“Take your vitamins!” Your parents probably told you this, and although mother knows best, doctors also know a few things about what your body needs. Their research indicates that too much of a good thing can have negative effects on your health. Check with your physician if you take any of these common vitamin supplements:

Vitamin A. In the proper amounts, vitamin A is essential to reproductive health, good bones, immune functions, and can be beneficial to people suffering from such conditions as celiac disease, pancreatic disorders, and Crohn’s disease. Vitamin A deficiencies, usually caused by malnutrition, can lead to problems in vision, skin disorders, and infections such as the measles, and other health issues. But such deficiencies are rare in the U.S. and other developed countries, so there’s probably no need to overdo it.

Vitamin C. In its natural form, vitamin C has been known to boost immune functions, but despite its popularity, no evidence firmly links it to prevention of such ailments like the common cold. It is important to the growth and repair of bodily tissues, and it contains antioxidants that might help fight cancer. Because it’s water-soluble, your body will eliminate any excess vitamin C it doesn’t need, but too much of it can cause stomach cramps, nausea, and heartburn. Excessive doses could produce kidney stones.

Vitamin E. This essential nutrient is frequently recommended because of its antioxidant qualities, but except in rare cases of vitamin E deficiency, evidence is slim of any clear medical benefits of a supplementary dose. In one study of the effect of this vitamin in fighting prostate cancer, results showed a 17% increase in the rate of cancer among subjects taking higher doses. Your best bet is to focus on naturally occurring sources of vitamin E in cereals, fruits, and green leafy vegetables - such as spinach - meat, and nuts.