• Information on vitamins often conflicting, confusing

    December 2007

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    Several studies about vitamins have been done over the past decade, but they often present conflicting results making it difficult for consumers to determine the benefits and potential risks of vitamins.

    “More than half of Americans are taking dietary supplements—mostly multivitamins—but scientists aren’t certain about their benefit.”
    – J. Michael McGinnis, MD

    Are vitamins helpful, or not?

    In March 2006, the Wall Street Journal reported on research that suggests vitamin supplements may be doing more harm than good. For example, a federal science panel recently concluded there is no evidence for recommending certain vitamin supplements for cancer prevention. On the other hand, other recent reports suggest vitamins are very beneficial. Some experts claim taking the recommended daily nutrients increase general health and thus help cancer prevention.

    To sort this out, the National Institutes of Health formed a panel to critique supplements. Dr. J. Michael McGinnis, who chaired this panel, stated “More than half of Americans are taking dietary supplements — mostly multivitamins — but scientists aren’t certain about their benefit.”

    Regulation of dietary supplements

    Federal law enacted in October 1994 created a new regulatory framework for the safety and labeling of dietary supplements. Certain information must appear on dietary labels including, a descriptive name of the product, information about the manufacturer, a nutrition label, and a complete list of the ingredients.

    Currently there are no FDA regulations that establish a minimum standard of practice for manufacturing dietary supplements. Manufacturers are responsible for ensuring their products are safe before they are marketed, but the FDA does not approve vitamins or other dietary supplements. The FDA can take action if a supplement manufacturer is making false claims or the supplement is deemed to be unsafe after it goes on the market. Supplement makers are not allowed to make claims about a specific disease and cannot claim their product will diagnose, cure, mitigate, treat or prevent a disease.

    Vitamins do not go through the same rigorous testing that drug products endure, making it important to be well informed about a product before taking it. 

    Meeting your nutritional needs

    Most experts suggest if you eat a balanced diet, as outlined in the dietary guidelines, vitamin supplements are not needed and won’t provide any further benefits. However, according to the U.S. Centers for Disease Control and Prevention, only about 25 percent of Americans get the proper amount of micronutrients from foods. Dietary Guidelines for Americans, a booklet of science-based advice from the U.S. Department of Health and Human Services and the U.S. Department of Agriculture, offers a healthy eating plan that:

    • Emphasizes 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 and added sugars.

    The guidelines also recommend Americans read the nutrition facts label on packaged foods. To be healthier and get the optimal nutrition from foods, Americans should use the “percent daily value’ column (%DV) to gauge vitamin nutrition. A low %DV is considered to be 5 percent or less, while a high %DV is considered to be 20 percent or more.

    Finally, the guidelines recommend the most important supplements to be potassium, fiber, vitamins A and C, calcium and iron.

    The vitamins

    Vitamin E is marketed as being beneficial to heart health by decreasing coronary disease, but the research is inconclusive as to whether it provides any benefit. Several studies have shown no statistically significant difference between vitamin users and non-vitamin users in regard to coronary disease. More research is needed in this area.

    Vitamin C has long been touted as an immune booster. Although the research is often conflicting, there does seem to be a slight decrease in the duration of colds among vitamin C users. Additionally, vitamin C may help to prevent some colds, especially in extreme conditions. The studies do show some risk to taking vitamin C, particularly in patients with cancer. Analysis in the British Medical Journal, a cancer journal, reported last year that antioxidant supplements, including vitamin C, should be avoided by patients being treated with cancer.

    B Vitamins, including folic acid, vitamins B-12 and B-6, have been shown in some studies to lower homocysteine, an amino acid thought to be a risk factor for heart attack. However, other studies show taking B vitamins do not lower the risk of heart attack. Yet, the research in folic acid supplements is very conclusive and shows pregnant women who take folic acid have a dramatic reduced incidence of neural-tube defects in their babies.

    Calcium and vitamin D studies have also produced conflicting data. A 2005 study published in the British Medical Journal did not find a reduction in fracture risk among women who took calcium and vitamin D. However, a more recent study by the Women’s Health Initiative suggested calcium and vitamin D is associated with a lower risk of hip fracture in women over 60.  


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Page last updated: 8/7/2015 1:23:42 PM
  • What the news means for you

    Understanding vitamin research

    Kelly Smith, PharmD, FASHP
    Clinical Pharmacist

    Wright, Heather, MDInpatient It seems we often hear reports from the media about a study that found we should have more of one particular vitamin. Then we hear a conflicting report about the same vitamin. Vitamin studies are often based on flawed research contributing to the slew of misinformation and controversy over the best vitamin regimen.

    “It is clear a healthful diet plays an extremely important role in preventing illness.”  

    When interpreting results from vitamin studies, make note of all the factors that can influence the results, including the age and health of participants. Often vitamin studies are conducted on participants who were already very sick. More research is needed to understand the effect of vitamins on healthy individuals.

    A healthy diet and a multivitamin

    Although vitamin research can be inconclusive and controversial, it is clear a healthful diet plays an extremely important role in preventing illness. Large dietary-intervention studies conclusively show a healthful diet reduces the risk of cardiovascular disease and other diseases.

    Vitamins should not be used to compensate for poor diet, but I believe they can be used to help supplement essential vitamins consumers may not be able to get in their everyday diet. If you have difficulty preparing fresh food, a supplement may be beneficial.

    I recommend a multivitamin rather than a cocktail of high-dose vitamins. A multivitamin provides an FDA-recommended amount of vitamins and decreases the chance of taking too much of one particular vitamin. If taking a multivitamin, do not take an additional vitamin supplement. 

    “Too much of even a good thing can be bad for your health.” 

    As with most things, too much of even a good thing can be bad for your health. Often I think people believe that because one vitamin is good for them, five vitamins will be even better. This is not the case. Vitamins can be harmful. Taking more than the FDA recommended amount can be very harmful to your body; some may even cause liver or nerve damage when taken in very large doses..

    Learning more about vitamins

    Be an informed consumer when deciding to take a supplement. Information on the Web can be a marketing ploy. Pay attention to the source and be selective in the Web sites you use to learn about supplements. Government sites, including the National Institutes of Health and the FDA (any .gov site) are some of the best sites to increase your knowledge.

    Talk to your doctor

    Be sure to inform your doctor or other health-care provider of all the vitamin supplements you are taking. Some vitamins can interfere with medications or cause side effects.

    Also talk with your doctor about the best vitamin regimen for you. Different types of people have different vitamin needs, so you and your doctor should work out what vitamin or mineral supplements are best. For instance, women of childbearing age who may become pregnant or who are pregnant need extra folic acid, iron and vitamin C. Your age, gender, medical conditions and lifestyle can all play a part in helping determine which vitamins you need to be healthy.

    If you are already eating the daily recommended allowance for a particular nutrient, you will likely not receive any further health benefit from taking a supplement of that nutrient. In fact, it could cause you to exceed the recommended amount and cause

    Kelly Smith is a clinical pharmacist at UK Chandler Hospital and a special faculty member in pharmacy practice and science at the UK College of Pharmacy.

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