Friday, 2 June 2017

Can we achieve a healthy sustainable diet by 2030?

Guest post by Christian Reynolds, Knowledge Exchange Research Fellow (N8 AgriFood project), Department of Geography, Faculty of Social Sciences, The University of Sheffield.

I recently attended the REFRESH Food Waste 2017 conference in Berlin. In the keynote speech of the conference, Vytenis Andriukaitis, (Lithuania's European Commissioner and designate responsible for Health and Food Safety) closed with the remark that Europe’s target is to halve food waste by 2030, and asked the audience if the goal of halving food waste is feasible or a fairy tale promise? 2030 is only 13 years away after all!

Likewise, the sustainable development goals are aimed for 2030, these include: ending poverty, ending hunger, increasing good health and well-being, climate action, and ensuring sustainable consumption and production patterns – the latter encompassing the aim to halve food waste.

Many of these goals require large changes to production methods and systems, modes of consumption, and general societal shifts on a global scale. This got me thinking about the challenge of shifting populations towards healthy, sustainable diets; is 2030 an achievable and realistic time frame?

Over the last couple of years there have been a few studies discussing how the UK, and global diets need to shift to meet healthy sustainable diets, (I will admit that I also have two in peer review at the moment). Some of my favourite studies currently published are Macdiarmid et al (2012), Green et al (2015), and van Dooren et al (2015). I also recommend reading Dantzig (1990) to get a glimpse of how this field of enquiry began.

These studies use mathematical modelling methods such as linear programming to calculate diets that:
  1. are optimised to be sustainable (for most studies this means low in associated greenhouse gas emissions (GHGE));
  2. meet the current healthy eating guidelines; and
  3. are not ‘unacceptable’ to the population.
This final item is a crucial, as if you do not constrain for palatability, the linear programme will calculate diets that are healthy, but only feature the foods with lowest environmental impacts. For example, Macdiarmid et al (2012) found a diet of 7 foods: whole-grain breakfast cereal, pasta, peas, fried onions, brassicas, sesame seeds, and confectionery to be sustainable and healthy. Stigler (1945) on the other hand proposed the following 7 foods: wheat flour, evaporated milk, cabbage, spinach, dried navy beans, pancake flour, and pork liver. Both of these are very ‘worthy’ but not varied enough diets to pass muster with the general population.

With this acceptability constraint in play, diets that are healthy and have lower GHGE are achievable with as little as 20-40% dietary shift resulting in up to 30% reduction in GHGEs (see Figure 3 from Green et al (2015). The majority of the studies include a reduction in animal products. For instance Macdiarmid et al (2012)’s sustainable diet featured 60% of the current intake of all meat for women in the United Kingdom and 48% of the intake of red meat (see Figure 1 from Macdiarmid et al 2012).

Figure 3. Deviations of optimised diets from current average diet, with associated reduction in greenhouse gas emissions from Green et al 2015
Figure 1. Proportions (by weight) of food groups in the final sustainable diet compared with the average current intake
of women in the United Kingdom (National Diet and Nutrition Survey 2008–2010). from Macdiarmid et al 2012

So are these changes in food consumption and purchase reasonable in a 13-year time period? Can we shift towards a healthy sustainable diet in 13 years?

For a quick check I looked up the rate of dietary change in the historic reports of the Family Food Survey. Looking over 13 year periods from 1945 to 2000, I found differing rates of changes in consumption and purchase for each food item (check out these amazing visualisations of Britain’s diet from 1945-2000, or look at the table I provide below).

Within all the 13 year periods between 1945 to 2000, all food groups have at maximum shifted by over 20%. This is good news, and indicates that change is possible for all food items in the British diet. However, what is less heartening is that total consumption and purchase of meat and meat products has only shifted by a maximum of 40%, while beef and veal consumption has only changed by a maximum of 47%. These rates of change need to be this high - if not higher - if we are to successfully shift toward a healthy sustainable diet.

So are healthy sustainable diets achievable or just a goal? Only time will tell. However, for now, here are some things that we can do to help the shift towards healthy sustainable diets:
  1. Focus on the foods that need to shift for both health and sustainability. Studies are finding that we need to increase fruit and vegetable consumption, increase oily fish consumption and reduce red meat and processed meat consumption. These are the main goals that we can work towards across the population.
  2. Pick our battles: focus on the foods that people have an appetite to change. From the table below we can see there are some foods that are easier to shift than others, for example starchy foods (a core of many British diets) have had much smaller rates of change than fruits and vegetables. Our relationship is already used to changing fruit and vegetable consumption, let’s focus there instead. 
  3. Technology and dietary change is our friend, let’s harness it. As society and technology develops, food consumption changes. Look at the changes in consumption of canned vegetables as better quality fresh vegetables were introduced. Likewise, the reduction in flour consumption as ready-made bread and other starches (rice, pasta, etc.) began to appear in the shops. How can we work with modern technology, such as improved food storage and processing technology, faster food transfer, and the advent of online shopping? Can we make online meal deliveries and food box deliveries lead to healthier and more sustainable diets?
Table: Britain’s diet from 1945-2000

Maximum 13 year change in food consumption/purchase 1945-2000Minimum 13 year change in food consumption/purchase 1945-2000
Liquid wholemilk 65.3%4.4%
Skimmed milk 99.0%0.0%
Yoghurt and fromage frais73.0%0.0%
Total milk and cream 27.8%4.5%
Natural cheese 23.0%0.0%
Processed cheese44.3%0.0%
Total cheese 44.1%8.5%
Eggs 67.1%7.5%
Oranges and other citrus fruit 74.0%16.1%
Apples and pears26.9%10.3%
Total fresh fruit 61.0%13.0%
Fruit juice 88.4%25.0%
Total other 50.4%9.6%
Total Fruit 68.3%11.4%
Fresh green vegetables36.8%15.2%
Other fresh vegetables24.5%7.8%
Canned vegetables92.0%11.5%
Frozen vegetables77.3%0.0%
Other vegetables and products 42.9%10.5%
Total vegetables and products22.2%6.9%
Cakes and pastries60.2%12.7%
Break-fast cereal55.8%11.4%
Total cereals (excluding bread) 19.9%5.0%
Bread & cereal products 23.1%6.4%
Preserves 51.9%21.3%
Total beverages 28.2%6.0%
Fresh white fish49.0%17.2%
Fresh fat fish65.3%32.3%
Cooked fish61.9%29.0%
Total fish and fish products 46.2%6.1%
All other fats 74.0%23.4%
Vegetable and oils64.1%0.0%
Low fat spreads53.8%0.0%
Reduced fat spreads80.0%0.0%
Total fats 37.4%5.0%
Beef and veal47.4%19.5%
Mutton and lamb55.4%17.6%
Bacon and ham68.3%7.5%
Pork, bacon and ham75.9%11.1%
Total meat and meat products39.8%8.6%

Christian Reynolds
Twitter: @sartorialfoodie

Photo attribution: "2006_04_10 Food waste. Peering into a dumpster at the GI Market." by Taz © 2006:

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