Study pinpoints “win-win” foods for dietary and planetary health

29 Oct 2019 --- For the first time, researchers have tied the health impacts of foods to their overall environmental impact, such as greenhouse gas emissions (GHG) and water usage. The results show that healthier diets, consisting of whole grains and vegetables, for example, would markedly reduce the environmental impact of agriculture and food production. The findings could help consumers, policymakers and food companies better understand the health and environmental impacts of food choices, the authors note.

The findings come at a time where the role of the food system, including food production and agriculture, has on the environment has come under an increasingly bright spotlight. In August, the Intergovernmental Panel on Climate Change (IPCC) ’s Special Report on Climate Change and Land also highlighted that, generally, a higher consumption of animal-based foods is associated with a higher estimated environmental impact, whereas increased plant-based food consumption is associated with a lower environmental impact. 

“Evidence suggests that nearly all land-based meats have higher environmental impacts than plant-based foods. A Poore and Nemecek (2018) analysis concludes that the most efficient (or least polluting) pork, beef, and poultry systems typically have higher environmental impacts than the least efficient (or most polluting) systems producing plant-based foods. In other words, changing diets will likely have a larger environmental benefit than will preferentially producing local or organic foods,” Dr. Michael Clark, University of Oxford, one of the authors of the study, tells NutritionInsight.Unprocessed and processed red meat are associated with the largest negative environmental impacts and the largest increases in disease risk. 

The research from the University of Minnesota and Oxford University found that of the foods associated with improved health (whole grain cereals, fruits, vegetables, legumes, nuts, olive oil, and fish), all except fish have among the lowest environmental impacts, and fish has markedly lower impacts than red and processed meats.

Foods associated with the largest negative environmental impacts – unprocessed and processed red meat – are consistently associated with the largest increases in disease risk. Thus, dietary transitions toward greater consumption of healthier foods would generally improve environmental sustainability, although processed foods high in sugars harm health, but can in fact have relatively low environmental impacts.

The findings also located two notable exceptions. The first, fish, is generally a healthier food but with moderate environmental impacts. The second was sugar-sweetened beverages, which pose health risks but have a low environmental impact.

Measuring health outcomes with environmental impacts
The study examined the food-dependance linkages between five diet-dependant health outcomes in adults: Type 2 diabetes, stroke, coronary heart disease, colorectal cancer and mortality. This was compared to five different environmental impacts of producing the foods: GHG emissions, land use, scarcity-weighted water use, and two forms of nutrient pollution – acidification and eutrophication.

There are proponents of meat consumption that highlight the role cattle plays in pasturelands for biodiversity conservation and carbon sequestration. However, Dr. Clark further notes that “having too many ruminants on pasturelands is detrimental to the environment. In short, they could play an important role, but only if the amount of ruminant production on pasture land were to decrease.”

On a further methodological note, foods such as trans fats, ultra-processed foods and added sugar, were not included in this analysis because no dose-response meta-analysis examined the association between consumption of these foods and health outcomes.

Essentially, the authors highlight that the same dietary changes that could help reduce the risk of diet-related noncommunicable diseases could also help meet international sustainability goals. Focusing diets on foods consistently associated with decreased disease risk would likely also reduce diet-related environmental impacts.

Public and private solutions could help shift food consumption toward healthier and more environmentally sustainable outcomes, the authors conclude.The researchers have tied the health impacts of foods to their overall environmental impact, such as greenhouse gas emissions and water usage. 

A diet for planetary health
“This study shows that replacing red meat with more nutritious options can greatly improve health and the environment,” says Jason Hill, bioproducts and biosystems engineering professor at the University of Minnesota College of Food, Agricultural and Natural Resource Sciences. “It’s important that all of us think about the health impacts of the foods we eat. We now know that making our nutrition a priority will pay dividends for the Earth, as well.”

At the UN Climate Summit in September focus shifted to the contribution of meat and animal products in driving global warming, environmental pollution and inefficient resource use. This mirrors the general swing in understanding around the importance of adapting our diet to one that is within planetary boundaries.

In January, the EAT-Lancet Commission on Food, Planet and Health launched a diet touted as being “for planetary health.” It hoped to be seen as a diet to feed a growing population of 10 billion people by 2050, without “dramatically transforming the global population’s eating habits, improving food production and reducing food waste.” The fare consisted of approximately 35 percent of daily calories derived from whole grains and tubers; protein sources mainly from plants – but including approximately 14g of red meat; and 500g of fruits and vegetables.

Such investigations are important as there appears to be a global move toward diets that are filled with unhealthy food groups and rising levels of processed and unprocessed meat and salt and sugar.

“I hope that these findings will influence consumer dietary choices in a way that shifts people to consume more foods that are wins for health and wins for the environment. Fortunately, there are foods that are both healthy and sustainable, meaning that there does not necessarily need to be competition between healthy and sustainable diets,” Dr. Clark concludes.

By Laxmi Haigh