All About Protein

Learn how to choose the best sources of this essential nutrient, including the ABCs of healthful proteins.

farm fresh eggs

Choose humanely produced eggs from chickens or ducks to get the highest nutritional benefit.

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Protein is one of the most essential building blocks of our bodies: Every cell in the human body contains proteins, and our bones, muscles, skin and hair are all made of this essential nutrient. When we eat foods containing proteins, our digestive systems break them down into amino acids that promote cell growth and healing. Our bodies also use proteins to produce hormones, enzymes and other body chemicals.

Like all nutrients, proteins are just one component of a balanced, healthful diet. Eating too much protein over time may cause weight gain and reduced liver function, while a protein deficiency can cause muscle wasting, weakness and, in extreme cases, even death. This guide deciphers nutritional, quality and environmental considerations for a variety of high-protein foods, so you can make the best choices for you and your family.

Protein and Diet

Unlike fats and carbohydrates, protein isn’t stored in our bodies, so we need regular replenishment. The Institute of Medicine recommends a minimum daily intake for adults of 8 grams of protein for every 20 pounds of body weight; that’s 60 grams of protein daily for a 150-pound person. Because protein-rich foods take longer to digest than carbohydrates, eating them can help with weight management by making us feel full longer and curbing the urge to snack between meals.

Animal-based foods certainly offer high levels of protein, yet debate surrounds several issues including animal treatment and meat’s effects on our health. In the past, doctors and nutritionists have recommended limiting our intake of meats and dairy products that contain high levels of saturated fats and cholesterol, as it was believed these types of fat were tied to an increased risk of coronary heart disease. Yet in recent years, research has determined that saturated fat isn’t as bad for us as we once thought. In fact, the Dietary Guidelines Advisory Committee, the nation’s official dietary guidelines panel, and the American Heart Association have both recently backed away from strict dietary restriction of saturated fats, urging instead that Americans drastically reduce sugar intake and eliminate intake of unhealthful trans fats, formed when liquid vegetable oils are hydrogenated (processed to remain solid at room temperature).

Despite these changes, eating a healthful, meat-centric diet requires consideration of a variety of factors, which we’ll discuss in detail later in this article. The best tactic for an overall healthful diet seems to be one that is well-rounded, and that includes a wide range of sources for various nutrients, including protein. Fortunately, many plants offer rich supplies of protein. Whether you’re carnivore or vegan, for optimal health choose organic, minimally processed protein foods and include plant-based proteins in your diet.

Go Local: Finding a local producer is almost always the best way to get the healthiest, most nutritious food. Find local producers of meat, eggs, milk, produce and more at your farmers market, or by visiting Local Harvest or Eat Wild.

Animal-Based Proteins

Red Meat

Both beef and pork are excellent protein sources and offer additional nutrition, including iron, B12, zinc and creatine. Beef averages 7.5 to 9 grams of protein per ounce and pork provides about 8 grams an ounce. Yet controversy surrounds red meat’s relationship to our health. Although some studies have found correlations between diets high in red meat and an increased risk in coronary heart disease, cancer and overall death, few (if any) randomized controlled studies have been conducted. Observational studies can only prove a correlation, and those who eat a diet high in red meat are often less health-conscious in general and also consume more sugar, overall calories and processed foods; are more likely to smoke; and exercise less.

In other studies, negative health effects have been associated with processed red meats—lunch meats, bacon and sausage, for example—but not with relatively unprocessed red meats such as lamb, beef, pork and others. Still more studies have found that negative health effects may be linked with common methods of preparation of red meat: Cooking meat over high heat can form cancer-causing compounds. And finally, research has determined that the way meat is raised affects its overall nutrition profile, with grass-fed and pasture-raised meat products containing higher levels of nutrients and healthful omega fats than their factory-farmed counterparts. As you can see, the effects of eating red meat on health are complex and comprise a number of factors.

Most red meat in the U.S. is raised in a factory farm setting. Profit and pricing pressures have led to concentrated animal feeding operations (CAFOs) such as feedlots and crowded warehouses. These production methods often necessitate the overuse of antibiotics, as diseases such as salmonella and E. coli may be fostered in such conditions.

USDA organic meats are raised without nontherapeutic antibiotics, pesticides or synthetic fertilizers. Grass-fed beef and pastured pork is produced from animals with continuous access to grass and forage during the growing season and not fed grain. Organic meat is not necessarily pastured and vice versa, but both methods represent a step toward raising healthier animals. Processed meats such as nonorganic hot dogs and lunch meats present unique health concerns as chemicals used in their production—for example, sodium nitrite—may be linked to certain cancers.

A+ Choice: Choose grass-fed beef and pastured pork. Look for unprocessed and certified organic meats, or buy from a local farmer you trust.


Chicken is an excellent source of protein—a cup of chicken meat provides about 35 grams of protein. Lean turkey is another good protein source, with 13 grams of protein in a 3-ounce serving. Duck, goose, Cornish game hen and other less-common poultry have similar average protein levels.

Unfortunately, finding healthily and humanely raised chicken can be daunting. Because chicken is produced on such a large scale, even USDA organic chickens may be subject to inhumane practices such as debeaking, the practice of cutting off a portion of chicks’ beaks in order to prevent cannibalistic behaviors that can occur when birds are raised in cramped quarters. (Find out how to help support humane treatment of farm animals.) Current organic standards also don’t address the issue of density, so chickens raised for organic meat can still be held in overcrowded warehouses. Some raising practices can affect the meat’s nutrition—for example, meat from birds fed animal byproducts grow faster but also produce excess fat. Poor raising conditions also increase the presence of pathogens such as salmonella and E. coli, thereby precipitating the need for the use of antibiotics and chlorine in the raising and processing of chickens. The best way to choose chicken that’s been raised well is to learn about its producer, whether by buying directly from farms or by researching brands and their chicken-raising practices.

A recent study by Consumer Reports revealed that most packaged grocery store chicken (both organic and conventional) harbored potentially harmful bacteria. To avoid contamination, always wash chicken thoroughly before cooking. Don’t let raw chicken or its juices come in contact with any other foods, and cook chicken to at least 165 degrees to kill any bacteria present.

A+ Choice: Your best bet is to buy directly from a farmer who provides birds a humane environment, including access to the outdoors, fresh vegetation to forage in for greens and insects, and room to run. At the supermarket, look for organic, pasture- raised poultry. You might also find products Certified Humane by the Humane Farm Animal Care association.

Go Wild: Because animals in the wild tend to be more active than their domesticated counterparts, wild game meats tend to be lower in calories and saturated fats. They’re also not subject to the use of medications and animal-treatment concerns of factory farming. Note that in corn and soy country, wild deer may likely contain Roundup and other pesticide residues.


Most fish are rich in protein; a 3-ounce serving of salmon, for instance, provides 23 grams of protein. Fatty fish varieties are especially high in heart-healthy omega-3 fatty acids, and studies suggest eating a 3-ounce serving of fatty fish twice a week can reduce risk of dying from heart disease by 36 percent. The health benefits of eating fish are complicated, however, by the fact that many types have elevated levels of pollutants such as mercury, dioxins, pesticide residues and polychlorinated biphenyls (PCBs)—their bodies accumulate these toxins after pollutants settle in waterways. The Environmental Working Group’s Consumer Guide to Seafood provides up-to-date information about seafood toxicity levels.

Seafood also warrants environmental concerns. Some species are endangered due to overfishing, or are caught or farmed in ways that harm other marine life or the environment. The Monterey Bay Aquarium’s website, Seafood Watch (including a smartphone app by the same name), can help you make eco-conscious buying decisions.

A+ Choice: Buy seafood from a knowledgeable dealer dedicated to sustainable practices, and ask questions. Cross-reference sustainable choices with toxicity levels; for example, Alaskan salmon, Alaskan sablefish and Pacific sardines all contain lower contaminant levels and are rated “Best Choice” by Seafood Watch.


Chicken eggs are a good source of protein, with 6 grams in an average large egg. Deciding which eggs to buy can be confusing, though. Typical supermarket choices range from factory-farmed white eggs (usually the least expensive) to natural, cage-free, free-range, omega-3, pasteurized eggs and more.

Although conventional brown eggs are sometimes priced higher, they’re virtually identical to white eggs except in color. “Natural” is a largely unregulated term, while “cage-free” can still mean chickens are raised in overcrowded warehouses. “Free-range” only means chickens have access to the outdoors—a definition subject to wide variances of interpretation. Omega-3-enhanced eggs are laid by chickens that have been fed dietary supplements, and pasteurized eggs are heated to reduce the risk of some food-borne illnesses associated with raw eggs.

Certified organic eggs might seem like the best choice, but many USDA-certified organic eggs are actually produced by large agribusiness companies using controversial practices, including debeaking and forced molting (starving birds to induce molting and another round of egg laying) to increase production.

A+ Choice: To ensure your eggs were laid by birds who aren’t subjected to inhumane practices, your best bets are to raise your own laying hens or buy pasture-raised organic eggs from the farmers market. Duck eggs are a delicious alternative; they have about 9 grams of protein each, and their shell helps them stay fresh longer than chicken eggs. You may be able to find duck eggs from local producers; check your farmers market or Local Harvest. The Cornucopia Institute (a nonprofit small farm advocacy group) has created a scorecard database.

Yes to Yolks

It’s common to see egg-white omelets in the “healthy” sections of restaurant menus, but eating the whole egg provides much more nutrition. For years, scientists thought that by reducing our consumption of cholesterol-containing foods, including egg yolks, we could reduce our own cholesterol levels. But it turns out our bodies are much more complex than that, and eating nutritious, filling fats is good for us and can help ward off weight gain. Recent studies suggest that regular egg consumption (up to two eggs a day, five days a week) doesn’t affect a healthy person’s lipid profile and may improve it. Note: If you’re diabetic, consult your doctor for nutritional recommendations.

Conventional Egg Production

Conventional egg production—the vast majority of egg production in the U.S.—is not a pretty business. Laying hens are crammed five or six to a cage in stacked rows of cages designed for automated feeding, watering and egg collecting. As many as 100,000 birds can be confined in a single warehouse, each bird with less than 67 square inches, about two-thirds the size of a sheet of paper, to call its own. The crowded conditions lead to cannibalism and other destructive behavior, so the birds’ beaks are cut off at an early age, a procedure that could be likened to cutting off a child’s fingertips in terms of its impact on the animals’ dexterity and sensory experience. The industry favors windowless warehouses with prolonged artificial light to stimulate maximum egg-laying. When egg production drops off, food is withheld as a way of sending the birds into a forced molt followed by another round of egg laying before being disposed of. These practices have paralleled the spread of salmonella as a bacterial contaminant in eggs—the reason we’re cautioned not to eat raw cookie dough. Crowded conditions, genetic uniformity and the widespread use of antibiotics in industrial agriculture also favor the development of new pathogens. —Laura Sayre

Milk and Dairy

Whether whole, 2 percent or skim, milk provides about 8 grams of protein in a 1-cup serving. Some studies have found milk from cows that are pasture-raised and grass-fed to be more nutritious than conventional milk, containing higher levels of healthful fats including linoleic acid, omega-3s, vitamin E and beta-carotene. Cheese is another good protein source; a 1-ounce serving of cheddar has about 7 grams of protein. Yogurt is a protein-rich breakfast or snack, with 14 protein grams in a 1-cup serving. Because it’s strained and more concentrated, Greek-style yogurt is a protein powerhouse; a 1-cup serving has up to 20 grams of protein.

Look for milk and other dairy products free of commonly used growth hormones including recombinant bovine growth hormone (rBGH) and bovine somatotropin (rBST). USDA organic dairy foods must be produced using only organic fertilizers and pesticides, and the cows cannot be given rBST. However, consumer demand for organic products has led to the deterioration of the organic standards by some companies. A better option is finding a local producer of hormone-free milk.

A+ Choice: Check out The Cornucopia Institute’s milk brand scorecard, which contains ratings of major organic milk companies to help consumers choose top-quality dairy products. Or look for local dairies that offer grass-fed milk from cows not injected with growth hormones. When it comes to cheese, look for varieties made with hormone-free milk. Always read the labels of yogurt containers, and choose those that only have a few ingredients, ideally just milk and active cultures; don’t contain added sugar; are made with organic milk; and list the names of the live cultures they contain. Yogurt is also incredibly easy to make at home using organic, grass-fed milk. Find instructions at Mother Earth News.

Hormones in Dairy

It’s fair to compare injecting cows with genetically engineered recombinant bovine growth hormone (rBGH) to injecting humans with steroids: It may have a short-term performance-enhancing effect (in the cows’ case, 5 to 15 percent more milk per lactation cycle), but cows treated with rBGH tend to have higher rates of mastitis (udder inflammation), reproductive disorders, hoof problems, diarrhea and other ailments. Because of these concerns, rBGH is prohibited in Canada, Australia, New Zealand and all European Union nations.

In the U.S., however, the FDA approved rBGH (also known as rBST) in 1993. The Monsanto Company is the sole vendor of the drug, trademarked Posilac, and today some 80 percent of U.S. cows are injected with growth hormones. Some research indicates that rBGH is not just bad for cows, it’s also bad for humans. “There’s no doubt whatsoever that rBGH use increases disease in cows, which in turn leads to more use of antibiotics,” says Rick North of Physicians for Social Responsibility. Farmers treat mastitis with antibiotics such as erythromycin, amoxicillin and penicillin. The more these are used in agriculture, the less effective they are against human diseases.

And then there’s the cancer risk. Studies have shown that rBGH increases levels of a hormone in milk called insulin-like growth factor 1 (IGF-1). IGF-1 is produced naturally by cows and humans, but elevated levels of IGF-1 in people are associated with breast, prostate and colorectal cancers.

Milk Glossary

Milk cartons contain an array of terms—whole, 2 percent or skim; homogenized; pasteurized or ultra-pasteurized. Our best recommendation is to choose whole milk from local, grass-fed cows that’s pasteurized, not ultra-pasteurized.

Whole milk: Whole milk is less processed than its low-fat counterparts. Removing fat from milk reduces its creamy texture, so producers add back in food additives to improve texture—usually powdered milk, which contains oxidized cholesterol, a substance researchers believe is much worse for our arteries than regular cholesterol, according to Michael Pollan’s book In Defense of Food.

Pasteurization: Pasteurization is the process of heating milk to kill harmful pathogens such as E. coli and Listeria. In the slowest and least common method, milk is heated to 145 degrees for 30 minutes. In High-Temperature Short-Time pasteurization, milk is heated to 161.6 degrees for 15 seconds, yielding a shelf life of two to three weeks. Ultra-Heat Treatment, commonly known as ultra-pasteurization, heats milk to 280 degrees for two seconds, yielding a shelf life of up to nine months.

Homogenization: A mechanical process that breaks down milk’s fat globules so they won’t rise to the top and form a cream layer, homogenization enables large-scale farms to mix milk from different herds. Homogenization also extends shelf life. “Cream-top” milk has not been homogenized.

Raw milk: Controversy surrounds this unprocessed, unpasteurized milk. The FDA warns against consuming raw milk, as it increases the chances of being affected by pathogens such as Listeria and E. coli, which can be deadly. Yet raw milk advocates argue that pasteurization eliminates many health benefits of milk, including enzymes, beneficial bacteria and vitamins. In some states, it’s illegal to sell raw milk. If raw milk is available in your area, look for a trustworthy supplier whose milk comes from grass-fed cows and whose farm you can visit. Children, babies, the elderly and those with compromised immune systems should not drink raw milk.

Our Advice: Choose Full-Fat Dairy

Dietary guidelines have urged Americans to choose low-fat dairy products under the thinking that whole-fat dairy products would lead to an increased risk of obesity. But that thinking is turning out to be misguided. In fact, research is finding that the opposite seems to be true: In one paper published by Swedish researchers and reported by NPR, middle-aged men who consumed high-fat milk, butter and cream were significantly less likely to become obese over a 12-year period compared with those who never or rarely consumed high-fat dairy. In another study published in the European Journal of Nutrition and reported by NPR, a meta-analysis of 16 observational studies found that consumption of high-fat dairy correlated with a lower risk of obesity.

Plant Proteins

Generally, choosing quality plant-based proteins is (thankfully) less complicated than identifying healthful meats, fish and dairy products. Many people choose organic produce out of a preference for plants grown without synthetic fertilizers, pesticides or genetic modification. Organic certification is expensive, however, and you can sometimes find top-quality produce grown organically by smaller, noncertified farms; just another way it pays to get to know local growers.

With a few exceptions, most plants don’t contain all of the complete amino acids that animal proteins do; foods that are low in one or more of the essential amino acids are called incomplete protein sources. Complementary proteins are two or more incomplete protein sources that together provide adequate amounts of all the essential amino acids; the classic pairing of rice and beans is a good example. It was previously thought that we needed to eat complementary proteins at the same time, but the latest research suggests that as long as we eat them throughout the day, our bodies can combine them and reap the benefits.


Beans are among the top plant protein sources, and the soybean could be crowned the Legume Protein King with 29 grams of protein in a 1-cup serving, cooked. Soy is also the basis for tofu and tempeh (see “Top Grade Mock Meats” for more information). Other high-protein legumes include green peas, chickpeas and lentils. Legumes are inexpensive, and the protein levels remain consistent whether you cook them from dried beans, fresh, frozen or canned.

A+ Choice: Nonorganic soy is grown with heavy use of pesticides. Choose organic fresh or dried beans. If using canned legumes, choose products in BPA-free cans and rinse before cooking or eating.

Soy Protein Isolate

Although they’re often promoted as healthful meat alternatives, veggie burgers, tofu dogs and other meat substitutes often contain soy protein isolate (aka isolated soy protein or SPI), a heavily processed ingredient that bears little resemblance to the plant from which it’s produced. While organic tofu, whole soybeans, tempeh and some soy milks are made with the whole bean, SPIs are made via a complex process that isolates the protein from other components of the plant, removing many of the beneficial nutrients such as essential fatty acids and fiber. You will also find SPI as an ingredient in convenience foods such as protein bars and cereal bars, and as a powdered protein supplement. Don’t confuse soy protein powder (made of SPI) with soy flour, a minimally processed product made from mechanically grinding whole soybeans.

More About GM Soy

At least 90 percent of the soybeans grown in the U.S. are genetically modified (GM), according to the USDA. Although the majority of this soy goes toward making animal feed and soybean oil (which accounts for close to 60 percent of America’s vegetable oil consumption), some of it is used to produce soy food products such as tofu, soy milk and, in particular, meat substitutes. In a peer-reviewed study recently published in the journal Food Chemistry, researchers found that Roundup Ready (aka GM) soybeans contain more herbicide residues than non-GM beans, and that the non-GM beans contained slightly higher protein levels and lower levels of omega-6 fatty acids (a fatty acid that, although essential to our diets, we typically consume too much of). To avoid GM soy products, look for organic products or those verified by the Non-GMO Project.

Whole Grains, Seeds and Nuts

Whole grains are a good protein source, with two slices of whole-grain bread containing about 8 grams of protein. Packaging on products such as bread and cereals can be confusing, though; “multigrain” and “whole wheat” might sound healthy, but those terms don’t indicate that all parts of the grain were used in the product. Instead, look for the words “whole grain”; then, check the ingredients list to make sure the whole grain is the first item on the list. Sprouted grain breads also generally offer a healthful dose of protein—for example, Alvarado Street Bakery’s Sprouted Whole Wheat Bread contains 10 grams of protein in two slices.

Quinoa is prepared like a grain, but it’s technically a seed. One of the few plant-based foods that is a complete protein source, quinoa contains all of the amino acids; a cup of cooked quinoa provides 8 grams of protein. Other high-protein seeds such as hemp (about 10 grams of protein in 3 tablespoons) or chia (about 7 grams of protein in 3 tablespoons) can be added to baked goods or sprinkled on cereals.

Raw nuts are another simple source of protein; 1⁄4 cup of whole almonds has about 7 grams of protein. Nut butters are an easy, delicious way to add protein to our diets; 2 tablespoons of peanut butter, for instance, contain about 8 grams of protein.

Most milk alternatives are made from nuts or grains, including varieties made from soy, almonds, rice, coconuts, cashews, hemp, hazelnuts and oats. Some have similar protein profiles to dairy milk; soy mik, for example, has about 6 grams of protein per cup.

A+ Choice: Choose organic products with minimal processing. Look for “whole grain” on packaging. Avoid nut butters with hydrogenated oils or added sugar. Read nut- and grain-based milk labels carefully, as some of these products have added sweeteners, or synthetic vitamins and other additives.


A number of vegetables contain moderate protein levels and, because most veggies are also rich in fiber, eating them can leave us feeling full and satisfied. Vegetables such as spinach, kale, potatoes, corn, broccoli, mushrooms and asparagus can all be good plant sources for protein.

A+ Choice: Look for certified organic produce at the store, and choose local when possible. You can also grow your own veggies or purchase produce raised without chemical fertilizers or pesticides from an independent farm or trusted grower at the farmers market.

A Comparison of Protein-Rich Foods

 Soybean nuts (roasted)
 1/2 cup
 Skinless chicken breast
 3 ounces
 Top round beef
 3 ounces
 Tuna  3 ounces
 Tempeh  4 ounces
 Greek-style yogurt (unsweetened)
 1 cup
 Seitan (wheat gluten)
 3 ounces
 Lentils (cooked)
 1 cup
 Salmon 3 ounces
 Edamame (frozen, cooked)
 1 cup
 Yogurt (plain)
 1 cup
 Chickpeas (boiled)
 1 cup
 Turkey breast (roasted)
 3 ounces
 Kidney beans (canned)
 1 cup
 Tofu  1/2 cup
 Peas (cooked)
 1 cup
 Milk (whole or reduced-fat)
 1 cup
 Quinoa (cooked)
1 cup
 Whole-wheat pasta (uncooked)
 2 ounces
 Whole-grain bread
 2 slices
 Peanut butter
 2 tablespoons
 Almonds (whole)
 1/4 cup
 Sunflower seeds (kernels)
 1/4 cup
 Cheddar cheese (shredded)
 1/4 cup
 Mozzarella string cheese (part skim)
 1 ounce
 Soy milk (plain, fortified)
 1 cup
 Eggs (raw, pasture-raised)
 1 large
 Asparagus (cooked)
 1 cup
 Rolled oats (uncooked)
 1/2 cup
 Brown rice (long grain, cooked)
 1 cup

Top-Grade Mock Meat

From burgers to deli slices, just about any kind of meat you can think of is available in a vegan or vegetarian alternative. Soybeans, grains and vegetables are common ingredients, but just because a product is meat-free doesn’t mean it’s healthful; some faux meats are highly processed and contain additives and preservatives. For savory flavor without the unsavory ingredients, try these nutritious meat substitutes.

Tofu: Sometimes called bean curd, tofu is made from soy milk that is cooked, curdled and pressed into a soft white block. Versatile and mild, tofu has about 10 grams protein in a 1⁄2-cup serving and can be seasoned, grilled, fried, or blended in soups and sauces. Choose organic varieties to avoid genetically modified (GM) soy and pesticide residues.

Tempeh: Made from cooked and slightly fermented soybeans and formed into a cake, versatile tempeh can be chopped and added to stir-fries and casseroles, and used in wraps and salads. Its flaky texture also makes it a good substitute for fish. A 1⁄2-cup serving has 15 grams of protein. Choose organic to avoid GM soy.

Seitan: Seasoned seitan, which is made from wheat gluten, tastes somewhat like chicken. It’s loaded with protein—20 grams in a 3-ounce portion—and can be used as a substitute for poultry in a variety of dishes.

Mushrooms: Rich, earthy and beefy, portobello mushrooms can be marinated and grilled like meat, or chopped and added to many recipes. A cup of grilled portobello mushrooms has 5 grams of protein. You can also find mushroom-based meat alternatives, such as Quorn, at the supermarket.

Lentils: Hearty, protein-rich lentils are the perfect substitute for ground beef; season them for tacos or form them into patties like burgers. A 1⁄2-cup serving of cooked lentils contains 9 grams of protein.