Some 20% of deaths that occurred worldwide in 2017 were associated with poor diet, a major new study has found.

The Global Burden of Disease study tracked dietary trends from 1990 to 2017 in 195 countries. It estimated that one in five deaths globally in 2017 - that is 11 million deaths - were associated with poor diet.

In 1990, the figure was around eight million.

The researchers said that people in almost every part of the world could benefit from improving their diets. They also noted that in 2017, more deaths were caused by diets too low in whole grains, fruits, nuts and seeds, than by diets containing high levels of foods such as trans fats, processed meats and sugary drinks.

"This study affirms what many have thought for several years, that poor diet is responsible for more deaths than any other risk factor in the world. While sodium, sugar and fat have been the focus of policy debates over the past two decades, our assessment suggests the leading dietary risk factors are high intake of sodium, or low intake of healthy foods, such as whole grains, fruit, nuts and seeds, and vegetables," explained the study's author, Dr Christopher Murray of the University of Washington in the US.

The study looked specifically at 15 dietary elements - diets low in fruits, vegetables, legumes, whole grains, nuts and seeds, milk, fibre, calcium, seafood omega-3 fatty acids, polyunsaturated fats, along with diets high in red meat, processed meat, sugar-sweetened beverages, trans fatty acids and sodium.

It found that overall, an estimated 11 million deaths in 2017 were attributable to poor diet, with diets high in sodium, low in whole grains and low in fruit together accounting for more than 50% of these deaths.

The causes of these deaths were cardiovascular disease (10 million deaths), cancer (913,000 deaths) and type 2 diabetes (almost 339,000 deaths).

The researchers found that intake of all 15 dietary elements was suboptimal in almost every region of the world and not one dietary factor was consumed in the right amount by all regions of the world.

The biggest shortfalls in optimal intake were related to nuts and seeds, milk and whole grains. The biggest excesses were seen for sugar-sweetened drinks, processed meat and sodium.

In fact, the world consumed, on average, just 12% of the recommended amount of nuts and seeds, but drank 10-times the recommended amount of sugary drinks.

Meanwhile, the world consumed only 16% of the recommended amount of milk and 23% of the recommended amount of whole grains, compared to 90% more than the recommended amount of processed meat, and 86% more sodium.

Uzbekistan was the country with the highest rate of diet-related deaths in 2019, while Israel was the lowest. Ireland was ranked 24th on the list, just behind the UK and ahead of Sweden.

The researchers said that the findings show that many existing awareness campaigns have been ineffective and new interventions are needed to rebalance diets worldwide.

However, these interventions need to be sensitive to the environmental effects of food systems, which can have an impact on things like climate change, soil degradation and the loss of biodiversity, they added.

Details of these findings are published in the medical journal, The Lancet.