Beef and soy-based food supplements differentially affect serum lipoprotein-lipid profiles because of changes in carbohydrate intake and novel nutrient intake ratios in older men who resistive-train.

OBJECTIVE: We examined if the predominant source of dietary protein influenced the lipoprotein-lipid profile in older men who performed resistive exercise training (RT).

DESIGN: This is a 14-week, randomized, repeated-measures study with a 12-week period of RT with supplementation of different sources of dietary protein (beef and soy).

SETTING: Nutrition, Metabolism, and Exercise Laboratory, Central Arkansas Veteran's Healthcare System, North Little Rock, Ark. Subjects Twenty-six healthy men were recruited, and 21 men (age 65 +/- 5 years, body mass index 28.2 +/- 2.6 kg/m 2 ) completed the study. Interventions For 14 weeks, all men were counseled to self-select a lacto-ovo-vegetarian diet. For 2 weeks (baseline), all men also consumed 0.6 g-protein/kg per day from portioned quantities of soy-based texturized vegetable protein foods. For the next 12 weeks, 11 men were randomized to continue with texturized vegetable protein foods (VEG group), whereas 10 men were randomized to receive 0.6 g-protein/kg per day from portioned quantities of beef (BEEF group) and continue their otherwise lacto-ovo-vegetarian diet. All men participated in RT 3 d/wk during this 12-week period. Assessments of upper and lower body muscle strength and power, serum lipoprotein-lipid profile, and dietary nutrient intakes were made at baseline and week 12 of RT (POST).

RESULTS: The BEEF and VEG groups increased ( P < .05) overall muscle strength and muscle power with RT, with no differences between groups. From baseline to POST, the BEEF group had increased concentrations of high-density lipoprotein cholesterol ( P = .025; HDL-C), low-density lipoprotein cholesterol ( P = .027; LDL-C), and total cholesterol ( P = .015: CHOL), with no changes ( P > .05) in triacylglycerol (TG), the CHOL/HDL-C ratio, or the TG/HDL-C ratio. The VEG group did not experience within-group changes ( P > .05) in any lipoprotein-lipid parameter. At POST, the concentrations of HDL-C, LDL-C, and CHOL were greater in the BEEF group compared with the VEG group. There were significant interaction effects for HDL-C ( P = .004) and the TG/HDL-C ratio ( P = .022). Multiple regression analysis determined that, regardless of intervention, change in the saturated fat/fiber ratio (SF/fiber) predicted CHOL (adjusted R 2 = 0.34); the SF/fiber ratio predicted LDL-C (adjusted R 2 = 0.36); the cholesterol/fiber intake ratio predicted HDL-C (adjusted R 2 = 0.26), and the change in carbohydrate intake predicted the CHOL/HDL-C ratio (adjusted R 2 = 0.37) and TG (adjusted R 2 = 0.44).

CONCLUSIONS: These results suggest that the lipoprotein-lipid profile in these older men was differentially affected by supplementation with beef versus soy-based foods during RT. Regardless of group, the lipoprotein-lipid changes were predicted by differences in the SF/fiber ratio and cholesterol/fiber ratio and increases in carbohydrate intake over time.