Selenium in Nutrition, Revised Edition (1983) / Chapter Skim
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8 SELENIUM AND HUMAN HEALTH
8 SELENIUM AND HUMAN HEALTH
Pages 114-132
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From page 114... ...
(1943) , who fed groups of 18 female rats a low-protein diet supplemented with 0, 5, 7, or 10 ppm selenium as seleniferous corn or wheat or 10 mg selenium/kg as a mixed inorganic selenide containing ammonium potassium selenide and ammonium potassium sulfide.
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From page 115... ...
Schroeder and Mitchener (1972) carried out two experiments in which mice were given either O or 3 ppm selenium as either sodium selenite or selenate in drinking water during their entire lifetime.
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From page 116... ...
The response of the male mice was less clear, perhaps because of a higher rate of spontaneous tumor formation or a greater resistance to the effects of the test chemical. The increased incidence of liver tumors in rats and mice given selenium sulfide differs from the studies with selenium compounds discussed above in that the hepatic tumors were seen in animals that had not developed cirrhotic livers.
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From page 117... ...
commented that the death rate due to malignant neoplasms observed among workers in a selenium rectifier plant in West England was about the same as that expected for the general population of England and Wales. Moreover, studies that have compared death rates due to cancer in different geographical areas with blood selenium levels in the general population are not consistent with the concept that high selenium intakes contribute to an overall increased human cancer mortality (see the section on cancer under the heading, "Low Selenium Exposures.
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From page 118... ...
(1980) gave 10-day pregnant rats either distilled drinking water or water containing 0.8 or 2.4 ppm selenium as sodium selenite or selenomethionine until the pups were weaned at 19 days of age.
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From page 119... ...
In fact, sodium selenite protected partially against the teratogenic effect of injected sodium arsenate or cadmium sulfate. On the other hand, selenium compounds have long been known to cause embryonic abnormalities when injected into the eggs of chickens (Palmer et al., 1973~.
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From page 120... ...
Aside from the two above reports involving seleniferous grain, there have been no animal studies that have investigated the carcinogenic potential of the forms of selenium that occur naturally in human foods. However, a comparison of public health statistics from various parts of the United States reveals that, if anything, the cancer death rate is lower in those areas of the country in which consumption of locally produced foods could result in an increased dietary selenium intake.
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From page 121... ...
The incidence of colon tumors was 6 of 15 in a group receiving 4 ppm selenium as sodium selenite in the drinking water, whereas the incidence was 13 of 15 in rats not treated with selenium. The total number of
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From page 122... ...
(1979) found that liver microsomes prepared from 3-methylcholanthrene-induced rats supplemented with 4 ppm selenium as sodium selenite in their drinking water produced less of the highly carcinogenic metabolite, N-hydroxy-2acetylaminofluorene (N-OH-AAF)
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From page 123... ...
In this study, groups of 35 hamsters were fed a torula yeast diet supplemented with 0, 1, or 5 ppm selenium as sodium selenite/kg for 2 weeks. Then they were continued on the diets and given weekly intratracheal instillations with a 0.5 percent MNU solution for 12 weeks.
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From page 124... ...
On the other hand, Poirier and Milner (1979) found that intraperitoneal injection of 1 mg selenium as sodium selenite/kg of body weight inhibited tumor development in mice previously inoculated with Ehrlich ascites tumor cells.
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From page 125... ...
(1975, 1978, 1979) concluded that age-specific heart disease mortality was lower in those states of the United States or countries of the world with high selenium intakes than in those states or countries with low selenium intakes.
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From page 126... ...
However, the amount of dietary selenium needed to prevent cardiomyopathy in humans apparently is very small, since blood selenium levels in children with Keshan disease were only about one-sixth of those reported in New Zealand, a country of known low selenium intake, and only about one-twentieth of those observed in the United States. It should also be emphasized that the pathology of Keshan disease is totally different from that characteristic of the degenerative heart conditions typical in the West.
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From page 127... ...
INFECTIOUS DISEASES Mice fed a chow diet supplemented with 0.7 ppm and 2.8 ppm selenium as sodium selenite had approximately 7 times and 30 times greater antibody titers, respectively, after challenge with sheep red blood cells than did mice fed the unsupplemented chow diet (Spallholz et al., 1973~. The primary immune response to sheep red blood cells can also be increased by injecting mice intraperitoneally with 3,ug to 5,ug of selenium as sodium selenite, although the increase is greatest when the selenium is given prior to or simultaneously with the antigen (Spallholz et al., 1975~.
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From page 128... ...
On this basis, Wallach postulated that selenium deficiency may play a key causative role in human cystic fibrosis, although marginal intakes of other nutrients, including vitamin E, zinc, copper, and riboflavin, as well as an excessive intake of polyunsaturated fat, were also thought to be involved. To support his hypothesis, Wallach and Garmaise (1979)
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From page 129... ...
SELENIUM SUPPLEMENTS As is readily apparent from the above discussion, numerous attempts have now been made to associate low or suboptimal selenium intakes with a wide variety of human diseases. For example, one investigator has questioned whether the optimal levels of dietary selenium for the postulated
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From page 130... ...
Because of the wide coverage given the hypothesis that selenium deficiency may play a role in cystic fibrosis in the popular press and various lay nutrition publications (see, for example, Shaw, 1979) , it has been estimated that several hundred cystic fibrosis patients in the United States may presently be following a high-selenium diet and/or taking selenium supplements (M.
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From page 131... ...
that combined supplementation of 1,2-dimethylhydrazine-treated rats with vitamin C in the diet and selenium in the drinking water led to an increased incidence of colon tumors as compared to unsupplemented rats or rats supplemented with selenium or vitamin C alone. This observation is of importance to human health because those persons taking selenium supplements may also be taking vitamin C supplements for other reasons.
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From page 132... ...
In well-nourished populations there is no evidence to indicate that selenium supplements have any prophylactic or therapeutic benefit against human diseases such as cancer, cardiovascular disease, or cystic fibrosis. Selenium supplements were reported to be of benefit against Keshan disease, a juvenile cardiomyopathy found in certain areas of the People's Republic of China, but this condition was not observed in any area where the daily dietary intake of selenium exceeded 30 ,~Ag/day.
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