Ronald M. Krauss, MD, on Whether We Should Tell Patients to Limit White Meat Intake, Too
Although current dietary guidelines encourage limiting red meat intake in favor of white meat, a study suggests that diets high in either red or white meat may have similar lipid and lipoprotein effects compared with diets high in plant-based proteins.
The study, published in the American Journal of Clinical Nutrition, was a randomized clinical trial including 113 generally healthy men and women aged 21 to 65 years with a body mass index of 20 to 35 kg/m2. Participants were randomly assigned to either high or low saturated fatty acid dietary patterns, and were further directed to consume red meat, white meat, and nonmeat protein diets in random order over the course of 4 weeks each.
Researchers found that individuals with higher intakes of red and white meat tended to have increased LDL cholesterol and apolipoprotein B (apoB) levels compared with those who consumed primarily non-meat protein sources.
Also of note, the results suggested that individuals with a high intake of saturated fatty acids had elevated LDL cholesterol levels, apoB levels, and large LDL particles compared with those who consumed low amounts of saturated fatty acids.
Consultant360 discussed these findings further with lead study author Ronald M. Krauss, MD, senior scientist and director of Atherosclerosis Research and Dolores Jordan Endowed Chair at the Children's Hospital Oakland Research Institute at UCSF Benioff Children's Hospital Oakland in California. Dr Krauss shared important key takeaways of the study, including what dietitians and related clinicians can recommend to patients.
Consultant360: Were you surprised to find that white meat has similar lipid and lipoprotein effects compared with red meat, given that dietary guidelines recommend consuming poultry and seafood over red meat?
Dr Krauss: I was surprised by the results, though they are consistent with some earlier findings. However, until now, no one has performed a systematic comparison of the effects of red meat, white meat, and non-meat sources of protein on cholesterol levels in diets where other major nutrients were kept constant, and where saturated fat intake was controlled and tested at high and low levels of intake.
C360: What types of white meat did participants consume, and could this have affected the outcome?
Dr Krauss: In this trial, white meat sources were primarily white poultry meats that were low in fat. No fried or otherwise high-fat sources of white meat were included.
C360: Are there any limitations to these findings regarding study population? Does more research need to be done before broad applications can be made?
Dr Krauss: This trial included 113 healthy men and women with cholesterol levels in the normal range, but the cholesterol effects we observed in this cohort should be applicable to individuals with higher LDL cholesterol who are attempting to lower LDL levels through diet. It is important to point out that there were a wide range of LDL responses, with some individuals demonstrating a much larger change than the average, and some in the opposite direction. Any individuals who wants to learn whether poultry intake is affecting their LDL levels can do so after limiting intake for several weeks and seeing how this impacts their LDL values.
C360: Could these findings have implications for future dietary guidelines?
Dr Krauss: These results only focused on dietary effects of cholesterol. While these would be expected to have corresponding effects on CVD risk, which remains the leading cause of death in the United States, many diet-related and other factors come into play and affect this risk.
Changes in dietary guidelines should be based on multiple studies and lines of evidence, not a single study. Moreover, as noted above, individuals can vary greatly in their nutritional needs for cardiovascular health. Nevertheless, this study could eventually lead to dietary guidelines that suggest avoiding high intake of both white meat and red meat (likely no more than twice per week), particularly among individuals with higher LDL levels, in addition to current recommendations favoring a higher proportion of vegetables, nuts, legumes, fruits, and unprocessed whole grains.
C360: What clinical takeaways should clinicians learn from your study?
Dr Krauss: As a clinician who treats cholesterol issues, I can share what I do in my own practice as a result of these findings, which I have known about for some time. When seeing patients who present with LDL levels above the desirable range for their degree of overall CVD risk, and particularly for those who wish to exhaust every dietary option before considering statin drugs, I suggest:
- Limiting sources of saturated fat, such as butter and full-fat dairy.
- Consuming lean red meat no more than once or twice per week.
- Testing the effects of avoiding poultry for 3 to 4 weeks, after which I check their blood levels of LDL.
- If this leads to a significant improvement in LDL, which I have observed in a number of patients, I advise them to continue limiting white meat intake and eat more plant-based whole foods, as well as fish.
- If there is no significant drop in LDL, I advise them not to worry about consuming poultry, although "moderation" is still in order.
Ronald M. Krauss, MD, is Senior Scientist and Director of Atherosclerosis Research and Dolores Jordan Endowed Chair at the Children's Hospital Oakland Research Institute at UCSF Benioff Children's Hospital Oakland; Professor of Medicine at University of California, San Francisco; and Adjunct Professor in the Department of Nutritional Sciences at University of California, Berkeley.
Bergeron N, Chiu S, Williams PT, King SM, Krauss RM. 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 [Published online June 4, 2019]. Am J Clin Nutr. https://doi.org/10.1093/ajcn/nqz035.