What is sustainable food?

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Whichever way we look at it, the food that we eat is going to have an impact on the environment it is produced in. Unless we all return to being hunter-gatherers (which frankly isn’t sustainable either!) our food will have to be farmed.

The challenge for society is to work out what we should eat, and how it should be grown, in order to be sustainable. But what do we mean by sustainable? There are a whole bunch of different ways to describe sustainable, it can be:

  • Low climate impact
  • Low water use
  • High biodiversity
  • Low input (pesticides / artificial fertilisers)
  • High welfare

However, just because a food ticks one of these boxes, does not mean it ticks them all. Over a short series of articles we’ll explore what these items mean and how they relate to the food we eat.

What is sustainable food?

Low climate impact foods

The climate impact of our food is influenced by three factors: where it is produced (was forest cut down to clear land for production?); what goes into it (feed & fertilisers – where do they come from?); and the natural processes that occur as a result of its growth (methane production, nitrous oxide loss, carbon deposition).

At surface value, there are definitely some foods to avoid if you want to reduce your climate impact. These include any crops or livestock that are produced in areas that are subject to deforestation (for example soya from South America; livestock that are fed high levels of South American soya; palm oil from Southeast Asia; and beef from South America). But what about other foods? We see lots of adverse press around meat consumption, e.g. the promotion of Veganuary, but is avoiding meat and animal products on climate grounds really the answer?

Livestock emissions

There are three key elements that contribute to livestock emissions: what the animal is fed on; the manure the animal produces; and, in the case of cattle, the methane that is emitted by rumination.

If you consume livestock that are fed on predominantly low input pasture, rather than concentrates with lots of soya in them, the footprint of these products is much reduced. The manures from these animals do produce emissions, but they also provide a valuable organic fertiliser that can be used to grow other crops. In so doing, they return much needed organic matter to the soil and improve the health of crop land.


Livestock fed on low input pasture have a smaller carbon footprint than those fed high soya concentrate food

Methane production is a natural part of the rumination process, but research is underway to find additives that can be included in feed, and novel types of feed (such as seaweed), that can be used to reduce these emissions.

Crop emissions

Crops have different emissions depending on how much is produced and using what inputs, so a high yielding crop such as potatoes will tend to have lower emissions per kilo of production than something lower yielding, like a cereal crop. The scale of this difference will depend on the inputs used: the more nitrogen used to produce yield, the greater the emissions.


Potatoes have lower emissions per kilo of production than cereals.

The source of the nitrogen is also important, as the manufacture of artificial nitrogen requires huge amounts of energy, and results in the release of nitrous oxide emissions (although there are technologies available to abate some of these emissions). In many cases, the use of organic manure can help to reduce the embedded emissions from fertiliser use and reduce the climate impact of the crop, but a source of manure is needed in the first place.

So, if you want your diet to have a low climate impact, my suggestion would be to eat all things in moderation. Buy seasonal food that has not needed extra resources to produce it at a time of year when it wouldn’t normally grow. Where possible, buy food from known sources so you can find out how it was produced. Most importantly, eat the food you buy. Any food that is wasted is a waste of emissions and will have a negative climate impact.

Look out for our next article which will discuss low water use and high biodiversity farming systems.

About the Sustainable Food and Farming team

The ADAS Sustainable Food and Farming team help clients to address their sustainability challenges.

Our agricultural background means we’re equally at home meeting face-to-face with farmers as we are engaging with senior management in global food and drink businesses.

This gives us the unique ability to work across all stages of the supply chain. For more information on improving sustainability within your supply chain, please contact

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