Lowering dietary fat changes plasma lipids and the fatty acid composition in young adults

The aim of this study was to investigate the effects of reducing the amount of dietary total fat on serum lipids and the plasma fatty acid composition in young adults. Sixteen male and 18 female subjects (aged 20-30 years) were given experimental meals including lunch and dinner for a 4-week period, but on weekends and holidays, no meals were provided. The experimental meals were designed to provide 2200 kcal/d for each male subject and 1800 kcal/d for each female subject, including 58%-68% of energy from carbohydrates, 10%-14% of energy from protein, and 20%-30% of energy from fat. During the dietary intervention period, the energy intake of dietary fat significantly decreased from 35.0% to 28.7% in males and from 37.9% to 32.3% in females. In female subjects, serum total cholesterol, LDL-cholesterol, and HDL-cholesterol significantly decreased in a 4-week period of diet. The experimental meal intervention was associated with a significantly higher 18:3 n-3 level as the percentage of total plasma fatty acids and with a significantly lower 20: 4 level and 18:2/18:1 ratio as the percentage of total plasma fatty acids in females. In male subjects, the 18:2 and total n-6 polyunsaturated fatty acid levels as percentages of total plasma fatty acids significantly decreased compared with corresponding values at week 0. Thus, the benefits of lowering dietary fat intake to 5%-7% of energy intake may favor changes in serum lipids in females and plasma fatty acid composition in both males and females.