Effects of dietary supplementation on work performance in Gambian laborers

Article Abstract:

The effect of nutritional deficiency on work output and economic productivity is an important issue in developing countries, where many people are unable to obtain enough nourishing food. It has been suggested that during periods of nutritional deficiency, the body can alter its metabolism so that the functional capacity of the individual is not affected. However, there is little scientific data to support this claim. To investigate this issue further, a study was designed to test the hypothesis that reductions in nutritional intake cause reductions in work output, and that the reductions in work output can be reversed by giving high-energy dietary supplements. The effect of providing food supplements on work productivity was determined in subsistence farmers in The Gambia, West Africa, during months when food shortages occur and farming activities are greatest. Two groups of 16 men were each observed for work productivity and nutritional status during two six-week periods: one period involved no nutritional supplementation, while during the other period, three high-energy meals were provided to the men every day. Work productivity was assessed during the final three weeks of dietary supplementation and compared with productivity during the period when no supplements were provided. Body weight decreased during the period when supplements were not provided and increased during the time when they were provided. However, food supplements had no significant effect on work productivity. It is concluded that if workers are sufficiently motivated they can maintain normal work productivity during short periods of nutritional deficiency. But it is cautioned that the long-term effects of nutritional deficiencies on work productivity were not addressed and that they may be different from the short-term effects reported in this study. (Consumer Summary produced by Reliance Medical Information, Inc.)

Developing countries, Food and nutrition, Farmers, Manual work, Gambia

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Longitudinal assessment of the components of energy balance in well-nourished lactating women

Article Abstract:

During pregnancy, the amount of prolactin in the blood increases. Prolactin is the hormone that stimulates lactation (milk production in the breasts). All physiological processes require energy and lactation is no exception. Lactation places an additional energy requirement on the mother's body. There are several ways that this increased energy demand can be met. One way is to increase the amount of energy consumed in the diet. Another way is to metabolize the body fat that has accumulated during pregnancy. A third way is to conserve energy by minimizing physical activity. Rats, for example, increase their food intake to meet their increased energy demands, while seals use fat and protein stores that have been accumulated during pregnancy to supply the additional energy required for lactation. To determine how humans meet the increased energy demand of lactation, 10 pregnant women were studied. Energy intake (EI), basal metabolic rate (BMR), total amount of energy used by the body (TEE), physical activity, and changes in body fat stores were measured at week 36 of pregnancy, at weeks four, eight and 12 of lactation, and when lactation had ceased. During the study period, EI tended to increase, TEE and physical activity decreased, and BMR did not change. In the women in this study, 56 percent of the energy required for lactation came from an increase in the amount of energy consumed in the diet and the rest was supplied by decreasing the amount of energy used for physical activity. These findings indicate that the increased energy demand in lactating women is met by increasing the amount of energy consumed in the diet and reducing physical activity. (Consumer Summary produced by Reliance Medical Information, Inc.)

Evaluation, Measurement, Energy metabolism, Lactation, Energy consumption, Milk production

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Energy expenditure and wasting in human immunodeficiency virus infection

Article Abstract:

Severe weight loss among men with HIV infection may be caused by a decrease in the amount of food energy taken in rather than an increase in the rate of use of stored energy. Doctors studied the energy use and food intake of 27 HIV-positive men during periods of weight gain and rapid weight loss to determine the factors leading to the rapid changes in weight during HIV infection. Among the patients, the average daily energy use was about 2750 calories (kcal) per day. This energy output was not significantly different from that of healthy men in the same age range. However, during periods of weight loss, the patients average total energy output decreased to about 2180 kcal/day because of reduced physical activity and decreased appetite associated with illnesses or side effects of drug therapy. The patients who were losing weight rapidly had the lowest level of total energy output, while those with a stable weight or a gain had the highest level.

Causes of, Physiological aspects, HIV infection, HIV infections, HIV patients, Weight loss

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