20 Feb 2019

Study shows high-fat diet bad for gut health

From Jesse Mulligan, 1–4pm, 1:20 pm on 20 February 2019

Eating a high-fat diet may affect the type and amount of healthy gut bacteria you have, according to new international research.

Researchers say those on a high-fat diet lost key bacteria and had higher inflammatory triggers, which could over time, develop into metabolic disorders such as heart disease, stroke and diabetes.

Gut Bacteria

Gut Bacteria Photo: Wikipedia

One of the report's authors, Jim Mann from Otago University, told Jesse Mulligan the research was carried out in China where diet has been changing over the last two decades.

“There’s immense concern that people in China have made radical changes to their diet in the last relatively short period of time.

The Chinese diet was really very low in fat in the past, very high in rice and carbohydrate and this is now moving towards a more western pattern,” he says.

Although done in China the research has implications for countries such as New Zealand, he says.

“When I first went to China you wouldn’t have seen a MacDonald’s in sight, whereas now fast food outlets are as common in Beijing, if not more, than they are in many western countries,” he says.

The control group in China was split into three each following over six months three defined diets: a traditional Chinese diet, an intermediate diet and a high fat western diet.

“The research was on a fairly large group, over 200 young healthy adults under the age of 35, fairly normal weight they were randomised into three groups.

“All their food was provided, so we got a pretty good idea they were eating the kind of food we wanted them to eat.”

The group on a high fat diet had higher cholesterol, he says, which was expected.

Prof Jim Mann

Prof Jim Mann Photo: Billy Wong/University of Auckland

“Of particular interest was what happened to the bacterial flora of the gut, the microbiome underwent radical changes in these three different groups.

“The low fat group had a bacterial profile which was compatible with low risk of a number of western diseases: heart disease and cancer.

The high fat group had a very different profile of bacteria in their gut, one more compatible with an increased risk of bowel cancer and also a much higher risk of inflammation leading to cardio vascular disease, heart disease and possibly diabetes,” Prof Mann says.

The results, he says, were pretty “pretty scary.”

“It’s a strong message for what is happening in China, but I believe also a strong message for New Zealand and other similar countries where at least some people believe there are benefits to a high fat diet.”

All three groups had consistent and similar intake of vegetables, he says.

“A lot of people have argued you can have a high fat diet as long as you have a lot of veggies, I think that’s a serious misapprehension. If you are having a really high fat diet you’re not going to get a high fibre diet at the level of fibre that will be protective against these diseases.”

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