Among 28 vitamin D supplements recently selected for independent testing, problems were found with eight products (29% of those reviewed), according to ConsumerLab.com, White Plains, NY.

Vitamin D plays a critical role in bone health and higher levels in the blood are associated with reduced risk of heart attack, depression, rheumatoid arthritis, asthma and other conditions. Vitamin D has become one of the most popular supplements in the U.S. with sales rising from $72 million in 2006 to $429 million in 2009 according the Nutrition Business Journal. It was the fourth most popular supplement in a ConsumerLab.com survey of its readers in 2010, used by 56% of respondents. In the recent tests, ConsumerLab.com evaluated vitamin D supplements as well as those containing calcium and/or vitamin K. Results were released in three separate Product Review reports on Vitamin D, Calcium and Vitamin K supplements.

The most common problem found by ConsumerLab.com with supplements containing vitamin D was the wrong amount of vitamins:

• A popular supplement for children listed 200 IU of vitamin D per two gummy bears, but actually contained 501 IU, 251% of the listed amount;

• a gummy product for adults listed 1000 IU of vitamin D, but contained only 317 IU, 32% of the listed amount;

• a liquid listing 42 IU of vitamin D contained only 18 IU, 44% of the listed amount;

• a tablet listing 800 IU of vitamin D contained only 664 IU, 83% of the listed amount;

• and a vitamin D/vitamin K supplement contained its listed amount of vitamin D but provided only 36.8 mcg of its listed 50 mcg of vitamin K per capsule, 74% of the listed amount.

Two other products containing combinations of vitamins D and K and calcium were found to be contaminated with lead: One contained 5.2 mcg of lead in a suggested serving of 4 capsules, and the other, a powder, contained 4.1 mcg in a suggested serving of 2 scoops. The FDA permits supplement manufacturers to set their own limits on lead in their products, but one state, California, requires a warning label on supplements that contain more than 0.5 mcg of lead per daily serving (or 1.0 mcg of lead in supplements that contain 1000 mg or more of calcium). Neither of the products with lead contamination had this warning label. Both also failed to disclose soy as a potential allergen. They contained a form of vitamin K2 called MK-7, which is made from fermented soybean.

A vegan vitamin D product that passed laboratory tests was not approved by ConsumerLab.com because it listed potential benefits of vitamin D but failed to provide the required FDA disclaimer for such claims.