Ashley Duncan

A diet rich in walnuts favourably influences plasma fatty acid profile in moderately hyperlipidaemic subjects

Objective: To compare two low fat diets one rich in walnuts on parameters of lipid metabolism in a group of hyperlipidaemic subjects.Design: A randomised cross over study.Setting: Department of Human Nutrition, University of Otago, Dunedin, New ZealandSubjects: Twenty one men with mean (s.d) levels of total and LDL cholesterol of 6.58 (0.60) and 4.63 (0.58) respectively.Interventions: For two periods of four weeks subjects were asked to consume two low fat diets (fat 30% total energy), one containing, on average, 78 g/d walnuts. Walnuts obtained through Lincoln University and the Walnut Growers Group (South Canterbury).Results: Participants reported a higher total fat intake on the walnut diet (38% compared with 30% on the low fat diet P<0.01) The most consistent change in fatty acid profile of triacylglycerol, phospholipid and cholesterol ester on the walnut diet was a significant (P<0.01) increase in linoleic acid. Triacylglycerol linolenate also increased significantly (P<0.01). Total and LDL cholesterol were lower on both experimental diets than at baseline, 0.25 mmol/l and 0.36 mmol/l respectively on the walnut diet and 0.13 mmol/l and 0.20 mmol/l respectively on the low fat diet. High density lipoprotein cholesterol was higher on both the walnut and low fat diets when compared to baseline (0.15 mmol/l and 0.12 mmol/l, respectively). When comparing the walnut and low fat diets only apo B was significantly lower (P<0.05) on the walnut diet.Conclusions: Despite an unintended increase in the total fat intake on the walnut diet, fatty acid profile of the major lipid fractions showed changes which might be expected to reduce risk of cardiovascular disease. The reduction of apolipoprotein B suggests a reduction in lipoprotein mediated risk, the relatively low myristic acid content of both diets perhaps explaining the absence of more extensive differences in lipoprotein levels on the two diets.Sponsorship: Nutrition Department University of Otago, New Zealand.

Effect of meals rich in heated olive and safflower oils on oxidation of postprandial serum in healthy men

The present randomised, crossover study sought to determine the effect of meals rich in safflower oil and olive oil (60 g) which had been heated for 8 h at 210 degrees C and the corresponding unheated oils on copper ion oxidation of dilute serum from 16 healthy men. Four hours after the meals rich in the heated oils, there were significant decreases of similar magnitude (-12%) in the lag time in conjugated diene formation during diluted serum oxidation. In the 12 subjects who consumed meals containing unheated oils, the lag time also decreased (-11%) significantly after the meal rich in unheated safflower oil (US) and did not change significantly after the unheated olive oil (UO) meal and these changes were different between the meals at a marginal level of significance (P=0.05). Our data suggest that susceptibility to oxidation of lipoproteins in low antioxidant environments similar to dilute serum may be increased in the postprandial period following meals rich in heat-modified vegetable oils and unheated oils rich in polyunsaturated fatty acids but not following meals rich in native olive oil. These findings may be relevant to the choice of fat to replace saturated fats in lipid-lowering diets and to low risk of coronary heart disease in communities which have a high consumption of olive oil.

Body mass index status is effective in identifying metabolic syndrome components and insulin resistance in Pacific Island teenagers living in New Zealand

Although adults of Pacific ethnicity living in New Zealand have more than double the prevalence of diabetes and cardiovascular disease than the general population, little is known regarding the presence of risk factors for these disorders among young Pacific Islanders. The study aim was to examine relationships between body composition, glucose and lipid metabolism, and components of the metabolic syndrome (MS) in a community sample of Pacific Island (PI) teenagers living in Dunedin. Anthropometry, body composition (dual-energy x-ray absorptiometry), glucose and lipid metabolism, insulin resistance (homeostasis model assessment [HOMA2], McAuley index), and components of MS were assessed in 80 PI teenagers (aged 15-18 years). Results showed that 6 participants had full MS, 2 had high fasting blood glucose values (>7.0 mmol/L), 55 had high adiposity, and 21 had insulin resistance. Assessment of the components of MS by body mass index (BMI) status showed that obese participants (n = 29) had a high prevalence (86.2% had one or more component), whereas only 10.5% of those with healthy BMI status (n = 19) had any MS component. Elevated fat mass had substantial effects on fasting insulin values, HOMA2, and the McAuley index because in data adjusted for age, sex, and lean mass, a 10% greater fat mass was associated with a 4.7% increase in fasting insulin, a 5.3% rise in HOMA2, and a 2.3% decrease in the McAuley index. Our results suggest that the antecedents of cardiovascular disease and type 2 diabetes mellitus occur frequently in young Pacific Islanders having high adiposity. We conclude that community studies of PI adolescents should focus on assessing risk factors whenever BMI values are high.

Glycated albumin is associated with body mass index in euglycemic adults but is not predictive of postprandial blood glucose response

The level of glycated albumin in circulation is an indicator of blood glucose control over the preceding 2 weeks. It is not known if the level of glycated albumin in circulation relates to an individuals postprandial blood glucose response.

Impact of fermentation conditions on the physicochemical properties, fatty acid and cholesterol contents in salted-fermented hoki roe

Hoki (Macruronus novaezelandiae) roes were used to produce a salted fermented (jeotgal-like) roe product at 4 °C and 25 °C. The impact of the fermentation temperature on the microbiological status, proximate analysis, acidity, colour, fatty acid profile and cholesterol content were determined over a 4-week fermentation period. Total bacterial count and total LAB (expressed as log CFU) increased with fermentation time (p < 0.001). Fermentation temperature did not affect the proximate analysis, but fermentation time increased both the ash content and decreased the protein and moisture contents in the roe (p < 0.001, for all). Products produced at 25 °C had a lighter colour (p < 0.001) compared to products produced at 4 °C. Fermentation did not affect the roe fatty acid profile, but cholesterol content in the roe was reduced (p < 0.001) at both fermentation temperatures. Results suggest that fermentation can be a feasible approach to reduce cholesterol levels in fish roe.