It's said that 180 million Americans begin their day with a cup of coffee. And with a coffee shop on almost every corner in the cities, many of us enjoy it all day long. There are many misconceptions, rumors, and half-truths about the risks and benefits. I will explain both sides, but I am also biased since I drink at least three cups throughout the day.
Caffeine is the most commonly consumed psychoactive substance in the world. After a recent trip to Europe, I think the most common European treat is a frappe (iced coffee) with a cigarette. It makes people feel less tired and increases their energy levels. This is because it goes through a pathway that increases brain neurotransmitters like norepinephrine and dopamine. This causes enhanced firing of neurons in the brain and the rest of the body, Brain Res Rev 1992 May-Aug 17(2):139-70. Many control studies show that coffee improves energy levels, mood, memory, reaction times, and general cognitive function.
Almost every over-the-counter fat burner supplement has caffeine. Caffeine is a natural substance that has been proven to aid in fat-burning. Several studies have shown that it boosts the metabolic rate, (Ann. Nutr. Metab. 1995:39(3) 135-42). Other studies have shown that caffeine specifically increases the burning of fat.
As I stated, caffeine increases norepinephrine, and some of this gets converted to epinephrine (adrenaline), but this is terrible if you suffer from anxiety, panic attacks, and insomnia. However, if you are on your way to a hike, the gym, or a basketball game, coffee increases cardiac output and improves muscle contractility. As a matter of fact, caffeine over a certain level in an Olympic athlete is considered drug doping and they are disqualified. The International Journal of Sport Nutrition and Exercise Metabolism (2004 Dec. 14(6) 626-46) says considering the above effects, it is not surprising that caffeine can improve physical performance by 11-12% on average. Whenever we consume anything, it takes a while to get absorbed into our system. Thus if you want to go exercise and are on an empty stomach, drink your coffee half an hour before. If there is food or a snack in your stomach, one to one and a half hours before. As an aside, when we exercise blood is shunted (diverted) from our digestive tract and sent to our working muscles. Most people are fine with this, but others may feel nausea when this blood shunting occurs, and they are not digesting their food while exercising, thus they train on an empty stomach.
Coffee may even help decrease the risk of diabetes. And most studies put this decreased risk at 23%-50% less. A large diabetes review looked at 18 studies with a total of 457,922 people. It showed each daily cup of coffee was associated with a 7% reused risk of developing type 2 diabetes (Arch Inter Med 2009; 169(22):2053-2063). We all know that coffee improves our mood. This is great when someone is depressed and as a result, has low energy. In a Harvard study published in 2011, women who drank four or more cups of coffee per day had a 20% lower risk of becoming depressed.
Coffee also reduces the risk of liver and colon cancer. One study of 489,706 people found that those who drank 4-5 cups of coffee per day had a 15 % lower risk of colorectal cancer (Arch. Intern. Med. 1996;156-525). In men, colorectal cancer is the third leading cause of death, after cardiovascular disease, and prostate cancer. In women, it is number four after cardiovascular disease, breast cancer, and cervical cancer.
It's also worth mentioning that coffee is the biggest source of antioxidants in the typical Western diet. And studies too numerous to list say coffee may actually help us live longer.
As with every "drug", there are potential side effects. My opinion, and the way I practice, is to not consume so much of anything that you start seeing side effects. It's not black and white, it's gray, and you don't have to stop taking that substance that's benefiting you in other ways, just take less. With less, most of the time, the side effect is not seen.
Drinking coffee stimulates the production of hydrochloric acid. This is awesome if you're about to have, are having, or just had a meal. With this acid, the body breaks down our food and kills E.Coli, Salmonella, and the rest of the infectious diarrheas. As a matter of fact, we all have had hundreds of exposures but our stomach acid took care of business. This acid breaks down our food, which decreases our chance of bloating, gas, IBS (irritable bowel syndrome), diverticulitis, and even colon cancer. However, a cup of coffee on an empty stomach is fine for most of us, but some can get gastritis (irritation of our stomach lining), IBS (due to our intestines moving to rapidly), and ulcers in the stomach and small intestine. In my practice, the major reason most patients suffering from IBS, is from consuming too much coffee, energy drinks, caffeinated soft drinks, and multiple other sources of stimulants, especially caffeine. Gastritis causes heartburn. Coffee also relaxes our lower gastroesophageal sphincter, allowing GERD (gastroesophageal reflux disease) to happen or get worse if you already have it. Also remember, whether caffeinated or not, coffee contains a good amount of tannic acid. Also, even "decaf" has a moderate amount of caffeine. Please research the particular brand you drink as to how much.
Coffee, as noted above, stimulates the intestines to move faster (called peristalsis) so it acts like a laxative to those who tend toward constipation. Also, excessive amounts of coffee (I don't know exactly how much is too much, but most sources consider five cups a day as moderate), can interfere with mineral absorption. Some sources say the toxin Acrylamide forms when coffee beans are roasted. This is the first I've heard on this and requires further study. Lastly, there is controversy regarding coffee causing or contributing to heart disease and stroke, I believe it prevents it. There is lots of data on both sides...
So is coffee a drug? If it is, it's certainly not the worst drug out there.