Multivitamins

The Position of The Academy of Nutrition and Dietetics

The Academy of Nutrition and Dietetics, which is the world’s largest organization of food and nutrition professionals, and a trusted source for credentialed, practicing dietitians, states that, “The best nutrition-based strategy for promoting optimal health and reducing the risk of chronic disease is to wisely choose a wide variety of nutrient rich foods… Wise selection of nutrient rich foods is generally the best strategy for meeting nutrient needs. Foods, particularly plant foods such as fruits, vegetables, whole grains, beans, nuts, seeds and teas provide an array of health promoting substances beyond vitamins and minerals, including polyphenols such as flavonoids… Data suggest that positive health outcomes are related more to dietary patterns, types and amounts of foods consumed than intakes of individual nutrients” (1).

The Research

I looked into several studies to determine what research shows about multivitamin use. Here’s what I found:

In a comprehensive review that considered only published studies that met critical standards, researchers found that use of multivitamins did not reduce the risk of the most strongly suggested chronic conditions (cancer; age-related sensory loss; cardiovascular, endocrine, neurologic, muscoloskeletal, gastroenterologic, renal and pulmonary diseases) (2). These studies were limited to a design that would prove a “cause and effect” relationship, while most studies that have shown positive correlations between multivitamin intake and positive health outcomes have used an observational design, meaning that they cannot prove that the multivitamin was the cause of the positive outcome. There could have been other variables, such as healthy diet and physical fitness (2).

Another article detailed specific multivitamin effects on mortality and morbidity:

• MORTALITY (risk of death): Multivitamin use was not associated with lower risk of total mortality (3)
• CARDIOVASCULAR DISEASE: some studies show slightly decreased risk of CVD mortality, while others show no correlation (3)
• CANCER: studies showed no correlation with lower risk of cancer (3)

Although multivitamins do not appear to reduce overall chronic disease risk, several nutrients in MVMs might benefit certain population groups (2).

• Vitamin C: associated with small decreased risk of total mortality; decreased risk of coronary heart disease mortality; slightly decreased risk of cancer mortality (3)
• Vitamin E: small decreased risk of total mortality; decreased risk of CVD mortality; not associated with cancer mortality (3)

How much of each vitamin and mineral do we need?

The Institute of Medicine’s Dietary Reference Intakes (DRIs) are the best available standards for estimating needs for healthy individuals depending on gender and age. However, each and every body is different, and each diet is different. There is no one size fits all multivitamin that will offer the perfect amount of nutrition to each individual. Nutrient supplementation cannot replace a healthy diet. However, supplements can be helpful for those with deficiencies. Supplements can increase specific nutrients in order to meet needs. How do you now if you have a deficiency? The best way is to see a healthcare professional. There are signs and symptoms of different deficiencies. However, the signs and symptoms may overlap with other scenarios. The best way to know if there is a deficiency present is to have lab work done to assess serum levels. Because this can be expensive, I would only recommend doing so if your doctor thinks it is necessary.

Several studies have found that multivitamin users tend to take in greater amounts of vitamins and minerals from their diet than those who do not take multivitamins. Showing that ironically, the populations at highest risk for being deficient in micronutrients are the least likely to take them (2).

Supplement Market

Dietary supplements are products containing vitamins, minerals, herbs, extracts, metabolites, concentrates, or combinations of the previous, intended to enhance a person’s diet, to be taken by mouth, and can be in many forms including pills, capsules, tablets, liquids or powders. Supplements are regulated by the Food and Drug Administration, but not as rigorously as we would hope. Health and nutrient claims must be approved by the FDA; however, structure and function claims (how they work, what they do in the body) do not require this approval. Good manufacturing practices are difficult to enforce, presenting a risk for cross contamination, jeopardizing purity and potency. However, there are programs such as Consumerlab.com, NSF International and US Pharmacopoeia, that allow manufacturers to pay a fee for them to evaluate their product. These programs test the supplements to confirm that they meet quality standards, and the supplements are then able to bear the organization’s seal of approval (1). Therefore, if you were to choose to start taking a supplement, I would recommend looking for one that is verified by a third party such as the previously listed organizations. It is also important to keep in mind that different populations need different amounts of nutrients. So choosing a supplement that is tailored to your age, gender, and other characteristics is best.

Nutrients of Concern

The most common nutrients that people are deficient in are calcium, potassium, magnesium, vitamin E and fiber. Adults specifically are most commonly deficient in vitamins A and C. Older adults are most commonly deficient in vitamin B12 and vitamin D. People with dark skin are commonly deficient in vitamin D. Adolescent females are most commonly deficient in folic acid and iron (1).

Effects of Multivitamins

Multivitamins have been shown to affect nutrient adequacy for vitamins E, A, B6 and zinc. They have been less likely to affect calcium, magnesium and potassium. They are most likely to cause people to exceed necessary levels for iron, zinc, vitamin A and niacin (1).

The Recommendations Published by the Academy of Nutrition and Dietetics for Supplemental Nutrients in Specific Populations (1)

Infants and children: 400 IU daily of supplemental vitamin D for those exclusively breastfed

Women of childbearing age who may become pregnant: 400 ug/day of folic acid from fortified foods or supplements

Pregnant women: 600 ug/day of folic acid + multivitamin for those low in iron or susceptible to low iron (vegetarian, etc)

Adults over 50: 2.4 ug/day of vitamin B12 (due to the fact that the stomach does not produce as much secretions to absorb B12 from food as we age); extra vitamin D from fortified foods or supplements (because aging causes decreased ability to synthesize vitamin D from sunlight)

Research shows that there is a positive association between vitamin D intake and bone mineral density in post menopausal women and older adult men. Research also shows that supplementation with vitamin D3 and calcium may reduce incidence of fractures in institutionalized adults (1).

Fat vs Water Soluble Vitamins

Some vitamins are water soluble, meaning they dissolve in water. These vitamins are not stored in the body and need to be replaced daily. However, fat soluble vitamins dissolve in fat before they are absorbed into the bloodstream. These vitamins can be stored in the body. Different types of vitamins are absorbed in different ways – so it is important to eat a variety of foods in different combinations to increase the likelihood of absorption. For example, fat soluble vitamins (vitamins A, D, E and K) are best absorbed when consumed with fat. Iron is best absorbed in its heme form (which is the iron found in meat.) However, non-heme sources have iron as well, just not as much, and are not absorbed as readily. It is better to consume non-heme iron with acidic foods such as citrus or vinegar, as it makes the iron more available for absorption. There have been several studies focused on the different vitamins and minerals and their best form of absorption, but it would be exhausting to memorize and impossible to integrate into a daily routine. Thus, I stand by the advice to choose a wide variety of nutrient rich foods.

Most vitamin supplementations are offered in a water soluble form. It would be difficult to offer fat soluble vitamins in a fat-soluble pill – so if you are concerned about not getting enough of the fat soluble vitamins, I would recommend taking those with a source of healthy fat.

Sources:

1. American Dietetic Association. “Position of the American Dietetic Association: Nutrient Supplementation.” December 2009. Journal of the AMERICAN DIETETIC ASSOCIATION. Page 2085.

2. Office of Dietary Supplements. “Multivitamin/mineral Supplements.”  8 July, 2015. National Institutes of Health.

3. Pocobelli, Peters, Kristal, White. “Use of Supplements of Multivitamins, Vitamin C, and Vitamin E in Relation to Mortality.” 13 July 2009. American Journal of Epidemiology.