Limited effect of dietary saturated fat on plasma saturated fat in the context of a low carbohydrate diet.
Level 2 - randomized trial
Small controlled crossover feeding trial
PubMed 20820932 · doi:10.1007/s11745-010-3467-3
What was done
Eight weight-stable men were fed two 6-week carbohydrate-restricted diets (CRD; 12% energy from carbohydrates) varying in fat quality, with all food provided. One diet emphasized saturated fatty acids (CRD-SFA, 86 g/d SFA) and the other emphasized unsaturated fatty acids (CRD-UFA, 47 g/d SFA). Changes in serum triacylglycerol (TAG), insulin, LDL-C particle size, plasma fatty acid profiles, and urinary 8-iso PGF(2α) were evaluated.
What was found
Both diets reduced serum TAG and insulin, increased LDL-C particle size, and significantly reduced plasma palmitoleic acid (16:1n-7). Plasma TAG SFA significantly decreased on CRD-UFA (27.48 ± 2.89 mol% vs 31.06 ± 4.26 mol% at baseline), but remained unchanged on CRD-SFA (33.14 ± 3.49 mol%) despite a doubling of SFA intake. CRD-SFA significantly increased plasma phospholipid arachidonic acid (ARA), whereas CRD-UFA increased EPA and DHA. Urinary 8-iso PGF(2α) decreased significantly (-32%) following CRD-UFA, and changes in urinary 8-iso PGF(2α) were inversely correlated with phospholipid ARA on both diets (r = -0.82 for CRD-SFA; r = -0.62 for CRD-UFA).
Why it matters
The study shows that in the context of carbohydrate restriction, doubling dietary saturated fat does not raise circulating plasma triglyceride saturated fatty acids, supporting the concept of enhanced saturated fat metabolism and reduced de novo lipogenesis.
Limits
The study sample was extremely small (n = 8) and comprised solely men, limiting generalizability. Long-term cardiovascular outcomes were not evaluated, and specific details on randomization and washout periods were not provided in the abstract.
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.