A new analysis published on 3 April in the Lancet links 20 per cent of global deaths to poor diet, equating to around 11 million deaths per year (1). The biggest risk factors were a high intake of sodium (salt) or low intake of whole grains, fruit, nuts and seeds, vegetables, and other healthy foods.

The Global Burden of Disease study 2017 was a massive collaborative effort funded by the Bill & Melinda Gates Foundation. The systematic analysis examined the consumption of major foods and nutrients across 195 countries and the potential impact a poor diet on disease, and ultimately, mortality.

Bad eating habits are known to contribute to various diseases from diabetes to cancers. But as Prof Nita Forouhi and Dr Nigel Unwin from the University of Cambridge write in their accompanying commentary, “the devil is in the details”.

The researchers evaluated 15 dietary risk factors were evaluated for their impact on mortality and disease including cancers, cardiovascular diseases, and diabetes.

WHAT DOES THE NEW ANALYSIS SHOW?

• Most people eat too few healthy foods leading to suboptimal nutrient levels;
• Whereas many people consume more than the recommended intake of unhealthy foods like sugary drinks, sodium, and processed and red meat;
• Diet contributed to 11 million deaths and 255 million disability-adjusted life-years (DALYs), where each DALY equals one lost year of “healthy” life;
• The three biggest dietary risks for death were high salt intake, low intake of whole grains, and not eating enough fruit;
• Finally, unsurprisingly, low-income was a major factor contributing to poor diet.

Although these findings are not totally new, they offer the opportunity for nations to compare themselves to other countries. Forouhi and Unwin also suggest the global-level data could act as an accountability tool. The authors hope this new information will stimulate appropriate policy interventions that support both optimal diet and sustainability.

SO WHAT SHOULD WE BE EATING?

Studies like this bring into focus the important question of what should the world eat? Particularly, given the current climate change and planetary woes. The results provide a much-needed push towards optimising diets for sustainable food systems, which can only be achieved with mainly plant-based diets.

However, the results also highlight the prohibitively high costs of healthy foods like fruits and vegetables. In low-income countries, the recommended two servings of fruits and three servings of vegetables per day per individual amounted to 52 per cent of household earnings in low-income countries, 18 per cent in low to middle-income countries, 16 per cent in middle to upper-income countries, and 2 per cent in high-income countries.

The study is not without limitations. Data were collected from several different sources and not available from all countries. Moreover, many of the populations included were of European descent and the analysis did not consider geographical variations in diet.

Nonetheless, the underlying message is clear ― most countries in the world would benefit from a more balanced diet. Forouhi and Unwin believe the evidence will stimulate the shift from nutrient-based to food-based guidelines.