麻豆传媒

THE bars and shakes were just the start. These days, there are high-protein cereals and high-protein yogurts, protein-fortified bread and cheese, protein-dense noodles and even ice creams loaded with the muscle-building macronutrient. What next, protein water? Well, yes actually. What will it be: still, sparkling or diet whey protein water?

Stroll through your local supermarket today and you can hardly fail to notice the P word. Usually accompanied with 鈥渉igh鈥� or 鈥渆xtra鈥�, it seems to be emblazoned on the packaging of almost every foodstuff possible. Many of us have come to see protein as a sort of elixir of health. Not only does it apparently help you build muscle, it will guarantee weight loss by keeping you fuller for longer. Hence the desire for all those high-protein products. But is there actually any evidence to suggest that these foods and drinks are beneficial?

Our bodies certainly demand protein. Together with fat and carbohydrate, it makes up the trio of basic macronutrients that humans need. Proteins are assembled from a repertoire of 20 amino acids, the basic building blocks of bone, muscle, skin and blood. It is especially important that we get enough of the eight so-called essential amino acids because, unlike the others, our bodies cannot make them.

So the protein we get from our food is vital. We have known that for a long time. In recent years, however, many of us have become convinced we need more of the stuff.

Even if you haven鈥檛 come across Weetabix Protein Crunch, say, or the Mars Hi Protein bar, the stats are instructive. The number of food and drink products launched with a high-protein claim in the UK rose by a whopping 498 per cent between 2010 and 2015, according to market research firm Mintel. More recently, in the three years to 2017, the proportion of new food and drink products launched with a high-protein claim jumped from 1.8 per cent to 4.3 per cent, and in the first three months of 2018 some 35 per cent of adults said they bought a non-sporting product branded as high in protein.

All of which is a bit strange, because pretty much all of us are getting enough protein already. Daily average consumption of protein in the UK is 87 grams for men and 67 grams for women aged between 19 and 64. This is about 50 per cent more than they require, according to official guidelines (see 鈥�Protein: are you getting enough?鈥�). Based on the same guidelines, the majority of those who regularly run, swim or cycle are also getting enough protein. Only people routinely engaging in endurance, speed or strength sports may need more in their diet.

鈥淰irtually no one in the UK is eating too little protein,鈥� says Tom Sanders at King鈥檚 College London. 鈥淚t might be the case for a bed-ridden older person who is not eating enough food full stop, but in free-living individuals, protein deficiency is almost unknown.鈥�

Why, then, are so many people so hungry for an extra protein hit? Makers of protein supplements and shakes use words like 鈥渕uscle fuel鈥� on packaging and, in some cases, images of bulging biceps. Those selling protein-fortified food use ambiguous language, describing their products as 鈥渃ontributing鈥� to the 鈥渕aintenance鈥� of muscle mass. The intended message is clear: that consuming lots of protein will make you stronger. But they don鈥檛 say so explicitly, because they aren鈥檛 allowed to. In 2010, the European Food Safety Authority concluded that there was insufficient evidence to support claims that whey protein increased strength, muscle mass or endurance in the general population. This means the chances that opting for a high-protein version of your usual breakfast cereal, for instance, will make you stronger are somewhere between minutely small and zero.

The science is less conclusive for people regularly doing resistance training. Indeed, research on the effects of high protein intake on muscle mass and various measures of athletic performance is conflicting.

A concluded that protein supplementation didn鈥檛 augment the effects of resistance training in people over 70 years old. But , published in 2017, found that extra protein did have a positive effect on strength and muscle mass in adults of all ages who were asked to do weights-based exercise, although these gains were minimal in those who hadn鈥檛 previously done such exercise. Pooling data from 49 previous studies, the review concluded that extra protein did increase the maximum weight that people could lift, typically over the course of six weeks, compared with those taking either placebos or just getting their standard levels of protein. Then again, of the extra weight they could lift, just 8.5 per cent was down to the extra protein and the rest was attributed to exercise. Those people who did resistance training only, with no extra protein, added 27 kilograms to the amount they could lift. Those who did the same training and ate more protein could lift an extra 29.49 kilograms.

鈥淚f people go to the gym and lift weights with some kind of plan then their muscles will grow to a variable degree,鈥� says Stuart Phillips of McMaster University in Hamilton, Canada, who led the study. 鈥淓xtra protein adds an additional layer but it鈥檚 a much smaller contribution than just going to the gym.鈥�

That may be surprising to those people who believe their muscle gains are down to protein shakes. But it is a conclusion supported by nutrition and exercise researchers. 鈥淔or elite athletes, [supplemental protein] might give you an extra 3 to 4 per cent,鈥� says Stuart Gray at the University of Glasgow, UK. 鈥淔or most people, it won鈥檛 have a noticeable effect.鈥�

鈥淔or most people, extra protein won鈥檛 bring any noticeable strength gains鈥�

Another myth worth busting here is the notion that it is best to consume protein supplements or high-protein foods shortly before or after workouts. US researchers who reviewed previous studies on this in 2013 found to support the hypothesis that it increases strength or muscle mass.

The promise of strength gains isn鈥檛 the only thing driving the protein craze. The other big claim is that consuming more protein will help you lose weight. The idea is that by keeping you feeling full for longer, protein stops you from snacking. And it seems people are buying into that message. A by Mintel found that a quarter of people who consume high-protein food or drinks in the UK did so to lose or maintain weight, and 36 per cent said they thought their purchases would keep them fuller for longer.

Are they misguided? Here again the science isn鈥檛 clear-cut. Research has linked the consumption of protein to the release of compounds known as peptides in the gut that are associated with feeling full. However, a 2011 review of eight randomised controlled studies looking at this found there was that high-protein diets were better for weight loss than high-fat or high-carbohydrate diets. Unfortunately, comparing high-protein diets with other weight-loss strategies over the long term is hard because people can neither be imprisoned in laboratories, nor relied on to accurately report what they eat.

This means we often have to measure the effects of high protein consumption on short-term hunger, appetite or later food intake. Again, different approaches have generated different answers. But there is some evidence that consuming more protein can make people feel fuller. A studies found that people eating high-protein meals reported feeling fuller than those consuming lower-protein meals.

However, Richard Mattes at Purdue University in Indiana, who led the 2016 analysis, doesn鈥檛 believe that feeling fuller in the short term necessarily translates to long-term weight loss. That is because how much we eat depends on cultural factors, such as portion sizes and snacking behaviour, as well as how hungry or full we feel. 鈥淭he protein effect is also quite small,鈥� he says. 鈥淪o for it to play a meaningful role would require a substantial change of diet, which I believe is not sustainable for most people.鈥�

Ultimately, the jury is still out on the likes of the Atkins and Dukan diets and the use of protein-based supplements as ways to lose weight. 鈥淭here have been studies that show the successful use of high-protein diets for weight loss, but they have been no more effective than other diets,鈥� says Gray. 鈥淚t鈥檚 very individual. High-protein diets can work for some people, but what鈥檚 important is being able to stick to cutting calories.鈥�

Products touting extra protein can sometimes come laden with extra helpings of sugar, too (see 鈥�Read the small print鈥�). 鈥淢y worry with products like high-protein sugary cereals and high-protein chocolate bars is that people will assume they are healthy,鈥� says Gray. 鈥淧utting a bit of protein in a chocolate bar does not make it healthy.鈥�

Another thing that rarely gets mentioned is the risk associated with stuffing yourself full of protein. There are good reasons why the UK Department of Health advises adults to more than twice the recommended daily protein intake.

Too much of a good thing

When the body has more protein than it needs, the excess is broken down and waste products are filtered from the blood to be excreted as urine. Research, albeit mostly in animals, has suggested that greater protein intake increases the workload on the kidneys, which do the filtering, potentially leading to damage in the long term. This hasn鈥檛 been confirmed in human studies and some researchers are sceptical. However, randomised controlled studies, the gold standard when it comes to medical evidence, have shown that people with kidney disease who are put on low-protein diets are less likely to have renal failure or die from complications linked to their condition than those on normal diets.

Excess protein also leads to elevated levels of urea in the blood, and some research has linked consistently high levels to . A large, long-term study published in May 2018 that took into account other determinants of heart health, such as exercise and diet, seems to back this up. Finnish researchers found that men who reported high protein intake (an average of 109 grams per day) were more likely to experience heart failure than those who consumed the least (a daily average of 78 grams).

All of which makes you wonder: given the lack of evidence to support claims made for protein fortification, not to mention the risks, why the ever-growing demand?

Marion Nestle, a nutritional scientist at New York University, says our hunger for added protein has, in large part, been created by food companies. 鈥淐arbs are out, fats are out, and paleo and keto diets are hot right now,鈥� she says. 鈥淧rotein is all that鈥檚 left in the macronutrient category. These trends go in cycles. This is about marketing.鈥� Indeed, in her 2018 book, Unsavory Truth, Nestle argues that the food and drinks industry, especially those selling protein-heavy products such as meat and dairy, has distorted nutrition science by, for example, publishing only results that are useful in marketing their products.

So despite what you read on supermarket shelves, or in the fitness magazines that have played a big role in driving the craze, you probably don鈥檛 need more protein. Indeed, given the way the body deals with the excess, most people who splash out on high-protein water, or any other products from the ever-growing protein-fortified range, might just as well flush their money down the toilet.