Why eating sustainably is good for your health

The fundamentals of a sustainable diet are that it’s largely plant-based, includes sustainable sources of protein, and is low in processed foods and those high in fat and sugar. These latter foods all take a lot of resources to produce, and create a lot of waste. It’s also important to look at reducing the amount of food we throw away.

An increasing amount of research shows that a sustainable diet has health benefits too. Several studies have found that shifting to a more plant-based, seasonal and minimally packaged diet can reduce greenhouse gases as well as serious health conditions like diabetes, heart disease and some cancers. But how does eating sustainably have this effect?

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What are the benefits of a plant-based diet?

A plant-based diet is rich in plant foods including fruits, vegetables, legumes, nuts, seeds and meat protein substitutes like soy or seitan. It does include a small amount of animal protein and dairy products, so it’s not vegetarian or vegan, but does encourage you to eat plants over other types of produce.

Reducing the amount of meat you eat has significant health benefits. The NHS advises eating no more than 70g of red or processed meat – including steak, ham, sausages and bacon – a day, but over 90% of Brits eat 86g a day. This raises our risk of obesity, heart disease, and bowel and other digestive cancers. The WHO even classifies red meat, particularly processed meat, as carcinogenic to humans.

What’s more, rearing livestock for meat and dairy generates 12% of the world’s total greenhouse gas emissions. It also uses 83% of global farmland and roughly one-third of all freshwater on earth. No wonder climate experts repeatedly tell us going vegan is the best diet for planetary health.

This doesn’t automatically mean all vegan foods are good for you – many meat alternatives are full of additives, colourings and flavourings to mimic animal proteins. This pushes them into the category of ultra-processed foods, or UPFs, which are increasingly linked to poor health and negative environmental outcomes.

How are UPFs bad for the environment?

UPFs are highly processed foods, such as mass-produced cakes, crisps and ready-to-heat products like pizzas. They contain a lot of artificial additives including emulsifiers, sweeteners and flavourings, plus plenty of ‘unhealthy’ ingredients like trans fats, sugar and salt.

A growing body of research has found UPFs can raise our risk of heart disease, diabetes, high blood pressure, stroke, some cancers, mental health conditions like depression, sleep problems, digestive issues – UPFs are known to disrupt our gut microbiome – and early death.

Scientists are now looking at the impact UPFs have on the planet. Brazilian scientists say an increase in greenhouse gas emissions over the past 30 years can be directly linked to an increase in UPFs, while research published in 2022 found UPFs are responsible for:

36-45% of total diet-related biodiversity loss across the globe
up to a third of total diet-related emissions, land use and food waste
up to 25% of total diet-related water-use in a number of high-income countries

One of the reasons for this is that UPFs often contain soy and/or palm oil. The impact of palm oil production on the environment is well known but bears repeating – it’s responsible for large-scale deforestation and destroying the habitats of endangered species like orangutans. But the damage caused by UPFs goes beyond their ingredients.

Other studies have discovered the processing and packaging stages of UPFs – creating the trays, boxes and plastic film they’re wrapped in, for example – generate the greatest amount of emissions in the whole UPF system. This is most likely due to the resources involved in their production (water, paper, fossil fuels, ink, etc) and the plastic pollution caused by improperly discarded wrappers.

The good news is that reducing the amount of UPFs we eat improves environmental sustainability. Spanish researchers say the lower the amount of UPFs in our diet, the lower our environmental footprint. So, next time you find yourself reaching for a ready-meal, try one of our healthy fast-food recipes instead.

Is organic produce better for you?

This is (still!) a hotly debated topic. Some studies show there may be health benefits to eating organic food – for example, they contain higher levels of omega-3 fatty acids and more antioxidants than conventional produce – but there’s not enough evidence yet to give a decisive yes or no.

What may be more important is what’s not in organic food – namely pesticide residues and chemical fertilisers. Various studies have found organic produce is lower in heavy metals such as cadmium and has fewer traces of nitrates, while organic meat is less likely to contain antibiotic-resistant bacteria than intensively farmed meat.

However, we can say that organic farming is better for the environment. Evidence collected by the UN’s Food and Agriculture Organization found organic farms have healthier soil, greater biodiversity, cleaner water – as no synthetic fertilisers are draining away into the groundwater – and can store greater amounts of carbon in the soil, which helps combat global warming.

If you want to start buying organic produce, find out what labels you should be looking for here.

Is eating local or seasonal better for you?

Before we answer this question, we need to talk about food miles. In a nutshell, food miles are the distance your food travels from where it’s produced to where it’s eaten. Foods that have travelled a greater distance, often by air, have more food miles – and so a greater carbon footprint – than food grown or produced locally.

But this doesn’t mean local produce is automatically better for the environment. Out-of-season fruits and vegetables grown in heated greenhouses create more carbon emissions than those shipped in from warmer countries, despite their greater food miles. So, what’s the answer? As ever, it’s complicated.

You can buy fresh produce from a farmers’ market or get a delivery box, but fruit and vegetables start losing their nutrients as soon as they’re picked. If they were harvested a week ago, and then spend another few days in your fridge, there may be very little in the way of vitamins and minerals left by the time you eat them. Ask when and where they were picked to make sure you’re getting fully charged fruit and veg.

Freezing locally grown produce when it’s in season is another solution. Not only does this reduce food miles, it helps preserve vitamins and minerals; frozen produce has roughly the same nutrient content as fresh just after harvesting. Tinned or canned food is also surprisingly healthy – peaches, peas and sweetcorn retain many of their nutrients for months, even years, in storage.

Of course, there’s nothing better than eating fresh, local and in-season produce – watching Wimbledon wouldn’t be the same without strawberries – but remember there are other ways to take care of your health while caring for the environment.

Is a sustainable diet better for everyone?

Yes, overwhelmingly. If you’re still not sure, a recent study published in The Lancet concluded that switching to a sustainable diet – they looked at the EAT-Lancet or planetary health diet – could prevent up to 63% of deaths and 39% of all cancers, and reduce greenhouse gas emissions by up to 50% over 20 years.

In other words, eating sustainably really is the best way to guarantee a long and healthy life for you and the planet. It’s time to start eating for two.