Diet of plant-based foods, with daily protein and dairy servings, may be ideal for planet

Key takeaways:

• Nuts, legumes, vegetables and fruits were heavily emphasized in the planetary health diet.
• Global adherence to the planetary health diet could prevent 11 million deaths a year.

DENVER — The ideal planetary health diet — one that is good for both people and the planet — may be one daily serving of protein and dairy, with a high intake of a variety of plant-based foods, an expert said.

During his presentation at the Lifestyle Medicine Conference, Walter C. Willett, MD, DrPH, a professor of epidemiology and nutrition at Harvard’s T.H. Chan School of Public Health, discussed the findings of the EAT-Lancet report, which aimed to answer the question of how to feed a healthy and sustainable diet to an estimated 9.8 billion people in 2050.

According to the institution, this “planetary health diet” was designed to:

• define daily consumption ranges for every food group;
• accommodate various individual and local traditions and dietary preferences; and
• stay within “planetary boundaries” to decrease the risk for catastrophic and irreversible events in Earth’s ecosystem.

The EAT-Lancet Commission developed this diet by evaluating various kinds of studies — including randomized trials, long-term cohort studies and controlled feeding studies — on major food sources over a course of 3 years.

There were several notable findings, Willet said.

He noted that among major protein sources, lentils had the highest ratio of polyunsaturated fat to saturated fat (P/S), followed by tofu, almonds, salmon, chicken and beef.

“If we really want to go to high P/S ratios, we need to look at plant protein sources like nuts, soy products and other legumes,” he said.

Willet said another component of developing the planetary health diet included preventing major health outcomes. He highlighted one recent study that found one serving of red meat was linked to a 47% greater risk for type 2 diabetes.

The research “confirmed the previous observation of a pretty linear relationship and a significant increase [from] even going to two servings of red meat per week,” Willett said.

Willett also pointed out that there was significant variability in the ideal intake of grams per day for whole grains, which ranged from 0 g to 60 g.

“You don’t really have to have any grains in a diet,” he said, although he emphasized that any grains consumed should be whole grains.

Willett concluded that a healthy and sustainable diet may come down to a flexitarian diet, which consists of:

• one serving of dairy per day; and
• one serving of protein, like poultry, fish, red meat or eggs, per day.

“That’s on a basis of nuts, soy, other legumes, fruits, vegetables, whole grains and plant oils,” he said. “[It has] incredible flexibility and a variety of ways you can put that together.”

Willett added that although current global intakes of nuts, legumes and whole grains would need to be significantly increased to match the planetary health reference diet, 11 million deaths could be prevented a year if the diet targets were met.

Ultimately, “feeding 10 billion people a healthy diet within safe planetary boundaries is possible and will improve the health and well-being of billions of people,” Willett concluded. “This could allow us to pass onto our children a viable planet. But this is not going to be easy, and it will take the engagement of almost everyone.”

References:

• Plate and the planet. https://www.hsph.harvard.edu/nutritionsource/sustainability/plate-and-planet/. Accessed Nov. 1, 2023.
• Sustainability. https://www.hsph.harvard.edu/nutritionsource/sustainability/#sustainability-key-terms. Accessed Nov. 1, 2023.
• The EAT-Lancet commission on food, planet, health. https://eatforum.org/eat-lancet-commission/. Accessed Oct. 31, 2023.
• The planetary health diet. https://eatforum.org/eat-lancet-commission/the-planetary-health-diet-and-you/. Accessed Oct. 31, 2023.
• Willett W, et al. What is a healthy and sustainable diet? Findings from EAT-Lancet. Presented at: Lifestyle Medicine Conference; Oct. 29-Nov. 2, 2023; Denver.