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Clinical news

Mortality benefits of polyunsaturated fats in patients with type 2 diabetes

By Nicole MacKee
US researchers have confirmed that people with type 2 diabetes should favour foods higher in polyunsaturated fats (PUFAs) and avoid those with saturated fats to minimise their risk of cardiovascular and all-cause mortality.

In a prospective cohort study, published in the BMJ, 11,264 participants with type 2 diabetes from the Nurses’ Health Study and the Health Professionals Follow-Up Study were followed for a mean of 11 years.

The researchers found that a higher intake of PUFAs, compared with carbohydrates or saturated fatty acids, was associated with lower total mortality and lower cardiovascular mortality.

After multivariate adjustment, participants in the highest quartile of total PUFA consumption had a 24% reduced risk of cardiovascular disease-related mortality compared with those in the lowest quartile (hazard ratio, 0.76). This benefit was largely ascribed to linoleic acid, the researchers reported, which was the most abundant PUFA in the diet.

Clinical Associate Professor David Sullivan, Head of the Department of Clinical Biochemistry at the Royal Prince Alfred Hospital, University of Sydney, said the well-conducted study reinforced the traditional advice to prefer unsaturated, and particularly polyunsaturated, fats over saturated and trans fats.

He said there was a push for researchers to focus on ‘real food’ and styles of eating rather than on compositional analyses, but both types of studies were needed.

‘It’s only by doing this compositional work that we can advise primary producers as to what sorts of products are healthy and therefore should be produced in larger amounts,’ Associate Professor Sullivan said. ‘This research is pointing out that the PUFAs are favourable and we should be concentrating on that type of production; whilst the saturated fats are less healthful and, therefore, we should be regarding them more as treats and not producing them in such large amounts.’

In terms of advising patients with diabetes, he said it was always best to talk about whole foods than nutritional composition.

‘We well and truly recognise that we are better to be advising patients in terms of styles of eating, such as the Mediterranean diet,’ he said.

Associate Professor Sullivan said people with diabetes were likely to be more focused on controlling their glucose levels than on dietary fats, but it was useful to reinforce the importance of an overall healthy diet.
BMJ 2019; 366: l4009.