Consuming too many protein supplements could be doing you more harm than good

Getty/Peter BerglundRelying too heavily on protein shakes and supplements could be doing you more harm than good.
  • A new study claims done on mice suggests that consuming too many protein shakes and supplements may have harmful side effects.
  • Research from the University of Sydney concluded that relying too heavily on BCAAs (branched chain amino acids, which are found in protein shakes) may reduce lifespan, and cause weight gain and a lower mood.
  • The key advice is to make sure you get your protein from a variety of sources, as this will ensure you’re consuming the right balance of all nine essential amino acids.
  • Visit INSIDER’s homepage for more stories.

Thanks to the current vogue for fitness, the protein supplement industry is booming.

From bars and BCAAs (branched-chain amino acids) to shakes and even chocolate, there are seemingly endless protein-boosted products on the market to help you get your post-workout fix.

But a new study done on mice now suggests excessive protein consumption may ultimately be doing us more harm than good.

Researchers at the University of Sydney found that although protein is great for building muscle, consuming too many protein supplements could reduce lifespan, negatively impact mood, and lead to weight gain.

Though the study wasn’t done on humans, their main conclusion was that protein products aren’t necessarily bad for you, and protein is essential for repairing muscle, but you need to make sure you vary your protein sources and don’t rely too heavily on one.


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“While diets high in protein and low in carbohydrates were shown to be beneficial for reproductive function, they had detrimental effects for health in mid-late life, and also led to a shortened lifespan,” said lead study author Dr Samantha Solon-Biet.

“What this new research has shown is that amino acid balance is important – it’s best to vary sources of protein to ensure you’re getting the best amino acid balance.”

What are BCAAs?

There are 20 amino acids in total, nine of which are essential. If your diet contains enough of those, your body can make the 11 others itself.

BCAAs are essential amino acids found in foods containing protein, such as red meat, dairy, chicken, fish, and eggs, as well as beans, lentils, nuts, and soy proteins.

They are made up of three of the nine essential ones: leucine, isoleucine, and valine. These are broken down in muscle, whereas the other essential amino acids are mainly broken down in the liver.


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While whey protein powders are typically high in BCAAs, many gym-goers consume BCAAs separately as well, usually in the form of a powder added to water – this is likely the translucent liquid you may see fitness fans sipping during their workout.

Unlike protein powders, BCAAs contain no carbohydrates or fats, but they actually tend to be higher in calories.

The idea is that consuming BCAAs throughout the day will contribute to muscle growth, boost workout performance, and aid recovery, but many in the fitness industry think they’re unnecessary.

Some fitness companies have even launched EAA (essential amino acid) products containing all nine essential amino acids instead of just the three found in BCAAs.

“The biggest difference between BCAA and EAA is that BCAA contains a 4:1:1 ratio of three essential amino acids whereas EAAs deliver a superior blend of all nine essential amino acids that your body can’t make itself,” Dawid Lyszczek, New Product Developer at Myprotein, told INSIDER.

What did the study find?

The researchers examined the impact of BCAAs and other essential amino acids such as tryptophan on the health and body composition of mice.

Some were given twice the normal amount of BCAAs needed for life, others the standard amount, others half, and others a fifth.

It was found that the mice who were fed the most BCAAs increased their food intake, which led to obesity and a shortened lifespan.

What’s more, consuming high levels of BCAAs appeared to block tryptophan getting to the brain, which is known to boost mood.


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“Supplementation of BCAAs resulted in high levels of BCAAs in the blood which competed with tryptophan for transport into the brain,” explained Stephen Simpson, Academic Director of the Charles Perkins Centre, researcher from the School of Life, and Environmental Sciences Professor .

“Tryptophan is the sole precursor for the hormone serotonin, which is often called the ‘happiness chemical’ for its mood-enhancing effects and its role in promoting sleep. But serotonin does more than this, and therein lay the problem,” he said.

“This then lowered serotonin levels in the brain, which in turn was a potent signal to increase appetite. The serotonin decrease caused by excess BCAA intake led to massive overeating in our mice, which became hugely obese and lived shorter lives.”

What does this mean for us?

Registered dietitian and author of “The Low-Fad Diet” Jo Travers BSc RD MBDA believes the first thing to note is that the study was conducted on mice, and so the takeaways can’t be directly applied to humans.

“However, it does raise an important point about the roles of each nutrient and that balance is important,” she told INSIDER.

Travers stresses that eating a balanced diet should be your main priority.

“Getting a range of all foods – not just proteins – is important,” she said.

“For example, eating protein with carbohydrates stimulates the uptake of other amino acids to the muscles leaving tryptophan free to cross into the brain unimpeded, allowing more serotonin to be made.

“I think the thing to take from this is to get variety in your diet and get the balance right.

“Fill half your plate with veg, a quarter with carbs and a quarter with protein and the chances of you getting everything you need and not too much of what you don’t is really high.”

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