Plant-based diets are widely considered healthier and better for the environment than meat-based diets, but not all plant-based diets are created equal. Healthy, whole plant foods like fruits and vegetables are better for us and the environment than unhealthy plant foods like refined grains and sugary drinks.
Consuming the latter can not only lead to weight gain and metabolic syndrome, but agricultural production also requires more farmland and fertilizers, according to researchers from Harvard TH Chan School of Health and Brigham and Women’s Hospital.
Although red and processed meats unsurprisingly had the highest environmental impacts of all the food groups in the study, growing some common crops was found to produce the most greenhouse gases and require at the same time the most water, agricultural land and fertilizer. .
“The differences between plant-based diets were surprising because they are often described as universally healthy and good for the environment, but there are more nuances than that,” says Aviva Musicus, postdoctoral researcher in the Department of Nutrition at the Harvard Chan School. .who was the author of the study.
“To be clear, we are not claiming that less healthy plant-based diets are worse for the environment than animal-based diets. However, our findings show that plant-based diets can have different impacts on health and the environment,” says Musicus.
Not all plant-based diets are the same
It has long been known that different types of plant-based diets have varying health effects, and diets higher in whole grains, fruits, vegetables, nuts, legumes, tea and coffee are associated with a reduced risk of chronic diseases such as as cardiovascular disease and type 2 diabetes. At the same time, however, plant-based diets high in refined grains, potatoes, sweets, processed fruit juices and sugary drinks are associated with an increased risk of chronic disease.
The new study now indicates that these two different plant-based diets also have markedly different environmental impacts. Scientists learned this after analyzing the food intake of more than 65,000 participants and examining the associations of their diet with health outcomes and environmental impacts.
The researchers ranked the participants’ diets according to various food indices, with refined grains, sugary drinks, fruit juices, potatoes and sweets/desserts scoring highest in the unhealthy category, while that those in the healthy category had the highest scores for fruits, vegetables, grains. , nuts, legumes, vegetable oils and tea/coffee.
“Participants who ate healthy plant-based diets had a lower risk of cardiovascular disease, and those diets had lower greenhouse gas emissions and use of agricultural land, irrigation water and nitrogen fertilizers than diets that were higher in unhealthy foods of plant and animal origin.”
“Participants who ate unhealthy plant-based diets had an increased risk of cardiovascular disease, and their diets required more agricultural land and fertilizer than diets higher in healthy plant- and animal-based foods,” they write.
While these findings are not new to those familiar with nutritional science, they have helped reinforce the findings of previous studies showing that diets heavily animal-based have greater negative environmental impacts than diets. herbal.
The conclusion of this new study is that, for the good of our health and the environment, it is not enough to simply switch from animal food to plant food; instead, we must choose a healthy plant-based diet.
“Because human health ultimately depends on the health of the planet, future dietary guidelines must include a nuanced consideration of environmental sustainability and recognize that not all plant-based diets confer the same health benefits. and the environment,” said Daniel Wang, assistant professor in the nutrition department at Harvard Chan School, co-author of the study.
By Daniel T. Cross. Articles in English