The Role of Diets in Shaping the Global Burden of Disease

Diets are changing rapidly across the world, resulting in a bifurcation of policy challenges. On the one hand, low and middle income countries have been following in the footsteps of industrialised nations in transitioning from largely plant-based minimally processed diets towards consumption of highly refined, packaged foods, large amounts of meat, and high intakes of sodium, refined fats, and sugar.[1] The latter ‘westernised’ diet is associated with rising rates of obesity and diet related non-communicable diseases, which already in 2010 cost the world over $1.4 trillion in health care costs and lost productivity.[2,3]

On the other hand, the ongoing global dietary transition has barely increased the consumption of foods with a high nutrient value in low income countries, and it has not succeeded in reducing the number of people with inadequate access to minimum levels of energy. There are still hundreds of millions of individuals who are chronically undernourished, and billions who lack the vitamins and minerals needed for child growth, mental development, and adult labour productivity.[4] The combined global cost of undernutrition and micronutrient deficiencies has been estimated at between $1.4 and $2.1 trillion. [3] 

Poor diets lie at the heart of both kinds of problems. Of course, diet is not the only factor in good health and nutrition. Weight at birth, breastfeeding practices, access to clean water and sanitation, and a disease-free environment all matter to child growth and survival. Nevertheless, policymakers faced with an overall malnutrition-related bill of up to $3.5 trillion per year urgently need to find ways to address the underlying issue: poor diets represent both a public health concern and an economic time-bomb. 

In health terms, nutritional deficiencies (including protein energy malnutrition, anaemia, vitamin A deficiency, etc.) contributed more than 1.2 billion disability adjusted life years (DALYs) to the global burden of disease in 2010, with protein energy malnutrition and iron-deficiency anaemia both classed as “substantial contributors” to the total.[5] At the same time, cardiovascular and other circulatory diseases contributed 4.2 billion DALYs in 2010, while overweight and obesity were estimated to cause over 3 million deaths worldwide.[5,6]

Nutrient deficiencies also factor into the calculation of the global health effects of non-fatal disorders. For example, moderate and mild iron-deficiency anaemia, and goitre due to iodine deficiency are among the words top impairments to health in terms of their indirect contribution to other serious disorders. Indeed, nutritional disorders combined contributed to roughly 50 million years lived with disability (YLDs) in 2010.[7]

But diets are more than a cluster of nutrients; they are made up of combinations of foods. In estimating the global attributable mortality and DALYs for 67 individual risk factors and clusters of factors, Lim and colleagues showed that while high blood pressure (often associated with overweight and obesity) was the leading risk factor in 2010, the clustering of dietary risk factors and physical inactivity was responsible for the world’s largest disease burden (over 10 percent of the total).[8] Of the individual dietary factors, the largest attributable burden in 2010 was associated with diets low in fruits, high in sodium, low in nuts and seeds, low in whole grains, low in vegetables and low in seafood-derived omega-3 fatty acids.

This means that today we know more than ever before how important good diets are to preventing ill-health and death. High consumption of nutrient dense foods coupled with low intake of unhealthy foods unpins the solution to both undernutrition and diet related non-communicable diseases.[9] But unless something changes in the coming decades, undernutrition and nutrient deficiencies will continue to maim and kill, while diabetes, heart disease and other diet-related chronic diseases will become the dominant contributor to the global disease burden.[10] Assessing how diets changed in 187 nations between 1990 and 2010, Imamura et al. showed that intake of healthy foods and nutrients (those identified above) increased modestly, but consumption of unhealthy foods and nutrients rose at a faster pace.[11] Despite some improvement in high income country diets they are still among the worst in the world in terms of consumption of unhealthy foods, and low and middle income countries patterns are following closely behind.

What the world eats can promote good health and nutrition, lower health care costs, and enhance the economic output of an educated and highly productive workforce. What it currently eats is tending to poor health and undernutrition, high and rising health costs, and a huge economic cost burden. Looking to 2050, policymakers and their advisers need to pay much closer attention to the agriculture, value chain, trade and price policies that contribute both to the problem of poor diets and to the potential solutions. They also need to understand what policies can protect the production and consumption of nutrient-rich foods in the context of climate change impacts on agriculture. Better measurement of what people actually eat today is going to be important in such an agenda, but so too is the costing out of potential policies that can effectively tackle the bifurcated food and diet problems that currently span the entire globe. Success of the post-2015 sustainable development agenda will rest heavily on how urgently governments pay attention to this particular challenge.

by Patrick Webb

Professor Patrick Webb is the Policy and Evidence Advisor for the Global Panel on Agriculture and Food Systems for Nutrition, and he serves on the Lead Expert Group for the Foresight project. 

This article is part of a series of blogs on the themes covered by the Foresight project. Each blog-post will contribute to raise a discussion around the key question the project intends to answer: “What decisions to policymakers need to take in the coming decade to ensure that food systems deliver high quality diets that are accessible in low and middle income countries by 2035, particularly for women and children?”. 

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Photo: Simone D. McCourtie / World Bank