Anyone who says that you’re not going to use the math and science you learn in high school in real life obviously hasn’t tried to decipher nutrition studies, and for vegetarians, this can be an important skill. Because USDA guidelines tend to equate protein with meat, protein is a notorious health concern for loved ones of vegetarians. Thankfully, nutritionists have made information about their field accessible to laypeople who barely understood their high school science classes. Break out your biology and chemistry hats, it’s time to climb into Ms. Frizzle’s school bus and learn a little bit about what protein is, how it works, and how vegetarian diets can provide enough of it for our bodies.
What Is Protein?
Proteins can be found in many different parts of our bodies. Many of our body parts are made of protein: bones, organs, tendons, ligaments, muscles, hair, nails, teeth, skin. There are also many different types of “working proteins” that do specific tasks: they accelerate chemical reactions (enzymes), fight illness and disease (antibodies), transport oxygen (hemoglobin), regulate body functions like sugar levels and growth (hormones), and help build body tissues (growth and maintenance proteins).
The proteins are themselves made up of amino acids. In her “Complete Idiot’s Guide to Total Nutrition,” Joy Bauer compares amino acids to the alphabet. There are 20 different amino acids, and like the 26 letters that can be arranged to create words and even different languages, amino acids can also be arranged in many ways to create proteins that serve specific functions. Another analogy Bauer offers to explain the relationship between amino acids and proteins is comparing them to simple sugars, “which link together to form a complex carbohydrate.” Amino acids are the building blocks of proteins.
When you eat a food that has protein in it, your body breaks it down into amino acids. Then, your body rebuilds these amino acids into the protein sequences that it needs for specific purposes. Your body is doing this in its cells even as you read this article. Not all foods break down into the same amino acids. And, of the 20 amino acids, your body cannot make 9, and therefore it’s “essential” for you to eat foods that will yield these “essential amino acids.” The other 11 amino acids are also necessary for your body to function, but your body can make them without a particular external source of food.
Foods that are sources of complete proteins contain all the essential amino acids. You can easily make complete proteins by combining any two grains, legumes, and nuts/seeds.You can eat these complete proteins, or “complementary proteins,” in the same meal, or separately on the same day. You can also get complete proteins from animal proteins like fish, milk, cheese, and eggs.
How Much Protein Do You Need?
In the United States, the Institute of Medicine’s Food and Nutrition Board set up “standards of nutrient intake for populations” from the 1940s to the 1990s. These standards were called the Recommended Dietary Allowances (RDAs), and are described in Marion Nestle’s book “Food Politics.” In 1997, the RDAs were incorporated into a complicated system called the Dietary Reference Intakes, but the definition of RDAs remained the same: “the dietary intake level of specific nutrients that meets the requirements of most—about 97%—of the individuals in a population,” writes Nestle. RDAs are used for both public and individual health recommendations, and they are the basis for the package labels that contain information about the nutrients in the food you buy. Nestle writes that there are limits to relying on RDAs for any one individual’s health needs: for most people, the RDA standard intake levels are more than enough—“sometimes significantly higher” than what is needed. For a small minority of people, “the RDAs may be too low.”
This chart represents the RDAs for protein for a variety of age groups. For infants under six months old, an RDA is not provided, and instead, a mean intake for healthy breastfed infants is listed.
|Infants||Up to 6 months||9.1 grams per day (Adequate Daily Intake, not an RDA)|
|7 months–1 year||11 grams per day|
|Children||1–3 years||13 grams per day|
|4–8 years||19 grams per day|
|Males||9–13 years||34 grams per day|
|14–19 years||52 grams per day|
|19+ years||56 grams per day|
|Females||9–13 years||34 grams per day|
|14+ years||46 grams per day|
|Pregnant or Lactating||All ages||71 grams per day|
The source of the information in the above chart is the Food and Nutrition Board, Institute of Medicine’s 2005 “Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids.” In their book “Whole,” T. Colin Campbell and Howard Jacobson reveal that in 2002 the Food and Nutrition Board reported that it was safe for protein to comprise up to 35 percent of an individual’s daily calories, though for decades that figure had been 10 to 11 percent of calories. They write that the 2002 report seems to have aligned with the dual interests of the director of the Board at the time and “the majority (six out of the eleven) of the members of a companion policy committee (The USDA ‘Food Pyramid’ Committee),” all of whom had ties to the dairy industry.
Another way to figure out how much protein you need per day is to base the amount on how much you weigh or other personal factors. The Vegetarian Resource Group website reports that the RDA “recommends that we take in 0.8 grams of protein for every kilogram that we weigh (or about .36 grams of protein per pound that we weigh).” Nestle simplifies this equation in her book “What to Eat” to about “half a gram of protein for every pound you weigh.”
In their book “Eat Like the Animals,” David Raubenheimer and Stephen Simpson present a three-step process to find your ideal protein intake that factors in your “age, sex, and level of activity.” It uses a generic Harris-Benedict equation calculator to estimate your “daily energy (calorie) requirement.” After multiplying that amount by between 0.15 and .20, for a 15 to 20 percent protein diet depending on one’s age or reproductive status, you would divide that number by 4 “to get the number of grams of protein per day you should eat.”
How to Get Enough Protein as a Vegetarian
Eating a varied diet is a good way to get enough protein as a vegetarian. The Food and Nutrition Board of the Institute of Medicine has concluded that it’s okay for vegetarians to “consume complementary mixtures of plant proteins” to get their recommended amount of protein. In “What to Eat,” Nestle writes, “Even if you’re a vegan and eat no animal products at all, you almost certainly get more than enough protein from the grains, beans, and vegetables you eat.”
10 Best Vegetarian Protein Sources
The best sources of protein for any individual are not simply going to be a small number of specific, high-protein foods, but will form a pattern of eating a variety of foods that are minimally processed. These will include fruits, vegetables, grains, beans, and nuts, without much added salt and sugar. Determining how best to get this protein is a personal or community project that will likely take some trial and error, and may involve reading around or even consulting with nutrition and health professionals.
Vegetarians include vegans (no meat, eggs, dairy, or animal products), lacto-vegetarians (no meat and eggs, but yes to dairy), ovo-lacto-vegetarians (no meat, but yes to dairy and eggs), and semi-vegetarians (no red meat, but yes to poultry, fish, dairy and eggs). You could even include flexitarians here, as they eat varying degrees of meat but at a lower rate than the norm. The following list of foods from Bauer’s book offers 10 vegan (or the strictest of vegetarian), sources of complete proteins that you can try to make at home.
Complete Proteins Made of Grains and Legumes
- Peanut butter on whole-wheat bread
- Rice and beans
- Bean soup and a roll
- Salad with chickpeas and cornbread
- Tofu vegetable stir-fry with rice or pasta
- Vegetarian chili with bread
Complete Proteins Made of Legumes and Nuts/Seeds
- Hummus (chickpeas and sesame paste)
- Trail mix (peanuts and sunflower seeds)
Complete Proteins Made of Legumes and Nuts/Seeds
- Breadsticks rolled with sesame seeds
- Rice cakes with peanut butter
The above list represents a sampling of the types of complete proteins that vegetarians can create by combining any two of grains, legumes, and nuts/seeds. Grains include rice, barley, pasta, wheat, oats, and cornmeal. Legumes include beans, lentils, peas, peanuts, chickpeas, and soy products. Nuts and seeds include sesame seeds, sunflower seeds, walnuts, cashews, and pumpkin seeds.
High-Protein Vegetarian Meals
Following a high-protein/low-carb meal plan can be useful if your physician diagnoses you with hyperinsulinemia, but Bauer otherwise cautions against “‘high-protein’ diets” that are oriented towards weight loss. Strict vegetarians, or vegans, simply need to eat a variety of grains and beans to get enough protein—while also eating enough calories, and finding non-animal sources of vitamin B12. Meatless protein-rich foods include tofu, nuts, seeds, lentils, and tempeh. Ovo-lacto-vegetarians can also get their protein from dairy and eggs.
However, looking at food through the lens of its nutrient parts is just one way of understanding nutrition, and is in one sense quite a reductionist one, carrying a risk of missing a bigger picture. This kind of approach to nutrition can help us understand the science of how our bodies work. Yet food industry professionals have also taken advantage of single-nutrient, reductionist approaches to market particular foods and food products to the public without reference to a full healthy diet. Food system advocates and nutritionists, including Marion Nestle and T. Colin Campbell, suggest that by focusing too closely on single nutrients (like protein) or ingredients as features of food, we risk confusing and misleading ourselves on what to eat for optimal health.
Benefits of Eating Vegetarian-Only Protein
Vegetarians in the United States tend to be healthier than meat-eaters, with lower risks of heart disease and cancer than people who eat beef, pork, lamb, and chicken. Specifically, eating red meat seems to increase the risk of getting Type 2 diabetes, and cancers of the pancreas, breast, prostate, and kidney. To learn more about the politics of why the U.S. government nonetheless avoids advising Americans to eat less meat, you can read Nestle’s books “What to Eat,” “Food Politics,” and “Unsavory Truth.”
The diets of people in industrialized countries tend to exceed recommended daily allowances for protein since most meals contain animal proteins like meat and dairy. This type of high protein intake is associated with chronic diseases such as cancer, osteoporosis, kidney stones, poor kidney functioning, coronary heart disease, and obesity. In fact, eating too much protein, and not enough carbohydrates and fats, can result in protein poisoning, “a rare form of malnutrition” that happens when 40 to 50 percent of one’s daily calories are from protein, rather than the recommended 15 percent, write Raubenheimer and Simpson.
Another aspect of vegetarian protein is that eating it instead of animal proteins helps reduce the demand for animal agriculture (including aquaculture). The animal agriculture industry takes advantage of low-wage workers and puts them in dirty, dangerous, and demanding positions while keeping farmed animals in cramped, unhealthy spaces. Animal agriculture is also a major contributor to climate change and other environmental hazards.
Like the Amoeba Sisters say, “Proteins are kind of a big deal”—they are essential for us to live. Eating a variety of minimally processed, plant-based foods, as vegetarians can do, is good for your health and is a safe way to make sure that your body has all the nutrients it needs to function. Avoiding meat and animal-based products can also help you build a better world with every meal you eat, cook or share with others.
Hemi is a writer and educator.