Researchers found no evidence that consuming white meat has a more beneficial effect on plasma lipids and lipoproteins than red meat, regardless of saturated fat intake, according to study results published in The American Journal of Clinical Nutrition.
The investigators aimed to assess if saturated fatty acid intake affects cholesterol and atherogenic lipoprotein measures in adults consuming diets with varying sources of protein. Adults age 21 to 65 years were eligible for inclusion if they had a body mass index between 20 and 35 kg/m², blood pressure <150/90 mm Hg, fasting glucose <7 mmol/L, total and low-density lipoprotein cholesterol (LDL-C) ≤95th percentile for sex and age, fasting triacylglycerol <5.65 mmol/L, and were willing to forego vitamin supplements and alcohol for the duration of the study. Exclusion criteria included use of tobacco or recreational drugs; use of hypolipidemics, antidiabetics, antihypertensives, anticoagulants, or hormones; unwillingness to consume all study foods; weight loss >3% body weight in the previous 3 months; and history of coronary artery disease, diabetes, or another chronic disorder.
Participants consumed a 2-week baseline diet to test their adherence to a controlled dietary protocol. After, they were randomly assigned to one of 2 parallel arms (high or low saturated fatty acids) and within each, allocated to red meat, white meat, and vegetable protein diets for 4 weeks each in random order. The primary outcomes were LDL-C, apolipoprotein B (apoB), the sum of small and medium LDL particles, and total/high-density lipoprotein cholesterol.
For 2 consecutive days at the end of the baseline diet and after each experimental diet, venous blood samples were collected after an overnight fast for analysis of plasma lipids, lipoprotein particle subfractions, apoB, and glucose.
In total, 62 participants completed the high-saturated fatty acids diet arm and 51 completed the low-saturated fatty acids diet arm. LDL-C and apoB levels were higher after red and white meat diets than after the nonmeat diet, independent of saturated fatty acid content (P <.0001 for all, except apoB: red meat compared with nonmeat [P =.0004]). This was primarily due to increases in large LDL particles, as small and medium LDL and total/high-density lipoprotein cholesterol were not significantly affected by protein source (P =.10 and P =.51, respectively). Primary outcomes did not differ significantly between red and white meat. Independent of protein source, high compared with low saturated fatty acids increased LDL-C (P =.0003), apoB (P =.0002), and large LDL (P =.0002).
Limitations of this study included its short duration and that dietary sources like fish and grass-finished beef products were omitted. In addition, animal meat used in the study were lean cuts and were matched for saturated fatty acid content. Therefore, the findings cannot be extrapolated to the lipid and lipoprotein effects of higher-fat red meat products.
Researchers concluded that a high-vegetable content diet is recommended for cardiovascular health and that white meat did not differ from red meat in reducing cardiovascular risk. They suggested that future studies should “test the effects of [saturated fatty acid] content and dietary protein source on atherogenic lipoprotein indices as well as clinical [cardiovascular disease] outcomes in individuals with hyperlipidemia.”
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. doi:10.1093/ajcn/nqz035