Diabetes can be prevented by lifestyle change. The challenge is to develop public health approaches to support individuals with respect to incorporating the lifestyle changes needed to reduce the risk of diabetes into their everyday life.

A 13-wk dietary intervention was carried out with 23 members of the 1991 wintering party of an Australian National Antarctic Research Expedition. Canola margarine and canola cooking oil were substituted for usual dietary fats (butter, a margarine containing 28% saturated fat, a polyunsaturated margarine, and vegetable oil). Mean energy intake slowly decreased although body weight slowly increased during the 42-wk wintering-over period. During 13 wk of dietary substitution, mean total cholesterol and low-density-lipoprotein-cholesterol concentrations fell by 7.0% and 10.0%, respectively (P < 0.05, repeated-measures ANOVA). These changes were not found in a second wintering-over group that did not experience this dietary intervention. The data indicate that a relatively simple change to the food supply has the potential to produce significant beneficial changes in lipoprotein lipid profile.

Summary. Randomly bred chicken enibr>os were inoculated on days 5, 6 and 10 witb adult .\A blood and examined on day 13. Widespread haemorrhages oceurred on the body surface, the yolk sac was poorly developed and haemopoietic tissue of the yolk sac fokl.s was severely dt-pletiid. Lymphopoiesi.s in the tliymn.s was depressed and tlie difFerintintion of the l)irrsa of Fabricius was retirded. Tliese lesioiw are characteri.stic of a graft-versus-host reaction in very young (rather tlian l()-day-old) embryos and appear to result from the ilestniction of haemopoictic stem cells in the yolk sac thus preventing their dissemination to intra-cmbr>onic baemopoietk-organs.Since it has been suggested that yolk sac-derived stem cells are required for the development of proliferative lesions during a graft-versus-host reaction in oUlcr rmhryos, tlic pock-forming ability of these embryos depleted of stem cells by an early graft-\crsus-host reaction was examined. Randomly bred embryos inoculated on days o and 6 tleveloped very few jwcks in response to a third inoculation of adnlt AA hlood on day 10. In comparison. AA cliicken embryo.s inocnlated ou da\s .5 and fi witli adult .W blcK)d Iwfore inoculation oT adult allof:;eneic blond onto the dioridnllantoic inenihrane on ilay 10 developed nonnal numbcr.s uf pocks. Tliese results support the hypotliesis that yolk sac-derived stem cells are required for the development of proliferative lesions during a gnift-versus-host reaction.

Animal and human studies indicate that high saturated fat (SFA) diets can be obesogenic. Monounsaturated fat (MUFA) has acute (meal related) effects that influence energy metabolism. These include increased postprandial fat oxidation and greater diet induced thermogenesis, factors that attenuate weight gain. Chronic (diet related) studies for 12 weeks or more, demonstrate that people following high MUFA diets do not gain excessive weight even when eating ad libitum. In fact, we have observed greater body weight and fat loss in men following an ad libitum MUFA diet, when compared to a SFA diet. High MUFA diets designed for weight loss should also incorporate a high vegetable intake according to traditional Mediterranean patterns. Such diets will promote the utilisation of fat and also have a low energy density. In our experience these diets are well accepted, and offer the prospect of greater long-term adherence to dietary advice.