By Julianne Bierwirth, RD
Coffee has a chemical complexity that, through the roasting process, creates a broad range of vibrant flavor characteristics. This same molecular diversity is also responsible for a variety of health effects in humans. Caffeine is certainly the most well-studied, but it is far from the only pharmacologically active molecule extracted during a brew. Some of these chemicals are elusive, and their effects poorly understood. Others, after decades of research, have concrete benefits and detriments firmly borne out by data.
In this 8-part blog series, we delve into the myriad truths, half-truths, and indeed, fallacies, related to the impact that coffee has on your health. Is it good for you? Is it bad for you? Is it going to make your teeth brown? Does coffee make you smarter? Read on to find out!
Part 1: Digestion
High volume coffee drinkers know that coffee leads to yellowing of teeth (of aesthetic but not medical concern). More acidic coffee also softens the tooth dentin, increasing susceptibility to dental erosion. Acids of all kinds, including those in fruits and juices, temporarily weaken teeth for a window of about thirty minutes after consuming the food or drink. Cold brew lovers will be glad to know that their coffee is less acidic and that drinking coffee through a straw decreases the contact time, thereby mitigating the negative effects.
Those looking to minimize tooth erosion can brew with fluoridated tap water or rinse the mouth immediately after having coffee. Stains can be prevented by brushing after coffee, however dental professionals have recommended waiting thirty minutes or more before brushing to allow the dentin to reharden. Brushing is also the best cure for the most devastating effect of coffee drinking: bad breath.
For those who like their coffee piping hot there’s some bad news coming your way. A review of related research has found that people that regularly consume very hot beverages are about twice as likely to develop esophageal cancer as those who do not. These beverages not only damage the cells that line the esophagus, they exacerbate acid reflux. The heat damage from the drink and/or the chemical damage from the stomach acid puts enough strain on the cells to increase the chance of a cancerous cellular mutation.
The World Health Organization has responded to this research with the recommendation that hot drinks be consumed only below 69 °C or 149 °F, significantly cooler than many people drink their coffee. This is another boon for cold coffee products, however hot coffee is perfectly enjoyable at these safe temperatures.
The lower esophageal sphincter (LES) is a tight band of muscle food must pass through to get into the stomach compartment. It exists in part to create a barrier and keep the highly acidic stomach juices from traveling into the throat (heartburn). The quick opening and closing of the LES represents the very last ‘gulp’ in a swallow- the one you feel way down into your throat.
It seems that coffee may weaken the LES, meaning a potentially higher incidence of heartburn. This effect might be even more pronounced in people with gastroesophageal reflux disease (GERD). Fortunately coffee doesn’t seem to cause GERD, it just may exacerbate symptoms in some, and even that point is up for debate. Caffeinated and decaf coffees have both demonstrated a weakening effect on the LES; it is not caffeine but acidity that matters here. Less acidic coffees might weaken the LES less than their regular counterparts.
The profound effect of coffee on the stomach lining is most commonly felt as nausea or stomach pain, and barring medical complications, it easily avoidable. In response to coffee (but not caffeine) production of digestive gastric acid increases in the walls of the stomach. Any increase in the acidity of the stomach can be irritating if you haven’t eaten recently or if the lining of your stomach is inflamed due to a condition like gastritis or peptic ulcer disease.
As with GERD, coffee has not been shown to cause these chronic conditions, only exacerbate them. In individuals without chronic digestive issues the effect is easily avoidable by simply having a small snack or meal with or before your coffee.
A lesser known effect of coffee is exerted on the gallbladder. Attached to the small intestines just past the stomach, the gallbladder regularly releases cholesterol-filled bile into the intestines as part of the fat digestion process. In a condition called gallstones the cholesterol hardens within the gallbladder blocking the release of bile and causing pain, nausea, and vomiting.
Scientists years ago noted that people who experience gallstones also almost invariably abstain from coffee. It seems that caffeine causes the gallbladder to release bile, the regular flow of which keeps a stone from forming in the first place. But, as you can imagine, if you’ve already got a gallstone this contractile motion of the gallbladder can cause quite a bit of pain.
Coffee’s influence on the large intestines (colon) is probably its most notable feature outside of its psychological effects. About thirty percent of people experience the need to urgently find bathroom shortly after drinking their first cup of the day. This is an incredibly potent pharmaceutical effect of coffee that, again, cannot be attributed to caffeine.
Within approximately four minutes of consuming coffee, a signal is sent through the nervous system to stimulate peristalsis in the colon. This is a series of muscle contractions that convey food through the intestines. This creates a level of bowel regularity that can only be likened to eating a very large meal with a great deal of fiber.
This is the last bit of interest, though the science here is not quite solid yet. Based on the theory of how antioxidants may prevent cancer, coffee has been studied for its relationship to cancers of the mouth, esophagus, stomach, and intestines. Acidity and heat aside, there is some research to suggest that the antioxidants in coffee have a positive effect on preventing cell damage in the lining (epithelium) of these digestive compartments. This research is tentative, meaning that some studies find a benefit where others do not. If there is an effect it is either hard to isolate or else very small, but it is a point worth mention as coffee is the greatest source of antioxidants in the American diet.
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