Choosing a diet that’s less harmful to the environment is one way of contributing to a healthier planet. Dietary guidance must consider environmental sustainability alongside nutrition, according to this report of the position of the Society for Nutrition Education and Behavior (SNEB) in the USA.
When it comes to choosing what we eat, we all like to make up our own minds as far as possible. But the authors recognise that many of us would welcome some sound expert advice on how to eat in a way that doesn’t harm the world we live in. Dietary guidance that balances our health with the environment is key to pointing us in the right direction for a sustainable diet.
‘Improving the nutritional health of a population is a long-term goal that requires ensuring the long-term health of the food system as well.’ – Rose et al, 2019.
Our quest to save the planet
A sustainable diet is a pattern of eating that is good for our health, is widely available and affordable, and protects the environment for future generations.
A host of environmental issues, including climate change, loss of biodiversity (reduced variety and numbers of living organisms), land degradation, fresh water shortages and water pollution, threaten the health of our planet. These problems are caused, at least in part, by the agricultural practices that provide our food.
Advice on sustainable diets tends to focus on eating less meat and more plant-based foods. Of course, there’s more to it than this. We also need to ensure that we waste less food and that we don’t eat more than we need.
Food loss – the amount of edible food that is harvested but not eaten – is largely due to food waste especially in countries such as the USA. That’s because people frequently leave food on their plate, and food is thrown away by consumers or retailers because it looks unsightly or because it’s past its eat-by date. Such wastage not only has the environmental impact of the food produced but also causes further harm to the environment because of the disposal processes. One study showed that food losses accounted for 28% of the carbon footprint of the average US diet.
Agriculture damages the environment
Agriculture is one of the largest contributors to environmental damage. It poses a threat to the environment as it can involve:
- clearing forests to create arable land for crops and pasture for livestock
- a huge demand for fresh water
- widespread water pollution due to run-off of fertilisers and pesticides from soil
- production of greenhouse gases that are largely responsible for climate change.
To make matters worse, damage to the environment can reduce agriculture’s productivity, turning it into a vicious circle. Experts predict that up to 25% of world food production may be lost during the 21st century because of climate change, land degradation, water scarcity, and other environmental causes.
Impact of food on the environment
When we think about the harm a particular food causes to the environment, it is important to consider not only its agricultural production but also processing, packaging, transportation, preparation and cooking, and disposal of any remains.
In general, the environmental impact is higher for animal-based foods than for plant-based foods. For example, greenhouse gas emissions for the production of fruits and vegetables per kg of the food are typically less than 1 kg carbon dioxide-equivalents (putting the global warming gases – methane, nitrous oxide and carbon dioxide – on the same scale), while at the other end of the scale, beef has a value of over 30.
Is ‘organic’ best?
We may feel that organic foods are better for our health, but are they really best for the environment? Organic farming practices avoid the use of toxic chemicals and help to maintain local biodiversity and soil quality. But yields tend to be lower than for conventional agriculture, so organic farming may involve more land use.
While organically-grown grains have a lesser impact on climate change than conventional farming, organic production of some foods – such as poultry, eggs, beef, carrots and tomatoes – appears to have a greater effect on climate change than conventional production methods, research has shown.
One way in which research has suggested we could reduce the impact of our diet on the environment is by becoming ‘part-time’ meat eaters. This flexitarianism involves cutting back on animal foods and switching to a more plant-based diet but doesn’t require us to exclude any food group. Such a diet has the added advantage of improving our health.
We need advice to get it right
In our attempts to protect the environment, could we actually be doing it harm or putting our own health at risk? It is really important that well-trained nutritionists provide sound dietary advice so that people can choose a healthy sustainable diet, say the authors.
Given the serious concerns about the environment and the need to feed a growing population, SNEB recommends that environmental sustainability is an integral part of future dietary guidelines.
Future guidelines should provide specific advice, ‘…partly so that consumers will have an easier time identifying specific actions they can take to improve their own health and reduce the impact on the environment.’ – Rose et al, 2019.
As well as changing our own dietary habits, we can also achieve major advances in protecting our planet through sustainably intensifying our agriculture. This means producing more food from existing farmland with less pressure on the environment. This is exactly what’s been happening with the US diary industry, where more efficient production has cut back on the relative amounts of greenhouse gases produced. Hence a study showed that in 2007, the carbon footprint per billion kilograms of milk produced was only 37% of what it was in 1944.
(JL, Cady RA, Bauman DE. The environmental impact of dairy production: 1944 compared with 2007. J Anim Sci. 2009;87:2160-2167.)
