Dietary supplements are intended to supplement the diet, not to cure, prevent, or treat diseases or replace the variety of foods important to a healthy diet.
You do your best to eat right. You stay away from junk food, and you eat fruits and vegetables as often as possible. But, is your diet falling short of essential vitamins and minerals? Should you be taking dietary supplements?
According to the National Institutes of Health, more than half of American adults take at least 1 dietary supplement, most commonly a multivitamin.1 This is a good place to start if you think you are not getting all the nutrients you need from your diet. But keep in mind, dietary supplements are intended to supplement the diet, not to cure, prevent, or treat diseases or replace the variety of foods important to a healthy diet.
Our nutritional needs change as we move through different stages of life, so consider a multivitamin targeted for women in your age group. It should contain B vitamins; vitamins A, C, D, E, and K; and various minerals, such as calcium and magnesium. Also remember that to be fit and healthy, adjust your diet, as well as your vitamin and supplement intake, to meet the extra demands placed on your body and the specific needs of each decade.
19 to 30 Years of Age
Calcium builds strong bones, but is also important for healthy muscles, nerves, and heart. Women should be careful to get enough calcium throughout life, but you want to build bone density in your 20s because the body will lose some of that bone in later years. The more you start with, the better off you are. You need 1000 mg of calcium per day while you are in your 20s. Consider taking a calcium supplement if you do not receive enough calcium from your diet through dairy products, calcium-fortified orange juice and cereals, beans, leafy greens, almonds, and salmon.
Vitamin D, like calcium, is essential for bone health, and may reduce the risk of some cancers and heart disease. It also promotes calcium absorption in the stomach and intestines. Good sources of vitamin D include salmon, tuna, and fortified milk, juices, and cereals. With the help of sunshine, most of the vitamin D we get is made in the skin. If you are almost always indoors and get little or no sunshine on your skin, however, you may need to consult your doctor or dietitian about your vitamin D needs. Online Table 1 shows the recommended daily allowances for calcium and vitamin D in women.
Table 1: Recommended Dietary Allowances for Calcium and Vitamin D in Women
Iron helps to increase the amount of red blood cells in the body and keep blood healthy. Women with heavy menstrual bleeding or pregnant women need more iron in their diets or may need an iron supplement. Too little iron may lead to anemia. Iron comes from animal sources (heme iron) and plant sources (nonheme iron). Heme iron (from animal sources) is better absorbed than iron from plant sources; however, the absorption of iron from plant sources can be improved when these foods are eaten in combination with foods rich in vitamin C (such as orange juice, strawberries, or green, yellow, or red peppers). Animal sources include meat, fish, and eggs. Plant sources include nuts, seeds, and dark leafy green vegetables. Women 19 to 50 years of age need 18 mg of iron daily, pregnant women need 27 mg of iron daily, and women 51 years and older need 8 mg every day.
31 to 50 Years of Age
Folate, a B vitamin, is naturally present in a wide variety of foods, including vegetables (especially dark green leafy vegetables), brown rice, spinach, sprouts, broccoli, green beans, and potatoes. It is also found in fortified breads and cereals. Even if you are healthy and maintain a diet rich in folate, if you are pregnant or plan to become pregnant, folic acid supplements are recommended. Folic acid is a synthetic version of folate that helps the baby to develop and reduces the risk of having a baby born with spinal cord problems, such as spina bifida. Women of childbearing age need 400 mcg of folic acid every day. This daily amount increases to 600 mcg for pregnant women and to 500 mcg for breast-feeding women.2
Magnesium is important throughout each stage of life because it supports hundreds of functions throughout the body, including tooth and bone formation, growth, physical and cognitive development, and ensuring a healthy pregnancy. Magnesium is especially important for women older than 40 years, as it builds strong bones and prevents bone loss that may lead to osteoporosis. Magnesium may also help regulate blood pressure and blood sugar levels, reducing the risk of heart disease and diabetes.3 Legumes, nuts, seeds, whole grains, fortified cereals, and leafy green vegetables (eg, spinach) are good sources of magnesium. See Online Table 2 for the recommended daily allowances for magnesium.
Table 2: Recommended Dietary Allowances for Magnesium in Women
50 Years and Older
As you approach menopause, your body produces less estrogen, putting you at increased risk for heart disease, osteoporosis, and other complications. To build and maintain healthy bones, weight-bearing and musclestrengthening exercises are important. In addition to exercise, be sure to get the recommended daily allowance of calcium, which is 1200 mg for women 50 years and older.
Vitamin D is necessary for the absorption of calcium and is the essential companion to calcium in maintaining strong bones. The recommended daily intake of vitamin D is 600 IU after age 50 years, increasing to 800 IU after age 70.
Fish oil, found in cold-water, oily fish—such as salmon, mackerel, and sardines—is a rich source of the 2 essential omega-3 fatty acids: EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Studies indicate omega-3s may reduce the risk and symptoms of various disorders, including heart attack, stroke, some cancers, and rheumatoid arthritis. The American Heart Association recommends eating fish, especially oily fish, at least 2 times each week as part of a hearthealthy diet. Although omega-3 supplements have not been shown to protect against heart disease, there is evidence that eating seafood has a variety of health benefits.4 If you cannot eat fish or choose to not do so, talk to your health care provider to see if a fish oil supplement is right for you.
Vitamin B12 helps your body make red blood cells and keeps the brain and nervous system healthy. This vitamin is found mostly in animal protein: meats, fish, dairy products, and eggs. It can also be found in fortified breakfast cereals. As you get older, you can develop a reduced ability to absorb vitamin B12. If you become deficient, you may experience confusion, agitation, or hallucinations. Almost all multivitamins contain vitamin B12. Supplements that contain only vitamin B12 or vitamin B12 in combination with other nutrients, as well as a prescription form that is administered as a shot, are also available.
Before starting any vitamin or mineral supplement, talk to your health care provider to determine if doing so is appropriate, especially if you are pregnant, breast-feeding, or taking medications or have allergies to any medications or foods.
Ms. Bolt is a clinical pharmacist and medical editor residing in Northern California.