Red meat has been consistently associated with increased incidence of cardiovascular disease (1,2). Plant protein sources on the other hand seem to be protective of the heart and blood vessels (3,4). A systematic review of randomized controlled trials revealed decreases in blood LDL-cholesterol, non-HDL cholesterol and apoB lipoprotein levels when animal protein is replaced with plant protein (5).
Presently, dietary recommendations advise limiting red meat intake (beef, pork, lamb, horse) to prevent high LDL-cholesterol blood levels and cardiovascular disease. White meat (chicken, turkey, rabbit) is often recommended as a healthier alternative to red meat for heart health.
A definitively strong link between the consumption of white meat and cardiovascular disease has been elusive (6,7) even though previous trials have shown that lean red meats and lean white meats raise blood lipid (fat) levels in similar amounts (8,9). It has long been assumed that the saturated fatty acid (SFA) content of red meat is a major contributor to its association with increased risk of cardiovascular disease risk because of the robust association of higher dietary SFA levels with increased blood levels of LDL-cholesterol (10). Many studies have also shown that replacing saturated fats with whole carbohydrates and unsaturated fats reduces heart disease. For instance, follow-up studies on more than 127,000 participants of the Nurses’ Health Study and the Health Professionals Follow-Up Study found that replacing 5% of calories from saturated fat with equal calories from polyunsaturated fats, monounsaturated fats or whole-grain carbohydrates reduces risk of cardiovascular disease by 25%,15% and 9% respectively (11). Recently, the results of a new study were released with new information that should result in changes in the recommendations for dietary protein for preventing cardiovascular disease.
The study (12)…
This controlled, randomized, crossover study, known as APPROACH (Animal and Plant Protein and Cardiovascular Health) released its results on June 4, 2019. The investigation was designed to test for differences in blood lipids resulting from the ingestion of diets containing red meat compared with diets containing white meat or plant protein and to discover if these effects are modified by the presence of high SFA levels (approx. 14% of energy) compared to low (approx. 7% of energy) SFA intake.
Before being assigned to a study group, participants consumed a 2-week baseline diet to test their compliance to a controlled diet. Successful participants were then placed in one of two study “arms”, high-SFA or low-SFA. A total of 113 adults, 62 in the high-SFA arm and 51 in the low-SFA arm, completed the study.
Within each arm, three experimental 4-week long diets tested the effects of red meat (beef and pork), white meat (chicken and turkey) or no meat (legumes, nuts, grains, and soy products) on blood lipid levels. The three experimental diets were separated by a 2- to 7-week washout period when subjects ate their habitual diet. The three protein types, red meat, white meat and no meat, provided about 12% of the total energy of the diet. The approximately 13% of remaining protein required came from eggs, dairy, and vegetable sources. Processed meats, fish and seafood were excluded from the study. Although all investigators and their staff were “blinded” to the sequence of the diets, the nature of the different proteins meant that participants were aware of what type they were eating. All menu items, with the exception of fresh produce which participants purchased for themselves, were provided to each participant for the full duration of the study.
Compliance to the diets was assessed by measurement of urea nitrogen and creatinine in the urine of each participant during the second week of the baseline diet and the third week of each experimental diet. These measurements were used to calculate urea nitrogen:creatinine ratio which assessed dietary protein intake during each dietary period. In addition, grocery receipts and menu checklists were monitored.
Results showed that (12);
Concentrations of total cholesterol, LDL-cholesterol and non-HDL-cholesterol were significantly higher with both the red meat and the white meat diet compared to the no meat diet. This result occurred in both the high SFA-arm and the low-SFA arm.
Concentrations of all lipid types including lipoproteins, apolipoproteins and large-, medium- and small-LDL particles were similar between the red and white meat diets.
Blood levels of other lipid types, such as apoB and apoA, were also significantly higher following both meat diets compared to the no meat diet.
Concentrations of HDL-cholesterol showed a relatively small increase during consumption of the red and white meat diets, particularly in the high-SFA arm.
There were no interactions between the protein sources and the SFA level so that effects of the protein source were independent of those from the SFA level of the diets.
Regardless of the protein in the diet, high-SFA diets showed higher blood levels of total cholesterol, LDL-cholesterol, non-HDL cholesterol and apoB than diets low in SFA.
The cholesterol-raising effect of the meat protein diets and the high SFA diets were both associated with large LDL particles; small and medium particles were not affected by the dietary protein source. This may seem confusing because the media has made much of the fact that smaller, more dense LDL-cholesterol particles are the dangerous ones to look out for. However, all types of LDL-cholesterol are clearly established causes of atherosclerosis (the build-up of plaques within artery walls), regardless of their size (13). Studies have shown that though small LDL particles are the most potent ones, raising heart disease risk by 63% in women and 44% in men, large LDL particles also increase heart disease risk, by 44% in women and 31% in men (14). Concentrations of very-low-density lipoprotein, intermediate-density lipoprotein and HDL-cholesterol were not significantly affected by the protein source or the SFA content.
To sum up;
The authors of this study claim it to be the first to show that both red meat protein and white meat protein cause higher LDL-cholesterol and apo-lipoprotein levels than does vegetable-sourced protein in otherwise similar diets.
Red meat and white meat increase lipid levels by similar amounts.
The rise in LDL-cholesterol from the consumption of red and white meat is derived from effects of the protein itself independently of the level of SFAs.
The highest concentrations of blood LDL-cholesterol resulted from the combination of high SFA intake with either red or white meat as the major protein source.
Take home message…
This study provides no evidence for choosing white meat over red meat for reducing cardiovascular disease risk. In fact, it points out that white meat raises harmful LDL-cholesterol by the same amount as does red meat. Consequently, if you are worried about your blood cholesterol level, white meats are no longer a smart substitute protein choice. Instead, health benefits that can reduce your risk of cardiovascular disease are best attained by;
Exchanging all meats, whether red or white, for vegetable protein sources.
Eliminating saturated fatty acids and replacing them with unsaturated ones.
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3 Tharrey, M., Mariotti, F., Mashchak, A., Barbillon, P., Delattre, M., Fraser, G.E. Patterns of plant and animal protein intake are strongly associated with cardiovascular mortality: The Adventist Health Study-2 cohort. Int J Epidemiol . 2018;47(5):1603–1612.
4 Huang, T., Yang, B., Zheng, J., Li, G., Wahlqvist, M.L., Li, D. Cardiovascular disease mortality and cancer incidence in vegetarians: A meta-analysis and systematic review. Ann Nutr Metab . 2012;60(4):233–240.
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7 Bernstein, A.M., Sun, Q., Hu, F.B., Stampfer, M.J., Manson, J.E., Willett, W.C. Major dietary protein sources and risk of coronary heart disease in women. Circulation. 2010 Aug 31;122(9):876-883.
8 Maki, K.C., Van Elswyk, M.E., Alexander, D.D., Rains, T.M., Sohn, E.L., McNeill, S. A meta-analysis of randomized controlled trials that compare the lipid effects of beef versus poultry and/or fish consumption. J Clin Lipidol . 2012;6(4):352–361.
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12 Bergeron, N., Chiu, S., Williams, P.T., King, S.M., Krauss, R.M. Effects of red meat, white meat, and nonmeat protein sources on atherogenic lipoprotein measures in the context of low compared with high saturated fat intake: a randomized controlled trial. Am J Clin Nutr. June 4, 2019; nqz-35; DOI: 10.1093/ajcn/nqz035
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14 Mora, S., Otvos, J.D., Rifai, N., Rosenson, R.S., Buring, J.E., Ridker, P.M. Lipoprotein particle profiles by nuclear magnetic resonance compared with standard lipids and apolipoproteins in predicting incident cardiovascular disease in women. Circulation. 2009 Feb 24;119(7):931-939.