MANY VITAMIN D SUPPLEMENTS DO NOT CONTAIN LEVELS CLAIMED ON LABEL

Unlike prescription medications, the U.S. Food and Drug Administration does not routinely test to verify that nutritional supplements such as vitamins and minerals actually contain what their labels claim.  Numerous studies that have analyzed the contents of mainstream brands of supplements have found significant differences between the nutrient levels actually in the supplement and the amounts listed on labels.  A recent study that focused on vitamin D supplements again found that some contained a lot more vitamin D than the label stated while others contained markedly less.

In the new study, researchers analyzed 55 over-the-counter bottles of vitamin D supplements from 12 major manufacturers. They also tested vitamin D pills made at a compounding pharmacy, which creates individualized drugs. The manufacturers were unidentified.  Overall, the amount of vitamin D found in the supplements ranged from 9% to 146% percent of what was listed on the label.

The study found that the supplements produced by the compounding company were the least reliable while the manufacturers with the USP seal (which means their supplements’ contents are verified by the non-profit U.S. Pharmacopeial Convention) had the most reliable supplements. 

In recent years, use of vitamin D supplements has been rapidly growing.  It has been increasingly recognized that many Americans are deficient in vitamin D.  Low vitamin D is a concern because research has linked low levels to bone disease and a likely increased risk of diabetes, heart disease, low thyroid function, poor immune function, and some cancers.  Vitamin D is made naturally when our skin is exposed to the sun but too much sun exposure increases risk of skin cancer.  Some vitamin D is also available in foods such as milk and other fortified products, fatty fish oil, and sardines and other fish that contain bones.  Most at risk for low vitamin D are those who are elderly, obese, have dark skin, and/or live in locations farther from the equator (such as New York). 

What to do:  Vitamin D levels can be tested with your routine bloodwork.  Follow your doctor’s advice on supplementation.  If you have been taking a supplement for several months and do not see a rise in your vitamin D level, you may need to switch supplements.  When choosing supplements, opt for widespread brands because they are more likely to be tested than smaller brands.  Notably, in tests by Consumer Labs, price does not appear to correspond with quality.  Also, consider looking for the USP seal.  Some supplements that are USP certified include Sunmark, TruNature, Kirkland, Nature Made, and Berkley & Johnson.

Source:  LeBlanc ES, Perrin N, Johnson JD, Ballatore A , Hillier T.  Over-the-counter and compounded vitamin D: Is potency what we expect? JAMA Intern Med,  Feb 11, 2013; doi:10.1001/jamainternmed.2013.3812.  Available at: http://archinte.jamanetwork.com/article.aspx?articleid=1570096

Adapted from article available at:  http://www.nlm.nih.gov/medlineplus/news/fullstory_133910.html