Effects of intraduodenal infusion of lauric acid and L-tryptophan, alone and combined, on glucoregulatory hormones, gastric emptying and glycaemia in healthy men.

BACKGROUND AND AIM: In healthy men, intraduodenal administration of the fatty acid, lauric acid ('C12') and the amino acid, L-tryptophan ('TRP'), at loads that individually do not affect energy intake, reduce energy intake substantially when combined. C12 and TRP may also stimulate cholecystokinin and glucagon-like peptide-1 (GLP-1), which both slow gastric emptying, a key determinant of postprandial blood glucose. Accordingly, combination of C12 and TRP has the potential to reduce post-meal glycaemia more than either nutrient alone. METHODS: Twelve healthy, lean men (age (mean ± SD): 28 ± 7 years) received, on 4 separate occasions, 45-min intraduodenal infusions of C12 (0.3 kcal/min), TRP (0.1 kcal/min), C12 + TRP (0.4 kcal/min), or 0.9% saline (control), in a randomised, double-blind fashion. 30 min after commencement of the infusion a mixed-nutrient drink was consumed and gastric emptying measured (13C breath-test) for 3 h. Blood samples were obtained at baseline, in response to treatments alone, and for 2 h post-drink for measurements of plasma glucose, cholecystokinin, GLP-1, C-peptide, insulin and glucagon. 'Early' (first 30 min) and 'overall' glycaemic and hormone responses were evaluated. RESULTS: C12 + TRP and C12 delayed the rise in, but did not affect the overall glycaemic response to the drink, compared with control and TRP (all P < 0.05). C12 + TRP slowed gastric emptying compared with control and TRP (both P < 0.005), and C12 non-significantly slowed gastric emptying compared with control (P = 0.090). C12 + TRP and C12 delayed the rise in C-peptide and insulin, and also stimulated CCK and glucagon, compared with control and TRP (all P < 0.05). Only C12 + TRP stimulated early and overall GLP-1 compared with control (P < 0.05). CONCLUSIONS: In healthy men, C12 + TRP and C12, in the loads administered, had comparable effects to delay the rise in glucose following a nutrient drink, probably primarily by slowing of gastric emptying, as a result of CCK and GLP-1 stimulation, while TRP had no effect.

The Effect of n-3 Polyunsaturated Fatty Acid Supplementation on Androgen Status in Patients with Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis of Clinical Trials.

The anti-androgenic role of n-3 polyunsaturated fatty acids (PUFAs) among patients with polycystic ovary syndrome (PCOS) has recently been proposed. The present study aimed to systematically review clinical trials assessing the effects of n-3 PUFAs consumption on androgen status among adult females with PCOS. PubMed, ISI Web of Science, Google Scholar, and Scopus were searched up to December 2015. Clinical investigations assessing the effect of n-3 PUFAs on adult females with PCOS were included. Mean±standard deviation of change in serum total testosterone, sex hormone binding globulin (SHBG), and dehydroepiandrostrone sulfate (DHEAS) were extracted. Eight clinical trials with 298 participants were eligible. Meta-analysis showed that n-3 PUFAs supplementation marginally reduces total testosterone (mean difference [MD]: - 0.19 nmol/l; 95% CI: - 0.39 to 0.00; p=0.054), but not SHBG (MD: 1.75 nmol/l; 95% CI: -0.51 to 4.01; p=0.129) or serum DHEAS levels (Hedes' g: -0.11 nmol/l; 95% CI: -0.29 to 0.06; p=0.19) among adult females with PCOS. Subgroup analyses showed that only before-after studies (Hedges' g: 0.15; 95% CI: -0.27 to -0.04; p=0.01) and long-term interventions (>6 weeks) (Hedges' g: -0.17; 95% CI, -0.29 to -0.05; p=0.004) had reducing effects on serum DHEAS levels. The majority of long-term trials utilized a single group design (no control group). It does not appear that n-3 PUFAs supplementation significantly affects the androgenic profile of females with PCOS; however, some before-after and long-term intervention studies show reduced DHEAS levels. Future studies incorporating double blinded placebo controlled clinical trials with long follow-up periods are warranted.