Lean beef, in moderate quantities, can be part of a heart-healthy diet, a new study suggests.
Including up to 156g of lean beef daily in a healthy Mediterranean diet led to significant reductions in total cholesterol, non-high-density lipoprotein (HDL)-cholesterol and low-density lipoprotein (LDL)-cholesterol and LDL particle number.
The study, “Effect of varying quantities of lean beef as part of a Mediterranean-style dietary pattern on lipids and lipoproteins: a randomised crossover-controlled feeding trial,” was published in The American Journal of Clinical Nutrition.
Many observational studies have linked high red meat intakes with an increased risk of cardiovascular disease (CVD). However, a link between red meat intake and CVD does not mean red meat causes CVD.
Nutrients, foods, and food components are not eaten alone; they are instead eaten as part of a whole diet. The whole diet may, therefore, have a more significant effect on health than single foods.
The Mediterranean diet is a whole-food plant-based diet, promoting high intakes of fruit, vegetables, whole grains, legumes, nuts, seeds, and fish with moderate quantities of unprocessed red meat, milk, dairy products and red wine.
Previous studies show that Mediterranean diets containing less than 120g of red meat per week (0.5 ounces (oz) per day) reduce total cholesterol and LDL-cholesterol levels. A recent study has shown that eating a Mediterranean diet containing 500 g of red meat per week (2.5 oz per day) for five weeks still reduces total cholesterol and LDL cholesterol.
However, it is unclear whether eating red meat in quantities above the Mediterranean diet recommendations of 0.5 oz per week negatively affects cholesterol levels and other markers of heart disease.
Consequently, a team of researchers in the United States investigated the effects of three healthy Mediterranean-style (MED) containing daily amounts of either 14 g / 0.5 oz beef (MED0.5), 71 g / 2.5 oz beef (MED2.5) and 156 g / 5.5 oz beef on markers of CVD including LDL-cholesterol, total cholesterol, total LDL-particle number and large LDL-particle number. The three MED diets were also compared with an average American diet (AAD).
Participants were randomised to receive an AAD or either one of three MED diets for four weeks with one week in between where they ate their regular meals. The MED diets consisted of 41% fat, 42% carbohydrate and 17% protein, while the AAD consisted of 33% fat, 52% carbohydrate and 17% protein.
After excluding beef, the remaining protein on the MED diet came from fish, poultry, pork, nuts, eggs and legumes. All MED diets provided 250 milligram (mg) of EPA and DHA omega-3 fatty acids daily and contained less than 300 and 2300 mg of cholesterol and sodium, respectively, daily.
Olive oil was the predominant source of fat in all MED diets, and participants ate three to six servings of fruit and at least six servings of vegetables daily.
The diets were prepared on-site at each facility and consisted of three meals and two snacks daily using a seven-day rotating menu.
A total of 55 healthy adults, with a mean age of 49 years, body mass index (BMI) of 27, with healthy LDL cholesterol levels were included in the study.
Participants achieved significantly lower total cholesterol, non-HDL cholesterol and LDL-cholesterol levels after following all three MED diets compared with baseline levels and the AAD diet. Despite increased quantities of beef, LDL-cholesterol levels were lowered to similar levels after all three MED diets.
All diets significantly decreased triglycerides and LDL particle number from baseline, but “LDL particle number was lowered to a greater extent with MED0.5 (low) and 2.5 (moderate), suggesting greater CVD risk reduction with low to moderate amounts of lean beef incorporated in the diet when compared with similar amounts of lean beef included in the AAD.”
MED0.5 also achieved significantly greater reductions in large LDL particle number than MED5.5.
However, “all diets were associated with reductions in HDL cholesterol concentration and HDL particle number when compared with baseline.” Low HDL particle numbers and high small HDL particle numbers increase CVD risk in healthy individuals.
The researchers explained that “in the present study, the reduction in HDL concentration and particle number appears to be driven by the loss of small HDL particles…”, which is associated with a lower CVD risk.
Study limitations, the researchers wrote, included an inability to monitor participant compliance to the study, the lack of a control group eating a meat-free diet and the predominantly Caucasian study population.
“In conclusion, our results demonstrate that the consumption of a healthy Mediterranean-style dietary pattern with different amounts of lean beef (14, 71 or 156g per day) improves lipids and lipoproteins when compared with a typical American dietary pattern containing 71 g/day of lean beef,” the researchers wrote.
“These findings are consistent with the transition to dietary pattern-based recommendations and demonstrate that lean beef in amounts no more than 71 g (2.5 ounces/day) can be part of a healthy Mediterranean-style dietary pattern without attenuating the cardiovascular benefits.”