Walk into your local GNC and you'll see all the latest supplements to hit the market, all claiming to be the missing link you need in your dietary regimen to attain those elusive gains you've been searching for. Among these products are branched-chain amino acids (BCAAs.)
BCAAs have come to be revered as one of the holy grails of muscle growth and recovery. Amino acids are the building blocks of protein, and subsequently of muscle (in addition to hair, nails, skin, etc).
There are 20-22 total amino acids, and our body can synthesize some of these to rebuild tissue, but there are just 9 "essential" amino acids (EAAs). Our body cannot obtain these "essential" amino acids from our diet. Three of the 9 essential amino acids make up BCAAs.
What makes these so special? Leucine, in particular, is the key amino acid that stimulates muscle protein synthesis (MPS) by activating a protein called the mammalian target of rapamycin, or mTORC1.
For this reason, BCAAs have become a staple for many gym-goers. They usually consume them immediately post-workout or even throughout the day to maximize muscle gain. BCAAs have also been touted for improving immune function, increasing energy, recovery, reducing DOMS and even increasing cognitive function. However, many of these claims are confounding.
What Does the Research Say?
We need Leucine, as well as the other two branched-chain amino acids in our diet, in order to stimulate muscle growth. So if BCAAs are primarily responsible for activating our MPS, we should just consume more of them and rest easy knowing we've done ourselves a favor, right? Not so fast. More of something good doesn't always equate to "better."
Competitive Inhibition of Amino Acids
One problem with consuming only BCAAs is that they can compete for absorption with other important amino acids.
High doses of BCAAS can reduce production of the neurotransmitter serotonin, by limiting uptake of its precursor, tryptophan, in the brain.
This can be beneficial while exercising, since serotonin can induce fatigue. However, serotonin is also important for regulating anxiety, mood and attenuating depression-like symptoms.
Furthermore, BCAAs also inhibit tyrosine uptake into the brain, and thus catecholamine synthesis. And since brain catecholamines enhance physical performance, BCAA ingestion could actually reduce performance.
BCAAS for Gains?
Aside from the potential reduction in performance, the high quantities of BCAAs can inhibit absorption of the other EAAs, which are also crucial for MPS.
One study even showed a DECREASE in levels of muscle protein synthesis when BCAAs were ingested intravenously. But another study showed an increase in MPS post-workout when BCAAs were consumed. However, the increase was only transient and not as high as consuming BCAAs along with the rest of the EAAs.
Simply put, you need all the necessary building blocks to maximally stimulate MPS.
BCAA supplementation seems to be a better strategy in increasing recovery and decreasing muscle soreness following intense exercise. A study showed a decrease in plasma levels of Creatine Kinase (an indicator of muscular damage), which could be promising for athletes that are required to train frequently.
Essential Amino Acids
As previously shown, BCAAs alone are not enough to sustain MPS without the other EAAs. So should you consume EAAs instead? What about whole protein sources like whey?
When you eat protein, it will be broken down into amino acids by various enzymes and other chemicals in your stomach. EAAs are already in their most simple form, so they don't need to be broken down further. Thus, they are more readily absorbed than normal protein.
In addition, by consuming all the EAAs instead of just a few, you can prevent imbalances.
Choosing between EAAs and a complete protein source comes down to whether or not you can digest the protein, and in what time period do you need it digested by (e.g., prior to or after training).
A complete protein source contains all the essential, as well as non-essential amino acids. Most animal products are complete proteins, meaning they contain all EAAs.
Whey protein is largely regarded as the most effective for stimulating MPS, but not everyone can digest it properly, as it does cause GI distress in some.
Optimal EAA Usage
Research shows that ingesting 8-10 grams of EAAs is optimal for stimulating MPS. You can also obtain that amount of EAAs by consuming roughly 20-25 grams of high-quality whey protein.
One particular advantage of consuming EAAs over whey or another protein source is their rapid digestibility. Because they're already in their most simple form, they can act as an immediate stimulus for MPS.
EAAs While Fasting
The practice of fasting, particularly intermittent fasting, has been popularized as of late. Although you are technically not fasting once you consume any calorie-containing substance, the caloric load of EAAs is minimal. And since they are able to stimulate MPS to a great extent, they can limit excessive muscle protein breakdown while training in a fasted state.
- Consume 8-10 grams of EAAs 30-60 minutes prior to training in a fasted state
- Consume 8-10 grams of EAAs, or 20-30 grams of a complete protein source following training
The New Holy Grail of Muscle Building?
Although the benefits of EAAs outweigh those of using BCAAs, don't get caught up in the same game. We've all seen that "one guy" sipping his BCAAs throughout the workout, or even throughout the day to remain "anabolic." The truth is, our body is constantly in a state of muscle protein breakdown (MPB), as well as muscle protein synthesis. Both are necessary processes. As long as your MPS is greater than your MPB, the result will be greater gains. You can achieve a greater net MPS by having an adequate total protein intake, as well as performing resistance exercise, which elevates MPS levels even further. Aim for consuming 20-40 grams of protein or 8-10 grams of EAAs every 3-5 hours.
All supplements have their own shortcomings, so consult your registered dietician for specific recommendations. Don't rely on any one supplement, especially not excessively, and make sure to maintain a balanced nutritional regimen. It's important to note that the supplement industry is not well-regulated. Many of these products contain fillers, artificial sweeteners and other ingredients that we have not studied long term. Make sure to go with brands that are 3rd party tested. Companies such as USP (United States Pharmacopeia), NSF International or Consumer Lab perform rigorous tests to make sure products meet quality standards.
The gains from consuming BCAAs seem to be marginal at best, so you may be better off saving your money. BCAA supplementation also seems to be most beneficial in increasing post-workout recovery for those who are very active, but they can also create imbalances if taken in high quantities. EAAs may be a better option than just BCAAs by providing all the building blocks your body needs. However, consuming whole protein sources includes not only the BCAAs, but also EAAs, the rest of the non-essential AAs, as well as other nutrients that also aid in fueling your body. As is always the case, a proper diet is always the most effective way to augment gains.
SuJean Choi, Briana DiSilvio, Madelyn H. Fernstrom, John D. Fernstrom. Amino Acids, 2013, Volume 45, Number 5, Page 1133
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Jackman SR, Witard OC, Philp A, Wallis GA, Baar K, Tipton KD. "Branched-Chain Amino Acid Ingestion Stimulates Muscle Myofibrillar Protein Synthesis following Resistance Exercise in Humans." Front Physiol. 7;8:390, 2017.
Howatson, Glyn et al. "Exercise-induced muscle damage is reduced in resistance-trained males by branched chain amino acids: a randomized, double-blind, placebo controlled study," Journal of the International Society of Sports Nutrition vol. 9 20. 12 Jul. 2012, doi:10.1186/1550-2783-9-20.
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