivitamin. The Harvard article states that “A daily multivitamin, multi-mineral supplement offers a kind of nutritional backup, especially when it includes some extra vitamin D. While a multivitamin can't in any way replace healthy eating, or make up for unhealthy eating, it can fill in the nutrient holes that may sometimes affect even the most careful eaters.”[21]

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A 2009 study published in The American Journal of Clinical Nutrition reports that multivitamin use is associated with longer telomere length in women. Longer telomeres have recently been associated with longer life, and therefore multivitamins could have an anti-aging effect. However, this is the first study on this topic, so more studies must be done to confirm this effect.[22]

According to the Linus Pauling Institute, the 2009 study was an observational study, not a randomized controlled trial.

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In 2006 the National Institutes of Health convened an expert panel to examine the available evidence on nutrient supplements.[4][5] This review concluded that "Most of the studies we examined do not provide strong evidence for beneficial health-related effects of supplements taken singly, in pairs, or in combinations of three or more." They noted that multivitamins could provide health benefits to some groups of people, such as postmenopausal women, but that there was "disturbing evidence of risk" in other groups, such as smokers. The panel's report concluded that the "present evidence is insufficient to recommend either for or against the use of Multivitamin/Mineral Supplements by the American public to prevent chronic disease."

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Similarly, a 2006 report for the United States Department of Health and Human Services concluded that "regular supplementation with a single nutrient or a mixture of nutrients for years has no significant benefits in the primary prevention of cancer, cardiovascular disease, cataract, age-related macular degeneration or cognitive decline."[26] However, the report noted that multivitamins have beneficial effects in people with poor nutritional status, vitamin D and calcium can help prevent fractures in older people, and that zinc and antioxidants can help prevent age-related macular degeneration in people at a high risk of developing this disease.

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In 2007 the United Kingdom Food Standards Agency published an updated set of recommendations for eating a healthy diet.[27] The recommendations stated that pregnant women should take extra folic acid and iron and that older people might need extra vitamin D and iron. However, the report advised that "Vitamin and mineral supplements are not a replacement for good eating habits" and stated that supplements are unnecessary for healthy adults who eat a balanced diet.

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One study from 2008 found that multivitamin use had no effect on prevention of lung cancer. Participants in this observational study had been taking multivitamin supplements for an average of 10 years, and this use appeared to have no effect on the prevention of lung cancer.[28]

In February 2009, a study conducted in 161,808 postmenopausal women from the Women's Health Initiative clinical trials concluded that after 8 years of follow-up "multivitamin use has little or no influence on the risk of common cancers, cardiovascular disease, or total mortality".[29]

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A 2008 study found that multivitamin use increased the mean breast density in premenopausal women. Increased breast density is associated with a higher risk for breast cancer. The study surveyed premenopausal and postmenopausal women about their multivitamin use, and found that multivitamin use was associated with higher mean breast density in premenopausal women but not postmenopausal women. The length of time that the women had been taking multivitamins did not seem to affect their mean breast densities.[31]

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It is not yet clear whether or not multivitamins should be used by children, and if so, what dosages are appropriate. Several studies have been done to determine the efficacy of multivitamins against different conditions.

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One study done in 2002 followed 5-to-7-year old girls to determine the influence of their mothers on their multivitamin intake. About 200 mother and daughter pairs participated in this observational study. It was found that mothers who used multivitamin supplements were more likely to give them to their daughters. Daughters’ multivitamin supplement use was predicted by mothers’ beliefs, attitudes, perceptions, and practices regarding mothers’ own eating and child feeding practices, rather than by daughters’ diet quality. In the discussion, the study's authors recommended that mothers foster healthier patterns of food intake in daughters, rather than providing multivitamin supplements, because the daughters' vitamin and mineral intakes during the study exceeded recommendations.[35]

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Another study done in 2009 found that multivitamin use among eight year-old children does not decrease risk for development of allergies. However, it seemed that multivitamin use in the first few years of life decreased the risk of allergies in the children. This study observed over 2,000 children from birth to age 8, and evaluated their multivitamin use in relation to their development of allergic disease.[36]

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According to a study published in The American Journal of Clinical Nutrition in 2007, Tanzanian children born to parents who received multivitamin supplements during pregnancy had a reduced risk of anemia, compared to the control group who received placebo supplements.[37] However, a 2009 study published in the same journal found that iron and folic acid supplements were just as good at preventing anemia in children as multivitamin supplements were.[38] Therefore, it is unclear at this time if multivitamin supplements are helpful in treatment and prevention of anemia in children.

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Whole Source Mature Adult (Rite Aid) and One Daily (The Vitamin Shoppe)

Samples of one of the three lots we tested of One Daily and samples of two lots of Whole Source Mature Adult failed to break down properly in our dissolution test. And samples of two of the One Daily lots contained less than 90 percent of their labeled level of vitamin A, considered the cutoff for an acceptable margin of error by the U.S. Pharmacopeia, which sets industry standards for dietary supplements.

Both products also exceeded the USP‘s upper limits for nutrients: One Daily contained more than 125 percent of its labeled calcium, while Whole Source had more than 125 percent of its labeled zinc and more than 165 percent of its labeled vitamin D. Those amounts don't pose a health risk, but they do raise concern about the products' quality. And at about 13 cents per day, they were the most expensive of all the multis we tested. There are better choices.

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Beyond that, the benefit of a daily multivitamin for the average person is murky, and getting murkier. Proponents of the pills say they provide a sort of nutritional insurance policy, filling in the gaps for nutrients that people can't or, more likely, simply don't get enough of through their diets. The problem is, there's virtually no evidence that shows that doing so actually improves health in populations that don't have high levels of nutrient deficiencies.

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Large clinical trials have found that taking vitamins and mineral supplements, including multivitamins, doesn't lower the risk of disease compared with not taking a multivitamin. Most recently, researchers from the Women's Health Initiative, who tracked more than 161,000 women, concluded that women who took the pills had no lower risk of cancer, cardiovascular disease, or death from any cause over an eight-year period than those who didn't. In the Dietary Guidelines for Americans report released in June 2010, the Department of Agriculture says that daily multivitamin/multimineral supplements do not offer "health benefits to healthy Americans" and urges consumption of a balanced diet plus, when needed, supplements of nutrients like calcium, vitamin D, and B12.

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The tendency of health-conscious people to take vitamins has provided marketing fodder for vitamin manufacturers, says Irwin Rosenberg, M.D., senior scientist and director of the Nutrition and Neurocognition Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University. "The companies can say that people who take multivitamins are healthier, but that's a misrepresentation of the science," Rosenberg says. "It may be true that they're healthier, but the causal relationship between the multivitamins and the better health is questionable and unlikely."

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Avoid megadoses In general, look for no more than 100 percent of the Food and

Drug Administration's Daily Value of the essential vitamins and minerals (one exception is vitamin D, for which the DV is just 400 IU, less than what many people should take). Avoiding big doses is especially important with vitamin A: Just 200 percent of the DV of the retinol form, sometimes listed on labels as vitamin A acetate or palmitate, can increase the risk of birth defects and liver damage.

Look for products that don't exceed about 3,000 IU of vitamin A (2,300 IU for women), or 60 percent of the DV, ideally with at least a third from beta-carotene, the safer form of the vitamin. (Smokers shouldn't take beta-carotene because it may increase their risk of lung cancer.)

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Ignore special claims and add-onsClaims for benefits such as weight control

or increased energy are generally unsubstantiated. Even if botanical ingredients, food extracts, and other substances like lutein and lycopene did have a benefit, the amounts in a multivitamin are probably too small to have any effect.

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Consider a multivitamin geared to your age or gender

Men's and senior formulas usually don't contain iron, which is good because those groups generally don't need extra iron, and it can lead to organ damage in people with hemochromatosis, a genetic disorder that causes excessive iron buildup. Senior formulas may also contain more vitamin D. Women's vitamins may have some extra calcium, though rarely enough to meet the daily requirement without the need for a separate supplement.

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The use of multivitamins to improve health has been a subject of continued debate for some time. After reviewing the most recent literature, it appears there is little evidence to support the claim that daily multivitamin use in the general population has a positive impact on health. However, certain populations, such as the undernourished or those who have diabetes, do appear to derive some benefit from the use of multivitamins. Overall, more studies are needed to continue investigating this important question. One study, the Physicians’ Health Study-II, hopes to provide some answers by looking at multivitamin use and its prevention of cardiovascular disease and cancer, among other illnesses, in over 14,000 men. Concluded in late 2007, it is hoped that the results from this study will further elucidate the possible relationship between daily multivitamin use and improved health.