Q&A: Factors to consider when weighing the health benefits and sustainability of a diet

Adopting a “One Health” approach to diet choices and nutrition recommendations can offer health and environmental benefits, according to findings published in Science of the Total Environment.

A One Health approach involves “recognizing the interconnection between people, animals, plants and the environment,” Juliana Minetto Gellert Paris, a PhD candidate and junior researcher in the Center for Development Research at the University of Bonn in Germany, and colleagues wrote.

The researchers compared the environmental impact of food products commonly consumed by people in Germany’s North Rhine-Westphalia region to foods consumed in a vegan and Mediterranean diet. Paris and colleagues conducted a food cycle inventory of the emissions and energy use involved in each product’s life cycle, from crop or animal production to processing, distribution, retail and consumption.

The diets could not be easily ranked due to tradeoffs associated with each element of the One Health framework, according to the researchers. For example, although the vegan diet was more sustainably beneficial in many areas and had the lowest exposure to dietary risk factors, it also was associated with increased water consumption. Overall, though, a reduction in consumption of animal-based products greatly lowered the environmental impact values of the diets.

Healio spoke with Paris to learn more about implementing a One Health perspective to food choices.

Healio: Can you describe the One Health perspective?

Paris: The One Health perspective includes the health of the environment, the animals and the human at the same level. There is a need to target multidisciplinary connections in many geographical scales from global to local.

When I started to research nutrition and One Health, the only connection I could see was through foodborne diseases that are transferred via the food supply chain. I couldn't see a relation from the nutrition aspect with the environment. For example, is the health of the environment linked to pathogen transmission through the physical environment? Does the environment have its own health such as unbalanced functions and biochemical cycles? These are the questions that I included in my conceptual framework for this research.

Healio: What are the most important factors to consider when weighing the carbon footprint of a diet?

Paris: There are two things that we consider important factors within a diet: the quantity of food consumed per day and the underlying food product choices. Our study noticed that animal protein and beverages such as coffee, bottled water and beer play an important role in climate change. Meat-based meals and ready-to-eat meals with meat are examples of food choices that accounted for nearly one-third of the climate change impact in terms of carbon dioxide equivalent per day, considering the usual daily dietary consumption of people in Germany. Protein requirements can be replaced by whole foods, whole grains and legumes. With substitutions, you can supply the energy balance you need and lower your footprint related to highly energy-intense and resource-intense products produced by animal husbandry.

Healio: One of the factors you discuss in the study is transport. Should diets be hyper-localized?

Paris: Transport occurs in many stages of the life cycle of products. Transport of raw materials and intermediate transport of goods from one stage to another plays a role in sustainability in many ways. One point concerns the distance, type of transportation and fuel needed, which affects the overall energy use output of that food product. Our study assessed emissions from various food products (more than 100) throughout their life cycle, so we do not know precisely how much CO2-eq is related only to transport. But we live in a globalized world, where food value chains are globally interconnected and whose origin sometimes is estimated through trade mix-matrices of exporting countries. We need proper site monitoring and communication along the supply chain to effectively reduce impacts derived from food production and consumption.

Another sustainability issue is animal welfare. Transport is a concern for animal wellbeing and health. Transport can cause injuries, loss of weight and fatalities due to the conditions. It is an ethical question which involves the value of the carcass compared with diminishing animal suffering for that period of their lives as they head toward slaughterhouses.

Healio: What diet would you recommend to the average, healthy individual?

Paris: In our study, we assessed alternatives to Western diets that have healthier and more sustainable dietary patterns. The three dietary patterns assessed deliver sustainability gains in all spheres of the One Health approach. However, there are tradeoffs to consider. While reducing health and environmental impacts, the vegan diet increases water consumption. By increasing vegetable proteins from legumes and grains, you increase water consumption because these food products need irrigation and require more water use. Alternatively, the Mediterranean diet increases fish and seafood for better health due to the omega-3 intake but increases the impact on animal welfare, considering the number of animals affected to produce the same kilogram of food.

It must be noted that our analysis is based on the indicators assessed. The proportion of animal-based protein sources under a One Health perspective plays an important role in the sustainability of diets. The larger the share of plant-based food options, such as fruit, vegetables and whole grains, the greatest associated benefits for humans, animals and the environment. It's a balance and the type of protein source plays a role in deciding which diet is the best option. The greater the ratio of plant-based food and whole foods consumed, the more sustainable and healthier it is. If you look nutritionally at what we need from animal product, it is very little, but people sometimes eat meat in every meal.

Healio: How do plant-based meat substitutes compare to real meat?

Paris: The meat substitutes bring an opportunity to plan some plant-based meals for people who enjoy eating meat. The sensorial aspects are similar, but the nutritional and sustainable aspects are not the same. Further studies are required to access all meat alternatives today in the market, what nutritional benefits they bring and how sustainable they are. Overall, if you compare the plant-based item to an animal or dairy product, the animal product is still more damaging to the environment.

Healio: How do the carbon impact of vitamins factor in if you adopt a vegan diet?

Paris: If you give up meat and fish, nutritionally, you would still receive necessary vitamins by consuming milk and eggs. However, adopting a vegan diet, which is a personal choice, usually comes from personal ethical reasons. This diet is deficient in some micronutrients, vitamins and minerals, such as B12, vitamin D, calcium and iron. Therefore, it is important to seek food products that contain fortification or take vitamin supplements.

Today, the European diet is already deficient in vitamin D. Children must take supplements since birth. It is important to follow such dietary patterns under medical supervision. Each body is different, and many variables play a role in absorbing nutrients, which needs further assessment. Also, the sustainability of fortified food products or tablets needs to be assessed.

Healio: How should nutrition recommendations consider the environmental aspect of food choices?

Paris: The animal to plant-based food ratio should be carefully considered as well as the whole food to processed food ratio. The more animal products and highly processed products, the greater the environmental impact and/or health impact. And the selection of individual food choices, such as beverages, also depends on the sanitary conditions of the country. Water and tea are overall healthier and more sustainable than other beverages, such as coffee, beer, soft drinks and juices.

Healio: How can areas facing barriers to accessible and affordable whole foods balance a healthy and environmentally friendly diet?

Paris: This is an important and interesting aspect to consider: food accessibility and affordability, which depends on the food supply network of cities, the number of intermediates of the food chain and the value added. A proper assessment of food deserts and food supply issues within urban spaces is very important, especially in vulnerable socioeconomic areas. Several studies reveal that the vulnerable parts of society are usually more susceptible to unhealthy diets and developing more chronic diseases.

Reference:

Paris JMG, et al. Sci Total Environ. 2021;doi:10.1016/j.scitotenv.2021.151437.