Sharon Palmer, RDN

Eat more plants.  That’s the simple advice coming from everyone’s lips, from best-selling authors like Michael Pollan to the U.S. Department of Agriculture in the latest version of the Dietary Guidelines for Americans.  For the first time, the nutrition establishment, including the Academy of Nutrition and Dietetics and registered dietitians, researchers, and academics in the field of nutrition are in agreement that the diet prescription for optimal health and well-being is one that focuses on whole plants.  Scientific research is accumulating on the health benefits of a plant-based eating style, which include the reduced risk of cardiovascular disease, diabetes, Alzheimer’s disease, cancer, and obesity.  Throw in the environmental benefits, such as fewer resources required to produce food, and a plant-based diet seems like the clear winner in the race for defining the optimal diet for today, as well as the future.

Plant-based Eating on the Rise

Plant-based diets, such as veganism, have grown in popularity, thanks to the attention from stars like Oprah, who requested her entire staff to go vegan for one week on her television show last year; Alicia Silverstone, actress, vegan and author of The Kind Diet; and Ellen Degeneres, the popular talk show host who enthusiastically supports a vegan diet.  Yet, plant-based diets are very personal and unique, covering a wide range of dietary preferences and observances.  The definition of a plant-based diet is one that focuses on plants, which leaves room for a spectrum of choices, including vegan (no animal foods), lacto-ovo vegetarian (no animal flesh, but allows for dairy and eggs), pescatarian (no animal flesh, except for fish and seafood), and semi-vegetarian (small amounts of animal foods).  Adding to the mix is today’s generation of plant-based omnivores—those that are not interested in giving up animal foods completely, but recognize the health and environmental advantages of reducing their animal food intake.

You can thank the Meatless Monday program for fueling the idea that everyone—not just vegetarians—should eat less meat and more plants.  Their message is sweet and simple:  You and the planet can benefit by eating less meat, so just shun it one day a week.  Why not Monday? Countless organizations, restaurants, schools, and hospitals have jumped onto the Meatless Monday bandwagon to celebrate this simple concept.  While the number of vegans and vegetarians is still relatively low—about 5% of U.S. adults are vegetarians, and about half of those are vegans—16% now report eating no animal flesh at more than half of their meals, according to a recent Vegetarian Resource Group poll.

Plants Provide Optimal Health for Humans

Getting back to our roots by eating more whole plants in their natural form has a multitude of benefits for humans.  Since the beginning of time, we’ve enjoyed a unique relationship with the plants that surrounded us.  From the first time our early ancestors plucked wild seeds, grasses, herbs, grains, and fruits and saved them in pouches for the future, they realized that these powerful plants had the ability to nourish and sustain them.  Just like humans evolved over time to better suit their environment and survive threats, so did plants.  These remarkable, living plants built up defenses against forms of pestilence, such as the harmful effects of UV radiation, disease, and predators.  Plants developed thousands of phytochemicals, such as flavonoids and phenols, often concentrating them in the colorful outer skins of their fruits.  These compounds provided a self-defense system that ensured the species survived the test of time.  Today, scientists know that we have a symbiotic relationship with the plants that nurtured us over the melenia. We plucked their fruits, feasted on their nourishing properties, and spit out their seeds, thus helping the plant to propagate and survive.  This simple act helped to ensure the survival of both humans and plants, but we got something else in the bargain besides sheer calories to fuel our bodies.  All of those defensive compounds in the plants seem to confer similar properties to humans when they eat them.

It’s only been in the last few decades that scientists have begun to understand how the thousands of bioactive compounds found in plants, from resveratrol in grape skins to anthocyanins in blueberries, protect health.  These compounds, which are often the pigment responsible for the plant’s brilliant color, offer a range of antioxidant, anti-inflammatory, and unique therapeutic benefits.   Both oxidative stress, the damaging effects of free radicals on body cells, and chronic inflammation, when the body’s natural defense mechanism is triggered and doesn’t “shut off”, are at the root of today’s modern day chronic disease killers, such as cancer and heart disease.  Indeed, study after study has linked consuming plant foods—rich in antioxidant and anti-inflammatory properties—with lower disease risk.  And beyond that, particular plants and plant compounds have special activities.  For example, lutein and zeaxanthin found in yellow and orange vegetables like corn and orange peppers protect against advanced macular degeneration, the number one cause of age-related blindness in older people.  And tomatoes, rich in the ruby red pigment lycopene, show promise in the prevention of prostate cancer.

It’s important to note that the benefits found in plant foods are related to eating the whole food in its unique, complex form—fiber, vitamins, minerals, phytochemicals, and all.  A synergy is found among all of these nutrients in plant foods; when the nutrients are isolated and consumed individually in the form of a supplement, we don’t gain the same benefits.  Something special happens when we eat the plant food in its whole form, whether we chew a kernel of whole grain with its bran coating, endosperm and germ, or bite into a fresh strawberry and savor its skin, flesh, juice and seeds.  Unfortunately, our diets have grown distant from the whole plant foods that sustained us; today we often feast on processed foods that are unrecognizable from their plant origins.  The health benefits found in a plant-based diet are not attached to a diet filled with such refined, carbohydrates such as sugars, oils, and white flour—all technically plant foods.

Most traditional diets around the world, from the Mediterranean to Asia to South America, are based on plants.  In many less developed countries, where people still eat their traditional, plant-based diets, chronic disease rates are very low.  But when people move away from these countries to the U.S. and switch to a Western diet, characterized with the inclusion of large amounts of meat, saturated fat, processed foods, and salt and low amounts of whole plant foods, they begin to experience a surge in chronic disease rates.  This has been observed in many populations; probably never as famously as in the Pima Indians of Mexico, who enjoy very low rates of obesity and diabetes in their native environment, but once the Pimas leave their homeland for the U.S. and consume a Western diet, they are rewarded with obesity and one of the highest rates of type 2 diabetes in the world.

Our Meat Lover’s Society

Americans love their meat; a large steak sizzling on the barbeque is practically a national icon.  The problem is the size of that steak has swelled over the years, according to surveys.  Many steakhouse menus proudly offer a 16-ounce cut—a full pound of meat—and call their 8-ounce portion the “petite” serving.  This oversized attitude toward meat also pervades American home-style cooking, where we plan our meals based on what animal protein will star at the center of the plate.  An 8-ounce steak may be an ordinary dinner in America, but it’s considered obscene in many parts of the world, where it would be the appropriate amount to feed an entire family for a meal or even a week.  According to the National Cancer Institute, the U.S. consumes meat at more than three times the global average.

Our meat obsession wasn’t always so grand—the last century was marked with periods of economic hardship and food scarcity during which meat was considered precious.  A small piece went into a pot of soup or beans for flavor and the best cut was reserved for Sunday dinners.  Meat consumption has most assuredly risen over the years—it’s doubled between 1909 and 2007.  Across the world, meat consumption is typically an indicator of economic wealth: As income levels rise, so does meat consumption.  Despite a current shift toward higher poultry consumption in the U.S., red meat—including beef, veal, pork, and lamb—is still the clear winner, representing 58% of the meat we consume.  Americans are eating on average eight ounces of meat per person every day.

So, what’s the big problem with eating so much meat?  Several well-designed studies indicate that a high-meat diet—especially red meat and processed meat, such as bacon and hot dogs—is likely to cause health problems down the road, such as the increased risk of heart disease, type 2 diabetes, certain types of cancer, and metabolic syndrome—the clustering of several risk factors that put you at high risk for type 2 diabetes and heart disease (Circulation, 2010; American Journal of Clinical Nutrition, 2009; PLoS Med, 2007).  The negative effects of this type of diet could be caused in part by the presence of carcinogenic compounds in cooked and processed meats and by the absence of health-protective plants in this style of eating.  In fact, researchers from the National Cancer Institute report that, given the plausible scientific evidence linking red and processed meats to cancer and chronic disease risk, it might be time for health experts to start working on bringing our levels of meat intake down.

At the same time, research supports a number of bonuses from taking on a vegetarian diet.  In a position paper published by the Academy of Nutrition and Dietetics, in which an independent and systematic review of all the research on vegetarian-based diets was evaluated, the organization concluded that well-planned vegetarian diets are completely healthful and nutritionally adequate for people throughout all stages of life and that they have a number of health advantages, including lower blood cholesterol levels, lower risk of heart disease, lower blood pressure levels, and lower risk of hypertension and type 2 diabetes.  In addition, vegetarians tend to have a lower body weight and lower overall cancer rates, lower intakes of saturated fat and cholesterol, and higher levels of dietary fiber, magnesium, potassium, vitamins C and E, folate, carotenoids, flavonoids, and other phytochemicals.

A Healthier Diet for the Planet

There’s no doubt that our human ancestry withstood the test of time thanks to its hunter-gatherer traditions.  While we typically conjure up images of cavemen brandishing hand-crafted spears in pursuit of wild beasts, archaeologists like to remind us that early humans were probably prey more often than predator.  Plants were a much safer source of nourishment and early humans gathered an abundance of plant materials along their pursuit for survival.  Our early ancestors certainly relied upon animal foods such as game, fowl, and fish to supplement their plant food diets, but today’s world is vastly different.  The animal foods they consumed were wild, lean and rich in omega-3 fatty acids, but today’s meat supply is based on a modern system of confined animal feeding operations.  In a CAFO, animals are pressed together so tightly they can barely move, where they will live short, miserable lives, caked in manure and fed a grain diet laced with antibiotics they were never meant to eat—all for the purpose of providing cheap meat to the masses.

Today, we consume billions of pounds of animal products, contributing to inhumane animal practices and the use of large amounts of chemical pesticides and fertilizers to produce animal feed, as well as large volumes of water and fuel to take animals to market.  Byproducts of animal food production include greenhouse gas emissions, toxic manure lagoons, deforestation, and pollution of groundwater, rivers, streams, and oceans.

You can make a serious impact on your carbon footprint by eating fewer animal foods, according to several studies.  Italian researchers performed a life-cycle assessment to evaluate the cradle-to-grave environmental impact of several dietary patterns (European Journal of Clinical Nutrition, 2006.)  They discovered that an organic vegan diet had the smallest environmental impact, while a conventionally farmed diet that included meat had the greatest impact on the environment—and the more meat consumed, the greater the eco-impact.  Additionally, beef was the food with the single greatest impact on the environment; other high-impacting foods included cheese, fish and milk.  In essence, animals make inefficient “food production machines,” using up lots of feed, water, and fossil fuels to turn plants into protein, said the scientists.  To produce 1 calorie from beef requires 40 calories of fossil fuels, whereas producing 1 calorie from grains requires only 2.2 calories of fuel.  Thus, plant-based diets can play an important role in preserving environmental resources and in reducing hunger in poor nations.

According to a recent analysis conducted by CleanMetrics for the public advocacy organization Environmental Working Group, greenhouse gas emissions generated by conventionally raising lamb, beef, cheese, pork, and farmed salmon—from growing the animals’ food to disposing of the unused food—far exceed those from other food choices like lentils and beans.  EWG found that eating less meat can significantly reduce your carbon footprint.  If you ate one less burger a week for a year; it would be the equivalent of driving 320 miles less.  And if your four-person family took steak off the menu one day a week for a year, it’s like taking your car off the road for almost three months.  If everyone in the U.S. ate no meat or cheese for just one day a week, it would be like taking 7.6 million cars off the road.

Sure, our country is facing runaway obesity rates, but keep in mind that one billion people around the world don’t even have enough food to eat—a fact that will become even tougher to deal with in 2050, when nine billion people will fill the planet.  Let’s face it:  Our current agricultural practices and diet patterns are unsustainable.  But environmental experts agree on one important principal that could increase the world sustainability of food for the long haul: Growing animal feed on prime croplands, no matter how efficiently, is a drain on the human food supply.  Dedicating croplands to direct human food production could boost calories produced per person by nearly 50%, according to a recent report from researchers from Canada, the United States, Sweden, and Germany (Nature, 2011).

When you put the evidence altogether, the argument is quite compelling.  While our dietary past focused on balancing a plate with animal protein at its center, today’s plate should be focused on a variety of whole plant foods—whole grains, beans, lentils, peas, nuts, seeds, vegetables, and fruits.  This diet paradigm should help ensure the health of both humans and the planet for years to come.

Sharon is an award-winning nutrition expert and author of The Plant-Powered Diet and Plant-Powered for Life (The Experiment). She also serves as editor of Environmental Nutrition, writes for her blog The Plant-Powered Blog, and is a judge for the James Beard Awards. Living in the chaparral hills overlooking Los Angeles with her family, she speaks on plant-based nutrition frequently.

Author: Sharon Palmer