Exogenous Carbohydrate Reduces Cortisol Response from Combined Mental and Physical Stress.

Combined mental and physical stress is associated with exacerbated cortisol production which may increase risk for the progression of cardiovascular disease in individuals working in high-stress occupations (e.g., firefighters, military personnel, etc.). Carbohydrate (CHO) ingestion prior to physical stress may attenuate cortisol concentrations. This project was the first to investigate the effect of CHO ingestion on cortisol response from combined mental and physical stress. 16 men 21-30 years old were randomly assigned a 6.6% CHO beverage or non-CHO control 15 min prior to performing a dual-concurrent-stress challenge. This consisted of physical stress (i.e., steady state exercise) combined with computerized mental challenges. Blood was sampled 70, 40, and 15 min before exercise, immediately at onset of exercise, 10, 20, 30, 35 min during exercise, and 15, 30, 45, and 60 min after exercise. There was a significant main effect for treatment regarding mean cortisol concentrations (F=5.30, P=0.0219). The total area under curve for cortisol was less when CHO was ingested (T7=4.07, P=0.0048). These findings suggest that CHO ingestion immediately prior to combined mental and physical stress may attenuate cortisol responses.

Comparison of the effects of adding fish high or low in n-3 fatty acids to a diet conforming to the Dietary Guidelines for Americans.

OBJECTIVE: To compare the effects of diets containing high or low amounts of n-3 fatty acids on lipid levels in men. DESIGN: A continuous 40-day feeding study was conducted using a 5-day cycle menu. The control diet, which was fed the first 21 days of the trial, contained 32% of energy as fat and 44.4 g total dietary fiber per day. Total serum cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TGs) were evaluated 1 day before the trial began and on days 21 and 41. SUBJECTS: 17 men aged 21 to 42 years who were free-living individuals with no apparent illnesses or hyperlipidemia. INTERVENTION: The treatment diets, which were substituted daily for the regular entrees for the last 19 days of the trial, contained 180 g/day of either farm-raised catfish or wild Alaskan salmon. STATISTICAL ANALYSES PERFORMED: Serum data were analyzed using analysis of covariance with the initial values as the covariates. RESULTS: After 21 days on the control diet, TC and TGs decreased; however, there were no further decreases during the last 19 days when fish was consumed. LDL-C remained unchanged after the first 21 days but was lower than the initial value by day 41. HDL-C levels were similar over the 40 days. There were no significant differences in lipid levels of men who consumed catfish and those who consumed salmon. APPLICATIONS/CONCLUSIONS: Farm-raised catfish compared favorably to wild Alaskan salmon when incorporated into the total diet in regard to lipid levels in men.