In The BMJ, leading experts debate whether the food industry should fund health research, and if so, under what circumstances.

The food industry is crucial, fulfills key societal needs, and employs more people than any other sector in the UK, argue Paul Aveyard, professor of behavioral medicine at the University of Oxford, and Derek Yach, executive director at the Vitality Institute in New York.

"For these reasons, government policies seek to support the industry," they say, and "from this perspective, it would be absurd for health policy researchers to shun collaborating with the food industry."

Even though "industry promotes products that undermine public health, in many cases food industry and health goals clearly align and co-funding in-kind or in direct payment from industry is appropriate."

Leading manufacturers are investing billions of dollars to improve the nutritional quality of their products well in excess of public research investment, for example.

And if strong safeguards are in place to prevent bias, the integrity of collaboration research should not be doubted, they argue.

They recommend that researchers should be responsible for the design and conduct of the study, and have no commercial interest in the product.

Independent statisticians should carry out the analyses, and all results should be published regardless of outcome.

Payments of funding should be made to the organisation, not directly to the researchers, and reflect only the cost of the research.

"There are excellent examples of best practice in industry-funded food research," they explain. "The alternatives are that the research is not done, that it is done by the company itself, or that the public pay."

But Anna B Gilmore and Simon Capewell, both professors of public health at the University of Bath and University of Liverpool respectively, say that food industry funding biases research, and "seriously constrains" the fight against the obesity epidemic.

Evidence suggests that industries manipulate evidence, influence public and political opinion, and minimise regulation and legal liability.

And while the food industry is diverse, they highlight the clear conflict between ultra-processed food and sugary soft drinks companies, and public health, and similar evidence is now emerging for these.

For example, industry funding distorts the research agenda by "enabling corporations with vested interests to determine what research is done, and crucially, what is not done."

And results of industry-funded research have "uniquely favourable outcomes," they explain, adding that "even well-meaning scientists are often subconsciously biased, even by small gifts."

Disclosure and peer review are often cited as a sufficient redress to these criticisms, but studies show these are not sufficient.

More radical funding models are needed to enable industry to fund research while protecting research from their influence, they explain, such as manufacturer taxes, license fees or legally mandated contributions.

However, "change will not occur until public health researchers refuse to take the ultra-processed food industry money," they explain, which is a "surprisingly small proportion of total research funding, less than one-tenth in the UK or US."

"It worked for tobacco; in the early 1990s all bar one UK medical school took tobacco industry funding. That is unthinkable today," they conclude.