Considering switching to a plant-based diet? If you answered ‘yes’, you’re not alone. A 2019 report revealed that 42 per cent of Australians said they were eating less meat, or none at all (1).

But where does that leave protein, a nutrient commonly linked with healthy muscles and weight control? And how can you make sure you’re getting enough?   

Plant-based diets: Why all the fuss?

We know from research that eating patterns in which plants take centre stage have been linked with a lower risk of type 2 diabetes, cardiovascular disease, hypertension, obesity, metabolic syndrome and all-cause mortality (the death rate in a population) (2).

Taking this a step further, studies show a reduced risk of disease when protein comes from plants, such as nuts, legumes and wholegrains, instead of from animal sources, such as meat. 

What’s the role of protein in the body?

We need protein throughout life to create, maintain and renew our body’s cells and tissues.

Proteins are made up of around 20 different amino acids, that link together in different combinations. Our body uses these as building blocks for muscle, bone, skin and blood, and to make other compounds, such as enzymes and hormones.

Protein can also use be used as an energy source. It helps to keep us fuller for longer, and supports our immune system to fight off bugs.

Did you know? The body of a 76kg man contains about 12kg of protein – with nearly half of this protein present as skeletal muscle (3).

How much protein do we need?

The Recommended Dietary Intake (RDI) for Australian adults, aged 19-70 years, is 64g protein per day for men, and 46g for women (3).

Older Australians need more than this, as do very active people, pregnant and breastfeeding women, and people who are ill or have undergone surgery.

The key to meeting your protein needs is to make sure you eat a wide variety of foods over the day, in adequate amounts. By doing this, it’s relatively easy for most people to take in enough protein. In fact, most Australians exceed their daily protein target!

Nuts: Plant protein powerhouses

Nuts offer a package of nutrients, including plant-based protein, healthy mono- and poly-unsaturated fats, fibre, vitamins and minerals (such as vitamin E, magnesium, phosphorous, iron and zinc), and antioxidants.

Nuts have been shown to protect against heart disease, type 2 diabetes and metabolic syndrome, and have also been linked with increase longevity, too.

Most tree nuts provide about 3-6g of protein per handful (30g) – or around 10-20g of protein per 100g.

Table 1: The protein content of tree nuts

Protein (g)
per 30g handful
Protein (g)
per 100g
Almonds5.919.7
Brazil nut4.314.4
Cashew4.517.0
Chestnut1.03.4
Hazelnut4.514.8
Macadamia2.89.2
Pecan2.99.8
Pine nut3.913.0
Pistachio5.917.9
Walnut4.314.4
Mixed tree nuts4.013.2

Did you know? Pistachios and almonds have the most protein of all nuts, with just one handful (30g) containing around 6g protein.

How do some popular plant-based protein sources compare?

Table 2: The protein content of some common foods

Serve size*Protein (g)
per serve
Protein (g)
per 100g
Almonds30g (handful)5.919.7
Whole wheat
breakfast biscuits
30g (2 biscuits)3.612.0
Porridge (made
on water)
120g (1/2 cup)2.92.4
Baked beans150g (1 cup)7.44.9
Chickpeas150g (1 cup)9.36.2
Wholemeal bread40g (1 slice)4.511.2
Tofu170g20.412.0
Chia seeds30g5.016.5
Eggs120g (2 large)15.112.6
Red meat (lean,
cooked)
65g20.731.9

*Based on the serve sizes outlined in the Australian Guide to Healthy Eating.

Are proteins from plants as good as those from animals?

The answer might be in the company they keep!

Researchers from the Harvard School of Public Health recently proposed the term ‘protein package’ as a way to weigh up the pros and cons of the different food groups that offer protein (4).

This is because we don’t eat ‘protein’ as an isolated nutrient – instead, it’s part of the foods we consume.

Plant-protein package

Within the plant protein package, we receive fibre, polyphenols and higher amounts of nutrients, such as vitamin C and healthy unsaturated fatty acids. Importantly, research also tells us that plant-based protein has a lower environmental impact than animal-based protein.

Animal protein package

Animal proteins come with a package of essential nutrients, some of which are not found in plant-based foods (like vitamin B12 and choline), while others (think, iron and zinc) are typically found in higher quantities in animal-based foods. They are also better absorbed by the body (that is, more ‘bioavailable’), compared with plant-based sources.

On the flip side, the animal protein package is often a source of saturated fatty acids and/or heterocyclic amines (chemicals that are formed when meat is cooked at high temperatures).

A large study found that replacing just three per cent of daily energy (or kilojoules) from animal protein with plant protein was linked with lower all-cause mortality (5). The greatest risk reductions were seen when processed red meat, unprocessed red meat and eggs were replaced with plant-based sources of protein.

Good health – such as healthy muscles and weight control – can be achieved with both sources of protein (animal- and plant-based). So, what may be more important, for each of us as individuals, is the nature of the ‘protein package’ – that is, the other nutrients being provided by protein-rich foods and our particular needs for these within our overall diet.

Did you know? Health is the main reason Australians choose to eat less meat, closely followed by a four-way tie: the environment, animal welfare, cost, and an increasing availability of plant-based options (1).

A note on ‘complementary’ proteins

Some amino acids, 11 in fact, can be made by the body, so they’re known as ‘non-essential’ amino acids. The body can’t make the other nine amino acids – the ‘essential’ amino acids.

When it comes to the essential amino acids, ‘complete’ protein foods – typically, animal foods – contain all nine of these. Plant proteins usually lack at least one of the essential amino acids, so are considered ‘incomplete’ proteins.

This just means that people who eat vegetarian or vegan diets need a variety of protein sources, from a range of plant-based foods, throughout the day to get their essential amino acids. Thankfully, we’ve moved on from the days when it was thought that we needed to eat foods that provided all nine essential amino acids in one meal!

Three easy ways to up your intake of plant-based foods without sacrificing protein:

  • Top every salad you make with a handful (30g) of nuts.
  • Sprinkle chopped nuts on top of your brekkie cereal – or your avocado toast!
  • Add a can of beans, such as chickpeas, to your favourite curry recipe, and serve topped with nuts.   

The bottom line

Whole, plant-based foods, such as nuts, provide a package of nutrients, not least of which is protein! A plant-based diet can achieve the optimal quality of protein, without animal-based protein. If you choose a plant-based diet, the key is to include a variety of foods, in adequate amounts, over the day.

References

  1. Colman Brunton research for Food Frontier and Life Health Foods. Hungry for plant based: Australian consumer insights. (2019) Available at: https://www.foodfrontier.org/wp-content/uploads/2019/10/Hungry-For-Plant-Based-Australian-Consumer-Insights-Oct-2019.pdf
  2. Lonnie M., Johnstone AM., The public health rationale for promoting plant protein as an important part of a sustainable and healthy diet. Nutrition Bulletin, 2020. 45: 281-93.
  3. National Health and Medical Research Council. Nutrient Reference Values for Australia and New Zealand. Available at: https://www.nrv.gov.au/
  4. Guasch-Ferre M., et al., Meta-analysis of randomised controlled trials of red meat consumption in comparison with various comparison diets on cardiovascular risk factors. Circulation, 2019. 139: 1828-45.
  5. Song M., et al., Association of animal and plant protein intake with all-cause and cause-specific mortality. JAMA Intern Med, 2016. 176(10): 1453-63.
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