Calcium (800-1,000 mg)

• A common deficiency in the US, especially among women, good calcium nutrition throughout life is essential for achieving peak bone mass and preventing bone loss and risk of bone fractures.
• Calcium's protective effect on bone is one of the few FDA-approved health claims.

Chromium (120-200 mcg)

• Because of challenges in measuring the amount of chromium in foods and the human body, there is disagreement about the extent of deficiency in Western societies. Deficiency has been associated with blood sugar and cholesterol abnormalities, especially as people age.
• Although a causal relationship is doubtful, a few single case reports have described possible serious side effects in people taking large amounts, so people should stick to recommended amounts unless supervised by a doctor.

Copper (1-3 mg)

• While there is some indication that deficiency might be common in the US, the significance of this is unclear. It doesn't usually cause obvious symptoms, though supplementing with copper may help prevent bone loss.
• Since zinc can interfere with copper absorption, copper should be taken whenever zinc supplements are taken for more than a few weeks.

Iron (Recommendations should be determined by a doctor)

• Due to a rare condition that causes iron to accumulate to toxic levels in the body and also due to the association of high iron levels with some serious diseases, people should avoid iron supplements unless they have been diagnosed with iron deficiency.
• Groups at risk of iron deficiency include some vegetarians, menstruating girls and women, pregnant women, and female and adolescent athletes.

Magnesium (250-400 mg)

• Dietary deficiency may occur in up to 25% of adult women in the US and in even higher numbers of elderly people of both sexes, affecting bone health, among other effects.

Manganese (2-5 mg)

• While a typical diet provides enough for most people, those who eat a lot of refined and processed foods may be deficient as manganese and other trace minerals are often low in these foods. Deficiency has been associated with bone loss.
• Manganese may be especially important to include when supplementing iron, since iron can reduce its absorption and deplete it from the body.

Molybdenum (75 mcg)

• With a low potential for toxicity, little is known about human needs for this essential trace element. Deficiencies are rare and estimated requirements are based on what people typically receive in their diets.

Selenium (50-200 mcg)

• Though most people get enough in their diets, supplementing with higher amounts of yeast-based selenium is associated with decreased risk of cancer death. The upper end of safe long-term intake is estimated to be 400 mcg per day for adults.

Zinc (10-25 mg)

• Deficiency is relatively uncommon in Western countries, though supplements have prevented growth impairment in deficient children and have been shown to increase immune function in healthy people. (It isn't known whether these changes prevent infection or disease).
• Too much zinc has been reported to impair immune function and some healthcare practitioners recommend no more than 30 to 50 mg per day.
• Regular supplementation should be accompanied by copper supplements to prevent copper deficiency.

Other noteworthy nutrients:

Phosphorus

• Not included in most multivitamins because of its abundance in the diet. Elderly people, whose diets tend to be lower, may need supplementation. Calcium interferes with absorption, so older people taking calcium supplements might benefit from additional phosphorus.

Potassium

• Though severe deficiencies are uncommon in healthy people, some research suggests increased intake may help prevent high blood pressure and stroke. However, the maximum amount of potassium allowed in one pill (99 mg) is far below the recommended amounts (2,400 mg per day). Multiple pills should not be taken in an attempt to get a higher amount, since they can irritate the stomach; instead, eat several daily servings of fruits and vegetables.

Flavonoids

• A class of nonessential nutrients, flavonoids have antioxidant and other properties and have been reported by some, though not all, researchers to be linked with a reduced risk of heart disease.

Multivitamin supplements also frequently include other nutrients of uncertain benefit in the small amounts supplied, such as choline, inositol, and various amino acids.

Who is more at risk for deficiencies?

• People who have lost weight may be deficient in a wide range of vitamins and minerals.
• Vegetarians are at risk to become low in protein, vitamin B12, iron, vitamin D, zinc, iodine, riboflavin, calcium, and selenium.
• Vegans need the same nutrients as vegetarians, but vegans are more likely than lacto-ovo (dairy-and-egg eating) vegetarians to be low in protein, selenium, and B12.
• People eating macrobiotic diet: Deficiencies of vitamin B12, iron, vitamin D and other nutrients have occurred. This diet should be supervised by a dietitian or doctor.
• Elderly people living in their own homes are often deficient in vitamin D, vitamin A, vitamin E, calcium, and zinc, and occasionally of vitamin B1 and vitamin B2.
• Premenopausal women have been found often to consume low amounts of calcium, iron, vitamin A, and vitamin C.

(Click to see more detailed information on vitamins and minerals, including references.)

As natural substances, are supplements safer than drugs?

Nutritional (and also herbal) supplements are not necessarily safer just because they are natural: Some might produce unwanted side effects when a person takes too much, and if you are taking medications, you should always check with your doctor or pharmacist before adding nutritional supplements or herbs to your self-care.