Recent tests conducted by ConsumerLab.com, White Plains, NY, showed that more than 30% of multivitamins contained significantly varied amounts of ingredients than the product claimed or were contaminated with lead.

In addition, several products (including three for children) exceeded tolerable upper limits established by the Institute of Medicine (IOM) for ingredients such as vitamin A, folic acid, niacin and zinc.

Among 29 products for adults and children that ConsumerLab.com selected, tests showed that eight failed to meet their label claims or other quality standards and 12 others provided levels that may be too high for healthy individuals.

Three of four popular children’s supplements selected exceeded tolerable intake levels for vitamin A as retinol. For example, at the suggested daily serving for children over four years of age, one product provided 5000 IU of vitamin A. The IOM recommends a daily allowance (RDA) of only 1300 IU for children ages four to eight and an Upper Tolerable Intake Level (UL) of 3000 IU. Excess vitamin A in the retinol form may, in the short term, cause nausea and blurred vision, and in the long-term, lead to bone softening and liver problems. ULs for niacin and zinc were also exceeded by some of the products for young children. Excess niacin may cause skin tingling and flushing and high levels of zinc can cause immune deficiency and anemia.

In addition, many supplements like these generally provide more than the listed amount of ingredient to make sure that the product maintains potency over its shelf life, according to ConsumerLab.com. Although an accepted practice, actual levels may be up to 50% higher than the label indicates.

A reason why so many children’s vitamins exceed the newer recommended levels is that they are designed to meet “100%” of the Daily Values (DVs), which were last updated in 1968 and have yet to be reset by FDA. The out-dated DVs for vitamin A on supplement labels are actually two to three times higher than the newer RDAs and exceed tolerable intake levels for young children.

Several adult products also exceeded ULs for certain ingredients, particularly niacin. Two of three men’s multivitamins failed to pass testing. One contained 259% of its folic acid, yielding 2070 mcg per day. The RDA for folic acid is only 400 mcg per day and the UL for folic acid is 1000 mcg. Higher intake can make it difficult to detect severe vitamin B12 deficiency. In addition, folic acid supplementation at 1000 mcg per day has been associated with a more than twofold increase in prostate cancer risk.

Two out of five general multis were short on ingredients: one provided only 50% of its claimed folic acid and the other had only 70% of its calcium. Also, among four women’s multis selected, one provided only 66% of its claimed vitamin A; one of five seniors’ multivitamins selected contained only 44% of its vitamin A; and among three prenatal vitamins, one was short on vitamin A.

One of three vitamin waters selected contained 15 times its claimed amount of folic acid. Although the label notes that there are 2.5 servings per bottle, ConsumerLab.com cautions that drinking one bottle would provide 1500 mcg of folic acid—an amount over the upper tolerable level for adults. Children should not get more than 300 to 600 mcg of folic acid per day.

Alongside supplements for people, ConsumerLab.com selected two pet supplements for testing, but neither passed. One contained only 46% of the vitamin A and 55% of its claimed minimum amount of calcium. Another was contaminated with 6.45 mcg of lead per tablet. This is several times higher than the amount of lead (1.41 mcg) ConsumerLab.com found to be in this same product in 2007.

“Consumers need to be aware that problems with multivitamins are common,” said Tod Cooperman, MD, president of ConsumerLab.com. “Just as important, people need to determine their need for a supplement, factoring in other sources of nutrients in their diets.”