What to Look For in a Multivitamin

Most people today recognize the benefits of supplementing one’s dietary nutritional intake with additional micronutrients in the form of a multivitamin.

There is a plethora of data demonstrating benefits of such supplementation, particular among populations with increased nutrient requirements and/or reduced ability to ingest or absorb dietary nutrients. Examples of such include the elderly, pregnant women, individuals with chronic digestive problems, athletes, and individuals with restricted food intake such as “fussy” children who may eat poorly. Despite this general knowledge, many people remain confused regarding what to look for in a multivitamin.

Features to look for include:

• A vitamin A– and beta-carotene–free formula
• Activated forms of B vitamins including B12 and folic acid
• Respectable dosages of B vitamins—up to 25–50 mg of each
• Vitamin D at 1000 IU (25 mcg)
• Vitamin D at 1000 IU (25 mcg)

The importance of activated B vitamins arises from the fact that many individuals lack enzymes required to activate B vitamins found in many supplements. There is growing recognition among scientists that many individuals may carry genetic single-nucleotide polymorphisms (SNPs) that result in altered enzyme activity. This is especially true with respect to folic acid and vitamin B12. The methylfolate and the methylcobalamin forms are the active forms most easily utilized by the body, and do not require any further conversion. The same is true of other B vitamins: supplementation with the already-activated forms bypasses the need for the body to convert the vitamins prior to use. Ideally, a multivitamin will contain a decent dosage of B vitamins. While some multis may contain 5–10 mg or less, we like to see at least 25 mg—if not 50 mg—of each B vitamin.

Similarly, look for a respectable dosage of vitamin D. While the recommended daily allowance for vitamin D has recently been increased to 600 IU for adults up to the age of 70, there is a general consensus among vitamin D scientists that this is far too low; many individuals require higher amounts. We therefore try to ensure getting at least 1000 IU of vitamin D from a multivitamin. Some individuals may need to supplement more vitamin D in addition, but for vitamin D–adequate persons, 1000 IU seems to be a reasonable base dose.

There is good emerging science suggesting lack of benefit and possible harm from supplementation of vitamin A and beta-carotene.

Important data emerges from a series of studies conducted among pregnant women and their children in Tanzania, Africa. In this series of studies, 1,075 pregnant, HIV-positive women were enrolled to determine the impact of multivitamin supplementation. Tanzania is notorious for widespread malnutrition. The women received one of three interventions:

• A regular multi
• A multi free of vitamin A and beta-carotene
• A placebo

Results showed that women receiving the multi free of vitamin A and beta-carotene experienced the following benefits: improved weight gain during second and third trimesters, reduced risk of maternal death, reduced risk of maternal progression to HIV, reduced risk of developing high blood pressure during pregnancy, and increased measures of infant development in the resulting offspring (Psychomotor Development Index score increased and risk of developmental delay decreased at 18 months of age). There was also a decrease in child mortality and HIV transmission from mother to infant with supplementation of a vitamin A–free multi.[1–5]

On the other hand, women supplemented with a multi containing vitamin A and beta-carotene experienced no benefit relative to placebo. In fact, there was evidence that vitamin A supplementation increased HIV transmission from mother to infant.[2] It seems that even in this extremely nutrient-deficient population, vitamin A and beta-carotene not only delivered no benefit, but seemingly erased the other expected benefits of a multivitamin. It seems unlikely that these nutrients have benefits among an adequately nourished, North American population. This is especially true when we consider the pervasiveness of vitamin A fortification among grain and flour products in North America: there is virtually no incidence of vitamin A deficiency in the Western world.

References

1. Fawzi, W.W., et al. “A randomized trial of multivitamin supplements and HIV disease progression and mortality.” The New England Journal of Medicine Vol. 351, No. 1 (2004): 23–32.
2. Fawzi, W.W., et al. “Randomized trial of vitamin supplements in relation to transmission of HIV-⁠1 through breastfeeding and early child mortality.” AIDS Vol. 16, No. 14 (2002): 1935–1944. .
3. McGrath, N., et al. “Effect of maternal multivitamin supplementation on the mental and psychomotor development of children who are born to HIV-⁠1–infected mothers in Tanzania.” Pediatrics Vol. 117, No. 2 (2006): e216–e225.
4. Merchant, A.T., et al. “Multivitamin supplementation of HIV-positive women during pregnancy reduces hypertension.” The Journal of Nutrition Vol. 135, No. 7 (2005): 1776–1781.
5. Villamor, E., et al. “Effect of multivitamin and vitamin A supplements on weight gain during pregnancy among HIV-⁠1–infected women.” The American Journal of Clinical Nutrition Vol. 76, No. 5 (2002): 1082–1090.