How to Know Recommended Dietary Allowances of Vitamins

Experts continue to debate the merits of vitamin supplements. Some recommend following the recommended daily allowance (RDA), while others suggest that higher doses are essential for optimal health and recommend the daily optimal intake (DOI).

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Multivitamins
• Vitamin B Complex
• Vitamin C
• Vitamin D
• Vitamin E
• Vtamin K
• Vitamin C

1. Vitamin A is a fat-soluble vitamin. It has an RDA between 4,000 and 5,000 IU (international units) for adults and a DOI of 10,000 to 50,000 IU.

2. B1, or thiamine, is part of the B-complex vitamins and is water soluble. The RDA is 1 to 1.4 mg, and the DOI is 15 to 30 mg.

3. B2, or riboflavin, a B vitamin, has an RDA of 1.6mg and a DOI of 5 to 15 mg.

4. B3, or niacin, is also a B vitamin. The RDA is 13 to 18 mg, and the DOI is 100mg.

5. B5, or pantothenic acid, also part of the B group, has an RDA of 4 to 7 mg and a DOI of 100 to 1,000 mg.

6. B6, or pyridoxine, another B vitamin, has an RDA of 2 to 2.2 mg and a DOI of 35 to 50 mg.

7. B12, or cobalamin, also a B vitamin, has an RDA of 3 mcg (micrograms) and a DOI of 100 to 300 mcg.

8. Biotin, also a B vitamin, has an RDA of 100 to 200 mcg and a DOI of 300 mcg.

9. Choline, part of the B family, has no RDA, but the DOI is 25 to 300 mg.

10. Folate, or folic acid, a B vitamin, has an RDA of 400 mcg for adults and a DOI of 400 to 2,000 mcg.

11. Inositol, another B vitamin, has no RDA, but the DOI is 25 to 300 mg.

12. Paba-paraaminobenzoic acid, part of the B family, has no RDA, but the DOI is 25 to 300 mg.

13. Vitamin C is a water-soluble vitamin, which means it isn't stored by the body. The RDA is 60 mg a day, and the DOI is 1,000 to 5,000 mg.

14. Vitamin D is a fat-soluble vitamin, which means it is stored by the body. The RDA is 200 IU for adults, and the DOI is 200 to 400 IU.

15. Vitamin E is also a fat-soluble vitamin, with an RDA of 15 IU and a DOI of 600 IU.

16. Vitamin K is a fat-soluble vitamin necessary for proper blood clotting. It has no RDA, but the DOI is 750 mcg.

Tips & Warnings

• Taking a high-potency multivitamin/mineral complex is the easiest way to supplement.
• B vitamins are best taken together as a full B complex, unless you have a health problem that warrants extra dosages of a single one.
• Vitamin C may be taken along with a multivitamin for a larger dose.
• Take vitamin supplements with meals.
• Doses of over 3,000 mg of vitamin C may cause diarrhea in some people, and very high doses may interfere with results from certain medical tests.
• The fat-soluble vitamins A, D, E and K can be toxic when consumed in large doses over a prolonged period of time.
• Taking 100,000 to 200,000 IU of vitamin A for six to eight months can be toxic.
• Vitamin D can be toxic at doses of 1,000 to 3,000 IU.
• At doses of 1,800 IU, vitamin E may interfere with blood clotting.
• Menadione, a form of vitamin K (K3), may produce a type of anemia at large doses.
• Use caution if taking B3 doses higher than 1,000 mg.
• B5 causes diarrhea if more than 1,000 mg is taken.
• B6 may have some side effects in doses over 500 mg.
• Paba-paraaminobenzoic acid may be toxic at more than 12,000 mg per day.
• If you have any questions or concerns, contact a physician or other health care professional before engaging in any activity related to health and diet. This information is not intended as a substitute for professional medical advice or treatment.

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[josiebeth]

on 7/26/2009 Thanks for this - the vitamin store is so overwhelming!

[juliev579]

on 7/24/2009 there's also synthetic and natural vitamins. Make SURE your taking natural. I'm taking a vitamin by Viva and it's completely natural.

[troughyt]

on 3/22/2009 Good info! I have always used iherb.com for my vitamins. The Rainbow Light brand is very highly recommended by my nutritionist. There prices are about half of what my local health food store charges. If you use coupon code JOS874, you also receive $5.00 off your purchase.

[SueanneD]

on 10/29/2008 VERY good to know. It's always been something I've wondered about. Thanks.

on 6/30/2006 Of course there are dozens of vitamins, each with different benefits. Some of the main ones include:

Vitamin A: an important antioxidant, it also plays a part in maintaining healthy vision, boosting your immune system and healing wounds, and performs a whole host of functions to keep your skin looking good - keeping cells healthy, relieving skin disorders, and treating acne and wrinkles.

Vitamin B12: is essential to avoid fatigue, anemia, and nerve damage. It also plays a key role in numerous brain functions, including helping to prevent depression and memory problems.

Vitamin C: is probably the best known vitamin. An anti-oxidant, it has a role to play in boosting your immune system, protecting arteries, and healing wound.

Vitamin E: is also an antioxidant, and has been implicated in helping to prevent heart disease, some cancers, as well as boosting your immune system.