Mediterranean Diet with Lean Beef May Lower Heart Risk Factors
- Mediterranean diet combined with small to moderate portions of lean beef helped lower risk factors for developing heart disease, such as LDL cholesterol
Red meat such as beef has been associated with an increased risk for cardiovascular disease in previous studies.
But, researchers say, it has remained unclear whether red meat actually causes these effects or if they actually are caused by other diet and lifestyle choices that people engage in alongside red meat consumption.
Additionally, the researchers said many studies have combined both fresh and processed meats together when evaluating red meat consumption and health.
Processed red meats have a very different nutrient profile than fresh meat - for example, processed meat products are much higher in sodium - that could explain the red meat research that has been reported.
"The Mediterranean diet is traditionally low in red meat," researcher Jennifer Fleming said. "But, knowing that many Americans enjoy red meat, we wanted to examine how combining lean beef with the Mediterranean diet would affect cardiovascular risk markers."
The randomized controlled study included 59 participants.
Every participant consumed each diet for four weeks each, with a one-week break between each diet period.
Blood samples were drawn at the beginning of the study as well as after each diet period.
- Average American diet (the control diet)
- Mediterranean diet including 0.5oz/14g beef a day (the amount recommended in the Mediterranean diet pyramid)
- Mediterranean diet including 2.5oz/70g beef a day (amount average Americans eat in a day)
- Mediterranean diet including 5.5oz/154g beef a day (an amount previous research connected with certain heart health benefits)
All three Mediterranean diet periods included olive oil as the predominant fat source, three to six servings of fruits, and six or more servings of vegetables a day.
These diet periods provided 41% calories from fat, 42% from carbohydrates and 17% from protein and the beef included was either lean or extra-lean.
The researchers were able to use a special technology called nuclear magnetic resonance -- or NMR technology -- to measure the number and size of lipoprotein particles. This study was one of the first randomized controlled trials of the Mediterranean diet to use the technique.
"This is important because there is growing evidence to suggest that LDL particle number is more strongly associated with cardiovascular disease risk than total blood LDL concentrations alone," Fleming said. "Moreover, we were able to identify changes in apolipoproteins, specifically apoB, which are also associated with increased CVD risk."
After the data were analyzed, the researchers found that participants all had lower LDL cholesterol following the Mediterranean diet periods compared to the average American diet.
But while the total numbers of LDL particles were reduced following all three Mediterranean diet periods, they were only significantly decreased when following those periods that included 0.5oz/14g or 2.5oz/70g of beef a day compared to the average American diet.
Additionally, non-HDL cholesterol and apoB -- a protein involved in lipid metabolism and a marker of CVD risk -- were lower following all three Mediterranean diet periods compared to the average American diet.
"When you create a healthy diet built on fruits, vegetables, and other plant-based foods, it leaves room for moderate amounts of other foods like lean beef," Fleming said. "There are still important nutrients in beef that you can benefit from by eating lean cuts … or 93% lean ground beef."
David J. Baer, research leader at the United States Department of Agriculture - Agricultural Research Service, and study co-principal investigator, added, "This study highlights the importance of including lean beef in a Mediterranean dietary pattern that can yield heart-healthy benefits."
"Our study helped illustrate the benefits associated with a healthy Mediterranean dietary pattern that embodies balance, variety and the inclusion of nutrient-rich components, which can include low to moderate amounts of lean beef," Fleming said.
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Jennifer A. Fleming et al. 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. The American Journal of Clinical Nutrition https://doi.org/10.1093/ajcn/nqaa375