It's time to stop counting calories and focus on diet quality & policies that reduce malnutrition
A new paper by Malhotra and colleagues in the journal Open Heart (which is a medical journal, by the way, not a spiritual or philanthropic weekly), is being widely discussed by the nutrition and health communities. Its focus is on heart disease. More specifically, on the role of diet in heart disease.
That topic isn’t new, of course. A great deal of research has been undertaken over the years on the association between consumption of individual food items, nutrients, or anti-nutrients on heart disease and related illnesses. Dietary guidelines in many countries around the world draw on such research to craft messages like “increase the amount and variety of seafood consumed” (US 2010 Dietary Guidelines) or “eat plenty of vegetables and fruits” (India’s 2011 Dietary Guidelines). These exhortations are based on systematic reviews of clinical trials and population-wide epidemiological studies which consistently suggest that diets are hugely important as drivers of a variety of health outcomes.
For example, Lim et al. (2012) calculated how much of the global burden of disease (calculated in terms of Disability-Adjusted Life Years or DALYs) can be attributed to 67 individual or clusters of risk factors. They showed that dietary risk factors, coupled with physical inactivity, accounted for 10% of the entire global burden in 2010, and that the most prominent dietary risks factor was “diets low in fruits”.
Interestingly, the importance of fruit in diets — distinct from vegetables — was also noted by Green et al. (2015), who looked at data from 1980 to 2009 for 124 countries to explore how the proportion of total dietary energy provided by various food groups was linked to health outcomes. They showed that a greater supply of dietary energy in the form of fruit was related to lower mortality from ischaemic heart disease (IHD) – cases of which increased by 65% between 1990 and 2010 — while more energy supplied from meat, dairy products and vegetable oils was associated with higher levels of mortality from IHD.
The key messages from such research include: i) diets matter to health outcomes, and ii) the quality (composition) of diets matters as much as sufficiency of food intake – i.e. the nutrient balance is key, not just level energy consumed. Malhotra’s paper argues succinctly that “changes in diet can rapidly improve outcomes of cardiovascular disease.” Imamura and colleagues (2015) similarly argued — from a study of how diet quality has changed between 1990 and 2010 for 187 countries — that “healthy dietary patterns are a global priority to reduce non-communicable diseases.”
So…we should all try to eat more fruit. And we should try to include other foods in our diets that have been deemed ‘virtuous’ in terms of health outcomes, such as nuts and seeds, certain types of vegetables, appropriate amounts of animal source foods (including those of aquatic origin), beans and legumes, and wholegrains.
What the papers focused on heart disease do not point out, however, is that this also holds true for nutrition. Whether we’re talking about manifestations of undernutrition, micronutrient deficiencies or overweight and obesity, diet quality matters. It matters both as an underlying determinant and as a contribution to the solution. Indeed, focusing on improved quality of diets for all has to be a critical element of today’s global nutrition agenda.
Yes, many other factors contribute to nutrition outcomes – fully acknowledged. But, as the Global Panel on Agriculture and Food Systems for Nutrition has argued, “limited access of poor people to a healthy diet lies at the root of multiple burdens of food-related diseases in low and middle income countries”; and therefore policymakers should seek to influence the quality of food systems (from production through marketing to consumption) in ways that “are supportive of improved diet quality.”
This represents a serious challenge. Imamura’s study concludes that “increases in unhealthy [dietary] patterns are outpacing increases in healthy patterns in most world regions.” Not good! The authors suggest that researchers need to pay a lot more attention to elucidating the determinants of current patterns and trends, and that policymakers need to prioritise the search for cost-effective evidence based policies that can support improved and more equitable access to quality diets globally.
Easier said than done. On the one hand, the Global Nutrition Report of 2014 pointed out that data on “diet quality at the national and subnational levels are scarce”. On the other, the Global Panel notes that “evidence regarding appropriate policy choices linking agriculture via food systems to consumer choices resulting in high quality diets remains weak.”  These knowledge gaps need to be urgently addressed. What a shame that the framers of the post-2015 Sustainable Development agenda didn’t embrace this issue and identify targets for, and or metrics of, diet quality to help us achieve global nutrition and health goals.
Since high quality diets matter to resolving both undernutrition and diet-related non-communicable diseases, we have to find ways to ensure that all people around the globe have access to a diversity of high quality foods year-round. This will be an important challenge of the post-2015 era. It’s definitely time to stop counting calories and focus our research, funding and policy resources towards promoting dietary quality (as well as sufficiency). As Malhotra clearly states, the “Global Burden of Disease studies show that poor diet is consistently responsible for more disease and death than physical inactivity, smoking and alcohol combined.” So it’s high time for governments and global institutions to promote policies that can substantially reduce all forms of malnutrition, not just heart disease, in the coming decade.