Maintenance of a skeleton capable of resisting the stresses of everyday life is dependent on the mechanical forces applied to the skeleton during normal activity in a 1-G environment. When the effects of 1-G on the longitudinal skeleton are removed, as with space travel or inactivity, bone and bone mineral are lost because bone resorption is greater than bone formation. Ninety healthy young men were studied during 5-36 weeks of continuous bed rest. During inactivity, urinary calcium increases rapidly and by the sixth week of bed rest, output has risen by 100 mg/day, plateaus for several weeks, and then decreases but remains above ambulatory baseline thereafter. This occurred even though they received vitamin D supplements throughout the study. Calcium balance becomes negative after 2 weeks and by the end of the first month, 200 mg/day is lost. The loss continues at this rate for at least 36 weeks. Calcaneal mineral loses 5% of its mass each month. Attempts to prevent disuse osteoporosis with both mechanical and biochemical means, including exercise, skeletal compression, increased hydrostatic pressure to the lower body, supplemental calcium and/or phosphorus, calcitonin, or etidronate were not successful.
Fluoride balances were determined in healthy adult males under metabolic ward conditions. This is the first fluoride study to use the diffusion method in exploring the balances of subjects ingesting basal (i.e., everyday) diets with deionized water for cooking and drinking. Certain groups were given daily supplements of 5 or 10 mg. fluoride as sodium fluoride in divided doses with meals. Fluoride was measured in the diets, sodium fluoride tablets, urine, feces, and serum. Approximately 90% of the fluoride excreted was found in the urine and the remainder in the feces in all groups. In the control subjects, fluoride balances were uniformly negative (mean of -0.40 mg/day); in contrast, balances were uniformly positive (mean of +1.38 and +2.88 mg/day, respectively) in subjects receiving 5 or 10 mg F supplements daily. Serum ionic fluoride concentration increased proportionally to fluoride intake and averaged 0.016, 0.029, and 0.040 ppm in the control, 5-mg and 10-mg groups, respectively. These fluoride supplements did not cause any clinical or laboratory abnormality in any subjects.
A metabolic balance study was performed to determine the effects of wine vs ethanol on absorption of various elements. Calcium, phosphorus, and magnesium data are reported here. The study was divided into four 18-day experimental periods during which six healthy males were given, in random order, 1 liter/day of one of the following test beverages: Zinfandel wine (9.3% w/v alcohol); delacholized Zinfandel wine; pure ethanol (9.3% w/v aqueous solution); or deionized water. The test beverages were administered along with a controlled isocaloric diet in four equal feedings over a 12-hr period. Each man served as his own control. Urinary calcium and magnesium did not change appreciably during the course of the study. Urinary phosphorous, however, was significantly greater during wine and ethanol administration, suggesting that alcohol may affect the metabolism or renal tubular reabsorption of this element. Despite considerable individual variation, the data showed that wine and dealcoholized wine enhanced absorption of calcium, phosphorus, and magnesium. This apparently was due to an effect of one or more of the many congeners present in wine and absent in a calorically equivalent amount of pure ethanol. The natural acidity of wine also may have played a role in creating a more favorable intraluminal environment for absorption. There was no significant difference between experimental periods in serum calcium, phosphorus, and magnesium.
There are implications in the literature that wine is different from other alcoholic beverages and that it may even have a beneficial effect on the nutritional process. A metabolic study was undertaken in an attempt to document the effects of wine versus ethanol on absorption of various nutrients. Nitrogen and caloric data are presented here. During each of four 18-day experimental periods, six healthy, young men were given, in random order, a liter per day of the following test beverages: Zinfandel wine (9.3% w/v alcohol); dealcoholized Zinfandel wine; pure ethanol (9.3% w/v aqueous alcohol solution); and deionized water. These beverages were divided into four equal feedings and administered with a carefully controlled isocaloric diet over a 12-hr period. The subjects tended to lose weight on alcohol-containing regimens, suggesting that calories from alcohol may not be as efficient as those from fat and carbohydrate. Urinary excretion of nitrogen was significantly greater during wine and ethanol administration than during feeding of the other test beverages. This was reflected in an increase in uric acid and urea nitrogen output, primarily, the latter, suggesting that alcohol may directly affect protein catabolism. There was no significant difference in fecal nitrogen excretion between experimental periods.
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