Beef MUFA:SFA Ratio Affects the Acute Lipoprotein Response to Exercise
Diets high in monounsaturated fatty acid to saturated fatty acid ratios (MUFA:SFA) and exercise are independently linked to improved blood lipid profiles, yet the combined effects of these two factors have seldom been studied. PURPOSE: We tested the hypothesis that consumption of ground beef with a relatively high MUFA:SFA ratio compared with lower ratio ground beef and self-selected (SS) diets would amplify the effects of aerobic exercise on the blood lipid profile. METHODS: Healthy, untrained men (N = 14, height=181cm, weight=92.8 kg, BMI=28.2) weekly consumed five 114 g beef patties either high (HR=1.1) or low (LR=0.71) in MUFA:SFA ratios for 5 weeks (random order). Four-week washout periods were spaced between diets, and subjects were allowed to revert to their SS diets for 5 weeks after the second experimental beef diet. Diets and physical activity habits were assessed by self-reported records, but otherwise not controlled, and exercise training was not prescribed during the diet interventions. A single session of aerobic exercise (70% VO2PEAK , 1675 kJ) was completed during the last week of each diet. Fasting blood samples for lipid and lipoprotein analyses were obtained at seated rest 24 hour before (BE) and after (AE) each exercise session. RESULTS: Subjects did not report changes in their diet, other than that prescribed, or changes in physical activity patterns throughout the study. Diet (3) × Exercise (2) repeated measures ANOVA (alpha=0.05) demonstrated a significant interaction for total cholesterol (TC), LDL-C, HDL-C, HDL2-C, and HDL3-C. Follow-up statistical analyses revealed that blood concentrations (BE to AE, mg/dL) of TC (196±45 to 222±53), LDL-C (128±41 to144±47), HDL-C (46±8 to 53±11), HDL2-C (9±3 to 11±4), and HDL3-C (37±5 to 42±8) were significantly elevated after the HR diet, but did not change in response to exercise after LR or SS. CONCLUSION: In healthy men the beef MUFA:SFA ratio in the diet affects the characteristics of the blood lipid profile after aerobic exercise. Partial support from the National Cattleman’s Beef Association and the Sydney and J.L. Huffines Institute for Sports Medicine and Human Performance.