4th April 2019
This study, published in the Lancet today, has hit the headlines with news that globally, 1 in 5 deaths (11 million in total) in 2017 were associated with poor diet. Cardiovascular disease was by far the biggest cause of death, linked to 10 million deaths in the study. Interestingly the study found that overall, the lack of healthy foods and nutrients seemed to be more important in affecting disease risk than an excess of unhealthy ones.
This study looked at dietary intakes across 195 countries and quantified the burden of disease (population attributable fraction) that could be attributed to deaths related to cardiovascular disease, cancer or type 2 diabetes, as well as the impact of diet on ill health (as disability-adjusted life-years or DALYs).
Using data collated within each of the countries included, the study looked at 15 different aspects of the diet:
Low intakes of:
- Fruit, vegetables, legumes, wholegrains, nuts and seeds, milk, fibre, calcium, long chain omega 3s from seafood, and polyunsaturated fats.
High intakes of:
- Red meat, processed meat, sugar-sweetened drinks, trans fats and sodium.
There were varying levels of data available for each of these from the countries included, in particular for sodium (based on 24 hour urinary sodium excretion), which was only available in about 1 in 4 of the countries.
For each of the factors included, the optimal intake was calculated based on a meta-analysis previously carried out by Global Burden of Disease researchers. These figures differ from current public health advice in the UK, for example the total suggested for fruit, vegetables and legumes was 670g per day (compared to 400g or more that forms the basis of the UK 5 A DAY recommendation), the level suggested for fibre was 24g (as compared to 30g/day for adults in the UK) and for sodium, the equivalent as salt used was 7.5g/d (compared to 6g/day for adults in the UK).
Globally the study found that intakes of all the factors measured were ‘non-optimal’, that is below the optimum for the ‘healthier’ dietary attributes and above the optimum for the ‘unhealthier’ ones. No one country managed to reach the optimal level for all attributes and no one attribute was optimal across all countries.
Overall the study found that the largest number of diet-related deaths were associated with eating too much sodium and not enough wholegrains or fruits (the relative importance of the different factors varied by region - in Western Europe the factor associated with the greatest number of deaths was low wholegrain intake, followed by low intake of nuts and seeds and high sodium intakes). Across all 15 dietary attributes, more deaths were associated with not eating enough ‘healthy’ foods or nutrients than eating too much of those foods or nutrients classed in the study as ‘unhealthy’.
The countries with the lowest rates of diet-related death were Israel, followed by France, Spain and Japan. The UK was ranked 23rd, followed by Ireland and Sweden who were 24th and 25th respectively. The US was ranked 43rd, India 118th and China 140th. The country with the highest diet-related disease risk according to this study was Uzbekistan, which had ten times more diet-related deaths than in Israel. The association between of different nutrients and diet-related deaths varied by country with high sodium intakes being the biggest contributor in China and Japan, low wholegrain intakes the biggest contributor in the US, Russia and India and low fruit intakes the biggest contributor in Bangladesh, Ethiopia and the Democratic Republic of Congo. In an associated comment piece in the Lancet, the relative costs of fruits and vegetables across the globe were highlighted with three servings of vegetables and two servings of fruit accounting for 52% of household income in low income countries compared to only 2% of income in high income countries, representing a significant barrier to increasing intakes in low income countries.
The study is based on observational data and, inevitably with 195 countries included there were variations in how the data were collected. 15 dietary attributes were selected for inclusion in the study – some that are of interest to health such as saturated and monounsaturated fatty acids and free sugars across the diet (not just those in drinks) were not included in the analysis. The study also did not take into account lifestyle factors, such as smoking, obesity and physical activity, that can have a significant impact on the risk of the disease outcomes used in the study.
Overall the finding that it was the lack of healthy foods over and above the excess of unhealthy ones that had the greatest impact on disease risk is interesting and perhaps points to the importance of giving positive healthy eating messages about the foods we should eat more of and not just those we need to cut back on.