Understanding the results
So, tea and coffee may decrease your chances of developing ulcerative colitis, and soft drinks may increase your chance. Alcohol, well, was not significant one way or the other.
This alcohol result surprised the researchers. Alcohol itself can damage the mucous lining of the intestines which would seem to support a hypothesis of alcohol increasing the relative risk factor. More experimental studies could clear the air on this.
Coffee’s protection was not an unexpected result. Previous studies have shown that caffeine can protect intestinal cells from invasion by foreign bacteria. Caffeine has also been shown to protect against and slow down colitis in mice induced using dextran solfate sodium.
However, the coffee results were confounded by the fact that they had to use studies which had focused on smoking and ulcerative colitis. Again, more research into this specific beverage would be helpful.
Tea, like coffee, has caffeine, which can protect against colitis. The researchers also pointed to several studies in which green tea extract was used to protect rats against induced colitis.
Showing that soft drinks increase the risk of developing ulcerative colitis was perhaps not surprising, but it was also not something that other people had specifically looked at before.
Something interesting is that while caffeine has been shown to protect against colitis, and many soft drinks include caffeine, soft drinks overall increased the risk of ulcerative colitis more than caffeinated coffee reduced it. Perhaps it would be a good idea to compare caffeinated soft drinks against non caffeinated soft drinks.
The researches pointed out that they had to rely on other data for this, and that meant they had to wrangle with several biases. Not all of the studies used were experimental. The rest were epidemiological, which means that the participants were asked to self report their diet. That information is useful as a launching point for experimental research, but any conclusions drawn are suspect.
Also, the researchers could not control for other potential confounders, such as genetic background and how much of each drink was consumed. They tried to control as best they could but the results given above are best though as potentials, not hard data.
Tea and coffee are often lauded as healthy beverages while alcohol and soft drinks are bemoaned as harmful. When it comes to ulcerative colitis, this holds true, with tea and coffee maybe protecting against the disease while soft drinks might increase the risk of developing it.
It is important to remember that these results are not at conclusive as the researchers would have liked and the relative risk factors are much smaller than they seem. It would be a good idea to avoid drinking several liters of soda every day, but one every now and then is not the end of the world.