Comparison of low fat and low carbohydrate diets on circulating fatty acid composition and markers of inflammation.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 18046594 · doi:10.1007/s11745-007-3132-7
What was done
Overweight adults with atherogenic dyslipidemia followed either an ad libitum very low carbohydrate diet (VLCKD; 1504 kcal, 12% carbohydrate, 59% fat, 28% protein) or a low-fat diet (LFD; 1478 kcal, 56% carbohydrate, 24% fat, 20% protein) for 12 weeks. Investigators evaluated changes in circulating fatty acid profiles and systemic inflammatory markers.
What was found
The abstract reports directional comparisons without providing exact numerical values, confidence intervals, or p-values. Compared with the LFD, the VLCKD led to a marked increase in serum total n-6 PUFA (primarily arachidonic acid, 20:4n-6) and sharp increases in the n-6/n-3 and arachidonic/eicosapentaenoic acid ratios, alongside decreases in arachidonate biosynthetic intermediates. Total saturated fatty acids and 16:1n-7 consistently decreased following the VLCKD. While both diets decreased several inflammatory markers, the VLCKD produced greater overall anti-inflammatory effects, with greater reductions in TNF-alpha, IL-6, IL-8, MCP-1, E-selectin, I-CAM, and PAI-1. Increased arachidonic acid and n-6/n-3 ratios were unexpectedly inversely associated with inflammatory protein responses.
Why it matters
This study demonstrates that carbohydrate restriction reduces circulating inflammatory and endothelial markers more effectively than fat restriction in atherogenic dyslipidemia. It also challenges the assumption that increases in circulating arachidonic acid necessarily promote systemic inflammation.
Limits
The abstract does not state the total sample size, participant dropout rates, or exact quantitative values and p-values for the reported outcomes. The intervention duration was relatively short (12 weeks), ad libitum intake introduces potential adherence confounding, and findings are specific to overweight individuals with dyslipidemia.
Cited by
- supports When carbohydrate intake is reduced, humans can consume two to four times more saturated fat while maintaining significantly lower circulating plasma saturated fat levels.