The beauty of the pattern approach is that it's not necessary to know exactly what mechanism is leading to better health. "It could be one thing or multiple things," says Fung. For example, research recently suggested that the higher amounts of choline, an essential nutrient in the vitamin B family, and another nutrient called betaine—both of which are abundant in a Mediterranean diet—reduce inflammation, which may contribute to a host of diseases, says Steven Zeisel, director of the Nutrition Research Institute at Kannapolis, a branch of the UNC Chapel Hill School of Public Health. "But the truth is, I'd be foolish to rush out and eat those nutrients. I can eat closer to that pattern—less red meat, more olive oil—and not worry about which is the active ingredient," he says. In fact, it's not even clear that these patterns are healthier because of what's in them—it may be what's absent. "As soon as you eat the Mediterranean diet, you're eating less steak," says Gardner. "Maybe it had nothing to do with that. What we know is that if you eat that way, you're healthier."
So, is it that easy: We all just have to eat like the Greeks (or the Vietnamese, or the ancient Maya)? Well, yes and no. First, most of the evidence comes from observation, not rigorous scientific trials, so it doesn't prove cause and effect. But there's enough observational data to convince most researchers, and there is some experimental evidence: Trials showed that eating a low-sodium diet based on whole grains, poultry, fish, and nuts and lighter on the red meat, fats, and sweets lowered blood pressure.
A second caveat is that these ancient dietary patterns were long paired with a way of life that doesn't much exist in America—and it included a lot of exercise, says Pollan. Men in postwar Crete didn't laze around dunking bread in olive oil all day; they chased goats up hills. Even now, people in the Mediterranean and other parts of the world are more active, whether through vocation or because there's so much more walking as part of daily life. That's why the traditional food pyramids from Oldways all include exercise. (The government recommends 30 minutes a day of moderate exercise for heart health and 60 to 90 minutes a day for weight loss.)
And if you're watching your weight—and who isn't?—calories really do count. The key is replacing less healthful foods with healthier ones, not just adding tofu to your bologna sandwich or nuts to your sundae. As Pollan says, "Eat food. Not too much. Mostly plants." That doesn't mean eschewing all indulgences, but it does mean keeping an eye on day-to-day intake. "It's about the pattern over the long term," says Oldways' Gifford. "Do you think people in the Mediterranean get drunk after church on Sunday? Sure, they do! We're human, and you have to take the pressure off the pressure cooker."
Even with occasional excesses, adopting a sound dietary pattern may be both simpler and more wholesome than chasing down the latest superfood or nutritional supplement. "Finally, the field has come around to realize that it won't be a single nutrient," says Tucker. "We're back to old-fashioned advice: Eat a variety of good-quality whole foods. That's the way to stay optimally healthy."