Conventional wisdom tells us that the best places to look for the protein we need to build firm, lean muscles, strong bones, and healthy hair and nails are in the meat and dairy departments of our grocery store. Meat, poultry, seafood, eggs, milk, yogurt and cheese all deliver a wealth of protein and flavor. But a diet rich in animal protein can also carry some risks, so health-conscious folks often find themselves limiting their meat and dairy intake while worrying about where they’re going to get their protein. Well, they need look no further than the produce section.
Don’t believe you can build a strong, lean, well-muscled body on a plant-based diet? Next time you’re at the zoo, check out the giraffes. You’ll see them eating leaves, not steak. Plants can provide us, too, with more than enough protein to stay healthy and strong. That’s because our bodies can absorb protein from veggies, legumes, whole grains and nuts just as easily — and often more easily — than they can from animal sources.
Now, no one is saying that this means we should all turn vegetarian overnight. But the fact is, most Americans eat way more animal-based foods than are good for us. So it’s helpful to know that we can get the same 22 amino acids our bodies need to manufacture proteins, whether we’re eating a meatball sandwich or a tempeh stir-fry.
The best part is, a diet rich in plant-based protein not only delivers more nutrients and fiber per calorie, it can also reduce our risk of developing a number of diseases and chronic health conditions.
Protein Is Protein
Your body doesn’t really care whether you’ve eaten a cheeseburger or a bowl of chickpea stew — at least as it pertains to its protein sources. “For 20 years, we thought animal protein was more usable than plant protein, but that thinking was based on rat studies, and the human trials show otherwise,” says Jeffrey Bland, PhD, cofounder of the Institute for Functional Medicine in Gig Harbor, Wash., and former director of the Nutritional Supplement Analysis Laboratory at the Linus Pauling Institute of Science and Medicine (now the Linus Pauling Institute at Oregon State University in Corvallis).
Simply put, the body breaks down all proteins into their amino acid building blocks, which it then shuffles around and reassembles into everything from fingernails to hormones.
“Your body can use amino acids from anywhere — methionine is methionine no matter if it came from chicken or soy,” says Amy Lanou, PhD, senior nutrition scientist for the Washington, D.C.–based Physicians Committee for Responsible Medicine. But how quickly it can access that methionine, or any other essential amino acid, varies depending on the other components of the protein and how it’s prepared. For instance, the high-fat content in most animal protein slows its digestion. And if, by chance, you did not thoroughly chew your well-done porterhouse, it will take even longer.
While it does take your body more time to access animal proteins, they do contain all the essential amino acids in one place — an argument frequently used to champion the consumption of meat and dairy products. Among plant-protein sources, only soy can make the same claim. But recent research indicates that these “complete proteins” are by no means essential to good health.
“We used to think that the body needed to ingest all of the amino acids simultaneously in order to use them, but that is not the case,” Bland says. If you eat an array of plant protein during the course of a day — say oatmeal at breakfast, lentils at lunch and leafy greens at dinner — you should have no problem getting all nine essential amino acids. Your body can pull them together to make all the enzymes, hair and muscle it needs.
The Whole Package
A day’s worth of plant proteins also provides your body with a host of nutrients that animal products simply don’t contain. “Plants are filled with antioxidant and anti-stress phytochemicals such as flavonoids and carotenoids,” says Bland. “Animal protein has none.”
It is this nutritional package that makes plant proteins a healthier choice. Vegetables, beans, nuts and whole grains are packed with these disease-fighting nutrients (flavonoids, for instance, can help prevent cancer and heart disease; carotenoids can boost the immune system). They’re also packed with necessary fiber — something else animal protein lacks. “Most Americans are not even coming close to the recommended daily intake of 14 grams of fiber per 1,000 calories,” says Lanou. Lack of fiber has been associated with everything from mild constipation to colon cancer.
As a rule, plant protein also contains less saturated fat, which has been linked to high cholesterol, heart disease and high blood pressure, among other conditions. For example, a single 6-ounce porterhouse steak boasts a whopping 38 grams of complete protein, but it also contains nearly 44 grams of fat, 16 of them saturated. In contrast, a cup of cooked lentils has 18 grams of protein, but less than 1 gram of fat.
“We have also found that plant proteins contain higher levels of the amino acid arginine, which actually stimulates the body to make less cholesterol,” says Bland. In other words, switching to plant-based protein sources could reduce your cholesterol in multiple ways.
Too Much of a Good Thing?
Despite the popularity of low-carb, high-protein diet plans, getting enough protein should be the least of our nutritional worries. “Americans are having a love affair with protein,” says Lanou. “The average American eats nearly two times the protein needed by the body.” (For the record, the U.S. government’s recommended daily intake of protein is about 1 gram per kilogram of body weight. For the average person, that ratio translates into approximately 70 grams of protein per day — about 280 calories worth.)
While it’s true that protein is critical for building cells, muscles, hormones and enzymes, too much of a good thing is not healthy. Excess protein is stored as fat in the body, and numerous studies indicate that excess animal protein can be linked to kidney stones, diabetes, osteoporosis, high blood pressure and a number of cancers, including breast, colon and stomach. Plant protein, on the other hand, does not produce similar risks — even when eaten in excess.
Vegans, however, should be aware that by avoiding dairy products, as well as meat, they could be missing certain vital nutrients. “Proteinwise, there does not appear to be any missing [amino acids] if a vegetarian is obtaining an adequate amount of plant protein based on their unique needs,” says Kathie Swift, MS, RD, nutrition director for UltraWellness, an integrative wellness center in Lenox, Mass. However, she adds, “If you are vegan or considering embarking on this nutritional path, you should be aware there are some ‘conditionally essential nutrients’ [you may miss out on], including B12, omega-3 fatty acids and vitamin D.”
Fortunately, she notes, vegans can easily capture these nutrients with the appropriate nutritional supplements.
Making the Switch
Even if you are not eager to completely bypass ham or sidestep steak, there are other good reasons to consider reducing your intake of meat, fish and dairy, and getting more of your protein from plants. For example, processed meats such as bacon, sausage and lunchmeats have been linked to higher rates of stomach and prostate cancer. Dairy products have been connected to everything from prostate cancer to Parkinson’s disease. And certain species of fish, including tuna, are increasingly found to contain unsafe levels of mercury.
When revising your grocery-shopping list and perusing the produce section, you can be sure that most plant foods contain some protein, but add beans, quinoa, lentils and leafy greens to your shopping list and you’ll be in good shape. “Greens like spinach are actually 49 percent protein calories — so eat big salads,” says Lanou.
Of course, one cannot survive on salad alone (see “Get Your Plants In,” below). Accents of seeds, nuts and soy foods are also great ways to add protein, minerals and fiber to your diet.
“Soy has become quite controversial as of late,” says Bland. “I have looked at the data and I strongly believe that a few servings of correctly prepared soy foods a week is healthy for most people.” That means avoiding super-processed soy foods like soy bacon, imitation lunchmeats and soy bars, and choosing organic, unprocessed tofu, tempeh and edamame, instead.
Face it, you’ve got nothing to lose by replacing some of the animal protein in your diet with plant sources — except for a few disease risk factors, that is. And it doesn’t have to be complicated: Just choose veggie chili over chicken or tempeh tacos over tenderloin from time to time. Or simply serve smaller servings of meats, larger servings of veggies. You will be healthier for it.
Linda Knittel is a nutritional anthropologist and freelance writer in Portland, Ore.