Healthy you, healthy planet? Research suggests the two may be closely linked.
In a new study, presented in July at NUTRITION 2023, the flagship annual meeting of the American Society for Nutrition in Boston, researchers used a tool they created called the Planetary Health Diet Index (PHDI) to review foods and their impacts on human and environmental health.
The results show that individuals consuming a more environmentally sustainable diet were 25% less likely to die within a 30-year follow-up period than those following a less sustainable diet.
“This diet index will help public health workers understand the current healthiness and sustainability of their population’s diet and serve as an indicator for dietary intervention effect,” said study author Linh Bui, a PhD candidate in the Department of Nutrition at Harvard T.H. Chan School of Public Health.
“Furthermore, policymakers can use such evidence to make decisions on prioritizing strategies that aim to increase the PHDI to achieve the global carbon neutrality goal by 2050.”
~ 5 foods that benefit human health and the planet ~
Lui told Healthline she’s always had a keen interest in mitigating human impacts on the environment. Her research team identified five key foods that positively impact human health and could increase lifespan.
* whole grains
* non-starchy vegetables (i.e., cauliflower, broccoli, mushrooms, and tomatoes)
* unsaturated oils (i.e., olive, peanut, walnut, sunflower, rapeseed, and corn oil)
“These healthy plant-based foods were associated with both low risk of chronic diseases, like coronary heart disease, colorectal cancer, diabetes, stroke, and total mortality, and low impacts to the environment, like water use, acidification, eutrophication, land use, greenhouse gas emissions,” Lui said.
~ Connecting healthy food and longevity ~
The new study was inspired by a report led by Dr. Walter Willet and published in the Lancet in 2019.
In the report, the authors indicated that much of the world was not adequately nourished and that food production was pushing environmental systems and processes beyond safe boundaries. They called for a global overhaul of the food system.
“I was very astonished by the powerful impact of diet choices on the environmental capacity of the planet,” Lui said.
Willett became Lui’s academic advisor at the Harvard T.H. Chan School of Public Health. He later helped her develop the PHDI, which became the impetus for this new longitudinal study that follows 63,081 women and 44,275 men in the U.S.
The PHDI “gives folks a diet ‘score’ and then correlates those scores with folks’ risk of death from various causes, during a 30+ year follow-up period,” explains Maddie Pasquariello, MS, RDN.
“Notably, they integrated what they know about planet-friendly foods from a dietary reference guide called the EAT-Lancet reference, [the 2019 report authored by Willett]. which focuses on foods that are particularly sustainable from an environmental perspective.”
Lui said that the goal was to estimate the effect of adherence to a planetary-health diet on the risk of death.
The research suggests that eating more planet-friendly foods, such as plant-based proteins instead of red meat, lowers an individual’s chances of dying from conditions like cancer and heart, respiratory, and neurogenerative diseases.
“This result confirmed our hypothesis that higher PHDI was associated with lower risk of mortality,” said Lui.
Pasquariello said the findings can help healthcare providers, policymakers, people, and the planet.
“They provide stark implications for the importance of a diet balanced with certain foods, namely whole grains, fruit, non-starchy vegetables, nuts, and unsaturated oils, in promoting overall health and lessening disease risk,” Pasquariello said. “These findings also underscored how, in doing so, we can be thoughtful of our environmental impact as well.”
Trista Best, MPH, RD, LD, of Balance One Nutrition agrees with this assessment of the findings but offers one critical caveat.
“The study does not provide detailed information on the specific barriers or challenges individuals may face in adhering to a sustainable diet,” Best said.
“It mentions that factors like health conditions, religious restrictions, socioeconomic status, and food availability can influence a person’s ability to follow such a diet. However, it does not delve deeply into the strategies to overcome these barriers.”
~ What does other research say about food that’s healthy for you and the planet? ~
Foods with a more significant environmental impact and adverse health outcomes in the study included red and processed meats and eggs.
What does other research say?
* A 2021 study of more than 3,000 people with an average age of 55 indicated that eating more whole grains was linked to lower cardiovascular disease risk, especially in middle and older adults.
* A 2022 systemic review of randomized-control trials indicated that greater whole-grain consumption could significantly lower inflammatory markers linked with chronic conditions.
* Research from 2021 indicated that higher consumption of fruits and vegetables was linked with reduced mortality, but the risk reduction plateaued around five daily servings of fruits and vegetables.
* Another study published in 2019 indicated that increased nut intake was linked to less weight gain long-term and a lower risk of obesity in adults.
Research on red meat and eggs has been mixed.
One 2022 study suggested some evidence that eating unprocessed red meat is linked with higher risks of disease and mortality. But authors wrote that it is not currently strong or sufficient enough to set conclusive guidelines. The authors called for more rigorous studies.
A 2020 study suggested that consuming plant foods like legumes and nuts instead of red meat could lower coronary heart disease risk in men. The authors also indicated that consuming whole grains and dairy instead of total red meat and eggs instead of processed red meat could also lower the chances of developing coronary heart disease.
Research from 2020 indicated that the link between egg consumption and cancer, diabetes, and heart disease has been conflicting, making dietary recommendations complicated.
More generally, a 2019 systemic review of randomized clinical trials indicated that plant-based diets offered benefits for metabolic measures in health and disease but that more research on cognitive and mental health outcomes was needed.
A 2020 review of 18 studies suggested that sustainable diets improved health outcomes while lowering greenhouse gas emissions.
“Plant-based foods typically require fewer resources like water and land compared to animal-based foods,” Best said.
“Additionally, the production of plant-based foods usually generates lower greenhouse gas emissions, making them more environmentally friendly choices.”
~ How to eat for your health with the planet in mind ~
Dietitians also share that the new research can empower people to make dietary changes.
“Developing an awareness of how our dietary choices affect human health and environmental sustainability is crucial,” said Kelsey Costa, MS, RDN, who represents National Coalition on Health Care (NCHC).
“By embracing planet-friendly foods, we can not only decrease the risk of chronic diseases but also promote longevity and reduce the environmental impact of our food production practices.”
Experts share that people can begin making small changes to improve their overall health while also reducing the environmental impacts of their food choices.
~ Start small ~
If you currently consume a ton of eggs or processed meats, switching to a nearly all plant-based diet in one week is going to take a lot of work and is potentially unsustainable.
Don’t pressure yourself to overhaul your diet in one day.
“Gradually introduce more plant-based foods into your meals, such as adding an extra serving of fruits or vegetables each day,” Best suggests.
“Pick one new recipe each week that contains a fruit or vegetable you don’t normally cook with or haven’t tried,” Pasquariello said. “This is a great way to build cooking skills and make these foods more exciting to eat.”
Mindset is also important. Remind yourself: Progress, not perfection.
“This approach can be beneficial because it doesn’t place too much pressure on individuals to make significant changes all at once, which can often lead to frustration and lost motivation,” Costa said. “Making small changes over time can increase the likelihood of successfully incorporating new habits into daily life.”
~ Eat local when possible ~
The types of foods a person consumes are only one factor in the carbon footprint of a diet.
“Locally-sourced foods require fewer resources for transport and are more likely to be grown,” Costa said.
Joining a local CSA or heading to a neighborhood farmer’s market are two ways to shop locally. Pasquariello agrees that shopping locally is often more sustainable but cautions it’s not currently attainable for everyone.
“Even in areas of the country where farmland makes up a large swath of the total land, we have to remember that much of the food produced there then gets shipped off to other parts of the country to feed livestock and be used in the production of processed foods…We have to acknowledge the burden it already is for some folks to buy from local farms and producers.”
~ Be mindful of food waste ~
Experts share that it’s not just about what goes into your body but what winds up going out with the trash.
“Wasting foods not only means wasting all the energy and water to create, transport, and deliver them but also produces more methane, a greenhouse gas, as they rot,” Lui said.
A little planning can make a significant environmental impact.
Consumers can help to reduce food waste by planning meals ahead of time and only buying what they will need rather than purchasing more than necessary,” Costa said.
~ Choose organic produce when you can ~
Organic produce is usually grown with fewer fertilizers and pesticides.
“Additionally, organic farming practices can help to restore soil health and reduce water contamination,” Costa said.
When feasible in terms of accessibility and finances, Costa recommends opting for organic produce.
~ Have fun with plant-based proteins ~
Getting creative in the kitchen can make swapping in plant-based options fun. Pasquariello suggests starting with beans, tofu, tempeh, and lentils.
“As you get used to them, instead of serving them on their own, play around with recipes that introduce marinades, sauces, and plenty of seasonings,” Pasquariello said. “Proteins like this are usually sponges for the flavors you add to them.”
~ Make it colorful ~
“Eat the rainbow” is more than a cliche. Best said it’s a way to eat for yourself and the planet.
“Aim to have a variety of colorful fruits and vegetables on your plate, as different colors indicate various nutrients and health benefits,” Best said.
Think green and yellow peppers with red tomatoes or eggplant with broccoli and carrots. Tofu fries are a way to gobble up numerous types of vegetables (and enjoy a plant-based protein).
Written by Beth Ann Mayer for Healthline ~ August 2, 2023