Effects of Dietary Fats on Cardiovascular Health and Insulin Sensitivity in Subjects With Abdominal Obesity

Rationale: It is well established that increased intake of saturated fatty acids (SFA) is associated with incidence of cardiovascular heart disease (CHD). This effect is mediated by dietary saturated fat's impact on fasting plasma cholesterol levels. Research is needed to clarify the association between dietary fatty acids and metabolic risk markers beyond lipid profile. World Health Organisation (WHO) has recommended reduced intake of SFA with energy replacement from monounsaturated fatty acids (MUFA) or carbohydrates (CARB). However, limited evidence is available on the effects of dietary fatty acids on insulin sensitivity and secretion. The current study is designed to investigate the effects of SFA versus MUFA versus CARB on insulinemic response and lipid metabolism in healthy individuals with central obesity.

Study design: A randomized, crossover, single blind design study was carried out. The subjects consumed controlled diets for 6 weeks each. They were provided 3 meals per day during weekdays in which SFA, MUFA and CARB diet was assigned to them randomly. Protein content was standardised at 14% energy. The SFA and MUFA diets each provided 31.5% energy intake from fat, with 69% of the total fats replaced by test fats (approximately 49 g/d based on a 2000 kcal basic diet). Each individual fatty acid provided approximately 7% of the total energy intake. The CARB diet provided approximately 34 g/day experimental fat based on a 2000 kcal basic diet. The CARB diet replaced 7 % energy of carbohydrate from total fat with the exchange from oleic acid (C18:1).

Hypothesis: Changing energy from dietary fat (SFA and MUFA) to carbohydrate will influence insulin sensitivity, endothelial and vascular function, pro-inflammatory markers and lipid metabolism differently in individuals with metabolic syndrome. SFA (palm olein) may be comparable with MUFA (high oleic sunflower oil) with regards to its effects on insulin sensitivity, endothelial and vascular function and inflammation