Smoking is bad for almost everything, and that includes our muscles. But what does science say about how smoking affects your body? Researchers at Nara Medical University in Japan have made an interesting discovery for bodybuilders and other strength athletes who still smoke: BCAA supplements can help counteract the negative effects that smoking has on muscles.
Does smoking affect muscles, and what role does BCAA play in this?
Muscle cells of smokers produce more myostatin, a protein that inhibits the growth and differentiation of muscle tissue. Researchers at the Copenhagen Muscle Research Center found this when they compared the quadriceps muscle cells of 8 smokers and 8 non-smokers. Researchers compared the muscle cells of smokers who smoked more than 20 cigarettes per day with the muscle cells of non-smokers of the same age. The subjects did not engage in sports. Before taking a sample of cells from the muscles of the subjects’ thighs, the researchers gave the subjects a dose of labeled leucine. This allowed them to see whether the cells absorb amino acids and whether they integrate into muscle protein, that is, whether they are used for synthesis.
Smoker’s cells absorbed amino acids in the same way as non-smokers did. But muscle protein synthesis was lower. “Smoking is a powerful inhibitor of the synthetic apparatus of muscle protein,” the researchers conclude in their study.
Smoking also stimulates the formation of end products of glycation in the muscles, thereby reducing muscle strength. The Japanese were curious if the muscle-reducing effects of smoking were in any way related to BCAA. Maybe smokers’ muscles absorb less BCAA? And if so, can smokers maintain muscle strength by taking a BCAA supplement?
To answer these questions, researchers from Japan developed an animal experiment in which one group of young rats was exposed to cigarette smoke for four weeks, and one group was not exposed. In both groups, half received standard food, and the other half received food to which BCAAs were added. BCAA-fortified foods contained approximately the same amount of amino acids as standard foods, but in a qualitative ratio, the emphasis was shifted in favor of BCAAs (12.5% of the total amount of protein was replaced by BCAAs).
Rats that inhaled cigarette smoke became less fast. This was partly due to the fact that they began to eat less.
The addition of BCAA did not normalize the decrease in the smoking rate of rats, but it counteracted the negative effects of smoking on muscle mass. The figure below shows the calf muscle weight in four groups.
The Japanese found that smoking lowers the concentration of BCAAs in the blood. Adding BCAAs can negate the smoking effect and restore the amount of BCAAs in the bloodstream.
The muscles of animals that inhaled smoke also contained less BCAA. That’s why their muscles were smaller than other laboratory rats. The addition of BCAA also normalized the amount of these amino acids in rat muscles.
In 2011, researchers published the results of another animal experiment in which they studied the effects of cigarette smoke.
In this experiment, they observed that exposure to tobacco smoke causes the immune cells in the gut to use more glutamine. This may explain why BCAA decreases as a result of exposure to cigarette smoke: smokers use more BCAAs to synthesize glutamine.
How smoking affects your body: Conclusion
“In conclusion, it should be noted that skeletal muscle depletion caused by cigarette smoke was associated with a decrease in skeletal muscle BCAA levels, while a BCAA-rich diet can improve cases of cigarette smoke-induced skeletal muscle depletion,” the researchers concluded.
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