DEAR DOCTOR: Doctors and nutritionists are now saying that taking vitamin and mineral supplements is worthless. But many of the foods we eat are fortified with vitamins and minerals. Are those additives worthless? If not, how are they different than taking a multivitamin?
DEAR READER: While it's true that there's a new awareness regarding dietary supplements, including multivitamins, the conclusion has never been that they are worthless. In some cases, vitamins and minerals can help to fill specific gaps in nutrition. For example, vegans, who don't eat food sources that naturally contain vitamin B12, and older adults, who can lack adequate stomach acids to absorb it, need the vitamin in a supplement form. Taking a folic acid supplement before and during pregnancy can prevent the baby from developing certain brain and spinal cord defects. And individuals on restricted-calorie diets can turn to supplements to bolster their vitamin intake.
However, when it comes to the sweeping health claims made by many vitamin manufacturers, which range from vague statements about an improved well-being to unproven claims about lower rates of an array of diseases and conditions, it's a different story. Multiple studies in recent years have shown them to be empty promises at best. There is also potential for harm for individuals using mega-doses of vitamins.
Your question touches on the vitamins and minerals added to our foods in the United States. While the practice has become widespread and, at times, questionable, it had its start in legitimate health concerns. In the 1920s, in response to an epidemic of goiter among school children in Ohio, a push was made to add iodine to salt. Goiter is the visible swelling of the thyroid gland, with iodine deficiency its primary cause. With iodine added to much of the salt in this country, goiter is no longer common. The addition of vitamin D to milk in the 1930s grew out of an effort to prevent rickets, a childhood disease in which young bones fail to grow properly. Vitamin D is crucial to the absorption of calcium, and children who didn't get enough had weak and soft bones that sometimes led to skeletal deformities, like bowed legs.
When the processed food industry took off, much of the nutritional value was routinely stripped out of foods. In the early 1900s, vitamin B deficiencies were common and pellagra, a disease marked by diarrhea and skin rashes, was common. In severe cases pellagra could lead to dementia, and in the early decades of the 20th century, it caused tens of thousands of deaths, particularly in the South. This led to the fortification of cereal flours and products with B vitamins and iron in the 1930s, and the start of a decline in pellagra cases in the U.S.
Today, it seems to us that the multivitamin and supplement industry, with retail sales topping $36 billion in 2017, is a cynical enterprise. In order to persuade people to buy its products, the industry must first frighten us into believing that our food sources are somehow inherently flawed or inadequate. But as studies increasingly show, and as more Americans are coming to understand, you can get the nutrients you need with a balanced diet grounded in real rather than processed foods.
(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.)
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