Vitamins and Minerals Supplement

Vitamins and Minerals: How Much Should You Take?

How much of a vitamin or mineral supplement should you take? Are your daily multivitamins enough, or should you worry about vitamin deficiency? Could you already be taking too much? It can be hard to tell -- especially with so many nutritional terms, abbreviations, and numbers out there. Here’s what you need to know.

What the Numbers Mean

To help people better understand the minimum and maximum doses for supplements, the Institute of Medicine has established some guidelines.

The RDA (Recommended Dietary Allowance) and the AI (Adequate Intake) are the amounts of a vitamin or mineral you need to stay healthy and avoid nutritional deficiencies. They are tailored to women, men, and specific age groups.

The UL (Tolerable Upper Intake Level) is the maximum amount of daily vitamins and minerals that you can safely take without risking an overdose or serious side effects. For certain nutrients, the higher you go above the UL, the greater the chance of having problems.

Separate from the RDA and the UL, the FDA uses a different measurement of nutritional intake.

The DV (Daily Value) is the only measurement you’ll find on food and supplement labels. That’s because space is limited, and there’s a need for one single reference number. That number is the amount of a vitamin or nutrient that a person should get for optimum health from a 2,000 calories-a-day diet. The DV is sometimes the same as the RDA and sometimes not.

Although the details may be different, just remember that the RDA and DV are both designed to help us get the nutrients we need to prevent disease and avoid problems caused by malnutrition.

But many people take higher doses of specific supplements in the hopes of gaining other health benefits, like added protection against or treatment of disease.

Is taking doses higher than the RDA or DV safe? For many vitamins and minerals, yes. In some cases, doctors even recommend it. Take vitamin D, for instance. The RDA of vitamin D for a 60-year-old is 600 international units (IU). But for bone health, the National Osteoporosis Foundation recommends 800-1,000 IU for that age group.

How Much Is Too Much?

Because high doses of some supplements can have risks, how do you know when it’s OK to take more than the RDA or DV and when it isn’t?

One way is to look for the UL (tolerable upper intake level) of a nutrient. The Institute of Medicine sets the UL after reviewing studies of that nutrient.

With many vitamins and minerals, you can safely take a dose much higher than the RDA or DV without coming close to the UL. For instance, the average person can take more than 50 times the RDA of vitamin B6 without reaching the upper limit. However, some people develop neuropathy symptoms with these higher levels of B6. So you should always be cautious. Here are some things to keep in mind.

Some supplements are riskier than others. With some vitamins and minerals, the upper limit is pretty close to the RDA. So it’s easy to get too much. For example, a man taking just over three times the RDA of vitamin A would be taking more than the upper limit. High doses of vitamin A -- and other fat-soluble vitamins like E and K -- can build up in the body and cause toxicity. Other risky supplements include the minerals iron and selenium.

Supplements are designed to supplement the diet.  Popping dietary supplements is not the answer to good health. Experts recommend eating a well-balanced, healthy diet and taking supplements to fill in any nutritional gaps. Or you can take a once-daily multivitamin with minerals for nutritional insurance.

The UL is often the limit for all sources of a nutrient. It can include the amount you get from both food and supplements. So when figuring out whether you’re reaching the UL on a particular nutrient, you usually need to factor in the food you eat.

You won’t find the UL on food nutrition labels or on your vitamin bottle. It’s not a number that most people know about. But it is available on government web sites -- and a complete list of nutrients with ULs is listed at the end of this article.

Most supplements don’t have a UL – or RDA or DV. The government has only set levels for a fraction of the vitamins and supplements available. For most of the supplements you see on the shelves, experts really don’t know the ideal or maximum dose.

Many nutrients, in too high a dose, can be dangerous. To be on the safe side, steer clear of the UL for any nutrient. And if you have a health condition, check with your health care provider before taking supplements. Most supplements have possible drug interactions and side effects.

The good news is that the average person is unlikely to take so much of a nutrient that he or she will run into trouble. But it’s always wise to check in with a doctor before you start using a supplement regularly. And that’s definitely true if you’re using any supplement in high doses or for prolonged periods of time.

Table: RDAs and ULs for Vitamins and Minerals

The Institute of Medicine has determined upper limits for 24 nutrients. This table only applies to adults age 19 or older. It also does not apply to women who are pregnant or breastfeeding, because they have different nutritional requirements. Anyone who is under 19, pregnant, or breastfeeding should check with a doctor before using supplements.

Vitamin or Mineral	Recommended Dietary Allowance (RDA) or Adequate Intake (AI) Nutrients with AIs are marked with an (*)	Upper Tolerable Limit (UL) The highest amount you can take without risk
Boron	Not determined.	20 mg/day
Calcium	Age 1-3: 700 mg/day Age 4-8: 1,000 mg/day Age 9-18: 1,300 mg/day Age 19-50: 1,000 mg/day Women age 51+: 1,200 mg/day Men age 71+: 1,200 mg/day	Age19-50: 2,500 mg/day  Age 51 and up:2,000 mg/day
Chloride	Age 19-50: 2,300 mg/day Age 50-70: 2,000 mg/day Age 70 and older: 1,800 mg/day	3,600 mg/day
Choline (Vitamin B complex)	Age 70 and older: 1,800 mg/day Women: 425 mg/day *	3,500 mg/day
Copper	900 micrograms/day	10,000 micrograms/day
Fluoride	Men: 4 mg/day * Women: 3 mg/day *	10 mg/day
Folic Acid (Folate)	400 micrograms/day	1,000 micrograms/day This applies only to synthetic folic acid in supplements or fortified foods. There is no upper limit for folic acid from natural sources.
Iodine	150 micrograms/day	1,100 micrograms/day
Iron	Men: 8 mg/day Women age 19-50: 18 mg/day Women age 51 and up: 8 mg/day	45 mg/day
Magnesium	Men age 19-30: 400 mg/day Men age 31 and up: 420 mg/day Women age 19-30: 310 mg/day Women age 31 and up: 320 mg/day	350 mg/day This applies only to magnesium in supplements or fortified foods. There is no upper limit for magnesium in food and water.
Manganese	Men: 2.3 mg/day * Women: 1.8 mg/day*	11 mg/day
Molybdenum	45 micrograms/day	2,000 micrograms/day
Nickel	Not determined	1.0 mg/day
Phosphorus	700 mg/day	Up to age 70: 4,000 mg/day Over age 70:3,000 mg/day
Selenium	55 micrograms/day	400 micrograms/day
Sodium	Age 19-50: 1,500 mg/day Age 51-70: 1,300 mg/day Age 71 and up: 1,200 mg/day	2,300 mg/day
Vanadium	Not determined	1.8 mg/day
Vitamin A	Men: 3,000 IU/day Women: 2,310 IU/day	10,000 IU/day
Vitamin B3 (Niacin)	Men: 16 mg/day Women: 14 mg/day	35 mg/day This applies only to niacin in supplements or fortified foods. There is no upper limit for niacin in natural sources.
Vitamin B6	Men age 19-50: 1.3 mg/day  Men age 51 up:1.7 mg/day  Women age 19-50: 1.3 mg/day  Women age 51 up: 1.5 mg/day	100 mg/day
Vitamin C	Men: 90 mg/day Women: 75 mg/day	2,000 mg/day
Vitamin D (Calciferol)	Age 1-70: 15 micrograms/day (600 IU, or international units) * Age 70 and older: 20 micrograms/day (800 IU) *	100 micrograms/day (4,000 IU)
Vitamin E (alpha-tocopherol)	22.4 IU/day	1,500 IU/day This applies only to vitamin E in supplements or fortified foods. There is no upper limit for vitamin E from natural sources.
Zinc	Men: 11 mg/day Women: 8 mg/day	40 mg/day