Dietitians Dish: Does the use of vitamins and minerals as dietary supplements improve health?

By Iustina Iznaola
July 29, 2014 at 2:29 a.m.

Iustina Iznaola

Iustina Iznaola

Vitamins and minerals, in addition to carbohydrates, proteins and fats, play an important role in providing adequate nutrition and preventing nutrient deficiencies that lead to adverse health effects.

For example, vitamin C treats scurvy, niacin treats pellagra. Vitamin D prevents rickets and osteoporosis and iodine treats goiter.

These, among many others, can prevent and treat potentially fatal diseases such as those mentioned above. The great news is that a balanced and varied diet that is rich in fruits and vegetables and lean protein has all the necessary nutrients to ensure good health.

However, the multibillion-dollar industry of dietary supplements has managed to convince many consumers through aggressive advertising that regular intake can prevent or treat certain chronic diseases, promote weight loss and improve overall health.

Many people would agree that their eating habits could be improved but prefer to take a daily supplement as quick nutritional insurance. Indeed the tendency among health professionals is to recommend a daily multivitamin supplement to prevent deficiencies. However, scientific evidence links long-term use of some supplements with increased health side effects.

Dietary supplements should be used as their name implies - to supplement the diet and not as substitutes for whole foods and meals. People's nutritional needs may be different throughout their life and at a certain point, they may truly benefit from taking supplements. For example, pregnant women should take iron and folate to prevent neural tube defects. Newborns are required to receive a shot of vitamin K at birth.

Elderly should take a higher dose of calcium to minimize risks associated with weakened bones. Vegetarians may be low in vitamin B12, riboflavin, iron and zinc and a daily multivitamin may be strongly recommended. Hospitalized patients who are seriously ill also benefit from taking supplements.

However, over-the-counter supplements should not be used by the general population at his or her pleasure and convenience.

Many supplements can cause more harm than good and toxic levels can build up gradually in the body. For example, vitamin E supplements when taken with an anticoagulant medication, such as Coumadin, can cause excessive bleeding.

Toxic levels of vitamin C may increase risk of kidney stones in people with kidney disease.

Dietary supplements are absorbed very differently than their natural form found in foods. For example, folate is absorbed at a higher concentration when taken as a supplement than when obtained from green vegetables.

For this reason, there is a strong recommendation that women begin taking folate supplements during the first three months of pregnancy.

On the other hand, excess beta-carotene from eating too many carrots will do no harm, but excess beta-carotene from supplements is linked with an increased risk of lung cancer in smokers.

The truth is that no one really knows what over-the-counter supplements can do to a person's health, because many of them do not need approval from the Food and Drug Administration before they are marketed.

Supplement companies do not have to provide the FDA with any scientific evidence that their supplements are safe. There are no federal guidelines to establish manufacturing criteria for purity, quality and composition of dietary supplements.

Therefore, the general healthy population should not perceive supplements as food replacers. They should be taken only with medical recommendation and for a limited period of time to correct any health concerns.

Current research indicates no toxicity of daily consumption of fruits and vegetables, but more evidence is needed to prove that dietary supplements provide more health benefits, if any, than harm. In addition, eating a diet based on wholesome foods is far cheaper than daily intake of supplements.

Iustina Iznaola is a registered dietitian at DeTar Hospital. Send questions or comments to



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