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ARS Home » Northeast Area » Boston, Massachusetts » Jean Mayer Human Nutrition Research Center On Aging » Research » Publications at this Location » Publication #37498
Title: ELDERLY WOMEN ACCOMMODATE TO A LOW PROTEIN DIET WITH LOSSES OF BODY CELL MASS, MUSCLE FUNCTION, AND IMMUNE RESPONSE

Author
item CASTANEDA CARMEN - TUFTS-HNRCA
item CHARNLEY JACQUEL - TUFTS-HNRCA
item EVANS WILLIAM J - PENN STATE
item CRIM MARILYN C - TUFTS-HNRCA

Submitted to: The American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: There is evidence that a large number of elderly women in the US and Third World Countries consume diets low in protein. The survival of these populations has suggested that there is con- siderable ability to adapt to low dietary protein levels. The available research data to date do not provide information about the extent to which the elderly can adapt to a variety of protein intakes over longer periods of time. In the present study, two levels of dietary protein, estimated to be the RDA and half the RDA levels, were fed to elderly women for 9 weeks at maintenance energy intakes. Clinical parameters of protein homeostasis e.g. nitrogen balance (difference between the amount of nitrogen ingested and excreted by the body), body composition, and biochemical and physiological function measurements were measured. The results of this study indicate that the elderly women were unable to adapt to the low protein diet but accommo- dated with losses of lean tissue (lean body mass and muscle mass), cellular immune response, and muscle functional capacity (neuromuscular muscle function and strength). Subjects in the higher protein group did not experience decreases in these parameters consistent with successful adaptation. Our findings indicate that the functional status and body composition of healthy elderly women were impaired when they consumed diets marginal in protein. This information is very important from a clinical and public health point of view.

Technical Abstract: A 9-week study of adaptation to marginal protein intakes was conducted in 12 elderly females. Subjects were randomized into two groups fed a weight maintenance diet containing either 1.47 (low) or 2.94 (adequate) g protein.kg body cell mass**-1.d**-1 (0.45 and 0.92 g.kg body weight**-1.d**-1, respectively). Mean nitrogen balance in the low protein group remained negative throughout the study. These subjects experienced significant losses in lean tissue, immune response and muscle function. The adequate protein group was in nitrogen balance throughout the study, without changes in lean tissue, and with improvements in immune response, serum immunoglobulins, albumin, and total protein levels, and muscle function. Thus, elderly women fed the low protein diet accommodated to the diet by compromising functional capacity, while those fed the adequate diet maintained functional capacity consistent with successful adaptation.