(P06-007-24) Dietary Polyunsaturated to Saturated Fatty Acid Ratio as a Predictor for LDL-C Response in Adults: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Objectives: Current dietary guidelines recommend limiting intake of saturated fat (SFA) and replacing SFA with unsaturated fat including polyunsaturated fats (PUFA). PUFA and SFA have opposing effects on LDL-C and therefore the dietary ratio of PUFA to SFA (P:S) may be a better indicator of LDL-C than SFA alone. The aim was to conduct a systematic review and meta-analysis of randomized controlled trials examining LDL-C responses to diets with a higher P:S ratio compared to isocaloric, total fat-matched diets with lower P:S ratios in generally healthy adults.

Methods: PubMed, Cochrane Central, and Web of Science were searched on August 29, 2023. Randomized complete feeding trials with a duration of ≥3 weeks and two test diets with P:S ratios differing by >0.3 that were approximately matched for energy, fiber, bioactive components and total fat were included. Studies including a concurrent weight loss intervention were excluded. Results were exported to Rayyan-Intelligent Systematic Review. Two independent authors conducted title and abstract screening, full text review, and risk of bias assessment using the Cochrane Risk of Bias Tool-2. Disagreements were resolved by a third author. Data were extracted by one author and checked by another author. Data were analyzed using the DerSimonian and Laird random-effects method (RevMan). The primary analysis evaluated the mean difference (MD) in LDL-C following diets with a higher P:S ratio compared to diets with a lower P:S ratio.

Results: A total of 981 articles were screened by title/abstract and 186 articles were eligible for full-text review. From these, 23 articles were eligible for inclusion. The trials included 1016 participants (mean age 39 years), with a mean duration of 29 days. Overall, diets with a higher P:S ratio (mean P:S ratio 1.3; PUFA 10.8% kcal; SFA 8.9% kcal) reduced LDL-C (MD -9.87 mg/dL; 95% CI -13.73, -6.02; I²=79%) compared to diets with a lower P:S ratio (mean P:S ratio 0.43; PUFA 5.1% kcal; SFA 13.5% kcal). Six of the 23 articles had low risk of bias, 16 articles had some concerns in at least one domain and one article had high risk of bias.

Conclusions: Compared to diets with a lower P:S ratio, a higher dietary P:S ratio was associated with greater LDL-C reductions in generally healthy adults.

Funding Sources: Department of Nutritional Sciences, Penn State