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By Mary Carpenter
COFFEE drinking has moved past its old bad rap to boast a myriad of health benefits—some immediate, such as faster glucose processing that leads to decreased risk for type 2 diabetes; and other benefits over time, such as lowering risks of heart failure and stroke, according to Johns Hopkins medicine. “For women, drinking at least one cup of coffee a day is associated with lowered stroke risk…the fourth leading cause of death in women.”
In addition, “coffee drinkers — decaf or regular—were 26 less likely to develop colon cancer,” reports the Hopkins team. And coffee may lower the risk of all cancers by strengthening DNA —thereby reducing breakage in strands that “can lead to cancer or tumors if not repaired by your cells.” Coffee drinkers are also more likely to have liver enzymes within a health range than those who don’t drink coffee.
“The overall evidence has been pretty convincing that coffee has been more healthful than harmful in terms of health outcomes,” said Harvard Nutrition Department Chair Frank Hu. In an interview with Discover magazine, Hu said “moderate coffee intake —two to five cups a day—is linked to a lower likelihood of type 2 diabetes, heart disease, liver and endometrial cancers, Parkinson’s disease, and depression. It’s even possible that people who drink coffee can reduce their risk of early death.”
“One of the most striking findings is that coffee drinkers are less prone to developing type 2 diabetes,” according to the Washington Post. “Many large studies have found that people who drink three to four cups of coffee daily have about a 25 percent lower risk of the disease compared with people who drink little or no coffee. Your likelihood of developing diabetes decreases about six percent for each cup of coffee you consume daily—but only up to about six cups.”
Most notable may be coffee’s ability to lower risk of neurodegenerative diseases, such as Alzheimer’s and Parkinson’s—and with the latter, to slow progression of the disease—when these are “caused by lifestyle and environmental factors, including age, obesity, and pesticide exposure,” according to biophysicist Mahesh Narayan at the University of Texas, El Paso. Narayan explained that “caffeic acid’s anti-inflammatory and antioxidant properties may help combat the effects of lifestyle and environmental factors that increase the risk of such disorders.”
To understand how coffee might work in the cells, researchers synthesized caffeic-acid-based Carbon Quantum Dots (CACQDs) from coffee grounds, ‘bite-sized’ nanoparticles…from carbon-containing precursors such as fruit peel, waste paper, and even salmon,” Narayan explained. But he warned that while coffee may be beneficial for most cases of neurodegeneration that occurs with Parkinson’s and Alzheimer’s disease —it is likely to be effective when these are are caused by genetic or familial disorders.
“Clinical symptoms (and therefore the clinical diagnosis) of neurogenerative disorders start years or even decades after the pathophysiological processes have been initiated,” according to UT Health Houston neurologist Natalie Pessoa Rocha. “Because of the very limited capacity (or no capacity) of neurons to regenerate, disease-modifying treatments must focus on preventing neuronal dysfunction/neuronal death.”
As for immediate effects of coffee, an individual’s physiological response depends in part on genetic inheritance. About half of the population, labeled “fast-metabolizers,” feels coffee’s effects more quickly—and because coffee passes through the body quickly, fast-metabolizers can tolerate greater quantities, and thus experience more of caffeine’s health benefits, University of Toronto researcher Sara Mahdavi told CBC radio news. In her study of more than 1,100 people ages 18 to 45 with early hypertension over a 16- year period, the more coffee consumed by fast-metabolizers, the more their rate of heart attack went down.
Fast-metabolizers also experienced no ill effects on kidneys—regardless of the amount of coffee they drank, which was “really quite miraculous,” said Mahdavi. In contrast, slow-metabolizers, who have greater sensitivity to caffeine, exhibited decreased kidney function based on three markers, including hypertension.
“There’s some people they have a sip of coffee, and they get really amped up and over-jittery,” geneticist Thomas Merritt at Laurentian University told the Canadian Broadcast Company. Health Canada guidelines recommend a limit of 400 milligrams of caffeine per day: an eight ounce-cup contains 118 to 179 milligrams, depending on the brew, with a double shot of espresso containing about 150 milligrams.
With molecules similar to those of the neurotransmitter adenosine, caffeine binds to adenosine receptors —which “turns off the sleep pathway and turns on a wake-up pathway instead,” Merritt told the CBC. Caffeine also provides “a hit of dopamine..sends messages of pleasure to the brain.”
For the healthiest coffee, use paper filters, notes Harvard’s Hu. “Unfiltered coffee is associated with higher rates of early death and can contain compounds that raise levels of LDL cholesterol.” Adding cream or sugar can also detract from coffee’s benefits.
My 23andMe profile listing me as a fast-metabolizer stated that moderate amounts of caffeine could have less effect on me—also that I might have “significantly higher anxiety levels after moderate caffeine consumption.” Whether due to anxiety or caffeine jitters, more than one cup usually feels too speedy. And about the one sugar dot added to my morning cup, I tell friendly critics about how my fast-metabolizer’s better glucose processing might help combat health risks.
—Mary Carpenter regularly reports on topical subjects in health and medicine.