Vitamin Intake - How Much is Too Much?
Frederick R. Jelovsek MD
"Is 10,000 mg of Vitamin A too much to take per day? I am 69, happy and healthy and exercise 1 hour daily. " Evelyn
Originally the recommended daily allowance (RDA) requirements of vitamins and minerals developed by the National Academy of Science's Food and Nutrition Board were set at levels just to prevent deficiency states. There is more and more evidence, however, that higher doses of these nutrients can be beneficial in preventing diseases and improving overall health. Another organization, the Council for Responsible Nutrition, has tried to look at how much extra vitamin and mineral supplements can be taken. For this, they have tried to look at the literature to find:
- NOAEL - the intake level at which there are no credibly-substantiated adverse reactions observed in humans;
- LOAEL - the lowest intake at which some adverse effects have occurred under certain circumstances. (For many vitamins, there simply are no reports or too few reports of adverse effects at any level and, therefore, no LOAEL number can be identified.)
The Council for Responsible Nutrition has an executive summary published which is available in an Adobe PDF ® format. The following table is modified and condensed from that summary.
| Nutrient | Function | RDA* | NOAEL | LOAEL |
|---|---|---|---|---|
| Vitamin A | Promotes growth and repair of body tissues, bone formation and healthy skin and hair. Essential for night vision. | 2,600 IU (800 µg Retinol Equivalents) | 10,000 IU (3,000 µg Retinol Equivalents)(with renal disease this level is less) | 21,600 IU (6,500 µg Retinol Equivalents) |
| Beta-carotene | Serves as an antioxidant and may help protect against certain cancers, cataracts and heart disease. Converted to vitamin A in the body. | None established | 25 mg | None established |
| Vitamin D | Aids in the absorption of calcium and helps to build bone mass and prevent bone loss. Helps maintain blood levels of calcium and phosphorous. | none established | 800 IU (20 µg) | 2, 000 IU (50 µg) |
| Vitamin E | Helps protect cells from free radical injury. Serves as an antioxidant and may help protect against heart disease, cataracts, and certain cancers. Needed for normal growth and development. | 12 IU (8 mg a- Tocopherol Equivalents | 1,200 IU (800 mg a- Tocopherol Equivalents) | None established |
| Vitamin K (phylloquinone) |
Needed for normal blood clotting and bone health. | .065 mg | 30 mg (as long as not taking anticoagulant drugs, e.g. Coumadin ®) | None established |
| Vitamin C | Promotes healthy cell development, wound healing, and resistance to infections. Serves as an antioxidant and may help protect against certain cancers, cataracts, and heart disease. May reduce heavy menstruation. | 60 mg | More than 1,000 mg (perhaps as high as 10,000 mg but note that some individuals get diarrhea and gastritis with gastrointestinal bleeding at levels of a 1,000 mg or more -FRJ) | None established |
| Thiamin (B1) | Essential for converting carbohydrates to energy. Needed for normal functioning of the nervous system and muscles, including the heart muscle. | None established | 50 mg | None established |
| Riboflavin (B2) | Helps in red blood cell formation, nervous system functioning, and release of energy from foods. Needed for vision and may help protect against cataracts. 400 mg/d may help prevent migraine headaches. | None established | 200 mg | None established |
| Nicotinic Acid | Promotes release of energy from foods and proper nervous system functioning. High intakes can lower elevated cholesterol. | None established | 500 mg (250 mg slow release ) |
1,000 mg (500 mg slow release) |
| Nicotinamide | Promotes release of energy from foods and proper nervous system functioning. | None established | 1,500 mg | 3,000 mg |
| Pyridoxine (B6) | Essential for protein metabolism, nervous system, and immune function. Involved in synthesis of hormones and red blood cells. | None established | 200 mg | 500 mg |
| Folic Acid | Needed for normal growth and development and red blood cell formation. Reduces risk of neural tube birth defects. May reduce risk of heart disease and cervical dysplasia. | None established | 1,000 µg (1 mg) | None established |
| Vitamin B12 | Vital for blood formation and healthy nervous system. | None established | 3,000 µg | None established |
| Biotin | Assists in the metabolism of fatty acids and utilization of B-vitamins. | None established | 2,500 µg | None established |
| Pantothenic Acid | Aids in normal growth and development. | None established | 1,000 mg | None established |
NOAEL - no observed adverse effects level
LOAEL - lowest observed adverse effect level
* RDA - recommended daily allowance from Nutrition Health Reports
What is a safe level of vitamin A supplementation?
As you can see from the table above 10,000 International Units (IU) of vitamin A is considered safe by the Council for Responsible Nutrition but I would give some caution. As little as 12,000 IU has caused hypervitaminosis A (permanent liver damage) in individuals with kidney impairment. Also, remember that beta-carotene may be converted to vitamin A in the body so if you are taking a beta-carotene supplement, you should cut down your amount of vitamin A. Finally, remember that a couple of carrots, several ounces of beef liver, or any fish oil supplements can raise your vitamin A intake by as much as 5,000 IU per day. I think if I were taking vitamin A supplements, I would stay down at least at 5000 IU per day and no more.
What are safe levels of mineral supplements?
The Council for Responsible Nutrition has also addressed safe levels of minerals in their executive summary published in an Adobe PDF ® format. The following table is condensed from that summary.
| Nutrient | Function | NOAEL | LOAEL | |
|---|---|---|---|---|
| Calcium | Essential for developing and maintaining healthy bones and teeth. Assists in blood clotting, muscle con-traction and nerve transmission. Reduces risk of osteoporosis and may also reduce the risk of preeclampsia in pregnant women. Reduces PMS symptoms. | None established | 1500 mg | More than 2,500 mg |
| Phosphorus | Works with calcium to develop and maintain strong bones and teeth. Enhances use of other nutrients. Essential for energy metabolism, DNA structure, and cell membranes. | None established | 1500 mg | More than 2,500 mg |
| Magnesium | Activates nearly 100 enzymes and helps nerves and muscles function. Also reduces PMS symptoms | None established | 700 mg | None established |
| Copper | Involved in iron metabolism, nervous system functioning, bone health, and synthesis of proteins. Plays a role in the pigmentation of skin, hair, and eyes. | 1.5 - 3 mg | 9 mg | None established |
| Chromium (III) | Aids in glucose metabolism and may help diabetics regulate blood sugar and insulin levels. | 50 - 200 µg | 1,000 µg | None established |
| Iodine | Part of the thyroid hormone. Helps regulate growth, development and energy metabolism. | 150 µg | 1,000 µg | None established |
| Iron | Necessary for red blood cell formation and function. Amount needed is higher in women of childbearing age. | 15 mg (elemental iron) | 65 mg (elemental iron) | 100 mg (elemental iron) |
| Manganese | Necessary for the normal development of the skeletal and connective tissues. Involved in metabolism of carbohydrates. | None established | 10 mg | None established |
| Molybdenum | Needed for metabolism of DNA and RNA, and production of uric acid. | 75 - 250 µg | 350 µg | None established |
| Selenium | Essential component of a key antioxidant enzyme. Necessary for normal growth and development and for use of iodine in thyroid function. May reduce risk of certain cancers. | 55 µg | 200 µg | 910 µg |
| Zinc | Essential part of more than 100 enzymes involved in digestion, metabolism, reproduction, and wound healing. | 12 mg | 30 mg | 60 mg |
Do you have recommendations for what vitamin and mineral supplements an adult woman should reasonably take?
The recommended daily allowances for vitamins and minerals would be a reasonable amount of supplementation for a healthy adult woman eating a well balanced diet. Sometimes supplementations above the recommended daily requirements help alleviate certain health problems.
- premenstrual syndrome - vitamin B6 magnesium oxalate 200 mg/day. calcium 1000 mg/day
- menstrual cramps -magnesium oxalate 600 mg/day
- heavy menses - vitamin C 500 mg/day, iron 65 mg/day, vitamin K 30 mg/day
- migraine headaches - vitamin B2 400 mg/day
- cervical dysplasia - folic acid 0.4 mg/day, copper 5 mg/day
- osteoporosis prevention - calcium 1000 mg/day, vitamin D 400 IU/day
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