Sustainable Protein Sources

We’ve all heard about protein.  It is a vital nutrient necessary for muscles and many chemical reactions that make up our body’s metabolism.  People commonly talk about meat and dairy being good sources of protein, but there are many plant foods that have good protein in them too.

Do I need to combine proteins? 

No! This is an outdated myth.

The USDA MyPlate Tips for Vegetarians website says:

“Combining different protein sources in the same meal is not necessary.”

The Academy of Nutrition and Dietetics Vegetarian resource says:

“It was once thought that plant proteins needed to be combined within a meal by mixing grains and legumes to create a “complete” protein, also called complementary proteins, with good amounts of all essential amino acids. Now we know that the liver can store the amino acids so we don’t have to combine them in one meal.”

Elephants are herbivores, they grow big and strong without combining protein!

How much protein do you need?

Terrapins are herbivores too!

The Recommended Daily Allowance for protein for adults is 46 grams per day for women and 56 grams per day for men. According to a national health survey the average American adult eats 99 grams of protein per day, far above the amount required for health. The recommended range for safe protein intake is 10-35% of your daily calories, so some athletes or taller individuals may have higher requirements .


What are some sources of protein? 

Almost every unprocessed food, except some fruits, have protein in them. You should not have to try hard to get enough protein. However, it is a good idea to include some protein in every meal for a balanced nutritional intake and to help keep you full.  Here are some sources of 10 grams of protein:


  • 1 2/3 large egg
  • 1/4 cup of chopped or sliced chicken breast
  • 1 1/2 oz of hamburger/ground beef (about the size of a tic-tac container)
  • 2/3 cups of cooked black beans
  • 1 1/4 cups of cooked chickpeas
  • 1/4 cup of firm tofu
  • 1 1/2 oz of seitan (about the size of a tic-tac container)
  • 1/2 cup of lentils
  • 6 tablespoons of sunflower seeds
  • 2 cups of cooked brown rice
  • 2 1/2 cups of broccoli
  • 1 cup of oats
  • 1 1/4 cups of dairy milk
  • 1/4 cup (32 shelled) of peanut
  • 8 squares (1/3 oz each) of dark chocolate
  • 1.5 slices (1 oz each) of cheddar cheese
  • 1 1/4 cups of green peas

In this colorful chart below, you can compare how sustainable these options are compared to each other. In the calories column, the darker the blue is, the more calories it has. In the right columns, more green = more sustainable and more red = less sustainable. The red X’s denote the three worst options of the bunch: eggs, hamburger, and dark chocolate. The green check marks denote the best options here: chickpeas, sunflower seeds, and whole peanuts.


Carbon and Water Footprint for Foods


Fun fact: It takes a lot more water and electricity to shell peanuts (and other nuts/seeds such as almonds, pistachios, pumpkin seeds.) so when you have a choice, try to go for the ones still in the shell. This is better for the environment and better for you too, since it slows down your eating.



Bonus round! Get your thinking hat on and keep reading if you’re interested in learning more about how sustainability statistics are calculated. There are many, many different sources now that show numbers and graphs about sustainability. It is important to look closely at their sources, details, and units (grams, kilograms, tons, gallons, etc in order to understand the whole picture.  Often, places will mention only the carbon footprint or the water footprint of a particular item which may make a product seem better or worse than it actually is. Also, the numbers may be given for production, transportation, processing, or any combination of the above. How can these factors change things?


For example, look at the chart below. This chart has the same foods, but they are each a 100-calorie portion. (In the earlier chart, they were each a 10 gram of protein portion.)  This chart shows oats as one of the most sustainable sources of calories and chicken as one of the worst. Interestingly, since chocolate is so high in calories, it actually doesn’t seem as bad here as in the previous chart since it takes a smaller amount of resources to produce just 100 calories of chocolate. This could be deceiving so people do not realize how bad chocolate farming, processing, and transportation is for the environment (unfortunately!).


Carbon and Water Footprint for foods




One more chart. This time, each food is in a 100 gram portion, which is about 4 ounces of weight. By this measure, the animal products continue to be very unsustainable. However here – broccoli is a winner! Because broccoli and other veggies are so light, it does not take as many resources to produce a large volume of food. This could be useful for somebody who is trying to lose weight and eat bigger portions, or it could be less useful for feeding low-income people who really need more calories as the first priority.



Carbon and Water Footprint for Foods


  • The vast majority of people do not need to worry about their protein intake, and do not need protein shakes or supplements.
  • It is not necessary to combine plant foods to make a “complete” protein.
  • In almost all cases, animal-sourced foods are far less sustainable than plant-sourced foods.
  • Choosing less processed foods (unshelled nuts, natural cheese, dry beans) are better for your health and the environment.
  • Look carefully at charts and graphs on marketing claims to be sure you understand what they are saying.
  • Whenever possible, eat locally grown fruits, vegetables, beans, and grains to be the most sustainable.

By: Maria Pittarelli, Dietetic Intern, June 17, 2016



Carbon Data was taken from this website:

Water Data was taken from this website:

Water Data was also taken from this article:

Nutrition Data was taken from



These calculations were made assuming a minimal transportation requirement to show the carbon and water costs of simply producing these foods. In many cases, foods are bought from far away or overseas and will require additional resources. Eggs were assumed to be large, conventionally raised, hard-boiled eggs. Chicken breast was assumed to be skinless, conventionally raised. Hamburger was assumed to be 80% lean, conventionally raised, grilled. Seitan was calculated with the numbers for wheat gluten, since data was not available for seitan in particular. Tofu was assumed to be firm.