Murray Skeaff

Randomised controlled trial of effect of fruit and vegetable consumption on plasma concentrations of lipids and antioxidants.

Abstract Objectives: To determine the extent to which plasma antioxidant concentrations in people with habitual low intake of fruit and vegetables respond to increased intakes of these foods. To examine whether advice to increase fruit and vegetables will result in reduction of concentrations of total and low density lipoprotein cholesterol. Design: Randomised controlled trial in which intervention and control groups were followed up for eight weeks. The intervention group was asked to consume eight servings of fruit and vegetables a day. Setting: Dunedin, New Zealand. Subjects: Eighty seven subjects with normal lipid concentrations who ate three or fewer servings of fruit and vegetables daily. Main outcome measures: Plasma concentrations of vitamin C, retinol, α and ß carotene, α tocopherol, lipids, and lipoproteins. Dietary intake assessed with diet records over four days. Results: The mean plasma vitamin C, α carotene, and ß carotene concentrations increased in parallel with increased dietary intake of fruit and vegetables in the intervention group. Concentrations of retinol, α tocopherol, lipids, and lipoproteins remained unchanged despite some increase in dietary vitamin E and a small reduction in saturated fat intake. Conclusions: Following a recommendation to increase fruit and vegetable consumption produces change in plasma concentrations of vitamin C, α carotene, and ß carotene likely to reduce incidence of cancer. More specific dietary advice to modify fat intake may be necessary to reduce the risk of cardiovascular disease mediated by lipoprotein and vitamin E. Key messages Increasing intake of fruit and vegetables raises plasma concentrations of vitamin C and α and ß carotene These changes in plasma concentrations of antioxidants are probably associated with reduced risk of cancer A simple recommendation to increase fruit and vegetable intake has little effect on plasma concentrations of α tocopherol, lipids, and lipoproteins More specific dietary advice to modify fat intake may be necessary to reduce risk of cardiovascular disease associated with lipoproteins and vitamin E

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.

Effects of dietary coconut oil, butter and safflower oil on plasma lipids, lipoproteins and lathosterol levels.

Objective: The aim of this present study was to determine plasma levels of lathosterol, lipids, lipoproteins and apolipoproteins during diets rich in butter, coconut fat and safflower oil.Design: The study consisted of sequential six week periods of diets rich in butter, coconut fat then safflower oil and measurements were made at baseline and at week 4 in each diet period.Subjects: Forty-one healthy Pacific island polynesians living in New Zealand participated in the trial.Interventions: Subjects were supplied with some foods rich in the test fats and were given detailed dietary advice which was reinforced regularly.Results: Plasma lathosterol concentration (P<0.001), the ratio plasma lathosterol/cholesterol (P=0.04), low density lipoprotein (LDL) cholesterol (P<0.001) and apoB (P<0.001) levels were significantly different among the diets and were significantly lower during coconut and safflower oil diets compared with butter diets. Plasma total cholesterol, HDL cholesterol and apoA-levels were also significantly (P≤ 0.001) different among the diets and were not significantly different between buffer and coconut diets.Conclusions: These data suggest that cholesterol synthesis is lower during diets rich in coconut fat and safflower oil compared with diets rich in butter and might be associated with lower production rates of apoB-containing lipoproteins.Sponsorship: The study was supported by the Health Research Council of New Zealand and the Anderson Telford Trust.

Interrelationship of indices of body composition and zinc status in 11-yr-old New Zealand children

Serum zinc and hair zinc concentrations of some New Zealand children aged 11 yr, were examined in relation to selected anthropometric indices. Serum zinc concentrations (n=453) in boys and girls were similar and were unrelated to anthropometric indices and hair zinc concentrations. Mean hair zinc concentration (n=620) of the girls was higher than that for the boys (2.95±0.49 vs 2.46±0.47 µmol/g; p<0.001). Correlation analysis demonstrated that, for the boys, all the studied anthropometric indices, with the exception of height, were significantly related to hair zinc concentration and that the confounding effects of mid-parent height and the timing of the adolescent growth spurt was small. Results for the girls were similar but less significant. Dichotomizing the hair zinc results divided both the boys and girls into two groups: those with hair zinc <2.44 µmol/g were heavier (girls, 39.0 vs 35.2 kg; boys, 36.6 vs 34.7 kg) and fatter (mid-upper-arm fat area: girls, 15.2 vs 12.0 cm2; boys, 11.1 vs 9.5 cm2) compared to their counterparts with hair zinc >2.44 µmol/g. The results demonstrate that in these healthy New Zealand children, those with lower hair zinc concentrations are fatter and heavier than their high-hair-zinc counterparts.

Changes in markers of inflammation, antioxidant capacity and oxidative stress in smokers following consumption of milk, and milk supplemented with fruit and vegetable extracts and vitamin C.

Two milk-based beverages delivering twice the average daily antioxidant intake were formulated, based on synergistic combinations of fruit and vegetable extracts, and containing vitamin C (1.00 mg/ml) for shelf stability. Smokers (n = 42) consumed prototype milk A, B or non-supplemented milk (no extracts or vitamin C; 200 ml) twice daily for 6 weeks. Fasting and post-prandial (2 h after milk consumption) blood samples were collected at baseline and the end of each treatment. Non-supplemented milk significantly reduced fasting inflammatory cytokines (interleukin (IL) 6, IL-1β, tumour necrosis factor-α) compared to baseline. Both supplemented milk-based beverages significantly increased fasting plasma vitamin C concentrations and antioxidant potential and decreased serum uric acid, compared to non-supplemented milk. The beverages did not induce post-prandial oxidative stress or inflammation. Therefore, regular consumption of the supplemented milks may confer health benefits because of increased antioxidant potential or through mechanisms resulting from increased vitamin C or decreased uric acid concentrations.

Vitamin D status and its predictors among pre‐school children in Adelaide

To assess vitamin D status and its predictors in a representative population sample of pre‐school children in Adelaide (latitude of 35°S).

Trans fatty acids : a cause for concern ?

The recommendation to reduce total and saturated fat is incorporated into the dietary guidelines for the general population in many western countries. In addition, dietary modification to reduce substantially the intake of saturated fats is a cornerstone of treatment in the hyperlipidaemias. Concern has recently been expressed regarding possible deleterious effects of trans isomers of unsaturated fatty acids on the lipoprotein profiles of both normo and hypercholesterolaemic persons. This review seeks to examine recent research in this area with a view to considering possible changes in the present dietary recommendations.

Are some diets "mass murder"? Dietary guidelines worldwide advise limiting saturated fat in favour of monounsaturated and polyunsaturated fats.

Smith’s views on saturated fat seem to have been strongly influenced by a few popular books and a limited selection of original publications.1 Lay authors are susceptible to bias because they rarely carry out a formal search of article databases and may not critique the evidence in totality. “Cherry picking” of evidence can lead to erroneous understanding. Smith incorrectly describes the Women’s …