A new cross-sectional study published in Frontiers in July 2025 has found a U-shaped association between UPF intake and overactive bladder (OAB) symptoms and this could potentially be a compelling development for those of us struggling to manage the symptoms of OAB.
First, what do we mean by ultra-processed foods?
Ultra-processed foods (UPFs) are products made using ingredients that you wouldn’t typically find in your own kitchen at home - emulsifiers, preservatives, artificial sweeteners, colourings and stabilisers. They often contain little to no whole food, and are designed to be convenient, tasty and long-lasting. Things like fizzy drinks, packaged snacks, ready meals, supermarket cakes, instant noodles and many plant-based meat alternatives are all UPFs.
UPFs are often criticised because they tend to be low in fibre and nutrients but high in salt, sugar and unhealthy fats. Research has linked high UPF consumption with a range of health issues, from obesity and type 2 diabetes to heart disease and depression. That’s why there’s growing concern about how these foods might also affect things like hormone balance, inflammation - and now, potentially, bladder health too.
What the new study found
Researchers looked at 23,482 adults and measured how UPF intake related to OAB symptoms. They reported a U-shaped pattern, with higher odds of OAB at the lowest and highest ends of UPF intake and the lowest odds in the middle.In plain terms, very low and very high UPF intake were both linked with higher odds of OAB, while moderate intake sat lowest on the curve.
The association appeared stronger in women, people who smoke, and those living with overweight or obesity. Because this was a cross-sectional study, it cannot prove cause and effect and the authors of the study emphasised that prospective studies are needed to confirm what’s going on biologically. It does, however, indicate a relationship that could be important for many of us struggling to identify triggers for OAB symptoms.
Is there any other research that supports this theory?
Yes! In an observational Finnish study published in December 2024, women aged 47–55 who regularly consumed highly processed ready meals and fast food were more likely to report stress leaks (e.g. when coughing or exercising) and urgency leaks (a sudden strong urge to pee). By contrast, having a higher‑quality diet, including everyday fruit, was associated with fewer stress leaks.
Again, it’s important to note that this is emerging, observational research so we can’t assume that the food we eat directly causes leaks, but it does highlight that the quality of our diet might play a role in our bladder health, alongside hormonal shifts, pelvic floor strength and weight as we’ve previously thought.
Why might UPFs affect the bladder?
We haven’t fully established the link but the research shows that there are some biologically plausible reasons that UPFs could impact our bladder health:
Irritants and additives: Some UPFs include artificial sweeteners, acids and carbonation that may aggravate urgency in susceptible people. Large cohort work in postmenopausal women found a small association between frequent (1-6 drinks a week) artificially sweetened drink intake and mixed incontinence.Other small trials also suggest certain carbonated or artificially sweetened drinks can trigger urgency in some adults.
Weight and pressure on the pelvic floor: Ultra-processed foods are often high in calories but low in nutrients, which can make it easier to gain weight without realising. And carrying extra weight — especially around the tummy — puts more pressure on the bladder and pelvic floor muscles.
One gold-standard study found that when women with overweight or obesity followed a healthy weight-loss plan, they had fewer bladder leaks each week. The improvement was likely down to reducing that pressure on the bladder and giving the pelvic floor a better chance to do its job.
So what does this mean for our diet day to day?
What this indicates so far is that balance is key. We know that identifying bladder irritants can help to manage symptoms of overactive bladder and urge incontinence, and the study suggests that extremes at either end of UPF intake could be linked - while a more moderate approach may be more forgiving on our bladder health.
If you’re noticing urgency or leaks, it’s reasonable to experiment with your diet alongside first-line care - and keeping a bladder diary can help you to identify foods - and UPFs - that may be triggering your symptoms. Record your fluid and food intake, alongside activity, for at least three days. This will help you to identify when your symptoms flare up and is recommended by NICE as a simple way to personalise our care when seeking help.
Use your bladder diary to start a conversation with your GP, too.
The bottom line
While this new research doesn’t mean UPFs directly cause bladder leaks, it does suggest that there could be a link between how much UPF we consume, and symptoms of overactive bladder. This helps support our knowledge to make healthy choices for our diet and fluid intake, and where possible make reasonable adjustments without the need to completely overhaul our food intake or adhere to strict diets. If you’re curious, try a short, structured experiment and keep notes. Your bladder will tell you quickly if you’re on the right track!
