What are vegetarian diets?
“The differences between plant-based diets have been surprising because they are often portrayed as universally healthy and good for the environment, but they are more subtle than that,” said Aviva Musicos, a postdoctoral research fellow in the Department of Nutrition at Harvard Chan School. The author of the interview for the study. To be clear, we’re not asserting 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 health and environmental effects.”
The study, which is one of the first to simultaneously look at the health and environmental effects of various plant-based diets, was published in the November 2022 issue of The Lancet Planetary Health.
Little research has been done on emissions from fertilizers
Previous research has documented that different types of plant-based diets have different health effects. For example, plant-based diets high in whole grains, fruits, vegetables, nuts, legumes, vegetable oils, and tea/coffee are associated with reduced risk of chronic disease, while plant-based diets high in fruit juices are associated with reduced risk of chronic disease. And sugar-sweetened beverages, refined grains, potatoes, and sweets are associated with an increased risk of chronic disease.
However, little research has been done to determine the environmental impacts, such as greenhouse gas emissions, high-quality farmland use, nitrogen from fertilizers, and irrigation water, for these dietary methods.
Researchers analyze more than 65,000 participants
Using data from the Nurses’ Health Study II, researchers analyzed the food intakes of more than 65,000 eligible participants, examining the associations of their diets with health outcomes, including relative risks of cardiovascular disease, and environmental effects. To distinguish between vegetarian dietary patterns, the researchers labeled the participants’ diets using different nutritional indicators, including those of a healthy and unhealthy plant-based diet.
Higher scores on the Unhealthy Vegetarian Diet Index indicated increased consumption of refined grains, sugary drinks, fruit juice, potatoes, and sweets/sweets; While higher scores in the Vegetarian Healthy Diet Index indicated higher consumption of vegetables, fruits, whole grains, nuts, legumes, vegetable oils, and tea/coffee.
People who follow a plant-based diet are less likely to get sick Cardiovascular disease
Participants who ate a healthy, plant-based diet had a lower risk of cardiovascular disease, and these diets had lower greenhouse gas emissions, use of crop land, irrigation water, and nitrogen fertilizers, than diets that were higher in unhealthy plant- and animal-based foods.
Participants who ate an unhealthy vegan diet had a higher risk of cardiovascular disease, and their diet required more farmland and fertilizer compared to diets that were higher in healthy plant and animal foods. The findings also bolster previous studies showing that diets higher in animal foods, especially red and processed meat, have greater adverse environmental effects than plant-based diets.
“Because human health ultimately depends on planetary health, future U.S. dietary guidelines must include careful considerations of environmental sustainability and recognize that not all plant-based diets confer the same health and environmental benefits,” said Daniel Wang, associate professor in the Department of Nutrition. at Harvard Chan School, Channing Department of Network Medicine at Brigham and Women’s Hospital and Harvard Medical School, and co-author of the study.
Read full article here