Shifting Diets; What is the substitution effect?

Shifting Diets; What is the substitution effect?

Many of us have seen, read or heard that to save the world we must all follow a vegan diet. In response you’ve most likely seen, read or heard that veganism isn’t the answer. Headlines are there to grab our attention, to entice us to open the link, buy the paper, watch the documentary. Any mention of this topic online can bring out the worst in us. Conversations end up stifled by strong points of view (on both sides). There is very little space left for balance or discussion around what is a sustainable diet.

Life is busy and choosing what to eat for yours and the planet’s health can be confusing. Too often we fall fowl of simple narratives. They work in our busy, noisy world. And so we find ourself battling over ‘shifting diets’ one way or the other. Everyone has an opinion on the matter. But I’m not here to give you mine. I hope instead to broaden the conversation enough that instead of having to choose between two polar ends, we can find a middle that’s fair, to people and place.

SHEP’s sub’s bench

SHEP is shorthand for sustainable, healthy eating patterns. We have some definitions on what it is and should include (read What is a sustainable diet?) but what does it actually look like on our plates? Generally, research suggests SHEP’s are sufficient in energy needs and nutritionally diverse, whole grain, tuber, fruit, vegetable based with little meat/dairy (using all cuts etc), unsalted seeds, nuts, certified fish, very little to no processed food. SHEP’s should also account for your geography (where you live), the season, what is culturally and socially acceptable and accessible. The Vegan v Meat diet is too simple a narrative when trying to asses what is sustainable and healthy for all. I’m sorry to tell you it, like life, is complex. In reality, there is no ideal, global diet.

One of these complexities includes the problem of ‘The Substitution Effect’. The substitution effect is trying to account for what happens when someone swaps out one food for another. It can be positive or negative. In the Vegan v Meat diet narrative, it is assumed that if someone stops eating meat they will substitute that with fruit and vegetables. But what if they substitute it with other foods like processed meals, refined breads, cereals or out of season fruit and vegetables? It may or may not benefit GHG emissions (air-frieght goods) or necessarily one’s health.

What if we were to tax foods based on their GHG footprint? Again this may benefit the climate in the context of meat but not our health. Sugar has one of the lowest GHG footprints. Higher prices on meat for example may just cause people to buy the same amounts of meat but spend less on fruit and vegetables. It could see people swap red meats for white meats which raises another set of environmental and health concerns, from biodiversity to soya production to antibiotic resistance. We could tax GHG intensive products and in tandem subsidised fruit and vegetables. But if everyone stopped eating meat/dairy what happens to all livestock farmers and their stock? What if they remain unemployed? Whats happens if the land that livestock lived on cannot be cultivated? What about the health of our agroecosystems? What about soils, biodiveristy, water, grasslands?

Drastic or Diverse

The substitution effect is not however an argument for a business as usual approach to what we eat. It does point out that we don’t fully know or understand all the whats ifs or account for all the known unknowns if everyone was to shift from one end of the diet spectrum to the other. Hence why the vegan v meat diet is too simple a narrative to bring about global dietary change. That doesn’t mean it has no merit. Would we be having this conversation if it didn’t exist?

In the end there are some things we can be confident in saying are ‘facts’. Most of us (in developed economies) both eat too much and eat to much meat and dairy products. We need to eat more fruit and vegetables. We also need to eat with the seasons and account for our geography. We need to support farmers, not big agri-business. We need to choose the farmers that farm livestock organically, holistically, regeneratively and in harmony with the landscape. If we did this, perhaps we can find that middle ground, supportive, fair, diverse diet that factors in the ‘sub’s bench’…..


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Comments (2)

  1. Hi,
    Great that you want to explore the subject of vegan diets in relation to global issues! We need more of this willingness to sift through all the data and details and not just get into polarised (and possibly heated) arguments.
    The only other feedback I’d like to offer is that I find the type face used on this site rather difficult to read. The down strokes on letters are very thin and it gives an overall appearance of being faint.
    Further down the page after the bold sentence starting ‘Help us nurture a culture of food citizenship…’ there is a sign like a label followed by ‘biodiversity, climate change, diets, Eco-concerns etc. This type face is much easier to read as each letter has the same thickness of line in all parts of the letter. It’s also still sufficiently different from the bold so that the latter stands out.
    Kind regards

    1. Hi Anne,
      Thank you for your feedback. We appreciate it. We’re glad you like the article also. Our intention is to raise points of discussion on these global issues that we need to address, together. Polarised debates too often divide rather then empower.
      Kind Regards
      Sinéad & Nathalie

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