Eat, Drink, and Be Healthy

by Walter Willett

  • Eat soy in moderation. Soybeans, tofu, and other soy foods can be a good alternative to red meat. Just don’t overdo it. Aim for a few servings a week, not a few a day. For women in the midst of menopause or beyond who are plagued by hot flashes or other problems related to estrogen loss, boosting soy intake for a while probably won’t do any harm and can be worth a try. At the same time, it probably isn’t much more effective than the tincture of time. For women living with breast cancer, moderation makes sense. No one should take pills that deliver concentrated soy protein or pure isoflavones unless there is a clear medical reason to do so.

  Fast Fact: Be Wary of Protein Supplements

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  Athletes, bodybuilders, and others take protein supplements, such as whey protein, to build muscle. Taking protein supplements without exercising has only a small effect on adding muscle and is no replacement for exercise. It’s an expensive strategy that isn’t any better than a high-protein diet. In addition, trying to rev up muscle growth with protein supplements might be accompanied by a revving up of cancer cells that lurk around for years and don’t show up until far down the road (see “High Quality Protein: Is Too Much A Bad Thing?” on page 134).

  CHAPTER EIGHT

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  Eat Plenty of Fruits and Vegetables

  AS A CHILD, YOU HATED to hear it. As a teenager, you promised yourself you’d never say it to your own children. Yet as an adult, it—“Eat your vegetables; they’re good for you!”—springs out of the mouth unbidden, like wisdom that must be passed from generation to generation.

  That’s actually a good description. “Eat plenty of fruits and vegetables” is timeless advice that science is only now catching up to. It is a simple, easy-to-remember, and tasty morsel of dietary advice that ranks high on the list of smart and healthy nutritional habits.

  With apologies to Elizabeth Barrett Browning, how do fruits and vegetables help thee? Let me count the ways. A diet rich in fruits and vegetables can:

  • decrease the chances of having a heart attack or stroke or developing diabetes

  • lower blood pressure

  • help you avoid constipation and the painful intestinal ailment called diverticulitis

  • guard against two common aging-related eye diseases: cataract, the gradual clouding of the eye’s lens; and macular degeneration, the major causes of vision loss among people over age sixty-five

  • delay or prevent memory loss and a decline in thinking skills

  • help you feel full with fewer calories and so control your weight and waistline

  • add variety to your diet and enliven your palate.

  Notice that I keep saying “fruits and vegetables.” Pills that contain one or two or ten substances made by plants just won’t do. Why not? Plants make a seemingly endless cornucopia of compounds that have biological activity in the human body. So far, only a tiny minority have been flagged as agents that may be responsible for the health benefits of fruits and vegetables, sometimes on the basis of surprisingly little solid evidence. The vast majority of phytochemicals have yet to be discovered, named, chemically characterized, and biologically evaluated. The odds are high that the benefits I listed for fruits and vegetables emanate from many different substances found in plants and quite possibly from the interactions among them.

  Why Supplements Are Not a Substitute for Fruits and Vegetables

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  So far, no one has found a magic bullet that works as well as fruits and vegetables against heart disease, cancer, and a host of other chronic diseases. In theory, one could cram all of the good things that plants make—essential elements, fiber, vitamins, antioxidants, plant hormones, and so on—into a pill. But it would have to be a very large pill, and scientists honestly can’t say they know exactly what should go into it. Or in what proportions.

  Take the antioxidant pigments known as carotenoids. When you eat a tomato or carrot, the different carotenoids it contains eventually work their way into different types of cells and different parts of each cell. This offers antioxidant protection throughout the cell and to a wide variety of cell types. When eaten in the proportions usually found in foods, carotenoids and other phytochemicals benefit cells by working together in ways we don’t yet completely understand. But when delivered in unnatural proportions or missing some essential components—say, via a poorly designed supplement pill—an oversupply of one carotenoid or phytochemical could block the activity of others.

  This isn’t to say that vitamin and mineral supplements are worthless. As described in chapter eleven, vitamin supplements are excellent insurance. But they aren’t a substitute for a healthy diet.

  Health issues aside, the biggest drawback is that a pill would always taste like a pill. It can’t give you the earthy smell and taste of a fresh ear of corn, the sweetness of a juicy tomato still warm from the afternoon sun, the crunch of an apple, the festive green of a snap pea or broccoli floret, or the smooth, nutty taste of an avocado. Stick with real fruits and vegetables: they contain a bounty of phytochemicals that do not come in capsules, and they taste better too.

  BUT FIRST, EXACTLY WHAT ARE FRUITS AND VEGETABLES?

  To a botanist, a fruit is any plant part that contains seeds. By the process of elimination, a vegetable is everything else: leaves, stems, flowers, roots, and bulbs. Things get hazy in the kitchen, though, because many of what are commonly called vegetables are technically fruits: Think of the seeds in avocados, cucumbers, eggplants, squashes, and tomatoes, to name just a few. In this book, I will stick with the culinary concept of fruits as sweet, dessert- or even snack-like foods, and vegetables as savory, salad- or dinner-type foods.

  Fruit or Vegetable?

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  The argument over whether certain foods are fruits or vegetables has been around for years. Back in 1893, the U.S. Supreme Court ruled that tomatoes were a vegetable, and they’ve remained so ever since. Why was the highest court in the land asked to make a legal and somewhat unscientific rule like that? Fruit importers John, George, and Frank Nix sued New York’s collector of customs taxes, Edward Hedden, to recover taxes he had levied on a shipment of tomatoes the Nixes had imported from the West Indies. Back then, imported fruits weren’t taxed, while vegetables were. In its decision, the Court acknowledged that tomatoes were technically fruits. But “in the common language of the people” the Court determined that tomatoes, as well as cucumbers, squashes, beans, and peas, “are vegetables which are grown in kitchen gardens” and are usually served at dinner with the main part of the meal and not as dessert.1

  I am not including potatoes and corn in the vegetable category, even though they are among the most popular “vegetables” in America (see “The Spud Is a Dud” on page 167). In your digestive system they act more like carbohydrates.

  FAMILY NUTRITION

  When studying the connection between fruits, vegetables, and health, it helps to talk about groups of plants. One of the most common classification schemes is by plant “family.” Those you usually find in the market or on the table include the following:

  • The crucifer family (Cruciferae) gets its name from the tiny cross you can see if you look at a recently sprouted seed. It includes a number of those vegetables that children (and some adults) instinctively but unwisely avoid—broccoli, Brussels sprouts, cabbage, cauliflower, collard greens, kale, kohlrabi, mustard greens, radishes, rutabaga, turnips, and watercress. Some members of the crucifer family are excellent sources of isothiocyanates, indoles, thiocyanates, and nitriles. These chemicals may protect against breast and some other types of cancer.

  • The melon/squash family (Cucurbitaceae) includes cucumbers, summer squashes such as pumpkin and zucchini, winter squashes such as acorn and butternut, cantaloupes, and honeydew melons.

  • The heath or heather family (Ericaceae) gives us cranberries, blueberries, lingonberries, and more. These fruits are particularly high in a flavonoid called anthocyanin, which may be linked to the prevention of diabetes,
heart disease, and dementia.

  • The legume family (Leguminosae) includes alfalfa sprouts, beans, peas, and soybeans. Legumes have plenty of fiber, folate, and substances called protease inhibitors, all of which may offer some protection against heart disease and cancer.

  • The lily family (Liliaceae) includes asparagus, chives, garlic, leeks, onions, and shallots. These vegetables contain a number of sulfur-containing compounds, especially allicin and diallyl sulfate, that may fight cancer.

  • The rose family (Rosaceae) includes almonds, apples, apricots, cherries, peaches, pears, plums, raspberries, and strawberries.

  • The citrus family (Rutaceae) encompasses grapefruits, lemons, limes, oranges, and tangerines. Citrus fruits are high in vitamin C and the carotenoid beta-cryptoxanthin and also contain the compounds limonene and coumarin, which have been shown to have anticancer properties in laboratory animals.

  • The solanum family (Solanaceae) is a diverse group that includes eggplant, peppers, potatoes, and tomatoes. Tomatoes contain high amounts of lycopene, a type of antioxidant that may play a key role in preventing prostate and other cancers.

  • The umbels (Umbelliferae) include carrots, celeriac, celery, parsley, and parsnips. Carrots are an excellent source of beta-carotene, which the body uses to make vitamin A. Strong evidence supports a benefit of beta-carotene and possibly the related compounds called carotenoids in maintaining memory into old age. Other studies suggest a possible role in preventing some cancers.

  While any one fruit or vegetable contains dozens, maybe hundreds, of different compounds that your body uses for something besides energy, no single fruit or vegetable contains all of the substances you need. That’s why it’s a good idea to get a few servings a week from each of these major groups.

  CHOOSE A RAINBOW OF FOODS

  It’s a good idea to eat for color variety as well. Painting your diet with the bold colors of ripe red tomatoes, crisp orange carrots, creamy yellow squash, emerald-green spinach, juicy blueberries, indigo plums, violet eggplants, and all shades in between not only makes meals more appealing but also ensures that you get a variety of beneficial phytonutrients.

  INADEQUATE GUIDANCE FROM THE USDA AND OTHERS

  Back in 1991, the National Cancer Institute launched its 5 A Day public health campaign. Through grocery store banners, labels on fruits and vegetables, public service announcements in the media, and educational materials for schoolchildren, it urged us to eat five or more servings of fruits and vegetables a day. This campaign was incorporated into early Dietary Guidelines for Americans as well as into guidelines from the American Heart Association, the American Cancer Society, the World Health Organization, and others. In 2007 it was replaced by a new campaign called Fruits & Veggies—More Matters.

  Presidential Passion for Olive Oil and Vegetables

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  Olive oil drizzled over roasted eggplant or grilled peppers conjures up images of Mediterranean cooking. Yet the use of olive oil is as all-American as the founding fathers. Here’s what Thomas Jefferson had to say about the olive tree and olive oil in a letter to William Drayton, a South Carolina lawyer, congressman, and planter: “The olive is a tree the least known in America, and yet the most worthy of being known. Of all the gifts of heaven to man, it is next to the most precious, if it be not the most precious. Perhaps it may claim a preference even to bread, because there is such an infinitude of vegetables which it renders a proper and comfortable nourishment.”

  Our third president knew something that cooks and chefs have rediscovered—that olive oil can perk up vegetables and other foods. Jefferson, a curious naturalist and ardent horticulturalist, repeatedly tried to cultivate olive trees in South Carolina and Georgia, but with little success. He ultimately had to rely on imported olive oil for his table. Little did he know that Spanish priests had brought olives to California in the late 1700s and that they would become a native source of olive oil for the country.

  The name of the new campaign, More Matters, gets to the heart of fruit and vegetable guidance. One thing it lacks is clear definitions about what qualifies in meeting the “More.” Two glasses of orange juice, an apple, an order of french fries at lunch, and a potato with dinner puts you well on the road to meeting its recommendation. While that’s better than no fruits and vegetables at all, it doesn’t offer the full dose of health benefits I describe here.

  The 2015–2020 Dietary Guidelines for Americans recommend eating a variety of vegetables from all of the subgroups: dark green, red and orange, and legumes (beans and peas). But they include potatoes and corn as vegetables, when the body recognizes them as starchy carbohydrates.

  NOT MEASURING UP

  Few of us take advantage of the incredible bounty of fruits and vegetables grown in this country and elsewhere. The average American relies on roughly a dozen fruits and vegetables. Daily consumption is just as limited, hovering around four servings a day, and that figure is vastly inflated by potatoes. A recent national survey showed that only 1 in 9 Americans gets the minimum recommended daily “dose” of five servings of fruits and vegetables a day.2 That limited consumption is a pity, given the clear-cut benefits of eating fruits and vegetables.

  FRUITS AND VEGETABLES PREVENT CARDIOVASCULAR DISEASE . . .

  A diet that includes plenty of fruits and vegetables can help control or even prevent high blood pressure and high cholesterol, two of the main precursors of heart disease and stroke. Even better, investing in a plant-rich diet pays off in terms of lower chances of developing several forms of heart disease and stroke.

  High blood pressure often sets the stage for stroke, heart attack, and other kinds of circulatory problems. High blood pressure, formally known as hypertension, affects more than 70 million Americans and a staggering 1 billion people worldwide.3 It’s increasingly common with age: under 10 percent of U.S. adults between the ages of twenty and thirty-four have high blood pressure, compared to more than 75 percent of those over age seventy-five. Up to 90 percent of Americans develop high blood pressure over their lifetimes. Sometimes called the silent killer, high blood pressure causes no real symptoms. That’s one reason at least one-third of people with it don’t know they have it. Of those who are well aware they have high blood pressure, many have a hard time keeping it under control.

  The effect on blood pressure of adding more fruits and vegetables to your diet, while not quite as huge as comes from exercise, is well worth the small effort. Among more than 185,000 men and women participating in the Nurses’ Health Studies and the Health Professionals Follow-Up Study, those who reported eating four or more servings of fruits and vegetables a day were about 7 percent less likely to have developed high blood pressure over a fifteen-year period than participants who reported eating four or fewer servings a week.4 Foods that appeared to be especially helpful included broccoli, carrots, tofu or soybeans, raisins, and apples.

  Other reviews and meta-analyses have shown that eating about thirty servings of fruits and vegetables a week (or just under five a day) was associated with a 30 percent lower risk of the most common type of stroke (ischemic stroke), the kind caused by a blood clot blocking an artery in, or to, the brain.5 My colleagues and I calculated that eating one extra serving of fruits or vegetables a day decreases the chances of having an ischemic stroke by about 6 percent. In that study, most of the benefit seemed to come from eating broccoli, spinach, kale, romaine lettuce, and citrus fruit or juice. Many nutrients in these foods contribute to the lower risk of stroke. One of them is folate, the plant form of folic acid (the terms are derived from the word “foliage”). Folic acid has been shown to reduce the risk of stroke when taken as a supplement too.6

  An innovative study called DASH, short for Dietary Approaches to Stop Hypertension, clearly showed that eating more fruits and vegetables can substantially lower blood pressure, especially as part of a diet low in animal fat.7 DASH wasn’t your garden-variety nutrition study but a full-blown clinical trial, much like those done to test a new dru
g. All 457 of the DASH participants—some with high blood pressure, some without—were randomly assigned to one of three diets: a control diet that mirrored the typical American diet (about three servings of fruits and vegetables a day, nearly 40 percent of calories from fat, and one dairy food daily); a fruit-and-vegetable diet similar to the control diet but with eight servings of fruits and vegetables a day; and a combination diet that included nine servings of fruits and vegetables a day plus three servings of low-fat dairy foods. The beauty of the DASH method was that all of the volunteers’ meals during the study were specially prepared in hospital kitchens, a strategy that minimized variation from person to person.

  After eight weeks, the combination diet (fruits and vegetables plus three servings of dairy) substantially lowered blood pressure among the volunteers who had high blood pressure. So did the fruit-and-vegetable diet, though not quite as much. For both experimental diets, the reductions were about as large as what drug therapy can do for mild high blood pressure. Both the combination diet and the fruit-and-vegetable diet also lowered blood pressure in people without hypertension, suggesting that this may be an easy, side effect–free way to prevent this condition. A second DASH trial showed that a low-salt version of the DASH diet can subtract a few extra points from blood pressure (see chapter eleven).

  Many components of the DASH diet contribute to its ability to lower blood pressure. A follow-up study showed that the single most important factor is the extra potassium provided by the fruits and vegetables.

  Cholesterol levels also seem to respond to a diet with plenty of fruits and vegetables. This may be one of the ways that fruits and vegetables reduce the risk of heart disease and stroke. No one knows for sure how fruits and vegetables lower cholesterol. Since eating more plant foods often means eating less meat and dairy products, lower cholesterol levels may come from eating less saturated fat. They could also be due to the ability of soluble fiber to block the absorption of cholesterol from food. In spite of what food companies are claiming, though, soluble fiber’s effect on cholesterol is relatively small.