High-oleic ground beef, exercise, and risk factors for cardiovascular disease in postmenopausal women
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Sixty-six percent of the ground beef consumed in the U.S. contains 16-30 percent fat by weight, and at the retail level, ground beef fat varies widely with regards to saturated, monounsaturated and trans-fatty acid content. Through two independent studies the effect of fatty acid composition of ground beef on selected cardiovascular disease risk indicators was evaluated. In the first study, 27 free-living normocholesterolemic men completed a three-way crossover dietary intervention. Subjects consumed five, 114-g ground beef patties per week for 5 wk with intervening 4-wk washout periods. Patties contained 24 percent total fat with monounsaturated fatty acid:saturated fatty acid (MUFA:SFA) of either 0.71 (low-MUFA, pasture-fed), 0.83 (mid-MUFA, short-term corn-fed), or 1.10 (high-MUFA, long-term corn-fed). Blood was collected from each subject before and at the end of each diet period. Overall, the ground beef interventions decreased plasma insulin, HDL2, and HDL3 particle diameter and -linolenic acid (18:2 (n-3)), and increased plasma arachidonic (20:4(n-6)). The greatest increase in HDL cholesterol from baseline (0.07 mmol/L) was after the high-MUFA ground beef intervention. An increase from baseline in LDL particle diameter (0.5 nm) occurred after the mid- and high-MUFA interventions.We concluded that low-MUFA ground beef from pasture/hay-fed cattle was no more heart healthy than high-MUFA ground beef from corn-fed cattle as judged by common clinical criteria. In the second study, 19 of 29 post menopausal women completed a two-way crossover design. Subjects consumed five, 114-g ground beef patties per week for 6 wk periods separated by a 4 wk washout period. The low-MUFA patties contained 19.4 percent fat with MUFA:SFA of 0.9. The high-MUFA patties contained 22.5 percent fat with a MUFA:SFA ratio of 1.3. In addition to patty consumption, the subjects completed a bout of exercise during the last week of each phase. Blood was taken before, each diet phase (24 hr before exercise) and 24 hr post exercise. Total cholesterol was increased by the high-MUFA patties with the most significant increase seen in HDL cholesterol, mainly HDL2b subfraction. Lipid-rich lipoprotein fractions were increased with the low-MUFA diet, but not by the high-MUFA diet. Very long chain fatty acids were depressed by low MUFA patty consumption. When unadjusted for plasma volume shifts (raw), exercise decreased triglycerides in all three phases. Raw VLDL cholesterol was reduced after exercise during the intervention phases. Raw RLP and IDL cholesterol were reduced after exercise during the high-MUFA intervention. HDL2b was reduced after exercise during the high-MUFA phase. LDL mean size increased and LDL mean density decreased after exercise during the low-MUFA intervention. HDL mean density increased after exercise during both ground beef interventions. The data indicate that high-oleic ground beef can reduce some cardiovascular disease risk factors and can be a part of a healthful diet. Exercise can have a beneficial impact on cardiovascular disease risk factors independent and in conjunction with ground beef consumption.
