Prediction of 24-h energy expenditure and its components from physical characteristics and body composition in normal-weight humans

Article Abstract:

Knowledge of the energy, or calories, needed by the body is necessary for the treatment of people who are or who have been obese, as well as other types of patients. Although variable across individuals, the energy needs of any one person are rather stable unless gross changes in eating patterns occur. During periods when weight is stable, energy needs equal energy expenditures and can be determined directly by calorimetry or estimated by calculations that rely on age, sex, and body weight. However, these last factors are not good predictors of basal energy expenditure (BEE). Rather, age, sex, and body weight are important only because they provide some indication of lean body mass (LBM), which correlates highly with BEE. Some methods of determining LBM are inaccessible and too expensive for routine medical use, but the bioimpedance method is an easy, quick, inexpensive, and relatively precise way of estimating LBM and fat mass. Total energy expenditure (EE) over 24 hours, and its components BEE, sleeping EE (SEE), and daytime EE (DEE), of 10 healthy subjects (four female) were measured in a high-precision respiration chamber and estimated by bioimpedance to determine the precision of bioimpedance techniques and to develop equations of EE using bioimpedance data. Repeated measurements of EE and its components were consistent for each person. There was variability among subjects, and all components of 24-hour EE were lower for females. Up to 93 percent of the variability among all subjects and for females was accounted for by differences in LBM, and equations were derived for EE, BEE, SEE, and DEE as a function of LBM. However, all study subjects were lean, but overweight and obese subjects tend to have less metabolically active LBM, so that the derived equations would be less accurate for these subjects. In addition, fat mass also contributes to EE. The study suggests that bioimpedance measurements of LBM allow reliable estimates of EE, but validation of these results with other groups of subjects is needed. (Consumer Summary produced by Reliance Medical Information, Inc.)

Measurement, Body composition, Energy metabolism

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Effect of chronic ingestion of a fermented dairy product containing Lactobacillus acidophilus and Bifidobacterium bifidum on metabolic activities of the colonic flora in humans

Article Abstract:

The bacteria that normally reside in the colon are involved in various physiological functions and may also contribute to the development of disorders such as cancer or inflammation of the colon. One of the most important physiological functions of the bacteria in the colon is fermentation, and changes in normal fermentation processes may result in diarrhea. Various studies have focused on the effect of diet on the normal bacterial flora of the colon. One study showed that fermented dairy products containing Lactobacillus acidophilus decreased the levels of enzymes that convert harmless substances to cancer-causing agents. To assess the effects of fermented dairy products, nine health volunteers received a three-week diet containing L. acidophilus, Bifidobacterium bifidum, and mesophilic cultures, such as Streptococcus lactis and S. cremoris. The production of methane and hydrogen and the activities of the fecal enzymes beta-galactosidase and beta-glucosidase were measured and served as indicators of fermentation. Because the enzymes nitroreductase, azoreductase, and beta-glucuronidase in the feces are associated with colon cancer, the levels of these enzymes were also evaluated. The findings reveal that the production of hydrogen and methane, and the activities of the fecal enzymes beta-galactosidase, beta-glucuronidase, and azoreductase were not altered over the three-week study. However, fecal beta-glucosidase activity increased and nitroreductase levels decreased. (Consumer Summary produced by Reliance Medical Information, Inc.)

Medical examination, Physiological aspects, Bacteria, Feces, Fermented foods, Colon (Anatomy), Colon

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