Can you eat food that is good for your health and the planet?
New research suggests it may be possible: People who eat mostly minimally processed plant-based foods like nuts, beans, fruits, vegetables, whole grains and olive oil, and moderate amounts of meat, fish, eggs and dairy products, were found to have lower rates of premature death from heart disease, cancer and other chronic diseases.
At the same time, their diets had a smaller impact on the environment, as they consisted of foods grown using relatively less land and water and produced with fewer greenhouse gas emissions.
The study, published Monday in the American Journal of Clinical Nutrition, was inspired by a landmark 2019 report from the EAT-Lancet Commission, which came up with a “Planetary Health Diet” that could sustain 10 billion people and the planet by 2050. Broadly speaking, the Planetary Health Diet encourages low consumption of meat and dairy products and high consumption of plants and whole foods. It was designed to be flexible and adaptable to different cultures, cuisines and individual preferences.
The new report is one of the first large-scale studies to look at how eating within a planetary health diet framework affects the chance of dying prematurely from a major disease. The study analyzed data from more than 200,000 men and women in the United States who were closely followed for more than 30 years. The new study found that:
Reduced Risk of Mortality: People whose diet most closely resembled the Planetary Health Diet were 30% less likely to die prematurely compared to people who ate the lowest amounts of the Planetary Health Diet's foundational foods. Reduced Disease: People who follow the Planetary Health Diet were 10% less likely to die from cancer, 14% less likely to die from cardiovascular disease, 47% less likely to die from lung disease, and 28% less likely to die from Alzheimer's and other neurodegenerative diseases. Reduced Risk of Infectious Disease: Women whose diet most closely resembled the Planetary Health Diet had a 38% lower risk of dying from infectious diseases. Improved Planetary Health: An environmental impact analysis found that this diet could lead to a 29% lower greenhouse gas emissions, a 51% reduction in arable land use, a 21% reduction in fertilizer use, and a 13% reduction in irrigation and water demand.
How to Practice the Planetary Diet
In this study, people whose eating habits adhered to a planetary healthful diet consumed large amounts of the following foods:
Whole fruits and nonstarchy vegetables such as carrots, broccoli, asparagus, cauliflower, cucumbers, and leafy vegetables. Peanuts and tree nuts such as walnuts, hazelnuts, pecans, cashews, and pistachios. Legumes, such as beans, lentils, and peas. Chicken and other poultry. Foods high in unsaturated fats, such as avocados, olive oil, and sunflower oil. Whole grains, such as brown rice, wild rice, oatmeal, quinoa, and barley, and foods made with whole grains (such as whole wheat and rye bread). Reduce your intake of red and processed meats, eggs, soft drinks, fruit juices, and processed foods that are high in sugar, such as candy, cakes, breakfast cereals, and desserts.
Walter Willett, lead author of the new study and professor of epidemiology and nutrition at Harvard T.H. Chan School of Public Health, emphasized that adopting a more planet-friendly diet doesn't mean you have to give up meat.
He described it as an omnivorous diet that allows for two servings of animal products per day. For example, a typical week on this diet might include one serving of dairy products such as milk, cheese, or yogurt per day, one serving of red meat per week, eggs per week, chicken per two weeks, and fish per two weeks.
The diet is relatively easy to follow, Willett said, because it prioritizes plenty of fruits, nuts and vegetables and a variety of plant-based protein sources, such as beans, lentils and other legumes.
“These pieces can be combined with flavors and foods from almost any traditional culture,” he added. “It's very flexible.”
Healthy eating can slow climate change
Food production accounts for about 30% of global greenhouse gas emissions, much of which is caused by methane emissions from livestock, widespread deforestation, food processing, farm machinery, the use of synthetic fertilizers, and other aspects of agricultural production.
Most of America's farmland is used to grow just two crops: corn and soybeans, which are used to feed livestock. This monoculture practice degrades soils, reduces biodiversity, and requires more irrigation, pesticides, and herbicides. Only about 5 percent of America's farmland is used to grow other vegetables, fruits, nuts, and legumes, Willett said.
Changing diets and food production systems alone won't be enough to reverse climate change, but it's an important step, Willett said.
“What this study shows is that we can change our diet to be much healthier than the average American's diet and have a huge impact on slowing climate change at the same time,” he added. “We don't have to sacrifice the health of the planet for the health of people. We can have both. It's a double win.”
The new study is observational, which means it found correlations, but not necessarily causation, between people's diet and their risk of major diseases. It's possible that other lifestyle habits could explain the findings, but the researchers took into account factors such as whether participants smoked, exercised, or drank alcohol, or whether they had a family history of heart disease, cancer, or other diseases. The health benefits of a diet high in nuts, olive oil, whole grains, fruits, and vegetables have also been demonstrated in rigorous clinical trials.
Marion Nestle, professor emeritus of nutrition, food studies and public health at New York University, said the federal government should adopt food policies that promote diets that are not only nutritious but also sustainable. “Governments can create clear dietary guidelines, set healthier standards for school lunches, support the production of food for people rather than animal feed and fuel for cars, and end subsidies for industrial meat production,” Nestle said. Nestle was not involved in the new study.
Have a question about healthy eating? Email us at EatingLab@washpost.com and we may answer your question in an upcoming column.
