Incomplete Vs complete protein: let’s break it down

Complete and incomplete proteins are two very different things and it’s all to do with the building blocks we call amino acids. Our body breaks down the protein from the food we eat, and converts it back into amino acids which it can then use to do things such as repair muscle tissues.

Until I studied nutrition, I didn’t know much about the structure of protein, let alone that there were different types. In this blog, I share some of my key learnings about the difference between the two protein types so that you too can learn about this food group.

What is protein?

Proteins are fundamental structural elements within every cell of the body and are involved in a wide range of metabolic interactions.

All cells and tissues contain protein, therefore protein is essential for growth and repair and the maintenance of good health.

British Nutrition Foundation

The biochemical activity of a protein is characterised by their individual structures. This is determined by the sequence of their constituent amino acids.

Out of the twenty amino acids, our body can synthesise twelve. The remaining nine are known as ‘essential’ or ‘indispensable’ amino acids and have to be obtained from sources of protein in our

Complete proteins contain all of the essential amino acids that the body requires, hence the word complete. These are found in animal products, including red and white meats, fish, dairy products and eggs.

Red meat such as beef is a source of a complete protein

Meanwhile, plant proteins lack some of our essential amino acids, and so they are classified as ‘incomplete’. This means you would need to eat a lot more of them in order to get enough protein for your body.

Some people believe that because animal protein is ‘complete’ that it’s the better source. However, vegetables, nuts, seeds, beans and pulses are also great sources of this macronutrient.

Tips for non-meat-eaters

If you are vegetarian or vegan, it’s important to combine foods that complement
each other in terms of their protein content, so that each food supplies the essential amino acids that the other lacks.

For example, grains and nuts contain methionine but are lacking in lysine and threonine. Meanwhile, vegetables and pulses contain lysine and threonine but lack methionine. Therefore, having meals that combine these elements, such as lentil curry and rice, is a great way of making to ensure you’re having a broader scope of amino acids .

Lentils, chickpeas, grains and veggies are all great sources of protein

If, like me, you eat a largely plant based diet, here are some great recipes diet that are super rich in protein (and seriously yummy!)

  • Avant Garde Vegan savoury breakfast muffins – these oat-ily delicious ‘grab & go’ muffins are full of protein-rich seeds, tofu and vegan cheese while the cayenne, chives, sun-dried tomatoes and olives give that YUM-factor.
  • Seitan black bean stir fry – seitan is a meat-like substitute made from wheat and is a great protein-packed alternative to steak, bacon, burgers and panko or bread crumb coated meats. This particular recipe also involves peanut butter and a mix of beans and veggies, a great combination of different protein sources.
  • Spicy tempeh ‘bacon’ and chickpea salad – a light & refreshing kale salad that is full of protein, vitamins, flavours, spices and some interesting textures!
  • Tofu, spinach scramble – this protein-dense delight takes just ten minutes to cook and works as a great breakfast, lunch or post workout snack. Crammed with nutrients and around 21g of protein.
  • Quinoa edamame edamame salad – quinoa and edamame are both excellent sources of fibre, protein and calcium, as well as a tonne of micronutrients including vitamin K, folate, B vitamins, iron and vitamin E. This colourful meal is one of my go-to dinners and is also super convenient if you make a big batch to spread across a couple days.

And that concludes this blog post. What are your views on plant vs animal protein sources? Do you have a plant-based diet and find it difficult to get enough protein into your diet? Did you learn something new from this post? I’d love to hear your thoughts – if you’d like to share them, please send an email to

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