Effect of varying quantities of lean beef as part of a Mediterranean-style dietary pattern on lipids and lipoproteins: a randomized crossover controlled feeding trial

Authors: FLEMING, JENNIFER - Pennsylvania State University; KRIS-ETHERTON, PENNY - Pennsylvania State University; PETERSON, KRISTINA - Pennsylvania State University; Baer, David

Submitted to: The American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/16/2020
Publication Date: 4/1/2021
Citation: Fleming, J.A., Kris-Etherton, P.M., Peterson, K.S., Baer, D.J. 2021. Effect of varying quantities of lean beef as part of a Mediterranean-style dietary pattern on lipids and lipoproteins: a randomized crossover controlled feeding trial. American Journal of Clinical Nutrition. 113:1126-1136. https://doi.org/10.1093/ajcn/nqaa375.
DOI: https://doi.org/10.1093/ajcn/nqaa375

Interpretive Summary: There is some evidence from survey studies which suggests that red meat consumption is associated with increased risk of cardiovascular disease. From these studies, it is unclear whether this relationship between red meat consumption and risk for heart disease is causative. Few randomized controlled studies (which are studies that can show cause and effect) have examined the effect of incorporating lean beef into a healthy dietary pattern such as the Mediterranean diet. The objective of this research was to evaluate the effects of a Mediterranean (MED) style diet containing different amounts of lean beef (0.5, 2.5 and 5.5 oz./day) on lipid and lipoprotein concentrations, particle number and size. Further, this research compared effects of the MED style diet to an average American diet with lean beef fed at 2.5 oz/day). This project was conducted as a multicenter, 4-period controlled feeding, randomized crossover study conducted at Penn State University and USDA, Beltsville. Participants consumed each of the 4 diets for 4 weeks with an approximate 2-week break between diets. Fasting blood samples were collected at baseline (start of study) and at the end of each 4-week period. Compared to the average American diet, total cholesterol, LDL (‘bad’) cholesterol and other cholesterol measures (apolipoprotein B and non HDL cholesterol) were lower following consumption of the three MED diets, and there were no differences among the three MED diets. All diets decreased HDL (‘good’) cholesterol and apolipoprotein A1 from baseline. All three MED diets significantly reduced LDL particle number from baseline; however, only after consumption of two MED diets, containing lower amounts of lean beef (0.5 and 25 oz/day), was there as significant reduction in LDL particle number compared to AAD. These findings are consistent with the transition to dietary pattern-based recommendations and demonstrate that lean beef in amounts up to 2.5 oz/day can be part of a healthy Mediterranean style dietary pattern without attenuating the cardiovascular benefits.

Technical Abstract: To evaluate the effects of a Mediterranean (MED) diet (carbohydrate 42%, protein 17%, fat 41%, SFAs 8%, MUFAs 26%, PUFAs 8%) with 14 (MED0.5; 0.5 oz), 71 (MED2.5; 2.5 oz), and 156 (MED5.5; 5.5 oz) g/d/2000 kcal lean beef compared with an average American diet (AAD; carbohydrate 52%, protein 15%, fat 33%, SFAs 12%, MUFAs 13%, PUFAs 8%) on lipid and lipoprotein concentrations, particle number, and size. This was a multicenter, 4-period controlled feeding, randomized crossover study. Fifty-nine generally healthy males and females (BMI 20–38 kg/m2; age 30–65 y) consumed each diet for 4 wk with a =1-wk washout between the diets. Fasting blood samples were collected at baseline and at the end of each 4-wk period. Lipid subfractions were measured by NMR. Compared with the AAD, all 3 MED diets decreased LDL cholesterol (MED0.5: -10.3 mg/dL; 95% CI: -5.4, -15.7 mg/dL; MED2.5: -9.1 mg/dL; 95% CI: -3.9, -14.3 mg/dL; MED5.5: -6.9 mg/dL; 95% CI: -1.7, -12.1 mg/dL; P < 0.0001). All MED diets elicited similar reductions in total LDL particle number compared with baseline (P < 0.005); however, significant decreases only occurred with MED0.5 (-91.2 nmol/L; 95% CI: -31.4, -151.0 nmol/L) and MED2.5 (-85.3 nmol/L; 95% CI: -25.4, -145.2 nmol/L) compared with AAD (P<0.003). Compared with the AAD, non-HDL cholesterol (P < 0.01) and apoB (P < 0.01) were lower following the 3 MED diets; there were no differences between the MED diets. All diets reduced HDL-cholesterol and HDL particle number from baseline (P < 0.01). Lipid and lipoprotein lowering was not attenuated with the inclusion of lean beef in amounts =71 g (2.5 oz)/d as part of a healthy low-saturated-fat Mediterranean-style diet.