The Dose-Response Effects of Lean Beef in a Mediterranean-Style Dietary Pattern on Established and Emerging Cardiovascular Disease Risk Factors
Open Access
- Author:
- Fleming, Jennifer A
- Graduate Program:
- Nutritional Sciences
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- February 22, 2019
- Committee Members:
- Penny Margaret Kris-Etherton, Dissertation Advisor/Co-Advisor
Penny Margaret Kris-Etherton, Committee Chair/Co-Chair
Connie Jo Rogers, Committee Member
Gregory C Shearer, Committee Member
Peter Lawrence Bordi, Jr., Outside Member - Keywords:
- Mediterranean diet
Lean beef
Cardiovascular disease
Lipids
Dietary patterns
Vascular health - Abstract:
- A Mediterranean (Med) dietary pattern is widely recommended because of an extensive evidence base showing beneficial effects on cardiovascular disease (CVD) risk and mortality. As with many dietary patterns, much of the evidence has evolved from observational trials consistently showing major reductions in cardiovascular morbidity and mortality. Notably, due to a wide range of adherence scales, the benefits of a Med diet on cardiovascular risk factors (i.e. lipids, lipoproteins, vascular health) is largely based on findings from a variety of similar plant-based dietary patterns. Moreover, the benefits of a Med diet on emerging CVD risk factors is somewhat lacking and/or inconsistent. Specifically, limited evidence exists among a U.S. population. This is important as adherence to plant-based diets is often hampered by restrictions on red meat, a staple of the American diet. Thus, the objective of this study was to evaluate the effects of a Med diet (CHO 42%, PRO 17%, FAT 41%, SFA 8%, MUFA 26%, PUFA 8%) with different quantities of lean beef (0.5, 2.5 and 5.5 oz/d) compared to an Average American diet (AAD; CHO 52%, PRO 15%, FAT 33%, SFA 12%, MUFA 13%, PUFA 8%) on multiple traditional and emerging CVD risk factors (lipids, lipoproteins, lipid subspecies, vascular health and HDL function) in a U.S. population. This was a multicenter, 4-period controlled feeding, randomized, crossover study conducted at Penn State University and USDA, Beltsville. Participants (n=66) included generally healthy normal to overweight/obese males and females (BMI= 20-38 kg/m2) aged 30 to 70 years. Participants were randomized to each of four diets for 4 weeks with an approximate 2-week break between treatments. Fasting blood samples were collected on two consecutive days at baseline (start of study) and at the end of each 4-week period. All three Med diets elicited similar lowering of total cholesterol (TC; p<0.0001), LDL-C (p<0.001), non-HDL-C (p<0.0001) and apolipoprotein B (apoB) (p<0.0001) that was greater than the AAD. All diets (AAD, MED0.5, MED2.5 and MED5.5) decreased HDL-C (-3.46 ± 1.11, -4.93 ± 1.14, -4.44 ± 0.93, and -3.31 ± 1.20 mg/dl, respectively; p<0.01) and apolipoprotein A1 (apoA1) (-8.63 ± 1.77, -11.45 ± 1.72, -11.21 ± 1.71, and -7.97 ± 1.90 mg/dl, respectively; p<0.0001). However, the combined effects of the three Med diets versus AAD, on ABCA1 cholesterol efflux were significantly higher following a Med style diet (3.2 vs. 3.6; p=0.012, respectively). All three Med diets significantly reduced LDL particle number, however only the reductions by the MED0.5 and 2.5 were significantly different from AAD. Compared to AAD all three Med diets significantly decreased brachial systolic and diastolic pressures (p<0.01 for all). Both the 0.5 oz./day (-3.30 ± 0.76) and 2.5 oz./day (-2.94 ± 0.76) Med diets elicited greater reductions in central systolic blood versus the AAD. A similar pattern was observed for central diastolic pressure. There was a significant treatment effect for pulse wave velocity (p<0.01); pulse wave velocity was lower following consumption of a Med diet containing 0.5 oz. lean beef/day (6.86 m/sec ± 0.14; p<0.05) and 2.5 oz. of lean beef/day (6.84 m/sec ± 0.15; p<0.01) compared to the AAD (7.10 m/sec ± 0.14). A dose response analyses showed a significant difference between the MED0.5 and 5.5 in total cholesterol and LDL particle number with the MED0.5 eliciting a greater lipid lowering effect. Our results demonstrate that lean beef at intakes equivalent to the average consumption in the U.S. (2.5 oz./day lean beef), may be incorporated into a Med style diet with no differences in cardiovascular risk benefits compared to a traditional Med diet with 0.5 oz./day lean beef. Despite there being no between treatment differences among the 3 Med diets, because lean beef intakes of 5.5 oz./day were similar to those for the AAD, our findings suggest that ≤2.5 oz./day of lean beef can be included in a Med diet and not compromise the cardiovascular health benefits of a Med diet with 0.5 oz. lean beef. Furthermore, the observed improvements in cardiovascular risk markers were consistent with previous findings suggesting our U.S. population adhered well to the diet and as a result achieved similar cardiovascular benefits.