THREE   MOSTLY PLANTS: WHAT TO EAT

If you can manage to just eat food most of the time, whatever that food is, you’ll probably be okay. One lesson that can be drawn from the striking diversity of traditional diets that people have lived on around the world is that it is possible to nourish ourselves from an astonishing range of different foods, so long as they are foods. There have been, and can be, healthy high-fat and healthy low-fat diets, so long as they’re built around whole foods rather than highly processed food products. Yet there are some whole foods that are better than others, and some ways of producing them and then combining them in meals that are worth attending to. So this section proposes a handful of personal policies regarding what to eat, above and beyond “food.”

EAT MOSTLY PLANTS, ESPECIALLY LEAVES. Scientists may disagree about what’s so good about eating plants—Is it the antioxidants in them? The fiber? The omega-3 fatty acids?—but they do agree that plants are probably really good for you, and certainly can’t hurt. In all my interviews with nutrition experts, the benefits of a plant-based diet provided the only point of universal consensus. Even nutrition scientists who have been chastened by decades of conflict and confusion about dietary advice would answer my question “So what are you still sure of?” with some variation on the recommendation to “eat more plants.” (Though Marion Nestle was slightly more circumspect: “Certainly eating plants isn’t harmful.”)

That plants are good for humans to eat probably doesn’t need much elaboration, but the story of vitamin C, an antioxidant we depend primarily on plants to supply us, points to the evolutionary reasons why this might have become the case. Way back in evolution, our ancestors possessed the biological ability to make vitamin C, an essential nutrient, from scratch. Like other antioxidants, vitamin C, or ascorbic acid, contributes to our health in at least two important ways. Several of the body’s routine processes, including cell metabolism and the defense mechanism of inflammation, produce “oxygen radicals”—atoms of oxygen with an extra unpaired electron that make them particularly eager to react with other molecules in ways that can create all kinds of trouble. Free radicals have been implicated in a great many health problems, including cancer and the various problems associated with aging. ( Free-radical production rises as you get older.) Antioxidants like vitamin C harmlessly absorb and stabilize these radicals before they can do their mischief.

But antioxidants do something else for us as well: They stimulate the liver to produce the enzymes necessary to break down the antioxidant itself, enzymes that, once produced, go on to break down other compounds as well, including whatever toxins happen to resemble the antioxidant. In this way antioxidants help detoxify dangerous chemicals, including carcinogens, and the more kinds of antioxidants in the diet, the more kinds of toxins the body can disarm. This is one reason why it’s important to eat as many different kinds of plants as possible: They all have different antioxidants and so help the body eliminate different kinds of toxins. (It stands to reason that the more toxins there are in the environment, the more plants you should be eating.)

Animals can synthesize some of their own antioxidants, including, once upon a time, vitamin C. But there was so much vitamin C in our ancestors’ plant-rich diet that over time we lost our ability to make the compound ourselves, perhaps because natural selection tends to dispense with anything superfluous that is metabolically expensive to produce. (The reason plants are such a rich source of antioxidants is that they need them to cope with all the pure oxygen produced during photosynthesis.) This was a happy development for the plants, of course, because it made humans utterly dependent upon them for an essential nutrient—which is why humans have been doing so much for the vitamin C producers ever since, spreading their genes and expanding their habitat. We sometimes think of sweetness as the linchpin of the reciprocal relationship between plants and people, but antioxidants like vitamin C play an equally important, if less perceptible, part.

So our biological dependence on plants goes back and runs deep, which makes it not at all surprising that eating them should be so good for us. There are literally scores of studies demonstrating that a diet rich in vegetables and fruits reduces the risk of dying from all the Western diseases. In countries where people eat a pound or more of fruits and vegetables a day, the rate of cancer is half what it is in the United States. We also know that vegetarians are less susceptible to most of the Western diseases, and as a consequence live longer than the rest of us. (Though near vegetarians—so-called flexitarians—are just as healthy as vegetarians.) Exactly why this should be so is not quite as clear as the fact that it is. The antioxidants in plants almost certainly are protective, but so may be the omega-3s (also essential nutrients that we can’t produce ourselves) and the fiber and still other plant components and synergies as yet unrecognized; as the whole-grain study suggests, plant foods are apt to be more than the sum of their nutrient parts.

But the advantages of a plant-based diet probably go beyond whatever is in the plants: Because plant foods—with the exception of seeds—are less energy dense than most of the other things you might eat, by eating a plant-based diet you will likely consume fewer calories (which is itself protective against many chronic diseases). The seed exception suggests why it’s important to eat more leaves than seeds; though unrefined seeds, including whole grains and nuts, can be very nutritious, they’re high in calories, befitting their biological role as energy-storage devices. It’s only when we begin refining plant seeds or eating them to the exclusion of the rest of the plant that we get into trouble.

So what about eating meat? Unlike plants, which we can’t live without, we don’t need to eat meat—with the exception of vitamin B₁₂, every nutrient found in meat can be obtained somewhere else. (And the tiny amount of B₁₂ we need is not too hard to come by; it’s found in all animal foods and is produced by bacteria, so you obtain B₁₂ from eating dirty or decaying or fermented produce.) But meat, which humans have been going to heroic lengths to obtain and have been relishing for a very long time, is nutritious food, supplying all the essential amino acids as well as many vitamins and minerals, and I haven’t found a compelling health reason to exclude it from the diet. (That’s not to say there aren’t good ethical or environmental reasons to do so.*)

That said, eating meat in the tremendous quantities we do (each American now consumes an average of two hundred pounds of meat a year) is probably not a good idea, especially when that meat comes from a highly industrialized food chain. Several studies point to the conclusion that the more meat there is in your diet—red meat especially—the greater your risk of heart disease and cancer. Yet studies of flexitarians suggest that small amounts of meat—less than one serving a day—don’t appear to increase one’s risk. Thomas Jefferson probably had the right idea when he recommended using meat more as a flavor principle than as a main course, treating it as a “condiment for the vegetables.”

What exactly it is in meat we need to worry about (the saturated fat? the type of iron? the carcinogens produced in curing and cooking it?) is unclear; the problem could be simply that eating lots of it pushes plants out of the diet. But eating too much industrial meat exposes us to more saturated fat, omega-6 fatty acids, growth hormones, and carcinogens than we probably want in our diet. Meat has both the advantages and disadvantages of being at the top of the food chain: It accumulates and concentrates many of the nutrients in the environment but also many of the toxins.

Meat offers a good proof of the proposition that the healthfulness of a food cannot be divorced from the health of the food chain that produced it—that the health of soil, plant, animal, and eater are all connected, for better or worse. Which suggests a special rule for people eating animal foods:

YOU ARE WHAT WHAT YOU EAT EATS TOO. That is, the diet of the animals we eat has a bearing on the nutritional quality, and healthfulness, of the food itself, whether it is meat or milk or eggs. This should be self-evident, yet it is a truth routinely overlooked by the industrial food chain in its quest to produce vast quantities of cheap animal protein. That quest has changed the diet of most of our food animals from plants to seeds, because animals grow faster and produce more milk and eggs on a high-energy diet of grain. But some of our food animals, such as cows and sheep, are ruminants that evolved to eat grass; if they eat too many seeds they become sick, which is why grain-fed cattle have to be given antibiotics. Even animals that do well on grain, such as chickens and pigs, are much healthier when they have access to green plants, and so, it turns out, are their meat and eggs.

For most of our food animals, a diet of grass means much healthier fats (more omega-3s and conjugated linoleic acid, or CLA; fewer omega-6s and saturated fat) in their meat, milk, and eggs, as well as appreciably higher levels of vitamins and antioxidants. Sometimes you can actually see the difference, as when butter is yellow or egg yolks bright orange: What you’re seeing is the beta-carotene from fresh green grass. It’s worth looking for pastured animal foods in the market and paying the premium they typically command. For though from the outside an industrial egg looks exactly like a pastured egg selling for several times as much, they are for all intents and purposes two completely different foods.* So the rule about eating more leaves and fewer seeds applies not only to us but also to the animals in our food chain.

IF YOU HAVE THE SPACE, BUY A FREEZER. When you find a good source of pastured meat, you’ll want to buy it in quantity. Buying meat in bulk—a quarter of a steer, say, or a whole hog—is one way to eat well on a budget. Dedicated freezers are surprisingly inexpensive to buy and to operate, because they don’t get opened nearly as often as the one attached to your refrigerator. A freezer will also encourage you to put up food from the farmers’ market, allowing you to buy produce in bulk when it is at the height of its season, which is when it will be most abundant and therefore cheapest. And freezing (unlike canning) does not significantly diminish the nutritional value of produce.

EAT LIKE AN OMNIVOR E. Whether or not you eat any animal foods, it’s a good idea to try to add some new species, and not just new foods, to your diet. The dazzling diversity of food products on offer in the supermarket is deceptive because so many of them are made from the same small handful of plants, and most of those—like the corn and soy and wheat—are seeds. The greater the diversity of species you eat, the more likely you are to cover all your nutritional bases.

But that is an argument from nutritionism, and there is a better one, one that takes a broader view of health. Biodiversity in the diet means more biodiversity in the fields. To shrink the monocultures that now feed us would mean farmers won’t need to spray as much pesticide or chemical fertilizer, which would mean healthier soils, healthier plants and animals, and in turn healthier people. Your health isn’t bordered by your body, and what’s good for the soil is probably good for you too. Which brings us to a related rule:

EAT WELL-GROWN FOOD FROM HEALTHY SOILS. It would have been much simpler to say “eat organic” because it is true that food certified organic is usually well grown in relatively healthy soils—soils that have been nourished by organic matter rather than synthetic fertilizers. Yet there are exceptional farmers and ranchers in America who for one reason or another are not certified organic and the food they grow should not be overlooked. Organic is important, but it’s not the last word on how to grow food well.

Also, the supermarket today is brimming with processed organic food products that are little better, at least from the standpoint of health, than their conventional counterparts. Organic Oreos are not a health food. When Coca-Cola begins selling organic Coke, as it surely will, the company will have struck a blow for the environment perhaps, but not for our health. Most consumers automatically assume that the word “organic” is synonymous with health, but it makes no difference to your insulin metabolism if the high-fructose corn syrup in your soda is organic.

Yet the superiority of real food grown in healthy soils seems clear. There is now a small but growing body of empirical research to support the hypothesis, first advanced by Sir Albert Howard and J. I. Rodale, that soils rich in organic matter produce more nutritious food. Recently a handful of well-controlled comparisons of crops grown organically and conventionally have found appreciably higher levels of antioxidants, flavonoids, vitamins, and other nutrients in several of the organic crops. Of course after a few days riding cross-country in a truck the nutritional quality of any kind of produce will deteriorate, so ideally you want to look for food that is both organic and local.

EAT WILD FOODS WHEN YOU CAN. Two of the most nutritious plants in the world are weeds—lamb’s quarters and purslane—and some of the healthiest traditional diets, such as the Mediterranean, make frequent use of wild greens. The fields and forests are crowded with plants containing higher levels of various phytochemicals than their domesticated cousins. Why? Because these plants have to defend themselves against pests and disease without any help from us, and because historically we’ve tended to select and breed crop plants for sweetness; many of the defensive compounds plants produce are bitter. Wild greens also tend to have higher levels of omega-3 fatty acids than their domesticated cousins, which have been selected to hold up longer after picking.

Wild animals too are worth adding to your diet when you have the opportunity. Wild game generally has less saturated fat and more omega-3 fatty acids than domesticated animals, because most of the wild animals we eat themselves eat a diverse diet of plants rather than grain. (The nutritional profile of grass-fed beef closely resembles that of wild game.) Wild fish generally have higher levels of omega-3s than farmed fish, which are often fed grain. To judge by the experience of fish-eating cultures like the Japanese, adding a few servings of wild fish to the diet each week may lower our risk of heart disease, prolong our lives, and even make us happier.*

Yet I hesitate to recommend eating wild foods because so many of them are endangered; many wild fish stocks are on the verge of collapse because of overfishing. Up to now, all the recommendations I’ve offered here pose no conflict between what’s best for your health and what’s best for the environment. Indeed, most of them support farming and ranching practices that improve the health of the land and the water. But not this one, sorry to say. There are not enough wild animals left for us all to be eating more of them (except perhaps deer and feral pigs), and certainly not enough wild fish. Fortunately, however, a few of the most nutritious fish species, including salmon, mackerel, sardines, and anchovies, are well managed and in some cases even abundant. Don’t overlook those oily little fish.

BE THE KIND OF PERSON WHO TAKES SUPPLEMENTS. We know that people who take supplements are generally healthier than the rest of us, and we also know that, in controlled studies, most of the supplements they take don’t appear to work. Probably the supplement takers are healthier for reasons having nothing to do with the pills: They’re typically more health conscious, better educated, and more affluent. So to the extent you can, be the kind of person who would take supplements, and then save your money.

That said, many of the nutrition experts I consulted recommend taking a multivitamin, especially as you get older. In theory at least, your diet should provide all the micronutrients you need to be healthy, especially if you’re eating real food and lots of plants. After all, we evolved to obtain whatever our bodies need from nature and wouldn’t be here if we couldn’t. But natural selection takes little interest in our health or survival after the childbearing years are past, and as we age our need for antioxidants increases while our bodies’ ability to absorb them from food declines. So it’s probably a good idea, and certainly can’t hurt, to take a multivitamin-and-mineral pill after age fifty. And if you don’t eat much fish, it might be wise to take a fish oil supplement too.

EAT MORE LIKE THE FRENCH. OR THE ITALIANS. OR THE JAPANESE. OR THE INDIANS. OR THE GREEKS. Confounding factors aside, people who eat according to the rules of a traditional food culture are generally much healthier than people eating a contemporary Western diet. This goes for the Japanese and other Asian diets as well as the traditional diets of Mexico, India, and the Mediterranean region, including France, Italy, and Greece. There may be exceptions to this rule—you do have to wonder about the Eastern European Jewish diet of my ancestors. Though who knows? Chicken and duck fat may turn out to be much healthier than scientists presently believe. (Weston Price certainly wouldn’t be surprised.) I’m inclined to think any traditional diet will do; if it wasn’t a healthy regimen, the diet and the people who followed it wouldn’t still be around.

There are of course two dimensions to a traditional diet—the foods a culture eats and how they eat them—and both may be equally important to our health. Let’s deal first with the content of traditional diets and save the form of it, or eating habits, for the next section.

In some respects, traditional diets resemble other vernacular creations of culture such as architecture. Through a long, incremental process of trial and error, cultures discover what works—how best to reconcile human needs with whatever nature has to offer us in a particular place. So the pitch of a roof reflects the amount of rain or snowfall in a particular region, growing steeper the greater the precipitation, and something like the spiciness of a cuisine reflects the local climate in another way. Eating spicy foods help people keep cool; many spices also have antimicrobial properties, which is important in warm climates where food is apt to spoil rapidly. And indeed researchers have found that the hotter a climate is, the more spices will be found in the local cuisine.

Of course cuisines are not only concerned with health or even biology; many culinary practices are arbitrary and possibly even maladaptive, like the polishing of rice. Cuisines can have purely cultural functions; they’re one of the ways a society expresses its identity and underscores its differences with other societies. (Religious food rules like kashruth or halal perform this function for, respectively, Jews and Muslims.) These cultural purposes might explain why cuisines tend to resist change; it is often said that the last place to look for signs of assimilation in an immigrant’s home is the pantry. Though as food psychologist Paul Rozin points out, the abiding “flavor principles” of a cuisine—whether lemon and olive oil in the Mediterranean, soy sauce and ginger in Asia, or even ketchup in America—make it easier for a culture to incorporate useful new foods that might otherwise taste unacceptably foreign.

Yet more than many other cultural practices, eating is deeply rooted in nature—in human biology on one side and in the natural world on the other. The specific combinations of foods in a cuisine and the ways they are prepared constitute a deep reservoir of accumulated wisdom about diet and health and place. Many traditional culinary practices are the products of a kind of biocultural evolution, the ingenuity of which modern science occasionally figures out long after the fact. In Latin America, corn is traditionally eaten with beans; each plant is deficient in an essential amino acid that happens to be abundant in the other, so together corn and beans form a balanced diet in the absence of meat. Similarly, corn in these countries is traditionally ground or soaked with limestone, which makes available a B vitamin in the corn, the absence of which would otherwise lead to the deficiency disease called pellagra. Very often when a society adopts a new food without the food culture surrounding it, as happened when corn first came to Europe, Africa, and Asia, people get sick. The context in which a food is eaten can be nearly as important as the food itself.

The ancient Asian practice of fermenting soybeans and eating soy in the form of curds called tofu makes a healthy diet from a plant that eaten almost any other way would make people ill. The soybean itself is a notably inauspicious staple food; it contains a whole assortment of “antinutrients”—compounds that actually block the body’s absorption of vitamins and minerals, interfere with the hormonal system, and prevent the body from breaking down the proteins in the soy itself. It took the food cultures of Asia to figure out how to turn this unpromising plant into a highly nutritious food. By boiling crushed soybeans in water to form a kind of milk and then precipitating the liquid by adding gypsum (calcium sulfate), cooks were able to form the soy into curds of highly digestible protein: tofu.

So how are these traditional methods of “food processing” different from newer kinds of food science? Only in that the traditional methods have stood the test of time, keeping people well nourished and healthy generation after generation. One of the hallmarks of a traditional diet is its essential conservatism. Traditions in food ways reflect long experience and often embody a nutritional logic that we shouldn’t heedlessly overturn. So consider this subclause to the rule about eating a traditional diet:

REGARD NONTRADITIONAL FOODS WITH SKEPTICISM. Innovation is interesting, but when it comes to something like food, it pays to approach novelties with caution. If diets are the product of an evolutionary process, then a novel food or culinary innovation resembles a mutation: It might represent a revolutionary improvement, but it probably doesn’t. It was really interesting when modernist architecture dispensed with the pitched roof; on the other hand, the flat roofs that replaced them tended to leak.

Soy again offers an interesting case in point. Americans are eating more soy products than ever before, thanks largely to the ingenuity of an industry eager to process and sell the vast amounts of subsidized soy coming off American and South American farms. But today we’re eating soy in ways Asian cultures with much longer experience of the plant would not recognize: “Soy protein isolate,” “soy isoflavones,” “textured vegetable protein” from soy and soy oils (which now account for a fifth of the calories in the American diet) are finding their way into thousands of processed foods, with the result that Americans now eat more soy than the Japanese or the Chinese do.

Yet there are questions about the implications of these novel food products for our health. Soy isoflavones, found in most soy products, are compounds that resemble estrogen, and in fact bind to human estrogen receptors. But it is unclear whether these so-called phytoestrogens actually behave like estrogen in the body or only fool it into thinking they’re estrogen. Either way the phytoestrogens might have an effect (good or bad) on the growth of certain cancers, the symptoms of menopause, and the function of the endocrine system. Because of these uncertainties, the FDA has declined to grant GRAS (“generally regarded as safe”) status to soy isoflavones used as a food additive. As a senior scientist at the FDA’s National Center for Toxicological Research wrote, “Confidence that soy products are safe is clearly based more on belief than hard data.” Until those data come in, I feel more comfortable eating soy prepared in the traditional Asian style than according to novel recipes developed by processors like Archer Daniels Midland.

DON’T LOOK FOR THE MAGIC BULLET IN THE TRADITIONAL DIET. In the same way that foods are more than the sum of their nutrient parts, dietary patterns seem to be more than the sum of the foods that comprise them. Oceans of ink have been spilled attempting to tease out and analyze the components of the Mediterranean diet, hoping to identify the X factor responsible for its healthfulness: Is it the olive oil? The fish? The wild greens? The garlic? The nuts? The French paradox too has been variously attributed to the salutary effects of red wine, olive oil, and even foie gras (liver is high in B vitamins and iron). Yet when researchers extract a single food from a diet of proven value, it usually fails to adequately explain why the people living on that diet live longer or have lower rates of heart disease or cancer than people eating a modern Western diet. The whole of a dietary pattern is evidently greater than the sum of its parts.

Some of these dietary parts flagrantly contradict current scientific thinking about healthy eating. By the standards of most official dietary guidelines, the French eat poorly: way too much saturated fat and wine. The Greeks too have their own paradox; defying the recommendation that we get no more than 30 percent of our calories from fats, they get 40 percent, most of it in the form of olive oil. So researchers begin looking for synergies between nutrients: Might the antioxidants in the red wine help metabolize the fats? Perhaps. But it seems unlikely that any single food, nutrient, or mechanism will ever explain the French paradox; more likely, we will someday come to realize there never was a paradox. Dietary paradoxes are best thought of as breakdowns in nutritionist thinking, a sign of something wrong with the scientific consensus rather than the diet in question.

But the quest to pin down the X factor in the diets of healthy populations (PubMed, a scholarly index to scientific articles on medicine, lists 257 entries under “French Paradox” and another 828 under “Mediterranean Diet”) goes on, because reductionist science is understandably curious and nutritionism demands it. If the secret ingredient could be identified, then processed foods could be reengineered to contain more of it, and we could go on eating much as before. The only way to profit from the wisdom of traditional diets (aside from writing books about them) is to break them down using reductionist science and then sell them for their nutrient parts.

In recent years a less reductive method of doing nutritional science has emerged, based on the idea of studying whole dietary patterns instead of individual foods or nutrients. The early results have tended to support the idea that traditional diets do indeed protect us from chronic disease and that these diets can be transferred from one place and population to another. Even some of the researchers associated with the Nurses’ Health Study have begun doing dietary pattern analysis, in one case comparing a prudent diet modeled on Mediterranean and Asian patterns—high in fruits, vegetables, and fish and low in red meat and dairy products—with a typical Western diet featuring lots of meat (and processed meat), refined grains, sugary foods, french fries, and dairy products. (The study found “strong evidence” that the prudent dietary pattern may reduce the risk of coronary heart disease.)* Another recent study of a traditional plant-based diet found that even when you tested it against a low-fat Western diet that contained the same proportions of total fat, saturated fat, protein, carbohydrates, and cholesterol, the people on the traditional diet did much better by an important measure of cardiovascular health. What this suggests is that the addition of certain foods to the diet (Vegetables and fruits? Whole grains? Garlic?) may be more important than the subtraction of the usual nutritional suspects.*

As the authors of the first study point out, the strength of such an approach is that “it more closely parallels the real world” in that “it can take into account complicated interactions among nutrients and non-nutrient substances in studies of free-living people.” The weakness of such an approach is that “it cannot be specific about the particular nutrients responsible” for whatever health effects have been observed. Of course, this is a weakness only from the perspective of nutritionism. The inability to pin down the key nutrient matters much more to the scientist (and the food industry) than it does to us “free-living” eaters in the real world.

HAVE A GLASS OF WINE WITH DINNER. Wine may not be the X factor in the French or Mediterranean diet, but it does seem to be an integral part of those dietary patterns. There is now abundant scientific evidence for the health benefits of alcohol to go with a few centuries of traditional belief and anecdotal evidence. Mindful of the social and health effects of alcoholism, public health authorities are loath to recommend drinking, but the fact is that people who drink moderately and regularly live longer and suffer considerably less heart disease than teetotalers. Alcohol of any kind appears to reduce the risk of heart disease, but the polyphenols in red wine (resveratrol in particular) appear to have unique protective qualities. The benefits to your heart increase with the amount of alcohol consumed up to about four drinks a day (depending on your size), yet drinking that much increases your risk of dying from other causes (including certain cancers and accidents), so most experts recommend no more than two drinks a day for men, one for women. The health benefits of alcohol may depend as much on the pattern of drinking as on the amount: Drinking a little every day is better than drinking a lot on the weekends, and drinking with food is better than drinking without it. (Food blunts some of the deleterious effects of alcohol by slowing its absorption.) Also, a diet particularly rich in plant foods, as the French and Mediterranean diets are, supplies precisely the B vitamins that drinking alcohol depletes. How fortunate! Someday science may comprehend all the complex synergies at work in a traditional diet that includes wine, but until then we can marvel at its accumulated wisdom—and raise a glass to paradox.