Aging, nutrient choice, activity, and behavioral responses to nutrients.
We directly measured nutrient consumption, activity patterns, and behavior in young volunteers and healthy elderly volunteers (N = 86) living in an identical environment. Compared to the young subjects, the elderly adults consumed fewer calories and less carbohydrate and fat, but not less protein, after adjustment for differences in body weight. Males of both ages consumed more protein than females after adjustment for body weight. All subjects snacked predominantly on carbohydrate-rich foods. The elderly subjects, however, consumed significantly fewer snacks than the young. Patterns of mood and activity also differed between age groups: the elderly volunteers were more active and alert than the young, especially early in the day, as measured by activity monitors and self-report questionnaires. We also examined the behavioral effects of high-protein and high-carbohydrate meals on these subjects because of the effects such meals can have on brain serotonin levels. The subjects ingested isocaloric carbohydrate- or protein-rich breakfasts and dinners and then participated in a series of behavioral tasks. Significant interactions between the type of meal consumed (protein versus carbohydrate) and the time at which they were ingested (breakfast versus dinner were observed. A protein meal consumed at breakfast induced more fatigue and sleepiness than an isocaloric carbohydrate meal; this was reversed in the evening when a carbohydrate meal induced more fatigue. Elderly subjects were less sensitive to sleepiness induced by carbohydrate in the evening. Overall, the young and old adults exhibited significant differences in calorie and carbohydrate intakes and also mood and activity, even when they chose their foods from an identical selection of food items and followed the same basic daily routines while living in a controlled study environment.
Lieberman
H R
HR
Department of Brain and Cognitive Science, Massachusetts Institute of Technology, Cambridge 02139.
Wurtman
J J
JJ
Teicher
M H
MH
D000328:Adult; D000339:Affect; D000368:Aged; D000375:Aging; D000596:Amino Acids / Q000097:blood; D001519:Behavior; D002940:Circadian Rhythm; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D002149:Energy Intake; D005260:Female; D006801:Humans; D008297:Male; D009747:Nutritional Physiological Phenomena
D000596:Amino Acids; D004040:Dietary Carbohydrates; D004044:Dietary Proteins