A dietitian reached out recently about a Crohn’s patient she’s working with, specifically asking for recommendations for someone with an isolated perianal fistula but no GI symptoms.
It’s a question I don’t get asked often enough, but one worth answering publicly, because the research is limited and the clinical guidance is sparse.
What is a perianal fistula?
A perianal fistula is an abnormal tunnel or connection that forms between the rectum or anal canal and the skin surrounding the anus. It’s the most common type of fistula in Crohn’s disease.
Treatment usually focuses on medical and surgical management to promote healing, prevent complications, and improve quality of life.
There’s very little research on nutrition management.
How nutrition fits in
Often when people come to see me with a perianal fistula, it’s for help managing fistula-related pain, especially with bowel movements.
We talk about modifying fiber and hydration to soften stool, minimize bowel frequency, and reduce straining and discomfort.
Some people also find that certain spicy or acidic foods burn on the way out, so we review potential food triggers.
But what do you do for someone who is hoping to use diet to help the fistula heal, outside of telling them “the evidence is limited”?
We know diet and lifestyle can influence the gut microbiome, gut barrier function, and inflammation — how many times have you heard me say that? 🤷‍♀️
We also suspect the development of perianal fistulas may involve both dysbiosis and a dysregulated immune system.
It gives us a reasonable starting point.
Dietary approaches worth considering
One case report suggests that the Crohn’s Disease Exclusion Diet combined with partial enteral nutrition (PEN) may help promote fistula healing, and another suggests it may help with symptom management. For the right candidate, it might be worth a conversation.
EEN is another option: there’s some data suggesting it may help with fistula healing, though the evidence is limited.
If someone is feeling well and isn’t looking to change what foods they eat, we can think about PEN — roughly 40 to 50% of calories from formula (nutritional shakes) while continuing their usual diet.
When shakes are a no-go, ensuring adequate calories, protein (around 1.2 to 1.5 g/kg body weight), and an overall whole-foods-based dietary pattern is always important.
Don’t overlook nutritional deficiencies
We also want to monitor bloodwork and food intake for nutritional deficiencies — zinc and vitamin C in particular, both critical for wound healing and tissue repair.
The bottom line
Even when the evidence is limited, there are still meaningful ways to support healing, nutritional status, and quality of life.
We lean on science, learn from our clinical and patient experiences, stay curious, and keep an open mind.
