The Role of Drinks in UC
As with Food, randomised, placebo-controlled trials involving drinks in UC are rare. We are therefore more reliant on epidemiology studies to determine what drinks should be avoided and which should be consumed. Please see the introduction to the Food page for a more detailed explanation. First, we examine drinks you should avoid:
Drinks to Avoid
Soft drinks
Soft drinks are non-alcoholic, highly processed sweet-tasting drinks that usually contain high amounts of sugar (or artificial sweeteners) alongside food colourings and other additives. As mentioned in Food, high levels of sugar are associated with a greater risk of developing UC (here), with every 10 grams of sugar added to daily diet increasing the risk of UC by 10% (a single can of cola contains ~35 grams). Moreover, "diet" versions of soft drinks could be even worse, as artificial sweeteners are also strongly associated with UC (here and here), as they are believed to induce adverse changes in gut bacteria (here) which may trigger the disease. The market availability of artificial sweeteners saccharin and sucralose (commonly used in soft drinks) in Korea has been strongly correlated with the incidence of UC cases in the country (here). Another meta-analysis of 16 studies (here) found that soft drinks consumption was associated with a ~70% increased risk of developing UC. Finally, au Australian study (here), found that consuming soft drinks twice or more per week was associated with a 55% higher risk of developing UC compared with drinking none. The author's recommendation on soft drinks is simple and unequivocal - never drink any.
Alcohol
There have been many studies done on the impact of alcoholic drinks on the development of UC and risk of relapse, but with some contradictory findings. Part of the complexity seems to be that the relative risks depend on 1) the amount drunk and 2) the type of alcohol consumed. Several studies have found that drinking red wine in moderation may actually be beneficial (here), possibly due to its high polyphenol content having positive effects on microbiome diversity (here), whereas consumption of other forms of alcohol are harmful. A discussion of some of these complexities is provided below, but the author would recommend avoiding alcohol entirely when in a flare and mainly keeping to modest amounts of red wine when in remission.
A US study published in 2022 (here) found there was no link between alcohol consumption and development of UC. However, it did find a higher risk of UC among those who drank >4 servings a week of spirits. Other studies have reported mixed findings, with a Taiwanese study (here) reporting a 2.3x increased risk of developing UC among people drinking alcohol vs those who did not and it found that the amount of alcohol intake was correlated with amount of UC risk (the highest level of drinking had 20x the risk). However, another study in Europe (here) found no associated between alcohol intake and the risk of developing UC.
In patients with diagnosed UC, alcoholic drinks are associated with a higher risk of relapse (here), with a 2.7x higher risk of relapse found in this study among those with a high intake of alcohol, which was statistically significant.
Drinks to Choose
Filtered Water
In the author's view, there is some evidence to suggest that it may be a good idea to drink filtered water rather than water directly from a tap. There are many synthetic chemicals found in tap water, some of which have been associated with the development of UC. For example, this concerning study (here) found that incidence of UC increased as exposure to PFOAs increased (i.e. it was dose-dependent) and that this trend was statistically significant (2.6x increased risk at highest quartile exposure). This study (here) also found a link between UC and PFOAs. PFOAs are "forever chemicals", which are widely used in manufacturing and do not degrade in the environment, tending to accumulate in living things; they have been found in almost every environment on Earth and are impossible to avoid completely. However, drinking water is thought to be a major means by which they enter humans (here) and some specialist filters are able to remove them (e.g. here). There are numerous other chemicals that have been hypothesised to contribute towards the development of autoimmune diseases such as UC, but this is an area of ongoing investigation and many questions remain.
Coconut Water
Remarkably, a randomised, double-blind, placebo controlled trial of coconut water in 97 patients with mild-moderate UC was carried out over 2019-22 and published in 2024 (here). This is the first such high quality prospective study of a specific food or drink in UC that the author has ever discovered. The results were extraordinary, showing that 8 weeks of 400ml of daily coconut water had a 57% response rate (vs 28% for placebo, which was coconut-flavoured water) and a 53% remission rate (vs 28% placebo). Both of these were statistically significant (p=0.014 and 0.02 respectively). Endoscopic remission was achieved in 22% of those drinking coconut water, vs 15% in placebo (not statistically significant). A microbiome analysis of clinical responders vs non-responders showed marked differences in composition. It is the author's view that coconut water would be an excellent addition to anyone's diet with UC, with no downside (aside from monetarily), though care should be taken to procure brands that contain no additives of any sort and which are ideally organic.
Kefir
Kefir is milk that has been fermented with kefir grains (colonies of bacteria and yeast). It has been drunk for hundreds of years, originating in the Caucasus. It contains up to 61 bacterial strains (here), with its probiotic content being around 4-5x higher than yoghurt (here), though this obviously varies hugely depending on both the yoghurt and kefir. There is strong evidence that drinking/eating kefir regularly (i.e. daily) can improve symptoms of many gastro-intestinal issues, including diarrhoea of C. difficile (here), irritable bowel syndrome (here) and ulcers caused by H. pylori infection (here). There is also some evidence that kefir can help to reduce colon inflammation in rats (here) and reduce the severity of colitis, also in rats (here). The author is only aware of one clinical study involving kefir in ulcerative colitis patients (here), which showed a statistically significant reduction in symptom exacerbations in the group that received daily kefir (100ml) vs those that received nothing, but the study was only small (21 patients). If you wish to try kefir, the author would recommend making it at home, as commercial brands often contain added sugar and have a lower diversity of bacteria present.
Kombucha
Originating in China, kombucha is fermented tea that is formed by the action of a symbiotic culture of bacteria and yeast, similar to kefir. The author was unable to find any reliable estimates of the number of probiotic microbes to be found within kombucha vs kefir, but it clearly varies greatly from batch to batch and is likely similar if fermented properly. It is also worth noting that merely a "higher" probiotic content does not mean "better", as the quality and diversity of probiotics within a food or drink is also important. There appears to have been less research on the impact of kombucha on UC than there has been for kefir, but there is no reason to think that it would be any less effective, in the author's view. However, home production of kombucha is more complex than kefir and for this reason, the author chooses to drink homemade kefir every day but drinks kombucha (shop bought) only occasionally.
Tea/Coffee
Epidemiological studies have shown that drinking tea and coffee likely provide a modest reduction in the risk of developing UC. One meta-analysis that combined data from multiple studies (here) found there was a 31% reduction in the risk of developing UC among tea drinkers, which was statistically significant, and a 42% lower risk among coffee drinkers, but this was not (only just) statistically significant and if one study was excluded, became significant. This epidemiological data is fairly convincing to the author that these drinks have a beneficial effect, possibly through polyphenol content which improves the diversity of the microbiome, but this is conjecture and there is no indication that the effect would be strong enough to benefit people with diagnosed UC. However, it seems unlikely that consuming these drinks will do you any harm (although caffeine can make diarrhoea worse (here), so you may want to avoid them when in a flare).