If you’re new to or interested in plant-based eating, you may worry that you won’t get enough protein for your active lifestyle. After all, plants usually have less protein per gram than animal foods, and they tend not to be absorbed as well. Yet, many plant-based athletes are thriving after ditching animal foods.
To gain some insight into the differences between animal protein vs. plant protein, we chatted with two registered dietitians: Marie Spano, M.S., R.D., a sports dietitian for the Atlanta Braves, and Samantha Cassetty, M.S., R.D., a nutrition and wellness expert and co-author of Sugar Shock.
How do animal and plant proteins differ?
Protein is a building block of skin, hair, teeth, nails, and major organs, and it also serves as an antibody, messenger, enzyme, transporter and storage. Protein is most known for its ability to stimulate muscle protein synthesis (MPS) for at least 24 hours in response to a single session of exercise, like running. In other words, it’s really important!
Protein is found in both animal and plant foods. For instance, you can get protein from animal sources such as chicken, fish, turkey, and beef, and you can get protein from plant sources such as soy, beans, legumes, nuts, and seeds. However, not all sources are created equal.
“Runners who eat only plant foods need more total protein each day because plant proteins generally aren’t as high quality as animal-based proteins,” Spano tells Runner’s World.
Protein quality often has to do with the amino acid profile of a food. As a quick refresher, amino acids are the building blocks of protein, which help your body build and repair muscle and regulate your immune system. There are 20 amino acids, but only nine are essential—as in, your body can’t produce them, but you need them to live.
Up until recently, it was a commonly held belief that plant foods are “missing” some of the 20 essential amino acids. Yet, a recent review of the research found that, more accurately, the amino acid distribution profile is “less optimal in plant foods than in animal foods,” meaning that some amino acids are limited in certain plant-based proteins.
But the good news is rectifying this issue is simple. “It’s a good idea to include different plant foods, such as pulses, soy foods, whole grains, nuts, and seeds throughout the day. It will help you meet your protein needs without having to eat a giant portion of any single food,” Cassetty tells Runner’s World.
Another difference between animal- and plant-based proteins is the quantity of protein per volume of food. For example, 3 ounces of chicken has about 20 grams of protein, as compared to about 6 grams in 3 ounces of chickpeas and 8 grams in 3 ounces of firm tofu.
To get the same amount of protein that you would from animal foods, you need to eat more if you’re a plant-based runner. Cassetty recommends varying the plant-based proteins in your meal.
She says that rather than eating 2 cups of chickpeas at 22 grams of protein, have a cup of chickpeas—at 11 grams of protein—½ cup of quinoa —at 4 grams of protein—and roasted veggies. Then drizzle 2 tablespoons of tahini—which is 5 grams of protein—on top.
How does your body absorb both types of protein?
“You can get and use the building blocks—amino acids—from animal proteins easier than you can from plant proteins,” says Spano. As a matter of fact, there are two rating systems used to determine the protein bioavailability [a measure of how much a substance is able to access your body’s circulation and reach the target area] of a food: the protein digestibility-corrected amino acid score (PDCAAS) and digestible indispensable amino acid score (DIAAS).
The PDCAAS system has been around since 1993 and looks at the amino acid quality of a food, whereas the newer DIAAS was proposed by the Food and Agriculture Organization of United Nations (FAO) in 2013. It determines amino acid digestibility at the end of the small intestine, providing a more accurate measure of the amounts of amino acids absorbed by the body.
Knowing the score of each individual protein is not necessary, but there are a few takeaways from these scoring systems. Mainly, soy is the only plant-based protein that scores just as high as meat and dairy. Potato, peas, and beans also come close to meat on both scales, although they are generally about 25 percent lower.
“Because those building blocks are not as bioavailable in plant proteins, you need a larger serving size of protein to meet your needs,” says Spano. In general, Spano advises aiming for a minimum of 30 to 40 grams of protein per meal if you are consuming only plant foods (as opposed to 20 to 25 grams of protein if you are consuming animal foods).
According to the Academy of Nutrition and Dietetics, if you’re a vegan or vegetarian who eats a variety of plant-based proteins throughout the day, you should have no problem meeting your protein needs. And if you rely on protein supplements, research suggests rice and pea protein may stimulate changes in muscle and strength just as well as whey protein.
Do you need more protein on a plant-based diet?
Research from the past 30 years indicates that athletes engaging in intense training may need anywhere from 1.2 to 2.0 grams of protein per kilogram (0.45 to 0.9 grams per pound) of body weight per day to maintain muscle mass. For a 150-pound runner, that’s anywhere from 68 to 135 grams of protein per day.
“A plant-based runner may need to eat slightly more protein than a runner who consumes animal foods, but it doesn’t have to be overly complicated,” says Cassetty.
Spano cites one study, which found vegetarian endurance athletes need 12 percent more—or about an extra 10 grams per day—total protein compared to omnivore endurance athletes. So for that same 150-pound plant-based runner, that adds up to 78 to 145 grams of protein per day.
Again, Cassetty stresses that “it’s important to consume protein from a variety of plant sources, and to distribute that protein over all of your meals and snacks.”
Here’s what a typical day for a 150-pound plant-based eater may look like:
→ Breakfast: Muesli bowl with ½ cup uncooked oats + 3 tablespoons of hemp seeds + 1 ounce almonds + fruit = 18 grams protein
→ Lunch: Lentil soup with 1 ½ cups of lentil = 30 grams of protein
→ Snack: 1 cup of edamame = 20 grams protein
→ Dinner: 5 ounces of tempeh with rice & veggies = 30 grams of protein