When biologist Stephen Le’s mother passed away from breast cancer in 2010, he set off on an unusual soul search: to reassess his diet. His parents had migrated to Canada from Vietnam, and he knew that Asian immigrants had an increased risk of cancer. “I wanted to see if there was anything I could alter [so] as not to pass this on to my family,” he says.
At the same time, his best friend had jumped on the Paleo diet bandwagon and was convinced of its health benefits. This made Le wonder whether a diet based on human evolution was the best for long-term health.
So Le, who is currently a visiting professor at the University of Ottawa, set off on an epic journey—first to China, then through Kenya, Australia, India, North America, and, most importantly, his ancestral home of Vietnam—to figure out how diet impacts health. And he came back with a theory: Our meals should align with what our own ancestors ate, not with the latest fad. In effect, not everyone should be eating kale salads and chia smoothies.
He says, for example, that the popular Paleo diet, which we think of as heavy on the meat and light on grains, relies on a “pretty superficial interpretation of evolution.” In fact, early humans ate a pretty wide variety of foods, depending on where they lived. (See Prehistoric Dining: The Real Paleo Diet.)
His advice is more specific: “Think cuisine, not nutrition.”
In his new book, 100 Million Years of Food: What Our Ancestors Ate and Why it Matters Today, Le argues that humans are predisposed to best process the same diets their families ate 500 years ago. For Europeans, that was very little red meat, which was a rare commodity until the past hundred years or so. For Asians, that’s heavy in rice, vegetables, and small amounts of animal protein like fish sauce.
Growing up, Le and his brothers were repelled by the stuff. But after visiting Vietnam, he came back with a nutritional appreciation. “Fish sauce is kind of like olive oil in Mediterranean cuisine,” Le says. With it, these simple, healthy diets were more palatable.
“Unfortunately we have this model in modern times where we think of this food being medicine: You are what you eat,” he says. “But really, we’re designed as omnivores to eat anything.”
To eat like your ancestors is pretty easy, he says. In Europe, the cookbook record stretches back for centuries, and Asia also has extensive historic documentation of what made the table. In most of the world, meat and dairy was a rarity, and these are the main culprits affecting dietary health today, Le says. Very few traditional cuisines used as much dairy as we do today, and the majority of us are still not adapted to process it (See How Milk Goes Down Around the World.)
Visiting Vietnam, Le found that the consumption of cereal in the morning and meat for lunch and dinner was in stark contrast to his relatives’ diet, which consisted of little sugar and just a small amount of animal byproducts in their rice and vegetables. He towered over his Vietnamese peers by about three inches and noticed that they towered over the previous generation by the same amount, which he attributes to increased access to milk and meat products.
That’s not to say one size fits all. A Mediterranean diet wouldn’t work for the Inuit in North America or the Maasai pastoralists in Kenya, who are biologically adapted to eat more meat and dairy. They don’t have the gut enzymes to break down the starches and sugar in many diets today.
For nations with on-the-rise economies, maintaining a healthy diet is a balancing act. While malnutrition is a major issue across the world’s poorer countries, an influx of wealth doesn’t guarantee health. “As soon as they make an economic transition from developing to developed, one of the first things is, they start buying meats and milk products,” Le says.
“If the goal is to live a long, healthy life,” eating an ancestral diet from 500 years ago is better, he says. “If the goal is to win an athletic contest, then the hundred-year version is better.”
In some parts of the world, prosperity does mean better health. Some cultures are still eating what their ancestors consumed. In Okinawa, Japan; the Greek island of Ikaria; and Italy’s Sardinia, income increased but diets stayed stable. With the medical care that came with increased wealth, health flourished—and these spots continue to be home to some of the longest living people, as Dan Buettner, the author of Blue Zones, has noted.
In America, Le looked toward the Amish, who have almost no obesity despite eating typically rich American food like meat and potatoes. He attributes this to the amount of walking they do, which is triple that of the average citizen.
While diets look backward, Le says that exercise, too, should align with our ancestors’ activities—meaning increased walking and not running, which puts stress on the body.
Since writing the book, Le no longer trims the fat off his meat or focuses on saturated fats or cholesterol intake. The modern substitutes for these—sugary sauces and MSG flavoring—are unhealthier than the simple original versions, he says. “I started enjoying food a lot more,” Le says. “And I’m not feeling guilty about it.”
Nina Strochlic writes for National Geographic magazine. She’s a Daily Beast alum. You can find her on Twitter.