(CNN) – If you can’t get through your day without a coffee break or two, here’s good news for you: What scientists know so far suggests coffee may help you stay healthy.
As usual with medical research, the operative word is “may.”
It’s hard to know for sure whether coffee is really causing good effects – lifestyles or behaviors associated with coffee consumption may also influence health. Also, different people have different tolerances for coffee – it can have short-term side effects that make people steer clear of morning brews.
So, doctors aren’t quite convinced enough to prescribe coffee – but they probably don’t need to, because so many people indulge in it anyway.
The point is: In general, regular coffee drinkers won’t be discouraged from continuing the habit, although there are exceptions.
“For most people, for people who don’t experience the side effects, the benefits far outweigh the risks,” said Dr. Donald Hensrud of the Mayo Clinic.
More is known about the overall association between coffee and positive health effects than about the mechanism behind it, said Dr. Alberto Ascherio, professor of epidemiology and nutrition at the Harvard School of Public Health.
Antioxidants are one potential reason that good outcomes are seen from coffee. Our bodies produce oxygen radicals, which are damaging to DNA. Antioxidants prevent them from doing damage, Ascherio said.
Although antioxidants are found in fruits and vegetables, research has shown that coffee is the top source of antioxidants for Americans.
Caffeine itself may also contribute to coffee’s positive effects on brain health. That may be because caffeine is an antagonist to adenosine receptors. These receptors normally slow down neural activity when the chemical adenosine binds to them, producing a sleepy feeling. But if caffeine binds to the receptors, the activity of neurons speeds up.
Coffee also appears to lower levels of insulin and estrogen, which is perhaps why a study last year found a lower risk of endometrial cancer in coffee-drinking women. Insulin also plays a role in prostate cancer, another disease coffee may help stave off.
The evidence is fairly strong for coffee preventing type II diabetes and Parkinson’s, and reasonably good for antidepressant effects, too, doctors say.
Just in the last few months, several new studies have been published highlighting other possible benefits of coffee. Again, none of them prove that coffee causes any effects at all; they are just associations.
Coffee drinkers may also be protecting themselves against basal cell carcinoma, the most common form of skin cancer, according to a July report in the journal Cancer Research. Other caffeinated beverages also seemed to reduce the risk of this slow-growing cancer. But scientists don’t yet know why this effect was observed.
Increased coffee consumption also is associated with longer life, according to Research in the New England Journal of Medicine. Again, no one knows what about coffee would make people live longer, but Ascherio theorizes it could be the protection against type II diabetes, Parkinson’s, depression and suicidal tendencies.
There have not been any large randomized controlled trials regarding coffee’s health benefits, or even to see whether caffeinated or decaf is better for you. Without this kind of research, there will be uncertainty.
While perhaps scientifically interesting, such an investigation hasn’t happened because of the economics involved, Ascherio said.
