ConsumerLab purchased and tested B complexes and individual B vitamins such as B-6, B-12, folate (including methylfolate), and niacin, as well as popular hair and nail formulas containing biotin (B-7). The tests revealed that five of the 26 supplements selected for testing contained as little as 53% to as much as 223% of the listed amounts of certain B vitamins. For example, one "hair, skin and nails" formula was found to contain more than twice its claimed amount of biotin, and a popular B complex was found to contain almost twice as much folic acid as claimed, putting it above the daily tolerable intake level.
ConsumerLab also noted that many B vitamins are "mega" vitamins, intentionally exceeding recommended daily intake levels and, in some cases, exceeding tolerable upper intake levels. While this is sometimes medically necessary, it can also be of concern because long-term use of excessive amounts of some B vitamins, like B-6, niacin and folate, can cause toxicity. High doses B-12 may cause acne or rosacea, and high doses of biotin can interfere with common laboratory tests, causing misleading results. The FDA decreased recommended intakes for many B vitamins in 2016, but these changes do not need to be reflected on labels until 2020 or later.
Among the products that were Approved in testing, ConsumerLab selected a Top Pick for each category of B vitamin, based on dosage, quality and value.
The findings are available online in ConsumerLab's new B Vitamin Supplements Review, which includes test results and comparisons for 34 products. Twenty-six of the products were selected for testing by ConsumerLab and eight others underwent the same testing through CL's voluntary Quality Certification Program.
The review summarizes the clinical evidence for B vitamin supplementation for uses such as helping to prevent birth defects, lowering cholesterol levels, and slowing age-related cognitive decline. The report explains important differences among forms of B vitamins, such as those of niacin (nicotinic acid, niacinamide, and inositol hexanicotinate), folate (natural folate, folic acid, and L-5-methyltetrahydrofolate), and B-12 (methylcobalamin and cyanocobalamin). It also discusses recent changes in intake guidelines for B vitamins and how these compare to amounts commonly found in supplements, as well as safety and potential side effects and drug interactions.