Vegan Protein Combinations

Plate of rice and lentil pilaf, which are complementary proteins.
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Vegans, or "strict vegetarians," may want to pay closer attention to the types of protein sources they consume because most plant-based foods are incomplete proteins. It's not that plant-based foods are low in protein -- you can get plenty of protein from plants. But almost every plant-based food is low in one or more essential amino acids that your body needs to thrive.

So what can a vegan do? Combine different protein sources every day and you'll get ample supply of all the amino acids.

First, A Little Amino Acid Chemistry

Let's talk about amino acids for a minute. Amino acids are the building blocks of protein. Your body needs them to make the protein structures that build and maintain the tissues in your body.

There are many different amino acids; they all have similar structures but are differentiated by their side chains. All proteins, no matter what food they come from, are made up of amino acids. But the number and order of the amino acids that make up a cow's rump or a navy bean are different from the ones that make up your body parts.

When you eat round steak or baked beans (or anything that contains any protein at all, even a tiny amount), your digestive system breaks it down into amino acids that are absorbed into your blood stream. From there, the amino acids are used to build the proteins that make up your muscles, organs and lots of other tissues.

Back to Essential Amino Acids

Not all amino acids are essential.

Your body can make many amino acids from the leftover bits of old amino acids and a few other raw materials found in the body, but there are some amino acids that the human body can't manufacture. These amino acids are called the essential amino acids because you have to consume them.

These are the essential amino acids:

  • Histidine
  • Isoleucine
  • Leucine
  • Lysine
  • Methionine
  • Phenylalanine
  • Threonine
  • Tryptophan
  • Valine

Animal proteins all contain every single one of these essential amino acids, so they're called complete proteins. If you're an ovo-lacto-vegetarian (only eggs or dairy products), you can get complete proteins when you eat the eggs or dairy products.

Plant proteins are a little different. Each plant that you eat has a different amino acid profile. For example, grains and cereals are extremely low in lysine. So low that they can't even be considered a source of lysine. If you only eat grains and cereals, you won't get enough lysine, and that's bad.

However, legumes such as peanuts, peas, dry beans and lentils contain a lot of lysine. On the flip side, legumes aren't good sources of tryptophan, methionine and cystine, but those amino acids are found in grains and cereals. As long as you eat some grains and some legumes, you'll get some of each essential amino acid.

Grains and legumes are called complementary proteins because when you combine them, you get all of the essential amino acids.

Nuts and seeds are also complementary to legumes because they contain tryptophan, methionine, and cystine.

You don't need to eat complementary proteins together at every meal. As long as you get a variety of proteins throughout the day, you'll get ample amounts of each amino acid. But, just in case you're interested, here are some ways to combine your complementary proteins.

Grains and legumes:

  • Black beans and rice 
  • Pasta and peas
  • Whole wheat bread and peanut butter
  • Bean soup and crackers

Nuts and seeds plus legumes:

  • Roasted nuts, seeds, and peanuts
  • Hummus (chickpeas and tahini)
  • Lentils and almonds

Soy is one plant protein that contains all the essential amino acids. It's also a good source of healthy fats and phytochemicals (plant chemicals that may be good for you). It's usually served as tempeh or tofu, and soy milk is a popular replacement for milk. Amaranth, quinoa, hempseed, and chia are also complete proteins.

Sources:

Gropper SS, Smith JL, Groff JL. "Advanced Nutrition and Human Metabolism." Sixth Edition. Belmont, CA. Wadsworth Publishing Company, 2013. Accessed June 8, 2016.

Smolin LA, Grosvenor, MB. "Nutrition: Science and Applications." Third Edition. Wiley Publishing Company, 2013. Accessed June 8, 2016. 

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