Of all the potential mood-altering drugs in the world, none are more ubiquitous in American society than coffee and alcohol. Both are very easy to find almost anywhere, and generally have their dangers of addiction or possible health risks minimized, largely considered harmless beverages when enjoyed by adults.
What's interesting about this is that, on one level, coffee and alcohol have opposite effects on the brain. Alcohol is a depressant that slows down mental functioning, whereas caffeine is a stimulant that can raise your level of alertness. Because of these opposing effects, many people believe that one will cancel the other out. It is not uncommon to hear that a cup of coffee can undo some of the unwanted effects of heavy drinking.
For the most part this a huge and dangerous misconception, because it can lead to people underestimating the impact alcohol has on them. However, current research has suggested there is at least one way coffee can be of some benefit to those consuming alcohol.
Coffee doesn't reduce drunkenness
The only real way to totally eliminate the effects of alcohol on the body is time. True sobriety means that the alcohol you've consumed was able to leave the bloodstream and be either eliminated or absorbed into the liver, that breaks it down into a way that will not be toxic to the body. It will vary based on age, gender, and weight, but it generally takes around an hour for one unit of alcohol to be absorbed. There's nothing you can do to speed that process along.
Alcohol does not just interact with the body in one way, but impacts multiple parts of the brain, often in ways that can't be totally controlled or predicated. If alcohol is making someone feel drowsy, coffee can seem useful in helping him or her feel more awake and alert.
To the drinker, this may feel like "sobering up," but it's not, and it can be dangerous to not make this distinction. Reaction times, decision-making processes, inhibitions, and several other functions of the brain are still going to be impaired by the alcohol. In fact, simply counteracting drowsiness can increase the chances of risk-taking behavior, or of continuing to drink after you should, as you become less aware of how alcohol is truly impacting you.
Coffee and liver damage
However, emerging research does suggest there is one way that drinking both coffee and alcohol can interact in a surprising and possibly healthy way. A 2006 study at the Kaiser Permanente Hospital in Oakland, California looked at over 125,000 people, and discovered that drinking coffee on a regular basis can reduce the possibility of alcoholic cirrhosis of the liver, one of the most common serious health effects of heavy drinking.
Consuming large amounts of alcohol taxes the liver, which can sometimes cause the liver tissue to thicken and scar to the point of being unable to function. Without a properly working liver, the alcohol and other toxins simply remain in the body, which can be very dangerous.
Generally, a person who three or more alcoholic beverages a day will be 20% less likely of developing cirrhosis if they also consume one cup of coffee. The protective effect goes up to 40% for drinking two or three cups, and 80% for four cups. Interestingly, drinking tea did not have this effect, indicating that this effect is caused by something other than caffeine.
However, as mentioned before, alcohol does not just impact the body in a single way. Coffee may, for reasons yet unknown, protect a heavy drinker from liver disease, but the person who thinks coffee can "undo" the damage of heavy drinking will still be vulnerable to cancers, mood disorders, brain damage, and a reduced immune system.
In fact, when used excessively, both alcohol and caffeine can raise your blood pressure to unhealthy levels, and combining them could be extremely risky. Sobriety or controlled responsible moderation, (defined by the National Institute on Alcohol Abuse and Alcoholism as no more than 3-4 drinks per day and 7-14 drinks per week) are the only ways to truly protect yourself from the health risks of heavy drinking.