Background/objectives: Consumption of n-3 polyunsaturated fatty acids (PUFA) has a favourable impact on inflammation and cardiovascular disease. However, the Western diet is characterized by a low n-3 PUFA intake and an imbalance in the n-6/n-3 PUFA ratio. Study the effect 10-week of diet modification to decrease the n-6/n-3 PUFA ratio on cardiovascular risk factors and resting energy expenditure.
Subjects and methods: Ten-week dietary intervention in 17 healthy subjects. Dietary intake, euglycemic hyperinsulinemic clamp, indirect calorimetry, lipid profile, hormones, inflammatory markers and erythrocyte membrane fatty acid composition were recorded before and at the end of the intervention. Comparisons are between baseline and post-treatment levels.
Results: Dietary records of the linoleic acid/alpha-linolenic acid ratio (baseline: 32.2 (s.d. 3.7) vs post-intervention: 2.2 (s.d. 0.1), P<0.0001) and erythrocyte membrane fatty acid composition reflected good compliance. Dietary intervention was associated with significant reductions in TNF-alpha (baseline: 2.2 (s.d. 0.3), post-intervention: 1.5 (s.d. 0.3) pg/ml, P=0.01) and low-density lipoprotein-cholesterol (baseline: 2.5 (s.d. 0.2), post-intervention: 2.3 (s.d. 0.1) mmol/l, P=0.03) and increased adiponectin (baseline: 6.5 (s.d. 0.7), post-intervention: 7.6 (s.d. 0.6) microg/ml, P=0.02). Fasting lipid oxidation was increased (baseline: 0.7 (s.d. 0.1), post-intervention: 0.9 (s.d. 0.1) mg/kg x min, P=0.01), whereas glucose oxidation decreased in both fasting (baseline: 1.6 (s.d. 0.1), post-intervention: 1.3 (s.d. 0.1) mg/kg x min, P=0.02) and hyperinsulinaemic conditions (baseline: 3.6 (s.d. 0.1), post-intervention: 3.3 (s.d. 0.1) mg/kg x min, P=0.04). Insulin sensitivity was not affected by the intervention.
Conclusion: A decreased n-6/n-3 PUFA ratio can be achieved with simple dietary counselling, resulting in multiple, potentially favourable effects on the metabolic and inflammatory profiles.