Ground Beef High in Total Fat and Saturated Fatty Acids Decreases X Receptor Signaling Targets in Peripheral Blood Mononuclear Cells of Men and Women.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 29663407 · doi:10.1002/lipd.12028
What was done
Five older men (age 68.0 +/- 4.6 years) and seven postmenopausal women (age 60.9 +/- 3.1 years) were randomly assigned in a crossover trial to consume five ground beef patties per week containing either 18% total fat or 25% total fat for 5 weeks each, separated by a 4-week washout period. Authors measured nutrient intake, plasma fatty acids, lipoprotein cholesterol fractions, LDL particle size, and mRNA expression of lipid regulatory genes in peripheral blood mononuclear cells.
What was found
Both 18% and 25% fat ground beef increased intake of saturated fat, monounsaturated fat, palmitic acid, and stearic acid (p < 0.05), whereas only the 25% fat beef increased oleic acid intake (p < 0.05). Both diets increased plasma palmitic acid and decreased plasma arachidonic, eicosapentaenoic, and docosahexaenoic acids (p < 0.05). Both diets decreased very low-density lipoprotein cholesterol concentrations, increased particle diameters, and increased LDL-I-C and LDL-II-C concentrations (p < 0.05). The 25% fat beef decreased peripheral blood mononuclear cell mRNA levels of ATP binding cassette A, ATP binding cassette G1, sterol regulatory element binding protein-1, and LDL receptor (p < 0.05). The 18% fat beef increased stearoyl-CoA desaturase-1 mRNA (p < 0.05). Numerical effect sizes and confidence intervals were not reported in the abstract.
Why it matters
The study suggests that high-fat ground beef intake downregulates leukocyte expression of cholesterol efflux and uptake genes while shifting circulating LDL toward larger subfractions.
Limits
The sample size was very small (n = 12 total), and the study evaluated only older men and postmenopausal women. Gene expression in peripheral blood mononuclear cells was used as an indirect surrogate for hepatic regulation. Exact numerical values and measures of variance were omitted from the abstract.
Cited by
- supports Excess saturated fat intake inhibits sterol regulatory element-binding proteins in the liver, leading to fewer LDL receptors being produced.