Despite the lack of evidence supporting the use of multis for the general population, there are some groups for whom a basic multi (supplying 100 percent of the Daily Value for most vitamins and minerals) makes sense:
- Women who may become pregnant should consume at least 400 micrograms daily of folate to help prevent neural tube birth defects—a basic multi is an easy way to get this. Folic acid, the form of the B vitamin folate used in supplements and fortified foods, is better absorbed than the folate naturally found in foods, which is why the U.S. Preventive Services Task Force and the March of Dimes advise a daily multi for women who may become pregnant. Premenopausal women, especially those who bleed heavily during menstruation, may also benefit from the iron in a multi.
- Pregnant or breastfeeding women should probably take a multi, but need to discuss this with their health care providers. There are many prenatal formulas.
- Strict vegetarians, who eat no animal products, may not get enough vitamin B12, zinc, iron and calcium.
- People on prolonged weight-loss diets (particularly ones that are very low in calories) or other restrictive diets may fall far short in nutrients. The same is true of people who are recovering from surgery or have a serious illness that disrupts normal eating.
- What about older people in general? Though there are few long-term studies focusing specifically on people over 65, many of them may benefit from a basic multi because they tend to have a harder time absorbing or utilizing certain nutrients. In addition, they are more likely to be on medications—notably proton pump inhibitors or H-2 blockers (for heartburn and reflux disease)—that block absorption of some nutrients. Some older adults may also have decreased appetite and eat less, and thus get fewer nutrients. Major problem nutrients are vitamin D, certain B vitamins and magnesium. In particular, older people have trouble absorbing vitamin B12, which is why “silver” multis contain higher amounts (usually 25 micrograms, four times the Daily Value). For people diagnosed with a B12 deficiency, even higher doses may be necessary.
Words to the wise: A multi need not cost more than a few cents a day, especially if you avoid (as you should) high-dose formulas. Store-brand and generic products are usually as reliable as brand-name pills. It’s best to get calcium from your diet, but if you don’t consume enough from food, be aware that multis don’t contain much, so you may need a calcium supplement. Similarly, if you want to get at least 800 to 1,000 IU of vitamin D a day, as many experts advise, a basic multi won’t supply enough (generally 400 or 500 IU).