A new report from ConsumerLab.com, White Plains, NY, cautions that the amount of vitamin A in supplements may be much higher or lower than the amount stated on labels, as only 60% of recently tested supplements contained claimed amounts.

Among 10 supplements recently selected for testing, ConsumerLab.com discovered that one delivered nearly double its claimed amount of vitamin A—of concern due to potential toxicity—and three others provided significantly less vitamin A than stated.

Vitamin A supplementation may slow the progression of macular degeneration, enhance healing after laser eye surgery and reduce the risk of certain cancers. Deficiency of vitamin A, which is rare in the U.S. but common in less developed nations, causes night blindness and increased risk of infection.

Toxicity with vitamin A, commonly sold as retinyl palmitate and referred to as preformed vitamin A, can occur at doses only moderately higher than required to prevent deficiency. Toxic effects of vitamin A include bone and liver abnormalities, as well as birth defects of the brain, eyes and head. Beta-carotene, or pro-vitamin A, does not carry this toxicity.

Tests of one cod liver oil supplement showed it contained 7818 IU of vitamin A as retinyl palmitate, nearly double its claimed amount of 4000 IU per teaspoon. Pregnant women, according to March of Dimes, should not exceed 5000 IU per day due to the risk of birth defects. This product should also be avoided by children under 13 years old, whose daily intake should not exceed 2000 IU to 5666 IU of preformed vitamin A, depending on their age, based on upper tolerable intake levels established by the Institute of Medicine.

Three supplements that were low in the ingredient contained only 68.2% to 77.5% of their claimed amounts of vitamin A (as retinyl palmitate and/or beta-carotene). Six vitamin A supplements passed the testing, including tablets and oils, along with six other supplements tested through ConsumerLab.com’s Voluntary Certification Program.
 
Brands covered in the new report include Country Life, Ethical Nutrients, Garden of Life, Health from the Sea, Metagenics, Nature Made, Nature’s Bounty, Nature’s Way, Puritan’s Pride, Rite Aid, Solgar, Source Naturals, Spectrum Essentials, Swanson, Vitamin Shoppe and Vitamin World. The report includes results for 16 products and information about three others similar to those that passed testing. The report also includes information about how to buy and use these supplements and potential side effects.