Monday, March 14, 2011

The ties that bind - healthy eating policies, agriculture, the economy, and population health

I am no economics expert nor claim to have all that much knowledge about ‘the economy;’ I have troubles simply deciding where to invest. However, from a population health perspective, I was so intrigued with this recent Lancet article in the series “Chronic Diseases and Development” that I wanted to share it with it you. It highlights the inextricable and complex connections between the global economy (specifically agri-trade), our food consumption patterns, and health – something that is only beginning to be realized. The paper also shows what can happen from an equity perspective – the global winners and losers of adopting healthy eating recommendations.  

There is no doubt that the way we have been eating for the last 30 years, has contributed in some way to the rise in obesity and chronic diseases like diabetes and cardiovascular disease. In fact, middle and low-income countries are now experiencing the ‘nutrition transition’ – a switch from primarily infectious to chronic diseases.
The authors assert that the reduction of the burden of chronic disease by healthier eating necessitates changes in agriculture, and manufacturing and trade world-wide. They first conducted a systematic review, to determine the most prevalent dietary recommendations developed by expert panels internationally (which was interesting in-and-of-itself and highlighted here) to inform their analysis. In short, the authors found broad consensus on the recommendations outlined below:
  • Eat large amounts of cereals, veggies, fruits, and pulses 
  • Try to eat >400 g/d of veggies and fruit 
  • Limit the amount of red and processed meats 
  • Avoid trans fats, saturated fats, and added sugars 
  • Try to get most of protein from plant sources 
  • Try to limit salt to < 5 g/d

The authors then focused on the population health impact of adopting saturated fat recommendations – selected because it has well established links to cardiovascular disease. Important to note here is that the major sources of saturated fat are from animals. What would happen then to the risk of cardiovascular disease in populations that adopted World Health Organization (WHO) recommendations to decrease saturated fat intake to 10% or less of daily caloric intake? The authors compared the UK and Brazil; the UK selected for its high quality population-level dietary data, and high-income status, and Brazil because it is one of the world’s largest exporters of chicken and beef, and a rapidly developing country that keeps 70% of its meat and poultry for domestic consumption.

The meat aisle at Carrefour. Photo credit: J. Michalski

Using present intakes and targeted reductions (to meet recommendations), ischemic heart disease morbidity and mortality as outcomes, and estimated exposure (saturated fat)–disease effect sizes from a meta-analysis (a compilation of the results from 11 cohort studies), the authors estimated that:
  • In the UK, a 22% reduction in population dietary saturated fat consumption could reduce the years- of- life- lost from ischemic heart disease by 7% and years-of-life lived with disability by 4%; 
  • In Brazil, these figures are 7% (showing that Brazilians on average don’t consume as much saturated fat at Brits), 3%, and 2% respectively

Okay, this seems intuitive; if a population’s consumption patterns are not too far above unhealthy, then adopting healthy recommendations likely won’t result in a big effect on health (Brazil) as compared to a population that is comparatively more unhealthy (UK). But Brazil is a developing country, where the majority of its Gross Domestic Product (GDP) is based on agriculture (which often can be said of low and middle income countries), whereas the UK is a high income country that eats a whole lot of meat. See where this is going? What could the adoption of healthy recommendations (like eating less meat to reduce saturated fat intake) by high income countries do to the global economy, and in particular low and middle income countries?

The authors approached this question using computable general equilibrium models, using again, the UK and Brazil as comparators. I can’t comment on the validity of this technique since I am not an economist, but I did find the the different health policy strategies (or ‘shocks’) and their respective outcomes on GDP quite eye-opening. The different shocks included looking at what would happen if consumption from all animal sources fell, just meat, and just dairy, and comparing the effects on UK domestic demand, Brazil domestic demand, Brazil international demand, and a combined effect for Brazilian domestic and international demand (a UK international demand was not modeled - not deemed plausible as they are not major exporters).

The different shocks mainly affect GDP in terms of:

  • Labour - there is an increase in supply and productivity as there are more healthy workers (because of eating better - based on authors' previous estimates for the UK and Brazil); 
  • Domestic consumption of agricultural products with decreasing production of meat and dairy 
  • Imports and exports of agricultural products with decreasing production of meat and dairy

The effects on GDP differed substantially by dietary strategy (shock) and by scenario. Reducing dietary intake from all animal sources had a fairly small effect on GDP in both the UK and Brazil. However, reducing intake from dairy sources had a large negative impact in both countries (-22% to almost -30%). Reducing meat intake only had the largest negative impact for Brazil - specifically when considering a combined domestic-international effect.

A farm in Brazil. Photo credit: AJ Lopes
Important things to keep in mind about this study (among others which are discussed in the paper itself):
  • First, these are estimates, kind of like a simulation 
  • The authors only considered ischemic heart disease; there are many other chronic diseases related to diet such as obesity, diabetes, and cancer 
  • Dietary data from Brazil was not as current or as high quality as that from the UK 
  • The added positive health effects of replacing animal source foods with plant-based sources was not considered 
  • The authors were unable to adequately model how the agricultural sector could adapt - say by switching from exportation of animal sources to plant-sources 
  • The effects of time could not be modeled

Nonetheless, this study lends insight into the complexities of population health and population health interventions. High income countries may have more to gain and less to lose than middle and low income countries, depending on the policy implemented. A global awareness of the interconnectedness of the economy, agriculture, food consumption and health is needed if we are to develop strategies that are sustainable; that is, balancing social, economic, and environmental interests. An example of just such an approach may be a policy to reduce food consumption from all animal sources; this was estimated to have a much smaller impact on GDP than reducing meat sources only, and is likely to still be beneficial in terms of health and the environment. Certainly striving to make diets sustainable world-wide will require further research (like this study) that is inter-disciplinary in nature.

Lock, K., Smith, R., Dangour, A., Keogh-Brown, M., Pigatto, G., Hawkes, C., Fisberg, R., & Chalabi, Z. (2010). Health, agricultural, and economic effects of adoption of healthy diet recommendations The Lancet, 376 (9753), 1699-1709 DOI: 10.1016/s0140-6736(10)61352-9