It’s the cartons of white stuff in your fridge that have local scientists all aflutter, and what they’re discovering suggests protein’s day has come.
A little boy darts around the garden. Chubby legs pumping hard, his body is grabbing an essential element from his diet and building it into his tissue and muscle, his growing brain and in fact his every cell.
While exotic supplements and cutting-edge elixirs wing their way here from all corners of the globe, there’s a piece of the nutrition puzzle that has some of New Zealand’s most prestigious nutritionists and white-coated scientists barely restraining themselves with excitement.
Turns out the emerging food superstar is humbly lying in wait in your fridge, contained within good old dairy, meat and eggs – and in your pantry, thanks to the wholesome goodness of legumes and grains.
It’s the stuff you’re made of, the stuff that constitutes a large part of every cell in your body. It’s one of the building blocks of you.
Why so essential?
Just like the busy toddler, as we go about our daily business, our bodies are in a constant state of repair. Most of the body’s tissue replenishes itself (though at varying speeds) throughout our lives, and without protein in our diet, we simply couldn’t survive. Nor could we repair or tone our muscles after exercise.
Protein is the stuff we’re made of, the bricks of our biological construction. The word protein comes from the Greek word proteios, which means ‘primary’ or ‘holding the first place’ and it was first used in 1883.
Our body uses it to make blood, skin and hair. It creates all the micro-machinery inside our cells, makes antibodies to build immunity and fight off infection, and is the essence of our very brain matter. In fact, 16 percent of a 76kg man is pure protein. But contrary to popular opinion – the kind that has us women dishing out the biggest steaks to the men and boys at the table and taking the smallest serving for ourselves – women need almost as much protein as men do.
It can even be used for energy if our diets are scarce in sugar and fats. In addition to the job of moving our bodies, 45-70 percent of our energy is spent each day powering essential internal tasks such as processing food, moving substances around inside our bodies, making and breaking hormones and enzymes, maintaining our bodies at the right temperature and keeping organs such as the heart and the brain sparking.
A common misconception is that protein-rich foods are the realm of the bodybuilder, and that upping our protein intake – let alone supplementing our diet with protein shakes – will have us looking like Nadzeya Ostapchuk.
But that’s just silly. This type of physique takes years of extreme training and a super-specialised diet to achieve. “Women aren’t going to bulk up, it’s quite difficult and not something that we naturally do,” says Results Nutrition Centre nutritionist Olivia Green.
In fact the opposite is true. Eating protein can actually help control our weight – by helping to decrease our appetite. “Proteins are the most satiating of the nutrients,” says David Cameron-Smith, a scientist at the Liggins Institute in Auckland.
In a 2011 study at the University of Sydney, people on a 15 percent protein diet were found to snack less between meals than people on a diet with ten percent protein. The researchers said one possible explanation is the theory that all animals have a fixed amount of protein that they will keep munching towards before they feel full – regardless of how much carbohydrate and fat they eat along the way. It’s a theory known as the ‘protein-leverage hypothesis’.
And so, to bust another myth. Protein plays a critically important role in the diet of all of us, not just grown men: it’s vital for everyone from children and busy women to adolescents and the elderly.
Recent research suggests protein is particularly crucial for those approaching their mid-40s and beyond, because we can start to lose our muscles from that time on.
“Muscle mass, which then influences body tone, starts to go down from age 35,” says Cameron-Smith. “Most people don’t start becoming aware of that subtle change until their mid-40s, but certainly by the time they get into mid-50s it is very visible both to the person and to everyone else how their body has changed. They don’t look like the spunk they thought they did when they were in their 20s and 30s. It’s sad but true.”
Looks aside, protein has far more fundamental effects on mobility and life satisfaction. In recent surveys carried out by the research division Fonterra Nutrition, adults aged 50-75 who supplemented their diet with 20g of protein at breakfast and lunch for three weeks felt a measurable increase in strength, sustained energy and increased movement.
When should you be upping your protein level?
A higher-than-normal protein intake is necessary in some cases. We need to be vigilant if we’re on a low food-intake diet, if we’re pregnant or lactating, if we’re training hard (especially after exercise, when our aching muscles are crying out for protein and are particularly able to absorb it), if we are at risk of developing obesity or diabetes, if we have an illness (such as cancer) or an injury, or if we’re elderly or adolescent. Or maybe we’re so run off our feet that sometimes it’s just easier to eat a bread roll rather than spend time cooking an egg or preparing meat.
Are you getting the right type of protein?
Over the last decade we have discovered that as well as quantity, it’s the quality that matters. “Just as we discovered in the 1960s that oils aren’t simply oils (there are many types, good and bad), we are increasingly discovering that proteins ain’t just proteins,” says Cameron-Smith.
Meat, poultry, seafood, dairy, soy and other plant sources are all absorbed, and used, differently by your body. And they either meet your unique needs (in terms of required amino acids) or they don’t.
Amino acids join together to make protein, and there are 20 amino acids in existence. Nine are essential for us to consume because they cannot be synthesised by our bodies. A complete protein contains all essential amino acids.
Kiwi scientists at the Riddet Institute in Palmerston North have helped develop a brand new way of rating protein, and an important outcome is that animal protein comes up trumps.
The new method pinpoints the efficacy of protein sources more accurately than before, and it has shown that the protein in soy (although it is a complete protein) and other plant sources is less digestible, and has less essential amino acids, than the protein in dairy. Milk protein concentrate, for example, is rated about 30 percent higher in quality than soy.
“Counting calories is not enough to manage appetite and body weight in the Western world, where food is abundant.
If you reduce your calorie intake but fail to reach your protein target, you will find it hard to resist hunger pangs.”
– University of Sydney nutrition specialist Professor Steve Simpson
However, a balanced diet is always necessary to get a full range of vitamins, minerals and fats, so we should think about combining various sources of protein within a meal.
“When you eat, say, milk and bread, you come up with a very balanced diet. This is because the wheat proteins are deficient in certain amino acids, and the milk has got surplus amounts of those mino acids – so together they are a very nice balanced food,” says Professor Paul Moughan of the Riddet Institute.
“If you have a meal that’s just a mixture of beans and bread without high-quality proteins, you end up with a meal that’s more poorly balanced and won’t be as well used.”
Added to a diet, high-quality protein is “beneficial in bringing about a balanced intake of amino acids. Egg, dairy and meat all came out really well on the new scoring system,” says Moughan. “Soya is not bad for you, but not as powerful as some others in forming a balanced protein diet.”
Vegetarians and vegans need not despair – but they must carefully plan their diets. Quinoa has taken the healthy living market by storm because it is a complete (and non-meat) protein. Otherwise, combining complementary protein sources is the best way to get complete protein.
Take, for example, corn and beans: corn is missing the amino acid lysine but is high in methionine, while beans lack methionine but are high in lysine. The Mexicans sure knew what they were doing.
To cook or not to cook?
The way a protein has been processed or cooked can make it easier or more difficult to digest. An egg is a great example – through cooking, it is changed from poor- to good-quality protein, even though it’s still made of the same components! A Journal of Nutrition study found 91 percent of protein from cooked eggs is absorbed, while only 50 percent of raw egg protein is absorbed.
But in other protein sources, says Moughan, the opposite effect occurs. For example, raw meat is quite digestible, but the more it is cooked, the less digestible it becomes. The amino acids in raw soya beans are poorly digestible. If it’s treated at the right temperature, digestibility levels are good; but if it’s overheated, digestibility and quality will plummet. As pieces of the protein puzzle become clear, one fact remains: all bodies are different, so eat what works for you.
Are we getting enough?
Severe protein deficiency is rarely seen in New Zealand. In the worst cases of malnutrition (such as those occurring in parts of Asia, Africa and Latin America), a lack of protein causes severe muscle wasting, a swelling of the extremities and belly, liver enlargement, and depigmentation of skin and hair.
Protein’s essential, but you needn’t go overboard on it (apart from some cases – see next page for details). For most adults, a typical Western adult diet that includes 11-15 percent protein is generally sufficient.
The New Zealand Ministry of Health says the main sources of protein in our diets are meat, poultry and fish (about 33 percent), cereals and cereal-based foods (about 25 percent) and dairy foods (about 16 percent). Vegetables provide about eight percent protein.
The key questions for most of us are: what’s the right amount for our body’s needs, and which are the best sources?