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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.
Vitamin Levels for Safe Supplementation
| 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 (1).
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.
Mineral Levels for Safe Supplementation
| 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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