22 January 2015

What does a healthy and sustainable food system look like?

Ever since ICN2 (which seems like a long time ago) I have been wondering what exactly a healthy and sustainable food system looks like (I know, I need to get a life).

A few friends sent me some papers (no comment on their need to get a life) and here is a quick summary of two that I enjoyed reading.

Global Diets Link Environmental Sustainability and Human Health, Tilman and Clark, Nature, November 2014

The paper characterizes 4 diets (by region): conventional Omnivorous diets (eat everything e.g. global average diet or an income dependent diet which is a projection of current global diets driven by projected income growth), Mediterranean (rich in fruit, veg, seafood, includes grains, sugars, oils, dairy, eggs, and moderate amounts of different meats), Vegetarian (includes not more than one serving of meat or seafood per month), and Pescetarian (vegetarian plus seafood).

The authors use 10 million person years of observations across 8 study cohorts to look at the health effects of these 4 different diets. They then link these 4 diets to greenhouse gas (GHG) emissions and cropland use.   

The biggest contribution of the paper is that it links diet types to environment AND to health outcomes.

There are no terribly surprising results.
  • Compared to the Omnivore diet, the other 3 reduce the relative risk of Type II diabetes, cancer and coronary mortality by 10-40%
  • Per capita greenhouse gas emissions of the current Mediterranean diet are similar to current omnivore diets, but lower than the 2050 projected omnivore diet.  The Pescetarian diet is next lowest in pc GHG and then the Vegetarian diet is the lowest at about half the pcGHG of the 2050 Omnivore diet.
The authors are careful to state that healthier does not automatically mean more environmentally friendly and vice versa.  They also stress that food choices are determined by culture, knowledge, price, availability, taste and convenience.  They also note that there are many other diets they could have looked at.

They don't say much about how their 3 diets are to be adopted and adapted -- and this is crux.

Elke Stehfest has a viewpoint article in the same edition of Nature commenting on the Tilman and Clark paper. Stehfest goes a bit further on this front, breaking it down into individual choice but also to the environment in which choices are made.  Making healthy (and sustainable) choices can be made easier or harder by regulation and policy. 

My perspective is that if individuals have the ultimate responsibility on the former, Governments have the ultimate responsibility on the latter.  Businesses also need to assume responsibility for providing healthier and sustainable choices for those who demand it and for making the choices easier for those who are on the brink of demanding it.  Ultimately do they want their customers and employees to be able to make sustainable and healthy choices (and survive!) or are they only interested in the short term?

Food, livestock production, energy, climate change and health  Anthony McMichael et al. Lancet, 2007

This paper is a lot older (and actually ahead of its time).  It also makes the connection between health and environment via diet, focusing more on meat consumption.

It notes that meat consumption in 2005-6 in high income countries was around 225g per person per day (yep, half a pound per day--on average). They also note that pastoral livestock systems emit more GHGs than intensive systems (although it is not clear what the denominator is here).

They argue for 3 things 
  • Less GHG emitting forms of dairy and meat farming (via technologies and farming practices)
  • Lower meat consumption in high income countries with according health benefits
  • A "tapering" of consumption increases of meat in the low and middle income countries.   I think this means a lower growth rate of meat consumption. 
They argue that for the high income countries, food consumption should not be any more exempt from policy than driving or flying when it comes to efforts to curtail the growth in GHGs. For the low and middle income countries they stress that "growth now, green later" simply may not be an option because non-green growth now could mean low or no growth in the future. 

It seems to me that until we can provide national policymakers with a list of a few specific things they can do (such as reducing state support for growth of animal feed and investing more in the R and D behind the low cost production of fruits, vegetables and fish) and then cost these out in terms of benefits versus costs, this issue will never even get a set at the table to plead this case.  My sense is that this movement will be driven by national governments rather than international governance.

How to guide diet choices towards health and environmental goods?  We have the general evidence, now we need the country-specific evidence -- and guidance for national policymakers on what to do.  

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