Ultra-processed foods now make up nearly half of the average Australian’s diet because the country has “fallen behind international best practice” on nutrition, a co-author of a major new global report says.

A series published in leading medical journal the Lancet on Wednesday found ultra-processed foods (UPFs) are increasingly replacing healthy, whole-foods in diets and are a “key driver of the escalating global burden of multiple diet-related chronic diseases”.

The Lancet series described these foods as a “major new challenge” to health.

It found Australia, alongside the USA and the UK, has some of the highest consumption rates of UPFs, making up more than half of the calories consumed each day. Such foods have become a “central part of dietary patterns for most of the population”.

Long-established processing methods, such as fermentation and canning, largely preserve the natural structure of foods and increase shelf life.

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But new technologies change the internal structure of food, chemically modify components, and use additives to produce ready-to-consume, long-lasting, and highly palatable products. These are known as ultra-processed foods.

The Lancet series outlines the “urgent, coordinated” public policies and collective actions needed to address the growing impacts of UPFs.

However, Prof Mark Lawrence, a co-author of the series from Deakin University, warned Australia was already behind.

“We have, at the moment, no national food and nutrition policy in this country,” Lawrence said, adding that there had not been one since 1992. “Instead, we have these piecemeal actions in the policy space.

“We’ve fallen behind international best practice. There are no taxes on sugar and soft drinks [like] other countries are doing.”

In their place, the health department’s healthy food partnership was “well intended”, but the strategies used had “unfortunately, very dire consequences” because they had been poorly designed, he said.

‘New vision’ needed for food system

Lawrence said the “classic example of a counterproductive policy” is Australia’s health star rating system, which focuses on individual nutrients like salt and sugar.

Because Australia’s largest food manufacturers were involved in developing the system, they influenced policymakers so that these ingredients could simply be replaced with ultra-processed alternatives and products could earn high ratings, research has found.

Policymakers needed to consider the cumulative health impacts of the “cocktail” of these novel ingredients over time, Lawrence said.

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Analysing evidence from more than 100 papers, the researchers involved in the Lancet series found associations between a high consumption of ultra-processed foods and a greater risk of things like obesity, type 2 diabetes, hypertension, cardiovascular disease and other conditions.

It comes as recent research led by the Massachusetts general hospital suggested ultra-processed foods may be linked to precursors of bowel cancer, and help explain rising bowel cancer in under-50s.

Australia has the world’s highest rates of bowel cancer in people under 50.

Dr Priscila Machado, a co-author on the series also from Deakin University, said while the Lancet series did not find strong evidence linking UPFs to bowel cancer, studies looking at the precursors were “very relevant” and more research was needed.

Alongside policies to address the supply chain, the authors called for policies to support the availability and affordability of fresh and minimally processed foods, and to address the socioeconomic and gender inequalities that drive demand for UPFs.

Lawrence points to a “gold standard” policy in Brazil that has legislated that 90% of foods available in public school lunch programs come from unprocessed or minimally processed foods.

Dr Philip Baker, a lead author of a paper in the series from the University of Sydney, said a “new vision” was needed for Australia’s food system to redistribute resources to more diverse local producers, rather than transnational corporations.

A spokesperson for Rebecca White, the assistant minister for health, said the Australia’s 2013 dietary guidelines were currently under review. This included “a systematic review of ultra-processed food consumption [and its impact] on mortality and chronic disease risk to inform the updated guidelines”.