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Experts caution on dietary advice purporting to show fat is good

Thursday 31 October 2013 1:24pm

The international media response to a BMJ opinion piece claiming to debunk the “myth” of saturated fat as a cause of coronary heart disease could undermine public confidence in lifestyle changes that have resulted in appreciable health benefits, say a group of experts in public health and nutrition representing a number of New Zealand health-related organisations.

They have also expressed concern regarding recent promotion in New Zealand of exceptionally low carbohydrate/high fat diets aimed at weight loss and reduced risk of some chronic diseases.

Professor Jim Mann

The group’s spokesman, University of Otago Professor in Human Nutrition Jim Mann, says avoiding and treating obesity is central to advice about food and physical activity for people of all ages aimed at reducing chronic diseases, including several of the most commonly occurring cancers in New Zealand; type 2 diabetes, coronary heart disease and stroke.

The groups include: the University of Otago’s Edgar National Centre for Diabetes and Obesity Research, the Agencies for Nutrition Action, the Australian and New Zealand Obesity Society (ANZOS); Dietitians NZ; the New Zealand Nutrition Foundation; the Nutrition Society of New Zealand; the Cancer Society of New Zealand; Diabetes NZ; the New Zealand Society for the Study of Diabetes (NZSSD); and the NZ Stroke Foundation.

WHO has commissioned studies, also published in the BMJ, that have confirmed the importance of total fat reduction (typically also involving a reduction in saturated fat) as well as the reduction of sugars in helping to reduce overweight and obesity. “There is no evidence that this is achieved in the long term by very low carbohydrate- high fat diets,” says Professor Mann.

In western countries a reduction in saturated fats has occurred in parallel with a reduction in blood cholesterol levels and coronary heart disease.

Professor Mann adds that although heart disease has many causes, in western countries coronary heart disease risk is directly related to cholesterol levels.

“In New Zealand the reduction in fat consumption from more than 40% towards 30% (and saturated fat towards 10%) since the 1970’s has been associated with a reduction in coronary heart disease death rates by more than two thirds,” he says.

“In parts of Sweden the trend towards reducing cholesterol levels has been reversed in association with the promotion and adoption of high fat diets.”

Most people tend to think of what they eat in terms of foods rather than nutrients and the expert group supports the concept that different dietary patterns are compatible with calorie balance, a healthy body weight and reduced risk of type 2 diabetes, coronary heart disease and several cancers. (See footnote below)

However, the group suggests that those who advocate for radical new dietary approaches have a responsibility to provide convincing peer-reviewed evidence of long term benefit as well as absence of harm. Such evidence does not exist for diets high in saturated and total fat, and very low in carbohydrate.

Footnote about current and validated dietary advice:

A variety of fruits, coloured vegetables, lean meat, fish, legumes, pulses, nuts, appropriate unsaturated oils, reduced fat dairy products and whole grain cereals can be combined in various ways in suitable dietary patterns. These foods and wholegrain varieties of breads and cereals are certainly in preference to other carbohydrate containing foods that are highly processed like white rice, pasta, and flour. A range of fat intakes is acceptable provided that there is emphasis on appropriate types of fat, but some degree of fat restriction is universally recommended by experts. Substantial limitation of “free” or “added” sugars is advised because they confer no health benefits and like alcoholic drinks may contribute substantially to calorie excess and deficits in some nutrients.
The BMJ article:

For further information, contact:

Professor Jim Mann
Director, Edgar National Centre for Diabetes and Obesity Research
University of Otago

ANZOS contact:
Associate Professor Anna Peeter
Head Obesity & Population Health | Baker IDI Heart and Diabetes Institute
President Australian & New Zealand Obesity Society
Baker IDI Heart and Diabetes Institute
Level 4, 99 Commercial Road, Melbourne VIC 3004
Tel 61 3 8532 1928

Agencies for Nutrition Action (ANA) contact:
Nicola Chilcott
Executive Director
Agencies for Nutrition Action
Level 6, 166 Featherston Street
PO Box 5680
Wellington 6145
Tel 64 4 499 6362

Cancer Society of New Zealand contact:
Dr Jan Pearson
Health Promotion Manager
Cancer Society of New Zealand
Tel 64 4 494 7276

New Zealand Society for the Study of Diabetes (NZSSD) contact:
Dr Jeremy Krebs
Endocrinologist, Wellington Hospital
New Zealand Society for the Study of Diabetes

Dietitians NZ contact:
Alexandra Chisholm PhD
Snr Research Fellow / Research Dietitian
Dept.of Human Nutrition
University of Otago
P.O. Box 56
Dunedin 9054
New Zealand
Tel 64 3 479 7514
Fax 643 4797 958

Diabetes NZ contact
Lisa Woods
Communications Manager
Diabetes New Zealand
PO Box 12441
Wellington 6144
New Zealand
Tel 64 4 499 7145

New Zealand Nutrition Foundation contact:
Professor Elaine Rush
AUT Professor of Nutrition
Scientific Director, New Zealand Nutrition Foundation

A list of Otago experts available for media comment is available elsewhere on this website.

Electronic addresses (including email accounts, instant messaging services, or telephone accounts) published on this page are for the sole purpose of contact with the individuals concerned, in their capacity as officers, employees or students of the University of Otago, or their respective organisation. Publication of any such electronic address is not to be taken as consent to receive unsolicited commercial electronic messages by the address holder.