Diet and Health Implications for Reducing Chronic Disease Risk (1989) / Chapter Skim
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13 Minerals
13 Minerals
Pages 347-366
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From page 347... ...
. If there is insufficient dietary calcium during bone formation, linear growth will be impeded and peak bone mass may not be achieved.
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Mean intakes DIET AND HEALTH FIGURE 13 - 1 Mean calcium intakes expressed as percentages of the 1980 RDA (NRC, 1980) for 1965 (females only)
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From page 349... ...
The 1977-i978 survey based on a 1-day intake indicated that males ages 9 to 18 maintained an average calcium intake at 90% of the RDA or above, whereas females in the same age range had progressively lower calcium intakes. Females ages 9 to 11 years, 12 to 14 years, and 15 to 18 years consumed 89, 72, and 64% of the calcium RDA, respectively.
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From page 350... ...
This association of bone mass with calcium intake is suggested by the results of a Yugoslavian study in which there was a 5 tO i0% higher metacarpal bone mass in the inhabitants of a "high-calcium" district starting at age 30 years and extending at least to age 75 years when the investigation terminated (Matkovic et al., 19791. it iS a logical extension of the above that the quantity of dietary calcium required tO achieve peak bone mass would be greater than that required to replace obligatory losses through urine, feces, and sweat (approximately 200 to 300 ma/ day)
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From page 351... ...
The quantitative contribution, if any, of this homeostatic mechanism to the decrease in bone mass and the increase in incidence of fractures in the elderly is not known and is the subject of intensive investigation. Epidemiologic and Clinical Studies PROBLEMS IN ES}IMAT1NG BONE MASS AND CALCIUM INTAKE In most epidemiologic studies of the rela tionship of dietary calcium to bone mass, investigators have used radiograms (measurements of cortical bone width, area, or calculated volume from x-ray images of metacarpal bones)
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From page 352... ...
Dietary calcium was lower than 800 mg/day in patients and controls in all these investigations. In another study, intakes were greater than 800 mglday in patients and controls, and no differences in calcium intake between the two groups were observed (Nordin et al., 1979~.
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(1984) found no change in bone mineral content at the distal radius when three groups of women with calcium intakes varying from below 550 mg/day to more than 1, 150 mg/day were given a 500-mg elemental calcium supplement daily.
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From page 354... ...
It is not clear whether the addition of calcium supplements to hormone-replacement therapy results in added benefit. PHOSPHORUS Although data from animal studies suggest that high levels of dietary phosphorus increase bone loss, detailed studies in humans show little to no effect of high phosphorus intake on calcium balance (see section on Phosphorus, below)
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From page 355... ...
The inconsistency among epidemiologic find ings may be, in part, a result of the high degree of collinearity among other dietary factors associated with blood pressure (e.g., potassium and protein) and the limitations in the methods of assessing calcium intake in noninstitutionalized populations (Kaplan and Meese, 1986; Lau and Eby, 1985~.
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From page 356... ...
Thus, whether or not they are ultimately proved to be related etiologically tO hyperter~sion, they should be investi gated independently in the SHR as a potential animal model of a clinical disorder of mineral and bone metabolism that might coexist with, or be caused by, certain hypertensive states. Dietary calcium supplementation lowers blood pressure in SHRs (Ayachi, 1979; Kageyama et al., 1986; Lau et al., 1984a; McCarron et al., 1981, 19851.
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However, there were no direct measurements of calcium intake in those study areas. In a pilot study of the effect of calcium supplementation on proliferation of colonic cells in patients considered to be at increased risk for colon cancer, Lipkin and Newmark (1985)
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(1984b) observed an inverse relationship between urinary magnesium and diastolic blood pressure levels in a subsample of the BeIgian population.
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States (HarIan et al., 1984~. Animal Studies Data from studies in animals show a consistent inverse effect of magnesium intake on blood pressure.
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There is no direct evidence that the impaired intestinal calcium absorption observed during menopause and aging can be overcome by increased calcium intake. Moreover, the evidence that calcium supplementation prevents the trabecular bone loss associated with the menopause is, at best, weak.
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1987. Dietary calcium intake and bone loss from the spine in healthy postmenopausal women.
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1986. Effect of calcium supplementation on diastolic blood pressure in young people with mild hypertension.
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1986. Effects of calcium loading on blood pressure in spontane' ously hypertensive rats: attenuation of the vascular reactive ity.
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1985. Blood pressure development of the spontaneously hypertensive rat after concurrent manipulations of dietary Ca2+ and Na+: relation to Ca2- intestinal fluxes.
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1984. Effects of high calcium intake on blood pressure and calcium metabolism in young SHR.
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1981. Calcium metabolism in the young adult male as affected by levels and form of phosphorus intake and level of calcium intake.
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