Down the hall, the scent of freshly baked bread fills a research kitchen as scientists pull loaves from the oven for experiments on carbohydrate metabolism. In other labs, strawberries, avocados and cranberries are under scrutiny. Here at the UCLA Center for Human Nutrition, founder David Heber, author of the popular What Color Is Your Diet?, directs research on the health attributes of foods. Recent discoveries include evidence that green tea might help to inhibit breast cancer, that substances in citrus fruits can repair damaged genetic material, and that any whole fruit or vegetable contains more powerful benefits than a single isolated compound.
Heber recently took time to talk candidly about his work and to muse about how findings from his lab move straight onto his own plate.
Q: What color is the diet of most North Americans?
Brown and beige with a lot of refined starches, sugars and fat. In America our problem is monotonous foods that have hidden fat and sugars that you can’t stop eating. You can’t eat just one: you keep eating and eating and eating.
One-third of Americans get 47 percent of their calories from junk food. These foods taste very good, so you tend to go to them when you’re stressed or haven’t planned out your meals. A basket of corn chips at a Mexican restaurant is 550 calories, two slices of pizza pack 1,000 calories. It adds up quickly. People forget what they ate yesterday, but it’s like a bank account: your body remembers.
Q: And you say fast foods tend to lack nutrients?
They lack healthful nutrients. The unhealthy diet has been associated with dental problems (gingivitis and inflammation of the gums), bone fractures and heart disease. Even in a person who remains thin, a high-fat, high-junk-food diet that raises cholesterol levels can lead to premature heart attacks. Finally, breast, colon and uterine cancers have all been associated with obesity, which creates an oxidant stress on the body.
Obesity doesn’t necessarily mean being big, by the way. It means a high fat ratio to your total weight. The obese person has more inflammatory burden in his or her body than a lean person, and inflammation is behind cancer and heart disease. So fruits and vegetables not only help by reducing the number of calories per bite, but the phytonutrients are also anti-inflammatory.
Q: How many fruits and vegetables does the typical American eat?
They eat three servings a day, and I like to joke that those are iceberg lettuce, French fries and ketchup. In fact, it’s not that far off because a quarter of the vegetables eaten in America are French fries.
Q: But isn’t it true that you can get a full day’s supply of vitamin C from a serving of French fries?
You can say something nice about anybody or anything. But the fact is that a sweet potato is a much better nutritional choice than a white potato. A medium white potato has about 220 calories. A medium sweet potato has 110, it has half the glycemic index, and it’s rich in beta carotene so it provides more quality in terms of cancer prevention.
Q: You advise women to eat seven servings a day of different-colored fruits and vegetables, men to eat nine. How is this possible?
“Servings” are very small—a cup of raw vegetables or a half-cup of fruit or cooked vegetables is a serving. It’s not very difficult to get five servings at dinner: 1 cup of steamed vegetables, a colorful salad with 2 cups of lettuce and a serving of fruit for dessert. Then all you need to do is to get another serving of fruit at breakfast and lunch.
Q: How important is it to vary the colors in choices of fruits and vegetables?
Some people aren’t adventurous, sticking to bananas, apples and an occasional green bean. Each of the colors has a specific role in the body. They represent families of chemicals, or phytonutrients, which benefit different parts of the body.
For instance, phytonutrients from the red group contain lycopene. There is some evidence suggesting lycopene reduces the risk of prostate cancer and also breast cancer. The yellow/green group, with spinach and avocado, benefits the retina, the back of the eye, which is like the film in a camera. This part of the eye receives the most ultraviolet light. Yellow/green vegetables help to protect the eye from the most common cause of age-related blindness, macular degeneration. The red/purple group tends to go into the brain. Raspberries, strawberries, pomegranates and cranberries have all been shown to improve mental function.
Q: In the summer, produce looks fantastic, and kids gobble up watermelon and berries. But what about the winter? Is frozen okay?
Frozen is actually better in some cases. It’s convenient and it’s self-empowering, because you don’t really have to throw anything away. I keep a bag of frozen spinach around in case my wife and I don’t want to cook vegetables that night. (I like spinach because I think of it as a super-vegetable.) We just warm it up in the microwave and put pasta sauce on top.
Q: Do you ever find yourself hungry because of all the “rabbit food” you eat?
If I were eating only fruits and vegetables I’d be hungry, but protein keeps me from being hungry.
Q: How much protein do you recommend?
To avoid protein deficiency you need around 10 percent of calories from protein. The optimum, from my point of view, is about 29 percent. Protein is the material needed to build muscles and organs and it helps to control cravings. When people take in enough protein to control their hunger, they don’t find themselves searching for trigger foods.
Q: There are high-fat, high-protein diets out there, but that’s not what you advocate, right?
I’m not high-fat. I’m high-protein, low-fat.
Q: Can you stick to your own advice when eating out?
When you go to a restaurant, be nice about it but ask the waitress, “Would you mind substituting a double serving of vegetables for those mashed potatoes?” Or “Could I have cut-up fruit instead of French fries?” They’re willing to do it—they’re very interested in your business. The other problem in American restaurants is the large portion size. If you’re going with a companion, have a salad and split an entrée.
Q: What keeps you inspired in your job?
“Physician, heal thyself.” I’ve been living by the same things I’m telling patients to do, and I’ve got to tell you I feel great. Three years ago I was 204 pounds with a 38-inch waist. Now, at age 56, 5'111⁄2", I weigh 180 pounds, have a 34-inch waist, and about 17 percent body fat with a lot of muscle mass. For me, I think I’ve found the answer. I feel energetic, I feel creative, and I’m addicted to my daily exercise (30 minutes of weight lifting and 15 minutes on the elliptical trainer). I think it’s the only healthy addiction.
Q: Are you worried about the American public?
Children in grade school coming down with adult-onset diabetes—I’m very worried about that. We should get more physical education back into the school system. We should be teaching kids about nutrition, teaching them home economics, so boys and girls can learn how to cook well and feed their future families. At all socioeconomic levels, people are still not eating enough fruits and vegetables. There’s not a lot of obesity at the country club, but there is a lot of cancer.
Q: Do you ever make exceptions to your regimen?
You should only pay attention to me 90 percent of the time. You need to enjoy your life and enjoy delicious foods. I recommend that one day a week you just have a really good dinner of whatever it is you want.
In David Heber’s Refrigerator
David Heber’s Typical Menu