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‘Controversial’ data challenge link between saturated fat and CV disease

By Bianca Nogrady
An international epidemiological study suggesting saturated and other fat intake is not linked to cardiovascular (CV) risk has been described as controversial.

The Prospective Urban Rural Epidemiology (PURE) study, published in the Lancet, examined the dietary intake of 135,335 individuals across 18 countries in relation to their total mortality and risk of major CV events over a median follow up of 7.4 years.

The study aimed to investigate the impact of diet in countries where overnutrition is common and undernutrition is of greater concern, including low-income countries such as Bangladesh, India and Pakistan, and middle-income countries such as Argentina, South Africa and Turkey, as well as high-income countries such as Canada and Sweden.

Researchers found that increasing carbohydrate intake correlated with increasing risk of total mortality, with a 28% higher mortality in the highest quintile of carbohydrate intake compared with the lowest. However, increasing total fat intake, and intake of each type of fat – including saturated fat – was associated with a significantly decreased risk of total mortality.

There was also no significant association seen between total fat intake or intake of different types of fat, and risk of myocardial infarction or CV disease mortality.

The highest quintile for intake of saturated fat was associated with a 21% lower risk of stroke than the lowest quintile.

While the authors suggested global dietary guidelines should be reconsidered in light of the findings, cardiologist Professor Clara Chow from The University of Sydney and The George Institute for Global Health argued the results were controversial and flew in the face of conventional understanding.

Professor Chow pointed out that there were some major potential confounders that couldn’t be controlled for in such an analysis – for example, the relative amounts of fat and carbohydrate in the diets of people in urban and rural settings in low-middle versus high-income countries.

‘The percentage of total energy that you get from fat is hugely different if you live in India versus if you live in higher income places like Canada and so in some ways, doing the analysis across all of those countries confuses a lot of the issues,’ Professor Chow told Cardiology Today.

Professor Chow pointed out that applying epidemiological and association data to individuals was challenging.

‘But if you’re a person who has had a heart attack, there are plenty of data to show that cholesterol lowering will reduce your risk of repeat CV events and cholesterol lowering can be achieved by lowering your total dietary saturated fat intake, and by cholesterol lowering medications like statins.’
Lancet 2017; http://dx.doi.org/10.1016/S0140-6736(17)32252-3.

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