Multivitamins can’t replace a healthy diet

DEAR DOCTOR >> Do I really need to take a multivitamin? My sisters are convinced that you can’t get all the nutrients that you need without one, but it seems to me that as long you’re eating right, you’re covered. DEAR READER >> Multivitamins are the most widely used supplements in the United States. It is estimated that between one-third and one-half of all Americans take a multivitamin each day. As a result, your question is one that comes up often in our practices. And while we can’t offer specific advice, we can share and explain the information we give to our patients.

The short answer is that for most patients, we believe that if you’re eating a balanced diet, one that includes whole grains, a variety of vegetables and fruits, adequate lean protein and dairy products, there is no need for a multivitamin. However, when a patient’s diet isn’t ideal, then a multivitamin can offer insurance for the deficient vitamins and/or minerals.

Of course, there are exceptions. Pregnant women and women who are trying to become pregnant need at least 400 micrograms of folate per day, a B vitamin that helps to prevent neural tube defects. For these women, a prenatal vitamin or a daily folic acid supplement is recommended. Nursing women have unique nutritional needs that may call for supplementation. Some elderly adults whose appetites have diminished and who therefore don’t eat a balanced diet may benefit from adding a multivitamin.

Someone on a restricted diet, such as a vegan, typically needs a B12 supplement. A strict vegetarian may require additional zinc, iron or calcium. And for individuals with chronic conditions such as iron deficiency anemia, B12 deficiency or malabsorption, or a history of gastric bypass surgery, then supplemental vitamins and minerals are necessary to maintaining good health.

So what are vitamins, exactly? They’re nutrients that we need in small quantities to maintain various metabolic functions that, when taken in total, add up to good health. Vitamins help the body to produce energy, ward off cell damage, facilitate in the absorption and utilization of minerals, and play varying roles in the regulation of cell and tissue growth.

Vitamins must be taken in food because the body either doesn’t produce them in adequate quantities, or doesn’t produce them at all. Vitamin D is a bit of an outlier. It’s an essential nutrient that does not naturally appear in food in adequate quantities, but is produced when our skin is exposed to the ultraviolet B rays in sunlight. It is also available in fortified foods like milk, fish and mushrooms.

Take an honest look at your diet. If you find some nutritional holes, our advice is to adjust and improve your eating habits. If you do decide to make a multivitamin part of your daily regimen, keep in mind that it cannot take the place of a balanced and healthy diet. Not only do fruits, vegetables, whole grains and leafy greens contain vitamins, they also provide fiber, which is important to good health. Whole foods also contain trace nutrients and other useful compounds that no pill or supplement can re-create. Eve Glazier, M.D., MBA, is an internist and assistant professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and primary care physician at UCLA Health.