- 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
- What should I look for in purchasing a multivitamin?
- Look for a multivitamin that has 100 percent of the Daily Recommended Intake (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.
- 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 type of vitamin D supplement is best?
- Two forms of vitamin D are used in supplements: vitamin D2 ("ergocalciferol," or pre-vitamin D) and vitamin D3 ("cholecalciferol"). Vitamin D3 is chemically indistinguishable from the form of vitamin D produced in the body, and there's evidence that it may be more effective than vitamin D2 at raising vitamin D levels in the blood. That's why some scientists recommend looking for vitamin supplements that contain vitamin D3. Other scientists believe that vitamin D2 and vitamin D3 are similarly effective.
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