In a recent study published in the journal nutrientsInvestigators in the United States evaluated the impact of high-fat (HFB) or low-fat (LFB) ground beef on vascular function.
Cardiovascular disease (CVD) is one of the leading causes of death worldwide. Central obesity, dyslipidemia, and hypertension increase the risk of CVD. Furthermore, measures of vascular function are independent risk markers for CVD. Red meat consumption is associated with CVD risk due to high levels of heme iron, cholesterol, and saturated fatty acids (SFAs).
However, the highest risk is seen with processed meat intake, with little or no association with raw meat intake when red meat consumption is within recommended levels. So far, studies have not evaluated the impact of red meat on vascular function.
Study: Assessment of vascular function in response to consumption of high-fat and low-fat ground beef in men. Image Credit: Mehmet Cetin / Shutterstock
About the study
In the present study, the researchers examined the impact of LFB/HFB consumption on vascular function in men. Participants were recruited in October and November 2019, and ground beef treatments began in February 2020. The data presented here was collected from a subsample of a larger study. Participants were instructed not to change their usual diet or physical activity.
Participants’ body composition, vascular function, and aerobic capacity were assessed two weeks before starting the LFB (5% fat) or HFB (25% fat) intervention. Participants completed two five-week interventions (five ground beef patties per week) with a four-week washout period in between. Vascular function and aerobic capacity were reassessed in the washout period and the last week of each intervention.
Carotid-femoral pulse wave velocity (PWV) measurements were obtained by fasting ultrasonography; the participants refrained from consuming alcohol within 24 hours prior to the measurements. Flow-mediated dilation (FMD) was assessed after an overnight fast. Body composition was analyzed by dual energy X-ray absorptiometry (DXA).
Oxygen consumption (VO2) was examined before and after the intervention to account for confounding factors that alter vascular measurements. It was measured during a treadmill incremental exercise test using a metabolic gas analysis system. VO max2 (V.O.2 max) was calculated using individualized linear regression based on VO2 and heart rate.
Thirty-two men were randomized to the HFB or LFB intervention; seven voluntarily withdrew or were excluded and two refused to provide vascular measurements. Overall, 23 men with a mean age of 39.9 years were included in the analyses. The FMD results indicated a significant main effect of the test. A follow-up paired t-test showed a greater FMD response after the HFB intervention than the baseline, LFB intervention, and washout time point.
There were no differences in the initial diameter of the brachial artery and the time to maximum dilation at any point. For PWV measurements, there were no significant condition, test, or interaction effects between study visits. Resting blood pressure (BP) measurements revealed a significant effect of systolic BP (SBP) status, with lower SBP during the HFB intervention relative to baseline or the LFB intervention. SBP was lower during the washout period than in LFB or at baseline.
SBP was not significantly different between the HFB intervention and the washout period. A significant effect of condition was observed for resting diastolic BP (DBP), which was lower during the HFB intervention than baseline or washout levels. Mean arterial pressure (MAP) was significantly reduced after the HFB intervention and in the washout period relative to baseline.
Total calorie intake was consistent throughout the study periods. A significant test effect was observed for percentage energy (%EN) from carbohydrates; it was lower during the HFB intervention than at baseline. Likewise, an interaction effect was observed for the % EN of fats and proteins. % NE for fat and protein was significantly higher during any of the beef interventions. The estimated VO2 max did not differ significantly between visits.
The investigators observed a greater FMD response with HFB compared to the LFB intervention, whereas PMV did not differ. Furthermore, DBP and SBP were lower during the HFB intervention. Recovery from FMD during the HFB intervention to normal levels of endothelial function suggests a lower CVD risk. PWV is unlikely to change with short-term dietary interventions, consistent with previous studies.
However, the findings demonstrated a decrease in BP with short-term HFB consumption, contrasting with the widely held view that foods high in SFA are unhealthy dietary choices. Taken together, the results showed that the HFB or LFB diet did not adversely affect vascular function and that the HFB intervention improved the response to FMD and was associated with reduced CVD risk.