The Effects of Dietary Fatty Acid Composition in High-Fat Meals on Ghrelin

Several peptide hormones are released from the gastrointestinal tract that influence neurons in the brain which regulate hunger and satiety. Ghrelin, which is a hunger inducing hormone, is released from the stomach during fasting and decreases after nutrient ingestion. The composition of dietary fatty acids within a high-fat (HF) meal may affect ghrelin levels differently. Purpose: The purpose of this study was to examine the effects of a HF meal (70% of total energy) rich in either monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs), or saturated fatty acids (SFAs) on circulating ghrelin levels. Methods: Eight female subjects (Age = 24 ± 2yrs, BMI = 21.3 ± 2.3kg/m²) completed 3 study visits (1 visit for each type of HF meal) in a random order. After a baseline blood draw subjects consumed one of the three HF liquid meals. Postprandial blood samples were then collected at 30, 60, 90, 120, 150, 180, 240, and 300 minutes. Blood was immediately centrifuged and the plasma was stored at -80°C until assayed. Plasma was assayed for total ghrelin using radioimmunoassays (RIAs). Results: There was a significant time effect (p<0.001), but no treatment effect or treatment by time interaction. The time effect was a decrease in ghrelin levels after meal consumption. The 5-hour postprandial ghrelin averages were 654 ± 16pg/ml for MUFA, 636 ± 18pg/ml for PUFA, and 655 ± 20pg/ml for SFA. Conclusion: The composition of dietary fatty acids within a HF meal did not differentially affect 5h postprandial ghrelin levels.