Background: The effects of a prolonged low-carbohydrate diet rich in n-3 fatty acids on blood lipid profiles have not been addressed in the scientific literature.
Objective: This study examined the effects of an eight-week ketogenic diet rich in n-3 fatty acids on fasting serum lipoproteins and postprandial triacylglycerol (TG) responses.
Design: Ten men consumed a low-carbohydrate diet rich in monounsaturated fat (MUFA) and supplemented with n-3 fatty acids for eight weeks. Fasting blood samples were collected before and after one week of habitual diet and on two consecutive days after 2, 4, 6 and 8 weeks of the intervention diet. Postprandial TG responses to a fat-rich test meal were measured prior to and after the intervention diet.
Results: Compared to the habitual diet, subjects consumed significantly (p < or = 0.05) greater quantities of protein, fat, MUFA and n-3 fatty acids and significantly less total energy, carbohydrate and dietary fiber. Body weight significantly declined over the experimental period (-4.2+/-2.7 kg). Compared to baseline, fasting total cholesterol, LDL cholesterol and HDL cholesterol were not significantly different after the intervention diet (+1.5%, +9.7% and +10.0%, respectively). Fasting TG were significantly reduced after the intervention diet (-55%). There was a significant reduction in peak postprandial TG (-42%) and TG area under the curve (-48%) after the intervention diet.
Conclusions: A hypocaloric low-carbohydrate diet rich in MUFA and supplemented with n-3 fatty acids significantly reduced postabsorptive and postprandial TG in men that were not hypertriglyceridemic as a group before the diet. This may be viewed as a clinically significant positive adaptation in terms of cardiovascular risk status. However, transient increases in total cholesterol and LDL cholesterol were also evident and should be examined further in regard to which particular subfractions are elevated.