Protein powder is popular because it’s a super quick and convenient way to get this important macronutrient. The amino acids that makeup protein primarily have a structural role and are only a secondary energy source during periods of starvation or intense exercise. You also need a certain amount of protein to stay in positive nitrogen balance and avoid a catabolic state.
No wonder protein supplements are popular! Scoop the powder into a glass, add liquid, and you have a quick protein snack. But is the focus on supplemental protein overkill? It’s true that certain groups of people can benefit from more protein in their diet. People who are physically active need more than sedentary folks and there’s some evidence that the elderly need more protein in their diets even if they aren’t that active. However, a new study suggests it may not be wise to mix up a concoction of amino acids, particularly branched-chain amino acids, after every workout. Here’s why.
Why Taking Protein Supplements Could Be Harmful
One of the most popular supplements people take for building muscle is supplemental branched-chain amino acids. The reason? Branched-chain amino acids turn on muscle protein synthesis, especially an amino acid called leucine. They do this by activating the mTOR pathway, the most important pathway by which muscles synthesize new muscle protein. Turning on mTOR helps with muscle hypertrophy.
When you take branched chain protein supplements, you get these three amino acids in an isolated form. In contrast, you can now purchase protein supplements that contain all nine essential amino acids, the amino acids your body needs but can’t make. Based on a new study, a more balanced ratio of amino acids may be better for your health. Here’s why.
What a Study Showed about Branched Chain Amino Acids
Researchers at the University of Sidney recently conducted a study on mice. While humans are different from mice, this study raises concerns about consuming large amounts of supplemental protein powder. In the study, mice ate varying amounts of branched-chain amino acids (BCAA) and other amino acids over the course of a lifetime. Some got the standard amount of amino acids, including branched chain ones, while others got double the amount of branched-chain amino acids on a daily basis. Others got half or even a fifth of the recommended amount of BCAAs.
When researchers followed the mice over time, they found those who got the most branched chain amino acids lived a shorter lifespan. They also had a higher rate of obesity and ate more food than their counterparts that got less branched chain amino acids.
Why might this be? Consuming large amounts of branched chain amino acids, or BCAAs creates an imbalance of these amino acids relative to non-branched chain amino acids. Two of these are threonine and tryptophan. The theory is that branched chain amino acids compete with tryptophan for entering the brain. With overconsumption of branched chain amino acids, less tryptophan enters the brain. This leads to a lowering of serotonin and an increase in appetite. Another downside to less tryptophan entering the brain is the impact it has on mood. Not only does serotonin impact appetite and the desire to eat, but lower levels are also linked with depression.
Of course, we can’t necessarily say these results apply to humans. However, there is evidence that diets rich in BCAAs have similar effects in humans. For example, a study found that higher levels of BCAAs in the blood were associated with the onset of insulin resistance. In fact, researchers are looking at whether levels of BCAAs in the bloodstream may be a helpful biomarker for predicting insulin resistance in people who are obese.
Other Reasons to Limit Protein Supplements
The protein powder you buy at the supermarket or health food store may contain some surprises. When the Clean Label Projected tested more than 134 popular protein powders, all were contaminated with one or more heavy metals. Plus, over half contained bisphenol-A (BPA), a chemical in packaging that may be a hormone disruptor. Surprisingly, organic brands contained even more heavy metals than conventional ones.
Any time something is so highly processed, there’s the potential for contamination. Many whole foods, both animal and plant based are good sources of protein and they’re in an unprocessed form. Also, it’s best to vary the protein sources you consume to avoid imbalances in amino acids and an overabundance of branched-chain amino acids. As this study shows, taking large quantities of branched-chain amino acids in isolation may have downsides.
If you must consume protein powder, choose an amino acid supplement that contains all nine essential amino acids and isn’t a concentrated source of BCAAs. Remember, amino acids compete with each other to get into the brain. If you flood your body with BCAAs, other amino acids may not make it as easily across the blood-brain barrier. Such an imbalance can, at least in rodents, trigger unfavorable changes in appetite and mood.
Keep Your Diet Balanced
You need more protein if you do intense workouts, as much as double the amount that a sedentary people need, but don’t go overboard. Keep your diet balanced. After a workout, consume carbohydrates to protein in a ratio of 3 or 4 to 1. Choose a source of protein that contains a balanced array of amino acids. Also, don’t consume more than 30 grams of protein at once. Some research suggests it’s harder to absorb more than 20 to 30 grams at a time. Plus, large quantities of protein, especially protein powder, can cause nausea in bloating in some people.
· Science Alert. “This Mouse Study Shows Why You Shouldn’t Overdo The Protein Supplements”
· Nature Metabolism (2019) “Branched-chain amino acids impact health and lifespan indirectly via amino acid balance and appetite control”
· J Diabetes Res. 2016; 2016: 2794591.
· J Physiol. 2018 Feb 15;596(4):623-645. doi: 10.1113/JP275075. Epub 2017 Dec 27.
· Clean Label Project. “2018 Protein Powder Study”