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Home / Choosing a Vegetarian Diet With Complementary Plant Proteins Will

Choosing a Vegetarian Diet With Complementary Plant Proteins Will

Plate of rice and lentil pilaf

Cultura / BRETT STEVENS / Getty Images

If you're a vegan, or strict vegetarian, you may want to pay closer attention to the types of protein sources you consume because most plant-based foods are incomplete proteins.

Being incomplete doesn't mean 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. How much of a problem is this and what can a vegan do?

It may sound bad, but as long as you eat a variety of protein sources every day you'll be just fine. The combination of different protein sources will ultimately ensure you get an ample supply of all the amino acids every day.

Understanding Amino Acids

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 bloodstream. From there, the amino acids are used to build the proteins that make up your muscles, organs and lots of other tissues.

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 (you eat eggs and dairy products), you can get complete proteins from those foods.

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.

Complementary Proteins

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.

Combining Proteins

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 if you're interested, here are some ways to combine your complementary proteins.

Grains and Legumes

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

Nuts and Seeds Plus Legumes

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

Plant-Based Complete Proteins

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. Edamame is another easy source of soy protein.

Amaranth, quinoa, hemp seed, and chia are also complete proteins, so adding any of these foods, along with combining your other protein sources, will help you get all your essential amino acids met every day.

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Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

  1. Hoffman JR, Falvo MJ. Protein - which is best?. J Sports Sci Med. 2004;3(3):118-30.

  2. Tessari P, Lante A, Mosca G. Essential amino acids: Master regulators of nutrition and environmental footprint?. Sci Rep. 2016;6:26074. doi:10.1038/srep26074

  3. Marsh KA, Munn EA, Baines SK. Protein and vegetarian diets. Med J Aust. 2013;199(4 Suppl):S7-S10.

Additional Reading

  • Gropper SS, Smith JL, Groff JL. Advanced Nutrition and Human Metabolism. Sixth Edition. Wadsworth Publishing Company, 2013.

  • Smolin LA, Grosvenor, MB. Nutrition: Science and Applications. Third Edition. Wiley Publishing Company, 2013.

Choosing a Vegetarian Diet With Complementary Plant Proteins Will

Source: https://www.verywellfit.com/vegan-protein-combinations-2506396