Our Experts Answer Your Questions
- What are vitamins?
- What should I look for in purchasing a multivitamin?
- Are time-release vitamins better for you?
- What's the difference between folate and folic acid?
What are vitamins?
Nutrition textbooks dryly define vitamins as organic compounds that the body needs in small quantities for normal functioning. Here's the translation: Vitamins are nutrients you must get from food because your body can't make them from scratch. You need only small amounts (that's why they are often referred to as micronutrients) because the body uses them without breaking them down, as happens to carbohydrates and other macronutrients.
So far, 13 compounds have been classified as vitamins. Vitamins A, D, E, and K, the four fat-soluble vitamins, tend to accumulate in the body. Vitamin C and the eight B vitamins—biotin, folate, niacin, pantothenic acid, riboflavin, thiamin, vitamin B6, and vitamin B12—dissolve in water, so excess amounts are excreted.
The "letter" vitamins sometimes go by different names. These include:
Vitamin A = retinol, retinaldehyde, retinoic acid
Vitamin B1 = thiamin
Vitamin B2 = riboflavin
Vitamin B6 = pyridoxine, pyridoxal, pyridoxamine
Vitamin B12 = cobalamin
Vitamin C = ascorbic acid
Vitamin D = calciferol
Vitamin E = tocopherol, tocotrienol
Vitamin K = phylloquinone
To learn more, read 5 Quick Tips for Getting the Right Vitamins.
What should I look for in purchasing a multivitamin?
Look for a multivitamin that has 100 percent of the Dietary Reference Intakes (DRI) for most vitamins. Be careful of supplements that have greater than 200 percent or 300 percent of the DRI, and be especially cautious of ones that have 1,000 percent of the DRI. In such large does, you will excrete out what you don't need for water-soluble vitamins such as vitamin C, and may experience liver damage or other toxic side effects for large doses of fat-soluble vitamins, such as vitamin A. One exception to this rule is vitamin D, as many people need more than the DRI. If your multi only has 400 IU of vitamin D, consider taking an extra supplement to get you up to 1,000 IU or 2,000 IU per day. Some people may need 3,000 or 4,000 IU per day for adequate blood levels, particularly if they have darker skin, spend winters in the northern U.S., or have little exposure to direct sunlight. If you fall into these groups, ask your physician to order a blood test for vitamin D.
To learn more, read 5 Quick Tips for Getting the Right Vitamins.
Are time-release vitamins better for you?
The idea behind time-release vitamins is that they provide a consistent amount of vitamins into your blood stream over the course of a day. However, time-release vitamins, unlike some time-release prescription medications, seem not to be useful and end up costing more.
What's the difference between folate and folic acid?
Folate is the form of the B vitamin found naturally in foods, and it is the generic term for the vitamin. Folic acid is the form of the vitamin that is added to multivitamins and to fortified foods (such as white flour and products made with white flour, breakfast cereals, "energy" or protein bars, and so on).
During digestion, the body converts folate into folic acid, which is then absorbed and used in multiple ways. Since vitamin pills and fortified foods contain folic acid, they can "skip" this conversion step, making folic acid more readily available to the body than folate from food.
To reflect this difference in availability to the body, government recommendations for folate are given in "Dietary Folate Equivalents," or DFEs: One microgram of folate from food equals 1 DFE; 1 microgram of folic acid from fortified foods, or from a vitamin pill taken with food, equals approximately 1.7 DFEs; 1 microgram of folic acid from a vitamin pill taken on an empty stomach equals 2 DFEs.
To learn more about folate and other B Vitamins, read Three of the Bs: Folate, Vitamin B6, and Vitamin B12.