BMI modifies the effect of dietary fat on atherogenic lipids: a randomized clinical trial.
Study Goal
The researchers aimed to compare the effects of substituting unsaturated fat (PUFA) for saturated fat (SFA) on LDL cholesterol and apoB concentrations in normal-weight versus obese individuals with elevated LDL cholesterol.
Results Summary
The PUFA diet significantly lowered LDL cholesterol and apoB compared to the SFA diet, with greater improvements observed in normal-weight participants than in obese individuals. BMI modified the lipid response, suggesting dietary recommendations may need adjustment based on BMI.
Population
83 men and women (aged 21-70 y) with elevated LDL cholesterol, stratified into normal-weight (BMI ≤ 25 kg/m²) and obese (BMI: 30-45) groups.
Effective Dosage
Diets differed by ~9 energy percent (E%) in SFA and ~4 E% in PUFA between groups.
Duration
6 weeks
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
SFA intake | increase | LDL cholesterol | - | - | increases | #1 |
PUFA intake | decrease | LDL cholesterol | - | - | lowers | #2 |
PUFA diet enriched with oil-based margarine | decrease | LDL cholesterol | total study population | -0.31 mmol/L; 95% CI: -0.47, -0.15 mmol/L | lowered | #3 |
SFA diet enriched with butter | increase | LDL cholesterol | total study population | 0.32 mmol/L; 95% CI: 0.18, 0.47 mmol/L | increased | #4 |
PUFA diet enriched with oil-based margarine | decrease | apoB | total study population | -0.08 g/L; 95% CI: -0.11, -0.05 g/L | lowered | #5 |
SFA diet enriched with butter | increase | apoB | total study population | 0.07 g/L; 95% CI: 0.03, 0.10 g/L | increased | #6 |
SFA diet enriched with butter | increase | LDL cholesterol | normal-weight participants | 9.7% (95% CI: 5.3%, 14.2%) | increased | #7 |
SFA diet enriched with butter | increase | LDL cholesterol | obese participants | 5.3% (95% CI: -0.7%, 11.2%) | increased | #8 |
PUFA diet enriched with oil-based margarine | decrease | LDL cholesterol | normal-weight participants | -10.4% (95% CI: -15.2%, -5.7%) | lowered | #9 |
PUFA diet enriched with oil-based margarine | decrease | LDL cholesterol | obese participants | -2.3% (95% CI: -7.4%, 2.8%) | lowered | #10 |
SFA diet enriched with butter | increase | apoB | normal-weight participants | 7.5% (95% CI: 3.5%, 11.4%) | increased | #11 |
SFA diet enriched with butter | increase | apoB | obese participants | 3.0% (95% CI: -1.7%, 7.7%) | increased | #12 |
PUFA diet enriched with oil-based margarine | decrease | apoB | normal-weight participants | -8.9% (95% CI: -12.6%, -5.2%) | lowered | #13 |
PUFA diet enriched with oil-based margarine | decrease | apoB | obese participants | -3.8% (95% CI: -6.3%, -1.2%) | lowered | #14 |
BACKGROUND: SFA intake increases LDL cholesterol whereas PUFA intake lowers it. Whether the lipid response to dietary fat differs between normal-weight and obese persons is of relevance to dietary recommendations for obese populations. OBJECTIVES: We compared the effect of substituting unsaturated fat for saturated fat on LDL cholesterol and apoB concentrations in normal-weight (BMI ≤ 25 kg/m2) and obese (BMI: 30-45) subjects with elevated LDL cholesterol. METHODS: We randomly assigned 83 men and women (aged 21-70 y) stratified by BMI (normal: n = 44; obese: n = 39) and elevated LDL cholesterol (mean ± SD, normal weight 4.6 ± 0.9 mmol/L; obese 4.4 ± 0.8 mmol/L) to either a PUFA diet enriched with oil-based margarine ( n = 42) or an SFA diet enriched with butter (n = 41) for 6 wk. RESULTS: Seven-day dietary records showed differences of ∼9 energy percent (E%) in SFA and ∼4 E% in PUFA between the SFA and PUFA groups. In the total study population, the PUFA diet compared with the SFA diet lowered LDL cholesterol (-0.31 mmol/L; 95% CI: -0.47, -0.15 mmol/L, compared with 0.32 mmol/L; 95% CI: 0.18, 0.47 mmol/L; P < 0.001) and apoB (-0.08 g/L; 95% CI: -0.11, -0.05 g/L, compared with 0.07 g/L; 95% CI: 0.03, 0.10 g/L; P < 0.001). Tests of the BMI × diet interaction were significant for total cholesterol, LDL cholesterol, and apoB ( P values ≤ 0.009). In normal-weight compared with obese participants post-hoc comparisons found that the respective changes in LDL cholesterol were 9.7% (95% CI: 5.3%, 14.2%) compared with 5.3% (95% CI: -0.7%, 11.2%), P = 0.206, in the SFA group, and -10.4% (95% CI: -15.2%, -5.7%) compared with -2.3% (95% CI: -7.4%, 2.8%), P = 0.020, in the PUFA group. ApoB changes were 7.5% (95% CI: 3.5%, 11.4%) compared with 3.0% (95% CI: -1.7%, 7.7%), P = 0.140, in the SFA group, and -8.9% (95% CI: -12.6%, -5.2%) compared with -3.8% (95% CI: -6.3%, -1.2%), P = 0.021, in the PUFA group. Responses to dietary fat were not associated with changes in polyprotein convertase subtisilin/kexin type 9 concentrations. CONCLUSIONS: BMI modifies the effect of PUFAs compared with SFAs, with smaller improvements in atherogenic lipid concentrations in obese than in normal-weight individuals, possibly supporting adjustment of dietary recommendations according to BMI. This trial was registered with www.clinicaltrials.gov as NCT02589769.