Can You Slowly Overdose On Vitamins?

Vitamins are micronutrients, substances you must obtain in small amounts from your diet that your body needs to function normally. Vitamins are grouped into water-soluble and fat-soluble categories. Unlike water-soluble vitamins, your body stores fat-soluble vitamins, which include vitamins A, D, E and K. Excess intake of fat-soluble vitamins can lead to a slowly accumulating overdose of these chemicals in your body, a condition known as hypervitaminosis. The most serious forms of this condition are caused by excess intake of vitamins A and D.

Upper Intake Levels

To help protect the public from inadvertently overdosing on vitamin supplements, the Institute of Medicine has established daily upper intake levels, or UIs, for several vitamins. Exceeding the daily UI for a given vitamin over time can lead to chronic hypervitaminosis. Established daily UIs for fat-soluble vitamins include 3,000 micrograms for vitamin A, 4,000 IU for vitamin D and 1,000 mg for vitamin E. Although an upper intake limit has not been established for vitamin K, the Institute of Medicine recommends that vitamin K should be obtained only from your diet to prevent excess intake.

Hypervitaminosis Prevention

Hypervitaminosis typically occurs from taking excessive amounts of vitamins from supplements. If you eat a well-balanced diet and take a single daily multivitamin, you are unlikely to be at risk for hypervitaminosis. If you take several vitamin supplements daily, however, it is important to check the amounts of vitamin A, D and E in each supplement to be sure you are not exceeding the UI for any of these micronutrients. Uncommonly, hypervitaminosis may develop when following a dietary plan that includes a large amount of food that contains a high concentration of a fat-soluble vitamin. Raw carrots, for example, are a favorite snack among people trying to lose weight. Five large carrots -- approximately 7 1/4 inches long or larger -- contain approximately 3,000 micrograms of vitamin A, the upper daily intake limit. Reduce the risk of hypervitaminosis A and stick to your weight loss program by including different types of raw vegetables as snacks, such as celery, radishes or sweet peppers, which contain little or no vitamin A.

Hypervitaminosis A

Hypervitaminosis A can cause problems in several body organs and tissues, leading to a variety of signs and symptoms. Irritability, blurred vision, dizziness, headaches, loss of appetite, nausea, vomiting, dry skin, yellowish skin discoloration, itching, hair loss and bone pain are among the possible symptoms associated with chronic vitamin A overdose. In extreme cases, hypervitaminosis A may lead to liver failure because this organ is the primary storage site for vitamin A. Be particularly careful not to take excess vitamin A during pregnancy, as this may lead to birth defects in your baby. Chronic hypervitaminosis A can also adversely affect your bones, increasing your risk of osteoporosis.

Hypervitaminosis D

For most Americans, inadequate consumption of vitamin D is a far greater health risk than hypervitaminosis D. This condition, however, can develop if you take too many vitamin D supplements. Excess vitamin D typically causes an abnormal increase in serums levels of calcium, which can lead to symptoms such as weakness, irritability, nervousness, nausea, vomiting, constipation, increased urination and excessive thirst. The calcium overload associated with hypervitaminosis D also increases your risk of developing kidney stones.