Protein in a Plant-Based Nutritional Program

How can you get enough protein on a plant-based nutritional program (PBNP)? This is the most common question that vegans and vegetarians get. I don't like those terms, but when I explain that I am on a PBNP, this is one of the first things people want to know.

Executive Summary
If you don't want to read the details below, here's a summary:

1. It's a myth that plants don't have complete proteins. It's true that some plants, like corn and rice, are low in one of the essential amino acids, but plants like beans, spinach, and broccoli, are complete proteins, that is, they contain all the essential amino acids, just like eggs.
2. It's a myth that all meats have better protein quality than plants. For example, the amino acid score for beef is 94 (a score of 100 or more means a complete protein, so beef is close), whereas the score for pinto beans is 105 (scores above 100 mean that the food has not only all the essential amino acids but in  ratio that is closer to the perfect ratio).
3. It's also a myth that to get complete protein from vegetables and grains, you have to match complementary foods in the same meal. For example, corn is low in lysine, and Romaine lettuce is low in methionine. If you eat them together, you'll have a complete protein. That's true. But in fact, you don't have to eat them in the same meal. You just have to eat them within the same day or two to get the benefits of a whole protein.
4. On the other hand, vegetarians and vegans like to say that it's easy to get all the protein you need on a plant-based diet. It's certainly possible. But it takes planning and effort

Amino Acid Scores
The information in this section was gleaned from the website SelfNutritionData, which is not a vegetarian or vegan website but just a general nutrition website.

What is an amino acid score (AAS)? Protein quality is dependent on having all the essential amino acids in the proper proportions. If one or more amino acid is not present in sufficient amounts, the protein in your diet is considered incomplete. A complete protein source is a food that contains all the essential amino acids in relatively good ratios. A score of 100 means that the protein is complete. A score higher than 100 means that the ratio is approaching the idea ratio for the amino acids required in the human diet. A score less than 100 means that one of more essential amino acids is not in sufficient abundance for the protein to be considered complete.

Quality of Protein
Let's look a some examples.These charts not only give the overall scores but show the relative amounts of each essential amino acid:

As you can see, eggs really are a great source of protein and corn isn't. No surprise there. But spinach, beans, and broccoli have higher quality protein than milk and beef.

Amount of Protein
Of course, the quality of protein is only part of the story. The other part is the quantity. So here is a comparison of the number of calories and the number of grams of protein in one cup of each of the following:

Eggs: 367 Cal, 24 g protein
1% Milk: 102 Cal, 8 g protein
Pinto beans: 206 Cal, 12 g protein
Spinach: 7 Cal, 1 g protein

So to get the amount of protein in a cup of eggs (about 3.5 large eggs), you'd have to eat two cups of beans and 24 cups of spinach.

Most of us need 50-70 g protein per day, so you can see that you have to eat a lot of vegetables. If you aren't trying to lose weight, it isn't so difficult. But if you are eating only 1500 Cal per day, you have to plan your diet carefully to get enough protein.

The bottom line for me is that I'm trying harder to eat more beans and spinach to make sure I'm getting enough protein.