Supplementation

For the most part, investigations have not shown reduced mortality with multivitamins.

Not captured in mortality data, however, are potential benefits that do not affect longevity in cohorts of older adults. Supplementation with beta carotene, vitamins C and E, and zinc is associated with slowing the progression of age-related macular degeneration.3 In older individuals, multivitamin supplementation is associated with improved memory and slowed cognitive decline.4 Multivitamins may help offset deficiencies following bariatric surgery. Commercial products including vitamins B12 and D are a convenient source of nutrients for which many people come up short. Folate supplementation in pregnancy prevents neural tube defects in infants.

Mortality analyses also miss important risks. Although food sources of beta carotene are associated with reduced cancer risk, supplemental beta carotene was found in 2 large, randomized clinical trials in at-risk individuals (smokers and asbestos workers) to increase risk of lung cancer.2 Multivitamins containing vitamin K may reduce the efficacy of warfarin. The inclusion of iron in a supplement, while below the tolerable upper level, adds to that consumed in foods, increasing the risk of iron overload, which is associated with an increased risk of cardiovascular disease, diabetes, and dementia. Similar concerns may apply to copper supplementation. Calcium and zinc may reduce the absorption of certain antibiotics. Vitamin E in pills does not reflect the full range of tocopherols and tocotrienols found in foods. These findings make a case for obtaining vitamins from food sources, rather than supplements, to the extent possible.

Refocusing nutrition interventions on food, rather than supplements, may provide the mortality benefits that multivitamins cannot deliver. Vegetables, fruits, legumes, and cereal grains are staples in areas of remarkable longevity, known as Blue Zones—Okinawa, Japan; Sardinia, Italy; the Nicoya Peninsula, Costa Rica; the island of Ikaria, Greece; and Loma Linda, California.5 In the Nurses’ Health Study and Health Professionals Follow-up Study, increased intake of vegetables and fruits was associated with reduced mortality, with maximum benefit observed for intakes at 5 fruit or vegetable servings per day,6 while substitution of plant protein in place of animal protein was also associated with reduced mortality.7 A healthful dietary pattern delivers micronutrients while also providing healthful macronutrients and fiber and limiting consumption of saturated fat and cholesterol.

Considerable evidence now shows that, apart from the aforementioned roles for vitamin supplementation, there is little health rationale for the use of multivitamin supplements. Micronutrients come most healthfully from food sources. When supplementation is required, it can often be limited to the micronutrients in question.