By John Kerr 30/08/2017


Chowing down on a high-carb diet could be worse for your overall health than eating a high-fat diet – if you believe the media coverage of a new international study. But a New Zealand expert warns the dietary implications of the findings aren’t that simple, especially for Kiwis.

The study

The new research, published yesterday in the Lancet, comes from the massive Prospective Urban and Rural Epidemiological (PURE) Study. The international team of researchers collected health and diet data from over 135,000 people in 18 countries for almost eight years. In particular, the researchers focused on how much of person’s total energy intake came from carbohydrates or fats.

In a nutshell, the study found that the people who got a lot of their daily energy intake from carbohydrates had a much higher risk of death during the study period than those who ate a diet low in carbohydrates. Eating a diet relatively high in fat, on other the other hand, was associated with a lower risk of death compared to a low-fat diet. The researchers found this pattern remained the same when considering just saturated fats (typically found in meat and dairy products) or monounsaturated and polyunsaturated fats (mainly from plants and fish).

The result that high(er)-fat diets weren’t linked to adverse outcomes suggests that current recommendations to restrict dietary fats (likely leading to increased consumption of carbohydrates for energy), could be off the mark.

“Our findings do not support the current recommendation to limit total fat intake to less than 30% of energy and saturated fat intake to less than 10% of energy,” said study investigator Dr Mahshid Dehghan, from McMaster University, Canada.

“Limiting total fat consumption is unlikely to improve health in populations, and a total fat intake of about 35% of energy with concomitant lowering of carbohydrate intake may lower risk of total mortality. In fact, individuals with high carbohydrate intake, above 60% of energy, may benefit from a reduction in carbohydrate intake and increase in the consumption of fats.”

Read the full findings on Scimex.org

 

Bread or butter? The new study suggests current recommendations around fat and carbohydrate intake should be revised.

 

What does it mean for NZ?

Experts in New Zealand, contacted by the Science Media Centre, warned the findings might not be so applicable for the average Kiwi diet.

Professor Jim Mann, Director of the Edgar Diabetes and Obesity Research, University of Otago, noted that, while impressively large, the study had limitations:

A major difficulty in interpretation results from the fact that the most striking effects were seen when comparing extreme levels of intake. For example, the risk of death was 28% higher among those with diets high in carbohydrate than in those with the lowest intakes. However, those with the highest intake were obtaining 77% of energy from carbohydrate and those with lowest intake 46% energy from carbohydrate.

In New Zealand, current intakes are not appreciably different from those in the low intake category. The ‘benefits’ of fat are similarly mainly apparent when comparing extreme levels of intake.

Carbohydrate intakes are highest amongst the predominantly rice-eating countries including China and countries in South Asia (carbohydrates providing 65 to 68% total calories) and it is these countries which the authors suggest might be particularly at risk from their high carbohydrate intakes.

Current guidelines which we endorse recommend that people continue to eat a diet that is rich in vegetables and fruit, legumes, pulses, nuts, wholegrains, and vegetable oils. Importantly, people should limit the amount of free sugars, salt and highly processed food.  A range of dietary patterns, including Mediterranean, Asian style and other traditional dietary patterns can be consistent with this approach.”

In an interview with Stuff.co.nz this morning, Prof Mann warned that people could be misled by the blunt recommendations to reduce carbohydrate and increase fat. “It’s going to cause enormous confusion. I have actually written to the editor of The Lancet about it. It’s a really confusing paper.”

 

Featured image: Flickr / Kim Ahlström