Distinct Effects for Excess Saturated vs Polyunsaturated Fat
Saturated promotes hepatic, visceral fat storage; polyunsaturated may promote lean tissue
MONDAY, Feb. 24, 2014 (HealthDay News) -- Overeating saturated fats is associated with increased liver and visceral fat storage compared with overeating polyunsaturated fats, according to a study published online Feb. 18 in Diabetes.
Fredrik Rosqvist, from Uppsala University in Sweden, and colleagues assessed liver fat accumulation and body composition by magnetic resonance imaging in 39 young, normal-weight subjects. The participants were randomly assigned to overfeeding with muffins high in saturated fat (palm oil) or n-6 polyunsaturated fat (sunflower oil) for seven weeks.
The researchers found that, although weight gain was similar in both groups, the saturated fat group had markedly increased liver fat and a two-fold greater increase in visceral adipose tissue. In contrast, the polyunsaturated fat group had a nearly three-fold greater increase in lean tissue. Increases in liver fat were directly correlated with changes in plasma saturated fat and inversely correlated with polyunsaturated fat. Transcriptome analysis of subcutaneous abdominal tissue showed differences in genes regulating energy dissipation, insulin resistance, body composition, and fat cell differentiation.
"In conclusion, overeating saturated fat promotes hepatic and visceral fat storage whereas excess energy from polyunsaturated fat may instead promote lean tissue in healthy humans," Rosqvist and colleagues write.
Financial ties to Novo Nordisk and AstraZeneca were disclosed.