Peta Bee gets the lowdown on how and why we should be eating the great ingredient of the moment, protein

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There is always an ingredient of the moment, a nutrition newcomer set to transform our health and our bodies for the better. And there’s no doubt that this year, protein reigns supreme. A Mintel report said that nearly one third of all food and drink launches in the last two years carry ‘high protein” claims on their labels, and one in five gym users told another survey that they take a protein supplement or snack of some sort in the belief it enhances their exercise. It’s hardly surprising it is cropping up in everything, from bread to ice cream and chocolate biscuits to cereals and crisps.

There’s good reason for the surge in demand. Studies - and plenty of them - have revealed that it is protein and not carbohydrate foods, that fill us up, leaving us less likely to nibble and binge. “Protein foods slow down the release of sugars into the bloodstream,” says independent nutritionist Ian Marber . “Adding it to foods like bread and cereals can lower the glycaemic index of a food so that it is more statiating and will give you a longer-lasting energy boost.”

Types of protein: Animal vs Plant

But if we all know why we should be eating a higher ratio of it to anything else, we aren’t always sure of the best form to get it. Animal-derived proteins like cassein, and whey in particular, have long been considered the gold standard for health benefits. A review by WHO earlier this year bolstered their reputation by suggesting they have the edge, in nutritional terms, over their plant-based alternatives. “In general, animal proteins are much more similar to our body proteins, and because of this are more readily and rapidly absorbed than plant proteins,” says Miguel Toribio-Mateas, chairman of the British Association for Applied Nutrition and Nutrition Therapy (BANT).

However, there are downsides to whey and cassein. As dairy derivatives - they are made from the watery, left-over liquid from milk - they can result in sensitivities and intolerances in some people. “There’s also the fact that animal proteins have a higher concentration of sulphur-containing amino acids,” says Toribio-Mateas. “When they are metabolised they become acidic which can cause intestinal problems for some people.” Industry analysts are predicting that, while whey is still protein king, it is set to face increasing competition as the popularity of unusual plant proteins looks set to explode.

Pea protein isolates are already a firm favourite among American health-foodies and is being added to energy bars and other products. Their selling point is that they are non-allergenic and among the richest sources of arginine, an amino acid that helps to build a lean and toned body. Around 6-12 grams a day of arginine has been shown to provide a boost to fitness and sports performance, so it’s no suprise that gym types are clamoring to get their hands on pea-protein products.

Then there’s rice protein isolate, which was shown in a study carried out at the University of Tampa last year to match the benefits of whey protein isolate when it comes to speeding up fat loss and accelerating the development of muscle tissue after a workout. Previously, researchers had found that animal-derived proteins including meat, eggs casein and whey, were superior to plant passed alternatives like soy in stimulating muscle growth and repair after weight training. But in the study, which is to appear in the Nutrition and Metabolism journal, rice protein couldn’t be beaten.

Toribio-Mateas says plant proteins are also seen as “more natural, pure and ethical”, an image that has been bolstered by the popularity of the paleo diet  in which they feature heavily. And although “levels of some amino acids are impaired in plant protein, meaning that that those feeding mainly on a plant protein diet can become deficient in these amino acids”, the emergence of blended plant protein products like the Sunwarrior range seems to offset that risk. With a mix of pea protein, organic hempseed and cranberry protein, made from extract of the American cranberry seeds, the new powders are billed as being more nutritionally complete than some of the single plant varieties.

So should we make the switch? If Toribio-Mateas had to choose, he would stick with whey. “Good quality whey made from cold pressed whey protein concentrate that’s derived from grass fed cows, and free of hormones, chemicals and sugar, provides all the key amino acids for producing glutathione, the body’s most powerful antioxidant, in the liver,” he says. “It also contains immunoglobulins, lactoferrin and alpha Lactalbumin that boost antioxidant production.”

Too much of a good thing?

Too much of any protein, though, is not good news. Guidelines suggest that we need a daily intake of around one gram of protein for every kilogram of our bodyweight to stay healthy. That means between 45 and 70 grams a day for an adult. We are hardly at risk of deficiency. In fact, the average intake in the UK is 88 grams a day for men and 64 grams for women. Marber says we can cope with a little more, but shouldn’t get carried away. “This notion that we all need to get huge amounts of it in our diet is completely overblown,” Marber says. “We like the idea of grabbing something that is protein-packed and believing it will stop us overeating and tone us up. But for the average person going to the gym a few times a week, it really is pointless trying to get more and more.”

Tiribio-Mateas adds that overloading on any kind of protein can lead to symptoms that include bloating, "feeling too or sickly full" and general discomfort. “Our bodies can only absorb around 10 grams of protein concentrates or isolates per hour, and it takes about 90 minutes for these to be broken down,” says. “As a rule of thumb our body only uses about 15 grams of protein in that time regardless of how protein-rich your shake or food is, and the leftover protein just gets excreted.”

In other words, it is no magic fix. Whether you opt for soy or pea, whey or rice protein, it should underpin a healthy diet, not dominate it.