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.

Unprocessed red meat in the dietary treatment of obesity: a randomized controlled trial of beef supplementation during weight maintenance after successful weight loss

“…Three randomized crossover trials evaluated the effects of including different amounts of mostly lean red meat as part of heart-healthy dietary patterns [i.e., Dietary Approaches to Stop Hypertension (DASH) and Mediterranean diets)] during eucaloric feeding in individuals with normal weight, overweight, or obesity ( 19 , 24 , 27 ). All these trials included controlled feeding periods (4–5 wk long) with all foods provided that aimed at keeping body weight stable.…”

“…All these trials included controlled feeding periods (4–5 wk long) with all foods provided that aimed at keeping body weight stable. Fleming et al ( 24 ) evaluated Mediterranean-like diets with 14, 71, or 156 g lean beef/2000 kcal/d against a control diet while maintaining total protein content (17–20% of all calories), and found that all 3 experimental diets decreased LDL cholesterol and apoB, but did not affect HDL cholesterol, apoA-1, and triglyceride concentrations. Some differences were observed in the extent of reduction in total LDL particle number, but these were confined to the large LDL subclass; none of the diets decreased small LDL particles, which are particularly atherogenic ( 24 ).…”

“…Fleming et al ( 24 ) evaluated Mediterranean-like diets with 14, 71, or 156 g lean beef/2000 kcal/d against a control diet while maintaining total protein content (17–20% of all calories), and found that all 3 experimental diets decreased LDL cholesterol and apoB, but did not affect HDL cholesterol, apoA-1, and triglyceride concentrations. Some differences were observed in the extent of reduction in total LDL particle number, but these were confined to the large LDL subclass; none of the diets decreased small LDL particles, which are particularly atherogenic ( 24 ). O'Connor et al ( 27 ) evaluated 2 Mediterranean-like diets containing lean red meat (beef and pork) at either 28 or 68 g/d (18–19% of all calories from protein), and observed that the meat-rich pattern decreased LDL cholesterol and apoB concentrations to a greater extent than the meat-poor pattern, but this coincided with an unintended small yet significant reduction in body weight.…”

“…Our results extend these observations and demonstrate no differences in any clinically relevant outcomes between diets that contain small or large amounts of mostly lean beef, consumed ad libitum after weight loss. Further, it is evident that diet-induced changes in body composition, energy metabolism, and cardiometabolic risk factors largely depend on the physiological state with respect to energy balance and body weight homeostasis, rather than the amount of red meat in the diet ( 19 , 24–27 ).…”

“…Previous clinical trials have demonstrated that unprocessed red meat in amounts from ∼15 g/d up to ∼150 g/d can be included as part of a healthy dietary pattern without adverse effects on body weight and cardiovascular risk factors ( 19 , 24–27 ), but the physiological effects of red meat consumption during weight loss maintenance are not known. Accordingly, the primary aim of this parallel randomized intervention trial was to investigate the effects of eating small (25 g/d) or large (150 g/d) amounts of red meat (beef) as part of a healthy diet—otherwise consumed ad libitum—on the maintenance of lost weight after successful weight loss, and secondarily on body composition, energy metabolism, and cardiometabolic risk factors.…”