It is vital that nutrition is central in discussions about the transformation of food systems so that we don’t risk encouraging dietary changes that might benefit the environment but could be detrimental to people’s nutrition and health. Furthermore, consideration needs to be given to the affordability and cultural acceptability of dietary recommendations to help ensure adoption and that all can benefit.
A new review paper from Steenson and Buttriss highlights the need to consider nutritional quality of diets alongside environmental benefits in order to achieve sustainable diets that benefit human and planetary health in an equitable manner.
To understand more about the composition of diets that are good for the planet as well as us, the paper reviews the evidence, identifying synergies between studies, differences and where trade-offs will be needed.
Greenhouse gas emissions
All of the identified studies estimated the environmental impact of different nutritionally-adequate diets using at least one indicator. Most commonly this was greenhouse gas emissions (GHGE), followed by water footprint and land use. Some also looked at broader aspects such as cost and cultural acceptability.
Some of the 29 studies reviewed looked at the potential environmental and health benefits of shifting diets to align better with existing dietary guidelines such as the UK’s UK’s Eatwell Guide. Others modelled theoretical diets or identified dietary formats that were more environmentally sustainable from among diets already documented in dietary surveys.
The review concludes that renewed emphasis on the advantages of following the Government-backed Eatwell Guide is a good place to start as this has been shown to deliver a 30% reduction in GHGE, as well as health benefits, compared to current diets and crucially describes a dietary pattern that is already familiar in the UK.
According to a study from Scheelbeek and colleagues, 30% of people already achieve at least five of the Eatwell recommendations, but there is plenty of room for improvement as only 0.1% achieve all nine.
Plant-rich diet with diverse protein sources
Eating a plant-rich diet with more wholegrains, vegetables, fruits, nuts and pulses, and diversifying our intake of protein-rich foods to include more plant-derived options, provided they are not high in salt or saturated fat, is a good way to eat more healthily and sustainably. That doesn’t mean that meat, milk, fish and eggs have to be cut out though, and these make an important contribution to intakes of essential nutrients in the UK.
We are already advised to moderate how much red and processed meat we eat for health reasons, and this is important for the environment too.
On average we are within the limit recommended for health (at an average of 56g/day compared to less than 70g/day across the week) but about a third of people are eating more. As highlighted in the recent National Food Strategy recommendations from Henry Dimbleby, if everyone in the UK complied with the current advice, this would reduce consumption of red and processed meat overall by about a quarter.
Milk and eggs
In contrast, the findings from modelling studies do not consistently show that we need to reduce our intakes of milk and eggs, perhaps due to trade-offs between the important nutrients these provide and their more intermediate environmental impact.
Decisions about appropriate substitutes for animal-sourced products all too often just focus on protein, but the review emphasises that this is not enough. We also need to consider delivery of the many other essential nutrients that these foods provide, which we cannot make ourselves, if we are to ensure that people’s nutrition does not suffer as dietary patterns shift.
It is the overall package of nutrients provided by foods that needs to be centre stage, especially when plant-based alternatives to animal-derived foods are in the frame, particularly the nutrients for which animal-derived foods are a notable contributor (e.g. iron, zinc, calcium, iodine, vitamin B12), typically in a readily absorbed form. Importantly, the advice about checking labels for the salt, saturated fat and sugar content still applies.
Judy Buttriss is director general of the British Nutrition Foundation