In January 2019, the Eat-Lancet Commission issued the world’s first scientific targets for a healthy diet that places food production within planetary boundaries.
The resulting EAT-Lancet reference diet promotes increased consumption of nuts, fruits, legumes and vegetables. It also suggests that global consumption of red meat and sugar needs to decrease by more than 50% by 2050.
In some regions, however, sharper adjustments may be required to meet the dietary guidelines. In North America, for example, people eat an average of 6.5 times the recommended amount of red meat, while countries in South East Asia consume just half the recommended levels.
The report authors calculated that globally, this diet shift could reduce mortality rates from diet-related noncommunicable diseases (NCDs), averting between 10.9 and 11.6 million premature deaths each year.
One year on, researchers from statistical consultancy EpiX Analytics have published concerns that these figures were miscalculated, and that in the US, the proposed diet would have no greater impact on mortality reduction than energy consumption changes.
Flawed calculations?
In a fresh report published 15 February 2020 in The Journal of Nutrition, EpiX Analytics colleagues argue the EAT-Lancet report did not meet standards for transparency and replicability, nor did it ‘fully’ account for statistical uncertainty.
“Our attempt to replicate the mortality calculations for the US revealed flaws in the assumptions and methods used to estimate the avoided mortalities,” noted the authors.
“After correcting some calculation errors and fully accounting for uncertainty in the avoided mortalities, the mortality reduction effect of the EAT-Lancet proposed diet in the US is no greater than the impact of energy consumption changes that would prevent underweight, overweight, and obesity alone.”
The report concludes that further independent validation is required before the EAT-Lancet report can be used to inform dietary guidelines.
Yet the EAT-Lancet Commission does not agree. According to Dr Marco Springmann, who co-authored the report, the NCD analysis ‘fully adhered’ to transparency and reporting standards, and included a comprehensive methodological appendix.
EAT-Lancet responds: ‘The number of avoidable deaths is sizeable’
The EAT-Lancet report included three estimates of impacts that dietary changes towards the EAT-Lancet diet could have for diet-related disease mortality.
Despite using different methodology, Dr Springmann, senior researcher on environmental sustainability and public health at the University of Oxford, told FoodNavigator they all arrived at roughly the same conclusion, “indicating significant reductions in diet-related disease mortality in each region”.
Concerning the US, the EAT-Lancet Commission estimated that dietary changes towards dietary patterns that are in line with the EAT-Lancet recommendations – flexitarian, pescatarian, vegetarian, vegan – could reduce premature mortality by 22-24% in 2030, depending on the dietary pattern.
“Balancing weight levels reduced premature mortality by about 17%, and changes in dietary composition 7-10%, with greater contributions in the more plant-based dietary patterns,” noted Dr Springmann.
In general, the relative contribution between changes in dietary composition and energy intake associated with weight changes depends on the level of overweight and obesity in a country, the co-author explained.
The US happens to have one of the highest levels of overweight and obesity. “That said, the number of avoidable deaths from changes in dietary composition – around 200,000 in the US in 2030 – is still sizeable and warrants to be taken seriously.”
Source: The Journal of Nutrition
‘The EAT-Lancet Commission’s Dietary Composition May Not Prevent Noncommunicable Disease Mortality’
DOI: https://doi.org/10.1093/jn/nxaa020
Published 15 February 2020
Authors: Francisco J Zagmutt, Jane G Pouzou, Solenne Costard
