Many people don't receive all of the nutrients they need from their diet because they either can't or don't eat enough, or they can't or don't eat the right foods. For some people, including those on restrictive diets, multivitamin-mineral supplements can provide vitamins and minerals that their diets often don't.
Pregnant women and people who smoke or consume excessive amounts of alcohol, or do both, have altered nutrient needs and can benefit from a supplement.
For older adults, lack of appetite, decreased sense of taste and smell, and denture problems can all contribute to a poor diet, as can eating alone or having depression. In addition, if you're 65 or older, it may be more difficult for your body to absorb and use certain nutrients. These include vitamin B-6, vitamin B-12, vitamin D and zinc. You may also need to increase your intake of calcium and vitamin D to protect against bone loss or thinning (osteoporosis).
(Source: Mayo Clinic website – www.mayoclinic.com)