Bioequivalence of n-3 fatty acids from microencapsulated fish oil formulations in human subjects.

Fish oil n-3 fatty acids (FA) have known health benefits. Microencapsulation stabilises and protects fish oil from oxidation, enabling its incorporation into foods. The aim of the present study was to compare the bioavailability of n-3 FA delivered as two microencapsulated fish oil-formulated powders or fish oil gel capsules (FOGC) taken with a flavoured milk in healthy participants. Formulation 1 (F1) composed of a heated mixture of milk protein-sugar as an encapsulant, and formulation 2 (F2) comprised a heated mixture of milk protein-sugar-resistant starch as an encapsulant. Participants consumed 4 g fish oil (approximately 1·0 g EPA and DHA equivalent per dose). Bioavailability was assessed acutely after ingestion of a single dose by measuring total plasma FA composition over a period of 48 h (n 14) using a randomised cross-over design, and over the short term for a period of 4 weeks using an unblinded parallel design (after daily supplementation) by measuring total plasma and erythrocyte FA composition at baseline and at 2 and 4 weeks (n 47). In the acute study, F1 greatly increased (% Δ) plasma EPA and total n-3 FA levels at 2 and 4 h and DHA levels at 4 h compared with FOGC. The time to reach maximal plasma values (T(max)) was shorter for F1 than for FOGC or F2. In the short-term study, increases in plasma and erythrocyte n-3 FA values were similar for all treatments and achieved an omega-3 index in the range of 5·8-6·3 % after 4 weeks. Overall, the results demonstrated human bioequivalence for microencapsulated fish oil powder compared with FOGC.

Whey protein isolate and glycomacropeptide decrease weight gain and alter body composition in male Wistar rats.

The effect of feed protein type on body composition and growth has been examined. Evidence exists that whey protein concentrate is effective at limiting body fat expansion. The presence of caseinomacropeptide, a mixture of glycosylated and non-glycosylated carbohydrate residues, in particular glycomacropeptide (GMP) in whey protein concentrate may be important for this effect. The influence of whey protein isolate (WPI) and GMP on weight gain and body composition was examined by feeding Wistar rats ad libitum for 7 weeks with five semi-purified American Institute of Nutrition-based diets differing in protein type: (1) casein; (2) barbequed beef; (3) control WPI (no GMP); (4) WPI+GMP at 100 g/kg; (5) WPI+GMP at 200 g/kg. Body composition was assessed, and plasma samples were assayed for TAG, insulin and glucose. Body-weight gain was lower (- 21 %) on the control WPI diet relative to casein, with a non-significant influence associated with GMP inclusion (- 30 %), the effect being equivalent at both levels of GMP addition. Renal and carcass fat mass were reduced in the highest GMP diet when compared with WPI (P < 0.05). Plasma insulin was lowered by GMP at the highest addition compared with WPI alone (- 53 %; P < 0.01). Plasma TAG in the WPI+GMP (200 g/kg) group were lower (- 27 %; P < 0.05) than the casein and beef groups. In conclusion, GMP appears to have a significant additional influence when combined with WPI on fat accumulation. WPI alone appears to have the predominant influence accounting for 70 % of the overall effect on body-weight gain. Mechanisms for this effect have not been identified but food intake was not responsible.

Selenised casein protects against AOM-induced colon tumors in Sprague Dawley rats.

Selenium (Se) has been shown to be protective against cancers in animal models at concentrations exceeding those considered essential for normal nutritional requirements. Organic forms of Se provided as dairy proteins were obtained from cows fed diets supplemented with yeast Se. The casein extracted from milk was found to contain approximately half the Se of the Se-enriched milk. This casein was included in a semi-purified AIN rodent diet so as to provide 1 ppm Se and 25% protein and was compared with AIN diets containing no added Se (control, 0.05 ppm), 1 ppm and 4 ppm Se as selenised yeast (Sel-Plex) Their influence on colon tumor expression was examined in rats induced with azoxymethane, the diets being introduced post-induction. The selenised casein diet at this concentration was effective in reducing colon tumor incidence (by 29%) and burden (decreased 52%, P < 0.05) relative to the control in rats 26 wk post-induction. Selenised yeast, when added at similar (1 ppm) and increased Se concentration (4 ppm), did not influence significantly colon tumor expression. However, in a second study, with Se yeast providing Se at 1 ppm, 4 ppm, and 8 ppm throughout the experiment, a significant reduction in tumors was observed with 8 ppm Se (colon tumor incidence was 15% lower and colon tumor burden was 35% lower, P < 0.05). However this was associated with a significantly lower body weight in the rats (down 10.5%, P < 0.05) indicating a possible disturbance with normal energy intake or metabolism. The form in which Se is presented in the diet may influence significantly its bioavailability and/or anticancer potential at given concentrations within a safe range. The efficacy of selenised casein and indeed other potential dietary sources deserve further investigation with regard to their ability to prevent colon tumors at concentrations considered safe in the diet.

Whole-grain rye and wheat foods and markers of bowel health in overweight middle-aged men.

BACKGROUND: Whole-grain cereal foods including rye have been identified as providing significant health benefits that do not occur when refined-cereal foods are ingested. OBJECTIVES: Foods (90 g) containing whole-grain rye flour and whole-grain wheat flour were compared with low-fiber refined-cereal foods for their effects on markers of bowel health and the metabolic markers insulin and glucose. DESIGN: Three 4-wk interventions were undertaken in a randomized crossover design with 28 overweight men aged 40-65 y who had no history of bowel disease. Against a background intake of 14 g dietary fiber (DF), the men were fed low-fiber cereal grain foods providing 5 g DF for a total of 19 g DF/d. High-fiber wheat foods provided 18 g DF, and high-fiber rye foods provided 18 g DF, both giving a total of 32 g DF/d. Fecal samples (48-h) and fasting and postprandial blood samples were collected at the end of each period and assayed. RESULTS: Both high-fiber rye and wheat foods increased fecal output by 33-36% (P = 0.004) and reduced fecal beta-glucuronidase activity by 29% (P = 0.027). Postprandial plasma insulin was decreased by 46-49% (P = 0.0001) and postprandial plasma glucose by 16-19% (P = 0.0005). Rye foods were associated with significantly (P = 0.0001) increased plasma enterolactone (47% and 71%) and fecal butyrate (26% and 36%), relative to wheat and low-fiber options, respectively. CONCLUSIONS: High-fiber rye and wheat food consumption improved several markers of bowel and metabolic health relative to that of low-fiber food. Fiber from rye appears more effective than that from wheat in overall improvement of biomarkers of bowel health.

A diet containing alpha-cellulose and fish oil reduces aberrant crypt foci formation and modulates other possible markers for colon cancer risk in azoxymethane-treated rats.

There is a need for better understanding of the roles of dietary fats and fibers in colon cancer risk. We examined the effect of different dietary fiber and fat sources on an azoxymethane (AOM)-induced colon cancer in rats. In a 2 x 3 factorial design, rats were fed a semipurified diet containing soy-derived fiber (Fibrim), alpha-cellulose (Solkafloc) or resistant starch (RS; Hi-maize) at 10 g dietary fiber/100 g diet, combined with fish oil (FO) or sunflower seed oil (SSO) at 10 g/100 g diet, and lard added to all diets at 10 g/100 g, to provide a total of 20 g mixed fat/100 g diet. Sprague-Dawley rats (28 d of age) consumed diets for 4 wk and then two doses of AOM (15 mg/kg body) were administered 1 wk apart by subcutaneous injection. Rats were killed after 13 wk of consuming experimental diets. Colons were fixed in formalin and aberrant crypt foci (ACF) were quantified after staining. ACF counts were higher (+66%, P < 0.01) in rats fed SSO and RS, than in those fed alpha-cellulose and FO. Rats fed FO had 19% fewer ACF than those fed SSO (P < 0.05). alpha-Cellulose was associated with the highest cecal butyrate concentration (P < 0.001), the highest beta-glucuronidase specific activity (P < 0.001) and the lowest cecal water cytotoxicity (P < 0.001) relative to soy fiber- and RS-fed rats. There were inverse correlations between the number of ACF and cecal butyrate concentration (r = -0.33, P < 0.05) and between cecal water cytotoxicity and beta-glucuronidase activity (r = -0.70, P < 0.001). The greatest protection was associated with alpha-cellulose as the fiber source and FO as the fat source as measured by colon ACF numbers in rats.