While governments have agreed to global health and environmental targets, most dietary guidelines are lagging behind, according to research published in the journal The BMJ.

The study found that 98% of dietary guidelines from 85 nations are incompatible with at least one of the international goals to tackle non-communicable diseases and climate change, thwarting commitments to meet those and others related to biodiversity, agriculture and water.

In line with the EAT-Lancet Commission’s recommendations in January last year, analyses confirmed that eating more wholegrains, fruits, vegetables, legumes, nuts and seeds, and less red and processed meat and dairy would be healthier for people and the planet.

Reducing excess energy intake, with more stringent guidelines on sugar and staple crops such as grain and potatoes, was also key for achieving lower mortality and accounted for half the reductions in land, water and fertiliser use.

Non-communicable diseases such as heart disease, type 2 diabetes and cancer cause more than half of the world’s deaths and are preventable with healthier lifestyles.

As far as planetary health, scientists have been calling for it to be integrated into national dietary guidelines for nearly three decades now, according to co-author Luke Spajic from Australia’s University of Adelaide, with another recent push in Australia and the US.

Yet the recommendations still fail to factor in the environment. In Europe, an analysis of 34 national guidelines similarly found nothing to address sustainability.

So what’s holding it up?

Spajic says there’s been a “significant backlash from industry groups”. In Australia, this caused environmental sustainability to be tacked on as an appendix rather than being integrated into the guidelines – holding up increasingly critical reform.

“Recent devastating droughts and bushfires in Australia have demonstrated that we must factor environmental sustainability into everything we do,” he says.

Indeed, the Intergovernmental Panel on Climate Change (IPCC) declared it’s impossible to meet climate targets without addressing the food system and land management.

To compare dietary guidelines with global health and environmental targets, the team, which also included scientists from the University of Oxford, UK, and Harvard and Tufts universities in the US, collated and scored quantifiable recommendations such as “eat five servings of fruit and vegetables a day”.

For comparison, they assessed the global guidelines from the World Health Organisation (WHO) and the EAT-Lancet Commission on Healthy Diets from Sustainable Food Systems.

With modelling, the team estimated how the recommendations could reduce death from prevailing chronic diseases and meet environmental targets to reduce greenhouse gas emissions and exploitation of land and freshwater resources.

Results showed that, on average, adoption of existing dietary guidelines would cut premature deaths by 15% and food-system related greenhouse gases by 13%. But a third were incompatible with the global health agenda on non-communicable disease and 67% to 87% did not align with the Paris Climate Agreement and other environmental targets.

The WHO’s guidelines didn’t fare any better. But adopting the EAT-Lancet recommendations would meet targets, producing a third greater reduction in premature death than if people followed current guidelines, and more than three times greater reductions in emissions.

While the assessment was rigorous and comprehensive, the researchers acknowledge limitations, such as uncertainty inherent in the qualitative nature of many national guidelines, and this was echoed by Lukas Schwingshackl, from the University of Freiburg, Germany, and co-authors in a related editorial.

Despite this, and other obstacles to change that need to be ironed out, they say reform is clearly needed, reinforced by policies to help people actually follow recommendations.

“The best dietary guidelines are meaningless if they are not backed up by targeted health promotion programs and procurement standards,” says study lead Marco Springmann from the University of Oxford, “or if regulation is not aligned across departments and sectors.”

In reforming guidelines, the group recommends proactive measures such as health promotion programs, concrete examples and recommendations, food sector regulation and menu alignment in school and work-place canteens.

To address continued industry resistance, Spajic also suggests health and environmental researchers and civil society groups join forces to advocate for healthier, sustainable dietary guidelines.