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THE SCIENTIFIC BASIS OF OTHER NUTRIENT DOSAGES OF NUTRITION INVESTIGATOR

Most of the U. S. population obtains most of the RDAs from the diet (1), and it is generally agreed that a well-balanced diet is essential to provide not only the established micronutrients, but also a variety of other important minerals (especially trace elements) and compounds (like lycopene) for which RDAs have not been established. The RDAs have been established to provide a higher level of the nutrient than is actually required to prevent short term deficiencies, to provide a margin of safety (2). Furthermore , it has been established that people who consume nutritional supplements are generally better nourished than the population as a whole (14), and thus have less need for most micronutrients than average. Considering this information, which micronutrients are safe and proven in supplement form, and which clearly are not?

Vitamin D - Things have changed dramatically as of 2005. Please see why members of the Institute of Medicine now are recommending 1,000 iu of vitamin D on a daily basis.

HISTORICAL INFORMATION: Although essential for calcium transport and bones, vitamin D also has a variety of hazardous side effects at elevated levels (1). Generally people obtain sufficient vitamin D from diet and sunlight. Those who are concerned about osteoporosis may actually be at risk of consuming too much vitamin D, as the ingestion of milk, calcium supplements fortified with vitamin D, and sunlight may add up to potentially toxic levels, especially over the long term. However, the requirement for mature women is estimated to be higher than for younger adults, and mature women have been shown likely to be deficient in vitamin D (2). For this reason, the mature women's formulation was to contain 200 iu of vitamin D(3).

1. Food and Nutrition Board, Recommended Dietary Allowances, 10th edition, National Academy Press, Washington, DC, 1989, pg. 97

"Establishing an RDA for vitamin D is difficult because exposure to sunlight results in synthesis of vitamin D by the skin. People regularly exposed to sunlight, under appropriate conditions, have no dietary requirement for vitamin D... Vitamin D is potentially toxic, especially for young children. The effects...include hypercalcemia and hypercalcuria, leading to deposition of calcium in soft tissues and irreversible renal and cardiovascular damage...dietary supplements may be detrimental for the normal...adult who drinks at least two glasses of vitamin D-fortified milk per day." "dietary supplements may be detrimental for he normal child or adult who drinks at least two glasses of vitamin D-fortified milk per day"

2. NIH, Optimal calcium intake, NIH Consensus Statement 12: 1-31 (1994)

"For all women and men over 65, daily intake is recommended to be 1,500 mg/day...In men and women 65 years of age and older, calcium intake of less than 600 mg/day is common...vitamin D insufficiency has been detected and may contribute to reduced calcium absorption...The physiology of calcium homeostasis in aging men over 65 is similar to that of women..."

3. Holmes, R. P., Kummerow, F.A., "The relationship of adequate and excessive intake of vitamin D to health and disease," J Am Coll Nutr 2: 173-199 (1983)

"...most individuals appear to be at risk of obtaining too much vitamin D rather than too little..." "The actual human requirement for vitamin D is not known. As a supplement, 2.5 mcg prevents rickets and ensures adequate Ca2+ absorption and bone mineralization."

Zinc - Although popularized by the advertisements for zinc lozenges (which careful reviews indicate are ineffective), zinc remains of questionable value for the general population in supplement form, particularly because the intake level which produces toxicity has not been determined (4). RDA levels of zinc are safe and proven, but supplementation can lead to levels well above the RDA. However, calcium in supplement form reduces the absorption of zinc, so that calcium supplement users run the risk of zinc depletion. Fortification of calcium supplements with small amounts of zinc prevent this (5), and so My Personal Health formulations containing calcium include the appropriate dosage of zinc to compensate.

4. Sandstead, HH, and Smith, J C Jr., "Deliberations and Evaluations of the approaches, endpoints, and paradigms for determining zinc dietary recommendations," J. Nutr 126: 2410S-18S (1996)

Table 3 median zinc intake

"Usual dietary intakes of calcium do not impair zinc retention. On the other hand, effects of high intakes of calcium supplements...indicate pharmacological amounts of calcium can be detrimental" "many Americans are at risk of zinc deficiency" "the maximal safe dose of supplemental zinc is not known [but 50 mg/day was hazardous]" "For zinc supplements, the safe dose was 0.25 mg/kg/d" [equivalent to 19.25 mg for elderly men, 16.25 mg for elderly women] "A separate study found that supplementation with 50 mg zinc/d caused decreases in erythrocyte superoxide dismutase activity"

5. Wood, R.J., and Zheng, J.J., "High dietary calcium intakes reduce zinc absorption and balance in humans", Am J Clin Nutr. 65: 1803-9 (1997)

"Our findings suggest that high-calcium diets [or supplements] can reduce net zinc absorption and balance and may increase the zinc requirement in adult humans." "Zinc deficiency has many untoward effects, including loss of appetite, growth retardation, skin changes, and immunologic abnormalities."

Beta-carotene - Beta-carotene has been removed from major long-term clinical trials because it has been shown to increase the risk of certain diseases while providing no evident benefit (6). There is also question as to whether it functions as an antioxidant (7). In particular, there are well-described mechanisms by which adequate levels of vitamins C and E reduce any potential benefit of supplemental beta-carotene (8).

6. Hornbach-Torres, T., "Physicians' Health Study Shows Beta Carotene Supplements to be Without Benefit or Harm", Press Release, Report on Women's Health Study, Jan. 19, 1996, [617-732-5008]

The longest primary prevention trail of cancer and one of the largest, 22,071 male physicians, 12 year trial. "beta-carotene supplements have no significant effect - positive or negative - on cancer or cardiovascular disease." "There was a substantial possibility that the supplements might be harming the participants"

7. Kohlmeier, L. and Hastings, S. B. , "Epidemiological Evidence Of A Role Of Carotenoids In Cardiovascular Disease Prevention", Am J Clin Nutr 62(suppl): 1370S-6S (1995)

"findings from the first single intervention trial conducted on a large free-living population casts doubt on the utility of b-carotene for all high-risk populations." "In vitro studies have shown that first a-tocopherol, then g-tocopherol, and then lycopene are consumed before beta-carotene is utilized as an antioxidant in LDL", therefore, with an adequate supply of vitamin E, there is no need for b-carotene supplement which has risks associated with it.

8. Krinsky, N.I., "The antioxidant and biological properties of the carotenoids", 7th Congress Intl. Assoc of Biomedical Gerontol, abstract 39 (1997)

"When it comes to in vivo systems, it has been much more difficult to obtain solid experimental evidence that carotenoids are acting directly as biological antioxidants. In fact...results suggest that carotenoids may function as pro- oxidants...This type of evidence raises the question as to whether it is still appropriate to group the carotenoids with the antioxidant vitamins such as vitamin E and vitamin C."

Selenium - Selenium is another very popular antioxidant widely marketed by the nutritional supplement industry. However, current research indicates that dietary levels are adequate to maximize plasma glutathione peroxidase (9), while the dosage at which long-term toxicity occurs has yet to be clearly established (10-11). Like beta-carotene, the requirement for selenium is spared by the much safer antioxidant vitamins C and E (12). For these reasons, no selenium is added to My Personal Health supplements.

9. Levander, O. A., and Whanger, P. D. "Deliberations and evaluations of the approaches, endpoints, and paradigms for selenium and iodine dietary recommendations", J. Nutr. 126: 2427S-34S (1996)

Table 1 shows the mean dietary intakes of U.S. men and women (90 and 74 mcg/day respectively) are in excess of the RDAs (70mcg/day). "[50 mcg/day] was selected [by the Food and Nutrition Board] as the lower limit of the Estimated Safe and Adequate Daily Dietary Intake of this mineral. The upper limit...was set at 200 mcg/d" "It was found that [41 mcg/day] was sufficient to maximize plasma glutathione peroxidase activity [the important antioxidant function of selenium]"

10. Williams, S. R., Nutrition and Diet Therapy, Mosby, St. Louis, 1993, pg. 712

"Selenium is also toxic in high chronic doses, but the level at which this toxicity occurs is uncertain."

11. Hathcock, J. N. "Safety limits for nutrients", J. Nutr. 126: 2386S-89S(1996)

"The RfD method uses a no observed adverse effect level or a lowest observed effect level [to determine the maximum safe dosage of nutrients established by the Environmental Protection Agency and utilized by the Food and Nutrition Board to set safe limits for nutrients.]" Table 1 shows the RfD [safe level of ingestion] of selenium is at most 350 mcg per day. "If the composite SF [safety factor] is adjusted to 10, the resulting RfD is 100 mcg/day, a limit that may be deemed appropriate by many nutritionists."

12. Watson, R. R. and Leonard, T. K., "Selenium and Vitamins A, E, and C: Nutrients with Cancer Prevention Properties", J. Am. Dietetic Assoc. 86:505-510 (1986)

"It has been estimated that 35% of all cancer incidence is related to diet." "Vitamin E spares selenium."[therefore, if you take enough vitamin E, you don't need selenium] "toxicity occurs at low dietary levels in animals, indicating a small range of safe intake." "Selenium compounds possess a high degree of toxicity, and an excess may have severe consequences...Only [with more human studies] should general use of selenium supplements be considered."

Other micronutrients - There is little evidence to suggest that other micronutrients are beneficial in levels above the RDAs which most people obtain in a good diet (13). This is particularly true for supplement users, who on average consume better diets than non-users (14). Although certain micronutrients may be warranted for specific medically-diagnosed conditions, and further research may disclose other safe and proven micronutrient dosages in the future, studies such as Losonczy et al (15) are consistent with the hypothesis that it is primarily antioxidant vitamins C and E, rather than other micronutrients, which may dramatically reduce the risk of age-associated disease.

13. U. S. Department of Commerce, "Statistical Abstracts Of The United States, 116th ed.", U. S. Government Printing Office, Washington, D. C., 1996

Includes information on how much nutrition the average person gets. See table No. 225

14. Dickinson, A, "Benefits of Nutritional Supplements", Council for Responsible Nutrition, Washington, DC, 1993, pg. 2

"NHANES II showed that people who took supplements had a higher mean intake of nutrients from their diet than non-users. The difference remained significant even after adjusting for the fact that supplement users have somewhat higher income and education levels than non-users."

15. Losonczy, K. G., Harris, T.B., and Havlik, R. J. "Vitamin E and vitamin C supplement use and risk of all-cause and coronary heart disease mortality in older persons: the Established Populations for Epidemiologic Studies of the Elderly", Am. J. Clin. Nutr. 64:190-6 (1996)

Study of 11,000 people over 66 for 3 years:

Relative risk of death, heart disease, and cancer in older people using supplements

Note that those taking a multivitamin have a greater risk of harm, and those taking both vitamin C and E supplements fare much better. For a partial explanation, see the essay on multivitamins.