Should You Take Multivitamins & Other Vitamins?

Most multi-vitamins are formulated to give you a significant proportion of your recommended dietary allowance of vitamins and minerals. You also, ordinarily, consume vitamins and minerals in many of the foods you eat. If you take additional supplements, you may exceed the upper tolerable intake level for one or more vitamins or minerals, especially if your normal diet contains prepared foods such as breakfast cereals that are fortified with extra vitamins and minerals. Before taking supplements, or giving them to your children, consult a health-care provider to make sure that the quantities are both safe and effective.

Fat Soluble Vitamins

Be especially careful to avoid more than the upper tolerable levels of the fat-soluble vitamins A, D, E and K, because they are stored in your fatty tissue and liver, and eliminated slowly. For adults, for Vitamin A the recommended daily allowance is 700-900 mcg and the upper intake level is 3,000 mcg. For Vitamin D, the RDA is 5 to 15 mcg and the UL is 50 mcg. For Vitamin D, the RDA is 15 mg and the UL is 1,000 mg and for Vitamin K the RDA is 90 to 120 mcg and the UL has not been determined.

Vitamin B6 or Pyridoxine

Although Vitamin B6 is water soluble and normally excreted in your urine, doses above the adult UL of 100 mg/day can result in nerve damage to arms and legs.

B3 or Niacin

The adult RDA for B3 is 14 to 16 mg and the UL is 35 mg. Very high therapeutic doses of 50 mg or more of B3 can cause liver damage and stomach ulcers. and should only be taken under the supervision of a health-care provider.

Vitamin C

The UL for Vitamin C supplements is 2,000 mg/day. Larger quantities can lead to nausea and diarrhea. Given that the efficacy of higher quantities for treatment of various ailments remains unproven, do not take supplements containing over the UL.

Minerals

Several minerals have well-established upper intake levels. For calcium, the RDA is 1,000 to 1,200 mg and the UL is 2,500 mg. In the case of iron, the RDA is 18 mg for menstruating women and 8 mg for other adults. Make sure not to exceed the UL of 45 mg of iron. Copper, zinc, iodine, sodium, manganese, fluoride, selenium and chloride also have well-established ULs and significant adverse effects if consumed excessively.