Grizzly bears may have diet lessons that can be helpful for humans

JIM SCHULZ/CHICAGO ZOOLOGICAL SOCIETY - A lesson for humans: Axhi was obese until the Brookfield Zoo in Chicago gave him food that resembled what grizzlies find in the wild.

When she was head of a cardiac imaging center at UCLA, Barbara Natterson-Horowitz was asked one day to perform echocardiography on the failing heart of the Los Angeles Zoo’s python. As the cardiologist gazed on an image of the snake’s one-ventricle heart, it occurred to her that snakes might offer clues for treating children born without a septum between their ventricles.

At that moment, she began to see a connection between the health of humans and that of what she would call our nonhuman brethren.

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Natterson-Horowitz is a leading figure in One Health, an initiative founded on the idea that closer collaboration between physicians and veterinarians can benefit all species.

“Until recently, the veterinary world has existed in a parallel universe to human medicine, and there has been no cross talk,” says Peter Rabinowitz, an associate professor of medicine at Yale Medical School.

“There are so many things that vets have discovered that are relevant to doctors in practice, and vice versa,” says Rabinowitz, who is soon to move to Seattle to start a One Health center at the University of Washington’s School of Public Health. As an example, he cites Rocky Mountain spotted fever, a tick-borne infection that can cause severe illness in both animals and humans. There have been cases where a vet making the diagnosis of this infection in a dog helped doctors identify the same disease in the dog’s owner.

Natterson-Horowitz’s 2012 book, “Zoobiquity,” co-authored with science writer Kathryn Bowers, has helped spur collaboration between vets and doctors.

“Zoobiquity” (an invented term that combines the Greek word for “animal” and the Latin for “everywhere”) offers a cross-species perspective on a range of human health problems. In a chapter on cancer, for example, the authors explore how to draw insight from the high incidence of breast cancer in jaguars and the low incidence of that disease in dairy cows. The book also looks at binge eating in grasshoppers, sexually transmitted diseases in koalas, drug addiction in wallabies and heart attacks in zebras.

The obese grizzlies

It was her chapter chronicling the impressive weight loss of Jim and Axhi, two formerly obese Alaskan grizzlies at Chicago’s Brookfield Zoo, that resonated most with me. As a family-practice doctor, I often see patients who are frustrated by repeated and unsuccessful efforts to lose weight.

This was a connection that Natterson-Horowitz had made in her own practice.

“I see a lot of patients who are overweight,” she told me. “I talk to them about what they are eating, about activity, about what is going on with them psychologically. But it is all targeted at them as an individual. Vets, on the other hand, have a very different approach. When they notice that an animal is getting fatter, they don’t look to the individual but to the environment.”

This makes sense, since veterinarians can’t tell their clients to count calories or hit the gym. To change behavior, their only option is to change the context in which that behavior is taking place.

In the case of the grizzlies, the Brookfield Zoo vets understood that the bears’ physiologies and innate behaviors were out of sync with their environment — thus, their obesity. So they designed what Natterson-Horowitz called “nature’s weight management plan.”

The zoo’s nutritionists took away the processed dog food, ground beef, loaves of bread, supermarket oranges, bananas, mangoes and iceberg lettuce that the bears had been eating.

Instead, they provided plants and animal protein that were seasonal and more closely resembled what grizzlies find in the wild. (As Natterson-Horowitz pointed out, there are no banana or mango plantations in the Canadian Rockies.) They chose vegetables and fruits such as kale, peppers, celery, heirloom apples — all more fibrous and seedy than the bears’ previous diet. And they replaced the hamburger meat with whole prey, such as fish and rabbits, which the grizzlies had to work harder to disassemble and eat.

They stopped placing food in the cages on a set schedule; they hid meals and added wax-worm snacks to the bears’ peaty foraging piles, which made the grizzlies burn calories as they rooted for each desirable morsel.

With this approach, the bears shed hundreds of pounds over the course of a year, leading Natterson-Horowitz to wonder whether a similar alterations in a human’s environment might be equally effective.

“I went into my freezer and saw that I had four frozen chickens in the back. There is something comforting about that. Vets call it food caching,” or hoarding, says Natterson-Horowitz, adding that all animals are hard-wired to hoard food.

She realized that one easy way to limit access to abundance — and, by extension, the tendency to overeat or eat too often — is to empty food caches at work, in the glove compartment and in the purse, and to shop for at most a few days’ worth of meals instead of stockpiling.

In choosing foods, she said, she focused less on certified organic foods and more on selecting ones that were seasonal, locally grown and less processed.

Research suggests that fruit and vegetables typically found in supermarkets are bred for shelf life and their ability to withstand transport but are often less nutritious and more caloric than traditional heirloom varieties. The Biochemical Institute at the University of Texas at Austin tracked the nutrient content of 43 of the most frequently cultivated varieties of produce from 1950 to 1999 and found a substantial reduction in protein content, B vitamin, fiber and antioxidants over that period.

Similarly, traditional whole grains such as quinoa, faro and barley are more filling and offer up fewer calories and more nutrition per mouthful than refined wheat and white rice. In general, these traditional foods also encourage the digestive system to work hard for each calorie.

Better gut bacteria

In addition to having lower sugar, more fiber and more nutrients, these heirloom and traditional foods tend to nurture a healthier assortment of intestinal bacteria, says Stanford School of Medicine microbiologist Justin Sonnenburg. “Basically, even though most of us are eating in a modern way, our genome is optimized to work with the microbiota [intestinal bacteria] that are promoted by traditional foods.”

Meanwhile, bonier cuts of meat can flavor a stew of lower-calorie legumes, vegetables and grains while making us, like those grizzlies, forage a bit more for the meat itself.

Buying heirloom and traditional foods usually means shopping at farmers markets, smaller groceries or food co-ops, which has the effect of altering the food environment in much the same way as the Brookside zookeepers did for the grizzlies.

Instead of slowly guiding a cart through a supermarket, you fill bags that you must carry, or you push a basket-hauling bike. (It is also likely that you’ll avoid being tempted by racks full of low-nutrient, high-calorie snacks that beckon in a supermarket.)

None of this sounds that major, but as the zookeepers found out, many small changes in environment had a big impact. Cooking from scratch isn’t quite stalking a rabbit or scrounging for wax worms, but it can change the ratio of calories expended to calories consumed. Compare, for instance, the energy needed to walk around a kitchen, chopping food, opening and closing a refrigerator and cleaning pots to the efforts involved in driving past a fast-food window or pulling the top off a commercially prepared dinner. And then multiply that over many days.

For an even more ambitious reworking of one’s food environment, consider growing much of one’s own food, which Natterson-Horowitz describes as essentially “organized foraging.”

The Brookside Zoo nutritionists not only changed what and how the bears ate but also tried to make their cages bigger and fill them with distractions so that eating was not their only pastime. Such “environmental enrichment,” which can be seen all over the National Zoo — from the octopus tank with its shelves, archways, tunnels and doorways to the orangutan cage with its swings and aerial cables — decreases the stress and boredom of captivity and related overeating.

We too tend to eat and drink more when we are bored, anxious and lonely. Structuring our environment with plenty of engaging activities can keep us away from the pantry, the fridge and the snack bowl. For those who work from home, setting up stimulating decoys — such as that day’s newspaper — between desk and kitchen is a good way to distract from eating. Eating with others (and not in front of a screen) can also lead to slower eating and fewer calories consumed.

So how does this relate to patients who come to me blaming themselves for again failing to lose weight? The lesson of “Zoobiquity” is that we are simply exercising our animal natures in an environment that is anything but natural.

Of course, we can’t truly reproduce the diet of our hunter-gatherer ancestors any more than the zookeepers can perfectly replicate the fare available to the grizzlies that still roam the Rockies. But perhaps it’s time that we take a cue from Jim and Axhi, and start to live a little more on the wild side.

Miller is an associate clinical professor of family and community medicine at the University of California at San Francisco Medical School. Her most recent book, “Farmacology: What Innovative Family Farming Can Teach Us About Health and Healing,” will be published this month.

 
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