Contrary to popular belief, consuming red meat and white meat such as poultry, have equal effects on blood cholesterol levels, according to research. The study, led by scientists at Children's Hospital Oakland Research Institute (CHORI) – the research arm of University of California San Francisco (UCSF) Benioff Children's Hospital Oakland – surprised the researchers with the discovery that consuming high levels of red meat or white poultry resulted in higher blood cholesterol levels than consuming a comparable amount of plant proteins.
Moreover, this effect was observed whether or not the diet contained high levels of saturated fat, which increased blood cholesterol to the same extent with all three protein sources.
"When we planned this study, we expected red meat to have a more adverse effect on blood cholesterol levels than white meat, but we were surprised that this was not the case – their effects on cholesterol are identical when saturated fat levels are equivalent," said the study senior author Dr Ronald Krauss, senior scientist and director of atherosclerosis research at CHORI.
Krauss, who is also a UCSF professor of medicine, noted that the meats studied did not include grass-fed beef or processed products such as bacon or sausage; nor did it include fish.
But the results were notable, as they indicated that restricting meat altogether, whether red or white, is more advisable for lowering blood cholesterol levels than previously thought. The study found that plant proteins are the healthiest for blood cholesterol.
This study, dubbed the APPROACH (Animal and Plant Protein and Cardiovascular Health) trial, also found that consuming high amounts of saturated fat increased concentrations of large cholesterol-enriched LDL particles, which have a weaker connection to cardiovascular disease than smaller LDL particles.
Similarly, red and white meat increased amounts of large LDL in comparison to non-meat diets. Therefore, using standard LDL cholesterol levels as the measure of cardiovascular risk may lead to overestimating that risk for both higher meat and saturated fat intakes, as standard LDL cholesterol tests may primarily reflect levels of larger LDL particles.
Consumption of red meat has become unpopular during the last few decades over concerns about its association with increased heart disease. Government dietary guidelines have encouraged the consumption of poultry as a healthier alternative to red meat.
But there had been no comprehensive comparison of the effects of red meat, white meat and nonmeat proteins on blood cholesterol until now, Krauss said. Non-meat proteins such as vegetables, dairy, and legumes, such as beans, show the best cholesterol benefit, he said.
"Our results indicate that current advice to restrict red meat and not white meat should not be based only on their effects on blood cholesterol," Krauss said. "Indeed, other effects of red meat consumption could contribute to heart disease, and these effects should be explored in more detail in an effort to improve health."
Background: Dietary recommendations to limit red meat are based on observational studies linking intake to cardiovascular disease (CVD) risk together with the potential of its saturated fatty acid (SFA) content to raise low-density lipoprotein (LDL) cholesterol. However, the relation of white meat to CVD risk, and the effects of dietary protein source on lipoprotein particle subfractions, have not been extensively evaluated.
Objective: We tested whether levels of atherogenic lipids and lipoproteins differed significantly following consumption of diets with high red meat content compared with diets with similar amounts of protein derived from white meat or nonmeat sources, and whether these effects were modified by concomitant intake of high compared with low SFAs.
Methods: Generally healthy men and women, 21–65 y, body mass index 20–35 kg/m2, were randomly assigned to 1 of 2 parallel arms (high or low SFA) and within each, allocated to red meat, white meat, and nonmeat protein diets consumed for 4 wk each in random order. The primary outcomes were LDL cholesterol, apolipoprotein B (apoB), small + medium LDL particles, and total/high-density lipoprotein cholesterol.
Results: Analysis included participants who completed all 3 dietary protein assignments (61 for high SFA; 52 for low SFA). LDL cholesterol and apoB were higher with red and white meat than with nonmeat, independent of SFA content (P < 0.0001 for all, except apoB: red meat compared with nonmeat [P = 0.0004]). This was due primarily to increases in large LDL particles, whereas small + medium LDL and total/high-density lipoprotein cholesterol were unaffected by protein source (P = 0.10 and P = 0.51, respectively). Primary outcomes did not differ significantly between red and white meat. Independent of protein source, high compared with low SFA increased LDL cholesterol (P = 0.0003), apoB (P = 0.0002), and large LDL (P = 0.0002).
Conclusions: The findings are in keeping with recommendations promoting diets with a high proportion of plant-based food but, based on lipid and lipoprotein effects, do not provide evidence for choosing white over red meat for reducing CVD risk.
Nathalie Bergeron, Sally Chiu, Paul T Williams, Sarah M King, Ronald M Krauss
[link url="https://eurekalert.org/pub_releases/2019-06/uoc–raw053119.php"]University of California San Francisco material[/link]
[link url="https://academic.oup.com/ajcn/advance-article/doi/10.1093/ajcn/nqz035/5494812"]American Journal of Clinical Nutrition abstract[/link]