Do you ever get confused about the latest food study, diet, or superfood? Well, you’re not alone. In a world full of scientific research and study, we still can’t seem to discover the whole truth about nutrition.
Here is an article from Stanford University’s Alumni Association, July/Aug 2013 issue that offers interesting insight into the world of food science studies and why one diet doesn’t fit all. It is written by Nathanael Johnson with a lot of information from nutrition researcher Christopher Gardner.
Nutrition advice is confounding and often contradictory. What are we supposed to believe? Writer Nathanael Johnson went shopping for answers.
By Nathanael Johnson
At a Whole Foods store in San Francisco’s Noe Valley, Rebecca Hanover examines the bank of dairy products, calm despite a swirling demolition derby of shopping carts, one of which contains her 19-month-old son, Leo. “I’ve been eating these,” she says, gracefully swooping a single-serving cup of organic yogurt just beyond Leo’s reach.
She inspects the label. “I don’t think they have added sugar. No. This was my attempt to not eat the flavored kind and be healthier. Although . . .” She purses her lips. “These are the cream-on-top ones so they probably have more fat. But the sugar—I’ve been thinking about this the last couple days and I feel like sugar is something I’m more worried about than fat.”
A lot of people are more worried about sugar than fat. It used to be just the opposite, of course. In the 1990s fat-free was the buzzword, and sales of low- or no-fat products soared. Then it flipped and corporations rushed to introduce low-sugar products. “Just about every major food company is thinking along these lines,” noted one food consultant’s annual trend report, observing that: “Among the new products being offered are Pepperidge Farm Sugar Free Milano cookies,” and “75% Less Sugar Cocoa Puffs.” Low-carb diets are ascendant. Hanover’s father-in-law, the futurist Ray Kurzweil, shifted the position he’d taken in one book (advising a low-fat diet) and wrote another (following a low-carbohydrate regime).
Given all the science that’s been done on nutrition you might think that we’d have nailed this down by now, but instead the messages coming out of nutrition research can seem more contradictory and capricious than ever. One example: Subway last year became the first fast food chain to get the American Heart Association’s seal of approval. A few months later, results from a research study suggested that the difference between eating at Subway or McDonald’s was insignificant.
I’d asked to tag along with Hanover, ’01, and watch her shop not because she’s a nutrition guru—just the opposite: The way she makes decisions about food is pretty typical. Stanford researchers have found that it’s not enough to study what foods are good and bad, healthy and un. Perhaps even more important than that science is the business of figuring out what makes people decide what they’re going to put in their mouths.
Hanover, a blogger (mommyproof.com) and former writer for the soap opera Guiding Light, isn’t neurotic about food. She doesn’t pretend to be up on the nitty-gritty of what’s considered healthy one day and poison the next. She admits that her buying choices are influenced by hazy assumptions that filter down to her from the zeitgeist—like the idea that sugar is more worrisome than fat.
The question of what to eat, when viewed through the lens of diet books and magazine weight-loss tips, can look frivolous, but in reality the stakes are high. In 2004 the U.S. surgeon general suggested that we are raising the first generation of Americans likely to have shorter lives than their parents. By 2030, experts predict, obesity could be the norm, which means that (statistically speaking) the toddler squirming around in Hanover’s shopping cart—who by this time had put tooth marks in the foil seal of one of the yogurt cups—is more likely than not to be obese by the time he turns 19. It seems doubtful that sugar-free Milanos will save us. But maybe a new way of thinking among food researchers can.
Nutrition researcher Christopher Gardner thinks our present confusion has a lot to do with an assumption that scientists made early on: There is a single healthy diet that’s right for everyone.
“For decades we’ve been asking the wrong question,” says Gardner, associate professor of medicine at Stanford’s Prevention Research Center. “It’s not ‘What’s the best diet?’ It’s ‘What’s the best diet for each unique person?’ ”
Gardner looks the way you want a nutrition scientist to look: healthy, with floppy grey hair and the low-blood-pressure mien of a beach bum. On a balmy Palo Alto afternoon he walks into a meeting room in the Veterans’ Hospital, trailed by his two small boys, and arranges the tables to approximate a cage (though he advertises it as a fort) to contain the kids in one corner of the room. It’s metaphorically appropriate to see Gardner as a scientist and a dad at the same time, because he’s trying to figure out how to study food as it fits into the real lives of real people. Earlier research, which tended to see nutrients in the abstract, fixated on the division of foods into simple categories: “good” and “bad.”
In the early days, the one-diet-fits-all approach seemed to work, and it allowed the science to move quickly. The 1900s were perhaps the golden age of nutrition research, when scientists were finding one vitamin after another until they had identified every nutrient that animals need to survive and reproduce. “It was really exciting,” Gardner says. “They were curing things like goiters and scurvy. But these were acute diseases; they were quick, you could watch them go away if you got the right fix.”
On the other hand, chronic diseases—cancer, heart disease, diabetes—are maddeningly difficult to study. “If I want to design a study around chronic disease, I might get 100 babies and randomize them so half get organic broccoli for 90 years, and see which get sick,” Gardner proposes, facetiously.
Gardner wouldn’t go back to the old days, though, because for all its success, that science also led to a series of mistakes that are now baked into the way we think about food. Once researchers had discovered all the essential nutrients, they assumed the hard work was finished. The next step was to pump these components of the ideal diet into the food supply: Add vitamins into Wonder Bread, fortify salt with iodine, and so on. Problem solved, right? Wrong. Very wrong. This strategy did eliminate diseases caused by nutrient deficiencies by dosing everyone with more than they needed, but it also gave rise to our current dietary quagmire, and the problem of nutrient super-sufficiency has proved much more subtle.
The notion that different people require different diets could render the great battle between low-carb and low-fat (not to mention the Paleo diet, and all the rest) totally irrelevant. Gardner began thinking seriously about this after running a study comparing 311 women on four different diets. Overall, people had lost weight on every diet, but not as much as they had hoped. “The average amount people lost on each diet was hugely disappointing, the key term there being ‘average,'” Gardner says. There was something else hiding in the data that caught Gardner’s eye: Some women had lost as much as 60 pounds on a diet—it had worked for them, it’s just that they were counterbalanced by others who had lost very little or even gained some weight during the study. He began to wonder if the real breakthroughs were occurring only when the right person was matched to the right diet.
After a promising pilot study, Gardner got the National Institutes of Health to fund a trial testing the hypothesis that different people should eat different things. Half the people in the study will randomly be assigned to an extremely low-fat diet, while the other half will go low-carb.
The researchers will watch closely to see if genetics, insulin or even the microbial ecosystem in the gut inclines people toward one diet or the other. If the experiment is successful it could lead to big things. But when I suggest that this could be the key to solving the obesity epidemic, it just makes Gardner laugh. “This could be important, but it would just be one little piece of the puzzle,” he says.
The history of nutrition science is littered with the remains of hypotheses that were once the next big thing, so it makes sense to cultivate humility. You can begin to see why, once the rest of the researchers gather in the room where Gardner has corralled his sons. As they begin comparing notes, the problems intrinsic to nutrition science immediately surface. These problems boil down to the fact that people cannot be controlled like Petri dishes, or fruit flies. Instead of conforming to strict protocols, we forget, we screw up, we lie. In short, we’re a scientific hot mess.
“I wanted to discuss the change in weight in the first cohort,” says Antonella Dewell, the project coordinator.
“There have been some changes from baseline?” asks Gardner. “Are they losing or are they gaining weight?”
“Gaining, they are all gaining weight.”
Gardner covers his face with his hands. “Holy cow.”
“One person gained 3 percent, one person gained 4 percent, one gained 7.6.”
“So, interestingly,” Gardner muses, “no one has been like, ‘I’m going to be in a study, I’m going to start losing weight now.’ It’s more like . . .”
The researchers begin to chuckle and another interrupts, ” ‘I’m about to lose weight, so I’m going to have my day!’ It’s true; they actually say that. It’s like the people who drink and smoke right before heart surgery because they figure, ‘They’re going to clean it all out anyway.’ ”
Eventually, the group decides they need to exclude from the study the person whose weight was fluctuating the most. Health and weight are determined by diet, but also by lifestyle, psychology and relationships. These categories don’t have firm borders; they bleed into one another. And all these confounding factors make it tricky to separate the signal from the noise when looking for correlations between food and health.
About five years ago, Gardner had a midlife crisis: He began to wonder if he was doing any good or just spreading confusion. It’s pretty depressing to consider that chronic diet-related diseases are only prevalent in cultures advanced enough to have an understanding of food science. Something about the modern way we eat is making us sicker and fatter each year, and nothing researchers do seems to help. The writer Michael Pollan likes to say that there’s a lot of important work going on in nutrition science, but it’s not quite mature yet. “It’s about where surgery was in the 16th century,” he jokes.
There’s a divide here when it comes to assigning blame. Some say the problem is located in the science (we’ve been given bad nutritional advice); some say the problem is located in our willpower (we just can’t follow the advice). Gardner thinks it’s both.
If you want to understand how this works, you can follow the money. All the confusion that comes from the imperfect science of studying chronic disease in messy humans has provided nice profits for diet book writers, who can plausibly claim that everything you thought you knew about nutrition is wrong (over and over again). It’s also been good for journalists, who are able to produce one counterintuitive headline after another. But clearly the biggest beneficiary of nutritional confusion has been the food industry.
Changes in lifestyle have converged with food industry attempts to increase the desirability of processed food to create a cultural shift in how we eat. Growing your own food was once a strategy against poverty, but for families struggling to fill bellies today, fast food often works out to be the most inexpensive option. Now, one in four “vegetables” eaten by children in the United States is actually a French fry. The amount Americans spend on fast food (after adjusting for inflation) has tripled since 1970. As Kelly Brownell, a psychologist specializing in obesity, puts it, “The food industry has worked systematically to force higher-profit, processed food into every aspect of our lives.” He points to the campaign to expand fast food into breakfast (once a ridiculous proposition) as an example. Flip-flopping news about the latest nutritional “discovery” worsens the problem. For Gardner, this hit home when the media reacted to an experiment that he ran on people eating garlic.
“I did this study to see if eating garlic would lower cholesterol, and it didn’t. And then one newspaper ran a headline that said, ‘Stanford finds garlic isn’t healthy!’ ”
That’s not exactly what the study had found, but the message people were getting was that you might as well be eating doughnuts.
“We get so we can’t see the forest for the trees,” Gardner says. “Here I am trying to do a study on garlic and cholesterol. Okay, fine, but meanwhile, all around me fast food restaurants are going up, and people are cooking less and less. And it’s the garlic that isn’t healthy?”
Of course, the drive-through, strip-mall restaurants are part of an even larger change: the transformation of America into an auto-centric landscape where it’s unsafe to move under your own calorie-burning power. Each year Americans spend a little more time sitting (often munching), and a little less walking. In other words, you can blame the limitations of nutrition science or you can blame willpower, but the real problem is the way our food environment has shifted around us.
Back in the rarefied aisles of Whole Foods, Hanover—somewhat self-consciously—is looking for the perfect hummus. Perhaps tacitly acknowledging that shopping at Whole Foods rather than, say, WalMart, sets her apart from typical food buyers, Hanover is self-deprecating about her food fixations. “In the fridge we have like seven hummuses. Hummi?”
She picks up a container and reads off the ingredients. “Chickpeas, water, canola oil, tahini, sea salt—so that seems like it’s pretty healthy. The nice thing is that Leo really likes it. We like to eat it on lentil chips,” she says, trailing off into laughter. “Oh my god, we sound ridiculous. You can acknowledge that this is absurd.”
It’s hard to eat differently from the people around you, because eating isn’t just about health, or pleasure, it’s also a cultural act—on some level what you eat defines your tribe. There’s enormous social pressure to conform to the norm. For Americans that means having a lot of fast food. Eating healthy becomes an act of social deviance, like going nude. Of course, in certain demographics (graduates of top-flight universities, for instance) there’s more stigma attached to McDonald’s than to Whole Foods. The sad irony is that the people most likely to tilt toward health-food attentiveness are those least likely to get fat: the affluent.
What’s a nutrition scientist to do when the sway of food culture renders the science moot? For Gardner, the key to breaking out of his funk was shifting focus: “Forget if it’s good or bad for you, now the question is, what do you need to do to get a kid to put a vegetable in his mouth? Does growing it help? What happens when we bring kids out to a farm over the summer and see if we can change their eating habits?”
To test that notion, Gardner’s team started a summer camp on an 11-acre organic farm in Sunnyvale for underserved kids. Hoping to make new eating habits stick, they sent kids home with their choice of vegetables. And then gave them cameras to take pictures of anything they wanted involving meal preparation. “Then we find out that they only have a hot plate to work with,” Gardner says. “Okay, now we’re getting somewhere! Now I can start to see why beets don’t work, and why they are going to keep eating hamburgers no matter how many studies we do saying, ‘eat vegetables.’ ”
The problem with this sort of work, and also the thing that makes it so exciting, is that when you tug on something like a beet root you find it is hitched to the entire universe. It turned out, for instance, that kids were not allowed to bring vegetables from the farm to school.
“It was illegal. The vegetables weren’t processed enough,” Gardner explains. “They came from the ground, they might have bugs on them.”
Stanford is well equipped to handle problems that are hitched to the entire universe, Gardner says. He turned to the Law School, which sought to make fresh vegetables legal in school. When his team realized that mass-produced foods are cheaper and therefore more attractive to poor families, they engaged researchers at the Graduate School of Business to tackle the money problem. The d.School also pitched in to develop better ways to grow food in rooftop gardens and abandoned lots.
“And then there’s the Earth Sciences people,” Gardner adds. “[Lecturer] Patrick Archie is doing agricultural techniques for small plots in cities, where the giant agribusiness methods don’t apply. And the Graduate School of Education starts having Jesse Cool [chef-owner of Cool Café] bring the master’s students out to the garden to inspire them to integrate food into their classes, to show kids how food grows, how photosynthesis works.”
This is more than lip service to a couple examples of cooperation. The University is investing money to pull all these schools and disciplines together around the problem of nutrition, to form the Stanford Food Helix, a set of courses that students can work their way through, all focused on the same problem.
Getting people working to change the food system may also be the key in getting them to improve their own diets. Gardner realized this when he began teaching undergraduates himself. It was a course on social, environmental and ethical issues in food production, and he decided to run a quasi-scientific experiment. He asked students at the beginning and end of the course what foods they were eating, and compared the answers with those of different students, who were learning instead about the health effects of poor nutrition. By the end of the class just about all of Gardner’s students were eating more vegetables and less fatty animal products—they were much more likely to have changed their eating habits than the students learning about health.
“It’s so intoxicatingly fascinating to see the lightbulbs go on in these students’ heads,” Gardner says. “Because, after 20 years of nutritionists recommending that people eat more fruits and vegetables, people don’t eat any more fruits and vegetables. I can tell you to eat differently because it’s good for you, and you’ll never change. But if I say, ‘If you eat differently you can help others,’ it can produce this huge shift in diet.”
This reasoning rings true for Hanover, who has made her way to the deli counter. One of her primary motivations for shopping at Whole Foods is the chain’s reputation for offering humanely raised meats. That may not have anything to do with nutrition, but it’s important to her. She lingers over the packaged chicken breasts. “I could make chicken tacos,” she says, and scans the label for some hint of provenance, or poultry lifestyle.
“I know I make a lot of assumptions,” she says. “Like, well, we are at Whole Foods, so it’s probably pretty good. I see all these words that are confusing—natural, organic—and I just take for granted that it’s good.”
Whether these assumptions are correct, the fact is that Hanover’s family has a healthier menu than most Americans. It’s clear that nutrition science has a way to go before it can offer the perfect diet tailored to your genotype and lifestyle, but in the meantime there are a lot of obvious big-picture improvements that can be made to the food system. It’s a problem with two arms, and Gardner’s team is wrestling them both at once.
Nathanael Johnson is the author of All Natural: A Skeptic’s Quest to Discover if the Natural Approach to Diet, Childbirth, Healing, and the Environment Really Keeps Us Healthier and Happier.
© 2012 Stanford University