What Are the Dangers of Vitamins?

Vitamins are chemicals that exist naturally in fruits, vegetables and grains. Humans must regularly ingest small amounts of vitamins to remain in good health. Vitamin pills can be taken when there are insufficient vitamins in a person’s meals. Vitamin dangers come in several forms: taking too much of a vitamin, taking extra amounts of a vitamin that is contraindicated for a medical condition, and taking a vitamin because of erroneous claims about a health function that it does not perform.

Too Much

Americans are encouraged to take extra vitamins. We are told to eat various items and to take vitamin pills because they are “full of vitamins.” But there can be too much of a good thing. In “Vitamins and mineral supplements,” a Better Health Channel essay posted by Australia’s state of Victoria, consumers are warned that overdoses of vitamins, known as vitamin toxicity, can damage a person’s health and may kill them. For example, overdoses of vitamin B6 can cause nerve damage in an otherwise healthy person.


Some vitamins are contraindicated, or prohibited, when extra amounts of the vitamin will make an existing medical condition worse. One famous instance illustrating when extra amounts of a vitamin are contraindicated is described in the U.S. National Cancer Institute article “Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Trial.”

The U.S. National Cancer Institute and the National Public Health Institute of Finland conducted a study from 1985 through 1993 to see if giving older male smokers extra beta-carotene, a form of vitamin A, would protect them from developing cancer. Habitual smokers often have preexisting lung problems that may lead to cancer.

Unfortunately, the extra beta-carotene increased the smokers’ lung cancer rate by 18 percent and their death rate by 8 percent.

Erroneous Claims

Because vitamins are widely available at low cost, and are known to be beneficial in normal quantities, many people are susceptible to widespread erroneous claims that higher doses of various vitamins are a cure-all for different diseases and medical conditions.

The Federal Trade Commission and the Food and Drug Administration have issued a joint warning, ” ‘Miracle’ Health Claims: Add a Dose of Skepticism,” in which they describe being deluged with erroneous or unproven claims that vitamins can cure arthritis or cancer in five days, treat impotence, help Alzheimer’s disease or ease insomnia.

The Federal Trade Commission notes that some claims for vitamins have been scientifically tested and proved true. Calcium can aid in fighting against osteoporosis or bone decline. Folic acid taken during pregnancy helps prevent brain and spinal cord defects in the baby prior to birth.

But the Federal Trade Commission strongly objects to health claims for vitamins and disease that are untested, erroneous or have been proved false.

Vitamin Safety

People interested in exploring whether an increased dose of a vitamin will provide an extra health benefit or aid them with a current medical problem should do research on the vitamin using reputable scientific sources. They should also consult a doctor, nurse or dietitian before regularly taking high dosages of any vitamins.

About this Author

Robin Elizabeth Margolis is a freelance writer in the Washington, D.C., area. She has been writing health care, science and legal articles since 1988. Margolis was the editor of a health law newsletter, and has a B.A. in biology, a master’s degree in counseling and a paralegal certificate.