Specific dietary changes needed to protect human health, the environment
Food production and consumption are key drivers of undernutrition, obesity, and climate change. In a new study, researchers have analyzed the potential for addressing these issues simultaneously by accounting for the role of food production in climate change.
The experts found that achieving adequate diets in most low- and middle-income countries will require significant increases in greenhouse gas emissions and water usage for food production.
“Our research indicates there’s no one-size-fits-all diet to address the climate and nutrition crises. Context is everything, and the food production policies for each country must reflect that,” explained study senior author Dr. Keeve Nachman, who is the director of the Food Production and Public Health program at the Johns Hopkins Center for a Livable Future.
The researchers developed a model that assessed how dietary changes across 140 countries would impact greenhouse gas emissions and freshwater use. The investigation was focused on plant-forward diets that ranged from no red meat to lacto-ovo vegetarian, which involves the consumption of some animal products like eggs and dairy.
According to the study, a diet that includes animal protein primarily sourced from low food chain animals, such as small fish and mollusks, has nearly as low of an environmental impact as a vegan diet. The researchers also found that reducing animal food consumption by two-thirds, or a “two-thirds vegan” diet, has a lower climate and water footprint than the more popular lacto-ovo vegetarian diet.
The findings suggest that high-income countries must accelerate the adoption of plant-forward diets in an effort to counter climate impacts and to address diet-related mortality.
The study authors emphasized that dietary recommendations or behavioral changes based on this kind of research could help strike a balance between health and nutritional needs and planetary boundaries.
“Our data indicate that it is actually dairy product consumption that explains much of the differences in greenhouse gas footprints across diets,” said study co-author Dr. Martin Bloem. “Yet, at the same time, nutritionists recognize the important role dairy products can have in stunting prevention, which is a component of the World Bank Human Capital Index.”
“The study findings highlight the difficulty in prescribing broad dietary recommendations to meet the needs of individual countries.”
The study revealed that a food’s country of origin can have vastly different environmental consequences. For example, one pound of beef produced in Paraguay contributes nearly 17 times more harmful emissions compared to one pound of beef produced in Denmark. This type of discrepancy is often due to the conversion of forests into grazing land.
“Where you get your food from matters,” said Dr. Nachman. “Trade patterns have an important influence on countries’ diet-related climate and fresh water impacts.”
“It would be satisfying to have a silver bullet to address carbon footprints and the impact of food production; however, with problems as complex and global as nutrition, climate change, freshwater depletion, and economic development, that’s not possible,” said Dr. Bloem.
“There will always be tradeoffs. Environmental impact alone cannot be a guide for what people eat; countries need to consider the totality of the nutritional needs, access, and cultural preferences of their residents. The good news is this research can be a part of the solution, as it now gives policymakers a tool to develop nationally appropriate strategies, including dietary guidelines, that help meet multiple goals.”
The study is published in the journal Global Environmental Change.
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