Pasta with cheese

Complementary proteins in vegetarian and vegan diets

In Eat well, Nutrition education by Rebecca Comments

Two of the most common responses I heard from friends and family when I told them I was newly vegetarian was “you won’t be able to eat enough protein!” or “you will get an iron deficiency!” Fair call, their concerns about inadequate iron intake were pretty reasonable – one in four Australian women don’t consume enough dietary iron (check out this blog post I wrote about dietary iron). Protein though? I thought that was a cinch! Protein is in heaps of plant foods, I’ll just eat more legumes and BOOM! Protein sorted.

What I didn’t know at the time was how proteins work and exactly what our bodies need to put that protein into action. Fortunately, variety is the spice of life, and the answer to a vegetarian’s protein needs! But let’s start from the beginning.

What is protein, exactly?

Protein isn’t actually one thing- there are thousands of types of proteins, all of which are made up of 20 different amino acids – the building blocks of proteins. These amino acids can be combined together in a vast number of ways to create proteins that perform crucial functions in our bodies. We know we need protein for our muscles, but did you know our bodies also need protein for our bones, teeth, skin, hair, cartilage, blood vessels, and blood cells? Proteins also catalyse countless physiological processes, can function as hormones, play a crucial role in immunity, and play a crucial role in many other life sustaining functions.

When we eat proteins, our bodies break them down into their amino acid building blocks and then reassemble them into whatever forms the body needs.

Our bodies can produce some of these amino acids itself, but there are nine amino acids that the body can’t make. These are called ‘essential amino acids’ because it is essential that we get these from our diets.

Lots of plants contain protein

Many plant-based foods contain protein – breads and cereals, legumes and beans, and some other veggies contain protein. Also, if you’re eating dairy and eggs they will also provide you with protein.

However, plants aren’t ‘complete’ proteins

When we eat meat, we’re consuming ‘complete proteins’ (plus other nutrients, of course!). The protein in meat contains all of the essential amino acids our bodies require, in the ratio we need to maintain health.

Plants are ‘incomplete proteins’, meaning they don’t contain all nine essential amino acids in the ratio required by our bodies.

If your overall diet doesn’t provide enough of a particular amino acid, then this amino acid may be limiting your body’s metabolic capacity. Think of it like this- amino acids are pieces of lego, and you need all of the pieces to build a lego house. If one piece is missing, the house can’t be properly built. If your body needs to, it can break down its existing sources of protein (e.g. your skeletal muscle) to provide the amino acids it needs for more important functions (e.g. keeping you alive). But we don’t want that!

That’s where complementary proteins come in

Vegetarians who eat a balanced, diverse diet should have no problems consuming enough protein each day. All that needs to happen is to combine a few plant protein sources in your daily diet to ensure you’re getting enough of all nine essential amino acids.

 You don’t need to be calculating anything, nor do you need to eat all of the complementary proteins at each meal – a mix of plant protein sources over the course of the day is fine.

Clever combinations

Here are a few suggestions that you can add to your repertoire – each protein source complements the other, and will give you the full suite of amino acids to support good health.

Grains and legumes

Ezogelin Soup

Ezogelin soup contains both lentils and rice – two complementary protein sources. Recipe on the blog.

  • rice and beans
  • pea soup and toast
  • lentil curry and rice
  • baked beans on wholegrain or wholemeal toast
  • lentil burger
  • corn tacos and kidney beans
  • brown rice or quinoa with chick peas
  • tofu and rice

Grains and dairy

Yes, I know dairy is not a plant food! But for lacto-ovo-vegetarians, combining even a small amount of dairy with plant foods can provide a more balanced amino acid profile.

Cheese sandwich

Cheese and grains, when consumed together, provide a balanced amino acid profile.

  • pasta and cheese
  • rice pudding
  • cheese sandwich
  • breakfast cereal with yoghurt or milk

Legumes or cereals and seeds

Falafel wrap

Falafel wraps contains legumes (chickpeas) and grains (wrap) and may be topped with a yoghurt or tahini dressing.

  • beans and sesame seeds
  • hummus (tahini and chickpeas)
  • bean casserole with toasted sesame seeds
  • falafel wrap
  • bean salad with tahini dressing
  • muesli with sunflower seeds and oats

References

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