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

Abstract

Background: It remains unclear whether red meat consumption is causatively associated with cardiovascular disease (CVD) risk, and few randomized controlled studies have examined the effect of incorporating lean beef into a healthy dietary pattern.

Objectives: 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.

Methods: 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.

Results: 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).

Conclusions: 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.This study is registered at clinicaltrials.gov as NCT02723617.

Keywords: Mediterranean diet; cardiovascular disease; lean beef; lipids; lipoproteins.

© The Author(s) 2021. Published by Oxford University Press on behalf of the American Society for Nutrition.

Figures

FIGURE 1

Study design. Clinical assessments were conducted across 2 consecutive days. AAD, average American diet; MED, Mediterranean-style eating pattern used in the study; MED0.5, MED diet with 14 g (0.5 oz) per day of lean beef; MED2.5, MED diet with 71 g (2.5 oz) per day of lean beef; MED5.5: MED diet with 156 g (5.5 oz) per day of lean beef based on a 2000-kcal diet.

FIGURE 2

CONSORT diagram showing the flow of participants through each stage of the randomized trial. AAD, average American diet; MED, Mediterranean-style eating pattern used in the study; MED0.5, MED diet with 14 g (0.5 oz) per day of lean beef; MED2.5, MED diet with 71 g (2.5 oz) per day of lean beef; MED5.5: MED diet with 156 g (5.5 oz) per day of lean beef based on a 2000-kcal diet; PSU, Penn State University.

FIGURE 3

Change from baseline in lipids and lipoproteins after 4 wk of consuming each test diet. Mean change (±SEM) from baseline (n = 59). The MIXED procedure in SAS (version 9.4; SAS Institute Inc.) was used to test for within- and between-diet effects. *,**,***Significantly different from baseline: *P < 0.05, **P < 0.01, ***P < 0.001. Where the main effect for diet was statistically significant at a value of P < 0.003 (Bonferroni adjusted α for multiple comparisons), post hoc testing was conducted and different letters are significantly different, P ≤ 0.01. AAD, average American diet; HDL-C, HDL cholesterol; LDL-C, LDL cholesterol; MED, Mediterranean-style eating pattern used in the study; MED0.5, MED diet with 14 g (0.5 oz) per day of lean beef; MED2.5, MED diet with 71 g (2.5 oz) per day of lean beef; MED5.5, MED diet with 156 g (5.5 oz) per day of lean beef based on a 2000-kcal diet; non-HDL-C, non-HDL cholesterol; TG, triglycerides.

FIGURE 4

Change from baseline in non-HDL subparticles after 4 wk of consuming each test diet. Mean change (±SEM) from baseline (n = 59). The MIXED procedure in SAS (version 9.4; SAS Institute Inc.) was used to test for within- and between-diet effects. *,**,***Significantly different from baseline: *P < 0.05, **P < 0.01, ***P < 0.001. Where the main effect for diet was statistically significant at a value of P < 0.003 (Bonferroni adjusted α for multiple comparisons), post hoc testing was conducted and different letters are significantly different, P ≤ 0.05. AAD, average American diet; MED, Mediterranean-style eating pattern used in the study; MED0.5, MED diet with 14 g (0.5 oz) per day of lean beef; MED2.5, MED diet with 71 g (2.5 oz) per day of lean beef; MED5.5, MED diet with 156 g (5.5 oz) per day of lean beef based on a 2000-kcal diet; TG, triglycerides.

FIGURE 5

Change from baseline in HDL subclasses after 4 wk of consuming each test diet. Mean change (±SEM) from baseline (n = 59). The MIXED procedure in SAS (version 9.4; SAS Institute Inc.) was used to test for within- and between-diet effects. #, number. *,**,***Significantly different from baseline: *P < 0.05, **P < 0.01, ***P < 0.001. AAD, average American diet; MED, Mediterranean-style eating pattern used in the study; MED0.5, MED diet with 14 g (0.5 oz) per day of lean beef; MED2.5, MED diet with 71 g (2.5 oz) per day of lean beef; MED5.5, MED diet with 156 g (5.5 oz) per day of lean beef based on a 2000-kcal diet.

FIGURE 6

Change from baseline in apolipoproteins after 4 wk of consuming each test diet. Mean change (±SEM) from baseline (n = 59). The MIXED procedure in SAS (version 9.4; SAS Institute Inc.) was used to test for within- and between-diet effects. *,**,***Significantly different from baseline: *P < 0.05, **P < 0.01, ***P < 0.001. Where the main effect for diet was statistically significant at a value of P < 0.003 (Bonferroni adjusted α for multiple comparisons), post hoc testing was conducted and different letters are significantly different, P ≤ 0.01. AAD, average American diet; MED, Mediterranean-style eating pattern used in the study; MED0.5, MED diet with 14 g (0.5 oz) per day of lean beef; MED2.5, MED diet with 71 g (2.5 oz) per day of lean beef; MED5.5, MED diet with 156 g (5.5 oz) per day of lean beef based on a 2000-kcal diet.

FIGURE 7

Change from baseline in plasma proprotein convertase subtilisin/kexin type 9 after 4 wk of consuming each test diet. Mean change (±SEM) from baseline (n = 59). The MIXED procedure in SAS (version 9.4; SAS Institute Inc.) was used to test for within- and between-diet effects. *Significantly different from baseline, *P < 0.05. AAD, average American diet; MED, Mediterranean-style eating pattern used in the study; MED0.5, MED diet with 14 g (0.5 oz) per day of lean beef; MED2.5, MED diet with 71 g (2.5 oz) per day of lean beef; MED5.5, MED diet with 156 g (5.5 oz) per day of lean beef based on a 2000-kcal diet.