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Distinguished professor Paul Moughan from The Riddet Institute is an expert in all things protein related.
The Riddet Institute is a Centre of Research Excellence (CoRE) focusing on fundamental and advanced food research. It's hosted by Massey University on the Palmerston North campus.
Dr Moughan answers some questions from the Country Life team.
What is protein?
Protein is a very important component for the human body. It's central to body function and therefore to nutrition.
We get proteins from the foods we eat - we don't need protein itself but rather the amino acids that are the building blocks of protein. When we eat protein, it gets broken down to amino acids and it is those that are absorbed.
There are nine essential amino acids. Some foods can supply all nine of those amino acids readily, while others might be deficient in one of those essential amino acids.
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How much protein do we need? Is there such a thing as too much protein?
The amount of protein we need depends on a persons age and weight. The average adult needs about 0.8 grams of protein per kilogram of body weight - so a person who weighs 80kg needs about 65g of protein per day.
Again though it comes back to the quality of the protein and the amino acids you can get from it. From a lesser quality protein you might need more to get the same benefit. We also need more protein as we age - about 1.5g compared to 0.8g.
Generally there's no such thing as too much protein for most people.
Distinguished professor Paul Moughan from the Riddet Institute. Photo: Supplied
Are all protein sources equal? What should people keep in mind at the supermarket?
There are major differences between proteins.
Consumer information is pretty poor. Looking at the protein content on a product's label is a good starting point but it doesn't speak to the quality of the protein.
As a general rule, animal-based proteins - so milk, dairy- based proteins, egg, meat, fish - are all very high quality. They have all the amino acids you need and they're highly digestible and highly available. Soyabean-based foods like tofu and tempeh are also high quality.
Peas and beans tend to be high in protein but the quality is not always high. A lot of the vegetable-based proteins are less good quality so you would need to consume more of them. Pea and potato-based proteins can be good for vegan or vegetarian diets though.
In the past it didn't matter too much because we generally consumed mixtures of proteins. Now there's a movement worldwide to go away from animal-based proteins more towards vegetable-based proteins and as we do that we need to be more careful. There have been studies of vegan and vegetarian diest which have found people were not meeting their total protein requirements in terms of quality.
Protein quality is going to become more of an issue. When we look at future world food needs, because the world population is growing, it's also ageing, protein is going to become a major consideration.
I personally think it shouldn't be vegetable or animal. It needs to be vegetable and animal. It may be very appropriate to move towards more vegetable-based foods but I think people who completely exclude animal-based foods may well be entering into the territory of nutritional inadequacy and problems with their diet. It's all about balance.
