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How Much Is Too Much? continued...

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.


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
Not determined.
20 mg/day
  • 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
  • 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

(Vitamin B complex)
  • Age 70 and older: 1,800 mg/day
  • Women: 425 mg/day *
3,500 mg/day

900 micrograms/day

10,000 micrograms/day
  • 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.

150 micrograms/day

1,100 micrograms/day
  • Men: 8 mg/day
  • Women age 19-50: 18 mg/day
  • Women age 51 and up: 8 mg/day
45 mg/day
  • 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.
  • Men: 2.3 mg/day *
  • Women: 1.8 mg/day*
11 mg/day
45 micrograms/day
2,000 micrograms/day
Not determined
1.0 mg/day
700 mg/day
Up to age 70: 4,000 mg/day Over age 70: 3,000 mg/day

55 micrograms/day

400 micrograms/day
  • 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
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

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.
  • Men: 11 mg/day
  • Women: 8 mg/day
40 mg/day


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