The Recommended Daily Allowances (RDA) are the level of intake of micronutrients, based on scientific knowledge, that are judged to be adequate to meet the needs of practically all healthy people. A common misconception is if a little is good, then a lot is better, especially in the case of vitamin and mineral supplements. Your body needs only a certain amount of micronutrients. Any excess will be excreted in your urine, or stored in your body at potentially hazardous levels. It has been said that Americans have the most expensive urine in the world because of the amount of vitamin and mineral supplements they consume.
If you eat a well-balanced diet, excess vitamin and mineral supplements should be unnecessary because they can have potential side effects.
- Vitamin A is necessary for healthy skin and night vision, but it can lead to liver damage and headaches in excessive amounts
- Vitamin C has been found to cause diarrhea in amounts greater than 1000 mg per day in some individuals
- Selenium may lead to tissue damage in combination with niacin, which can also cause liver damage
- Zinc has been noted to impair immune response in large doses
Consult your doctor, dietician, or pharmacist concerning the risks and benefits of taking supplements. This includes herbal products, which should be used with caution and preferably with medical advice.