Branched-chain amino acids, or BCAAs, are a triad of essential amino acids: leucine, isoleucine, and valine. These amino acids are vital for several physiological functions, such as muscle growth and repair. They are particularly effective at reducing muscle soreness and fatigue during exercise. If you are into fitness, BCAAs are a supplement you should consider adding to your routine.
BCAAs can enhance muscle growth and reduce muscle fatigue and soreness, the reason why they are so popular among athletes and fitness enthusiasts. They can also be an alternative energy source in the absence of glucose.
Excessive levels of BCAAs in the blood strain the liver and kidneys, causing long-term harm. Additionally, it can interfere with insulin sensitivity and potentially lead to elevated blood sugar levels, increasing the risk of type 2 diabetes onset. 
People with a rare genetic condition known as maple syrup urine disease should restrict their consumption of BCAAs since their bodies cannot metabolize them correctly.
High levels of BCAAs also have been linked to an augmented risk of heart disease as they can contribute to the build-up of plaque in the arteries and the disruption of the balance of other essential amino acids.
Bear in mind that these downsides are only from the overuse of BCAAs. Most people experience no adverse reactions when consuming the correct dosage. However, if you do experience any side effects, discontinue use and consult a healthcare professional.
The recommended dosage for leucine is between 2 and 10 grams, while for isoleucine, it is 48-72 milligrams per kilogram of body weight for individuals who are not obese. More studies are required to determine the optimal dose for valine supplementation.
A combination dose of BCAAs typically involves taking 20 grams of the three amino acids with a balanced leucine and isoleucine ratio. Adequate dietary intake of BCAAs eliminates the need for BCAA supplementation.
Limited research is available on the effects of taking BCAAs before or after exercise. One small study found that taking BCAAs before exercising resulted in less muscle soreness and lower markers of muscle damage. Another study found no difference in body composition or strength between taking BCAAs before or after weightlifting workouts.
Studies have yet to determine the optimal time to take BCAAs, suggesting that the window time for maximum muscle-building benefits from consuming protein may be as far as 5 hours after exercise. Timing of BCAA or other protein supplements may be less significant if you have eaten a meal or taken a protein supplement 1-2 hours before physical activity. 
Taking BCAAs during endurance exercises, such as distance running and cycling, may not improve physical performance but may help reduce mental fatigue.
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