We all know your diet can have a huge effect on your health. It can help you achieve a healthy weight and lower your blood pressure, while also reducing your risk of heart disease and diabetes. A good diet can improve your mood and concentration, and can even reduce your risk of getting some types of cancer. But your diet doesn’t just affect your mind and body it can also have a huge effect on the health of the environment around you. But which diet best strikes this balance of healthy body and healthy planet?

A recent BHF-funded study has decided to get to the heart of the matter by searching for the best ‘sustainable diet’.

Food for Thought

There are now nearly two billion adults across the world considered to be overweight or obese. On the other hand, underdeveloped food supply systems have led to two billion people having nutritional deficiencies and over eight-hundred million people seriously deprived of food.

The endless consumption that the human race needs to stay alive has a big impact on the planet. Farming is responsible for roughly 24% of greenhouse gas emissions, covers a staggering 37% of all land and uses over 90% of our fresh water. The overuse of fertiliser also causes so-called ‘dead zones’ in the ocean.

With the world population predicted to increase over the next few decades, and ever more people able to access diets rich in meat and dairy products, our burden on the world is only expected to increase.

Scientists funded by us think that a healthy, environmentally sustainable diet might be the best way to ensure a balance between health benefits and looking after the planet.

So is it possible to have your cake and eat it too? Even if we can change our diets to help lower our environmental impact, how do we know which diet is the ‘right’ one.

A recent BHF-funded study published in the Lancet Planetary Health used computer modelling to compare a range of different diets across more than 150 countries to determine the relationship between diet, health and environmental impact.

What’s on the menu?

The researchers investigated different diets including replacing animal products with plants, reducing over eating, lowering under eating and adopting a variety of common energy-balanced diets including:

· Vegan: A diet with no meat or fish, with no animal products like eggs or milk.

· Vegetarian: A diet with no meat or fish, but eggs and milk are permitted.

· Flexitarian: A semi-vegetarian with little meat and fish, but mostly plant products.

· Pescatarian: A diet with no meat, but does allow fish.

To work out which diet came out on top, the study looked at a wide variety of the effects of these diets — did people get enough vitamins and minerals, what did they die from, and how the diets impacted the environment through greenhouse gas emissions and how much water and land was needed.

Some of the diets stood out from the others. For people in high and middle income countries, replacing meat and animal products with plant-based alternatives had positive benefits for health for most people as well as on the environment. Early deaths from heart disease, stroke, type-2 diabetes and cancer were lowered by between 20–25% for all of the diets containing less meat.

But these diets all increased the amount of fresh water used and in low-income countries less health benefit was seen (possibly because fewer animal products were eaten to begin with), and the diets did not meet all nutrient recommendations including for protein as well as some vitamins and minerals.

Calorie counting was also found to reduce early deaths and improve body weight but only slightly improved nutritional deficiencies in most people and had a small beneficial effect on the environment.

In a nutshell

Flexitarian diets reduced early death rates by about a fifth, and vegan diets reduced deaths by nearly a quarter, but needed supplementation of some nutrients like riboflavin, calcium and vitamin B12 to be nutritionally up to scratch.

The plant-based diets largely had a positive impact on health and, except for water consumption, had a huge reduction in environmental impact (less land was used and less nitrogen and phosphorous was taken out of the soil) in most countries. Greenhouse gases in particular were massively reduced, in some cases by nearly 90%, with the greatest reduction for vegan diets.

Our Senior Dietitian Victoria Taylor said:

“This study provides interesting data on how meeting our nutritional needs can impact on the environment. “It uses modelling techniques to make predictions on different scenarios and these can be helpful for planning and policy development, but it’s still a personal choice as to whether you eat meat or not. However, it does support the recommendation that if you eat a lot of red and processed meat, cutting down and including more plant based foods in your diet could be beneficial to both your health and the environment.”

Through this type of research, we can learn more about how to consider the health and environmental impacts of our dietary recommendations, and how simple changes can ensure we protect both.