Science reveals more good news about the world's second favorite drink.
Coffee drinkers live longer. It's a fact. They have fewer diagnoses of cancer, diabetes, Parkinson's, and Alzheimer's. They don't stroke out as much, they're not as depressed, and their livers don't get as fatty.
Of course it may just be that grim-faced SOBs who are willing to stand in line at Starbucks for 20 minutes like pre-schoolers lining up for their sippy cup are just too damn stubborn to die.
It's more likely, though, that coffee's long list of health benefits has more to do with some of the over 1,000 biologically active compounds (most of them polyphenols) it contains.
The actions of these compounds have even been found to extend to skeletal muscle as the especially noteworthy coffee polyphenols – chlorogenic acid and caffeic acid – have proven to increase glucose transport to muscle by activating AMPK, the cellular master switch.
Other studies have shown coffee to increase satellite cell recruitment and subsequently accelerate the regeneration of injured skeletal muscle cells. One study involving 2,578 older Korean women even found that coffee consumption was inversely related to sarcopenia (loss of muscle tissue).
However, few, if any, studies have looked at coffee's effects on skeletal muscle function and hypertrophy... until now. According to the findings, coffee can now list muscle and strength building on its impressive resume.
What They Did
The researchers procured 30 mice and strictly regulated their environment. They got 12 hours of daylight and 12 hours of darkness. The temperature stayed the same. The activities of the mice were restricted to playing craps or reading the mouse aspirational novel, "Flowers for Algernon."
More importantly, they were given unrestricted access to food and water. One group ate a normal, unsullied diet. The second group ate essentially the same diet, only it was supplemented with 0.3% coffee. The third group's food was supplemented with 1% coffee. The animals stayed on the diet for 7 weeks and were weighed weekly.
What They Found
Coffee, in a dose-dependent manner (the bigger dose had bigger results), increased gastrocnemius muscle weight and muscle fiber size. Likewise, the weights of the quadriceps, tibialis anterior, and extensor digitorum longus all increased in weight (but not fiber size).
Perhaps curiously, the coffee for some reason had no effect on triceps and soleus muscles. The 1% dose, unlike the 0.3% dose, had the additional benefit of increasing grip strength in the mice. As far as fat levels, the coffee didn't alter levels of subcutaneous fat or epididymal (fat around the heart and organs).
In short, coffee increased muscle function and skeletal muscle hypertrophy in the mice. The researchers noted several causes, all at the biochemical level. The coffee elevated the expression of PGC-1-alpha, which improves muscle function and decreases fatigue.
Other contributing factors included suppression of myostatin (the less myostatin expressed, the more muscular growth) and an uptick of IGF1, a premier muscle growth factor.
What This Means to You
If you convert the dosage of coffee (note that it's coffee, not caffeine) used in the experiment from mice to humans, you get 27 mg/kg for the low dose and 81 mg/kg for the high dose. For a 200-pound man, that translates to about 2 cups a day (for the low dose) to about 4 and a half cups a day (for the higher dose).
Let's look at this realistically, though. You're not likely to develop any noticeable or appreciable amounts of muscle if you suddenly up your coffee intake from 2 cups a day to 4 or more.
I suppose it's possible, though, based on this experiment, to maybe experience some slight benefit to muscle size and strength if you're coffee naive, i.e., if you're not being exposed on a regular basis to coffee or the coffee polyphenols chlorogenic acid and caffeic acid (or any other polyphenols that might play a role in this phenomenon).
However, the takeaway from this study should probably be that there are plenty of good reasons to drink coffee every day and this is just another one. That, and cholorogenic and caffeic acid might be worthy of consideration as standalone supplements.
- Young Jin Jang; Hyo Jeong Son; Ji-Sun Kim; Chang Hwa Jung; Jiyun Ahn; Jinyoung Hurac; and Tae Youl Ha, "Coffee consumption promotes skeletal muscle hypertrophy and myoblast differentiation," Food and Function, 15 Jan 2018.