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Ask a Doctor is a series of physician-authored columns offering insights and advice on common health topics. It is not a substitute for seeking medical care.
As a family physician, I spend a good amount of time talking with patients about digestive symptoms such as bloating, acid reflux, constipation and changes in bowel habits. The gastrointestinal tract, or GI tract, which runs from the esophagus through to the colon, affects the entire body. GI symptoms often affect how people feel and function. It’s no wonder “gut health” trends are all over social media – but it can be confusing to understand what this term means and what advice is trustworthy. Here’s what I share with my patients based on what we actually know from evidence-based medicine.
1. What is the gut microbiome?
When people talk about gut health, there’s often a big focus on the microbiome, the trillions of micro-organisms that live primarily in the colon.
These organisms play important roles in:
- Digestion and metabolism,
- Immune system regulation,
- Hormone processing.
The gut microbiome likely plays an important role in overall health. But much of the research is still emerging. What we know is that gut function depends on more than just the microbiome. The health of the gut is dependent on how quickly food moves through the system, the integrity of the gut lining and the effects of diet, medications and the nervous system.
For this reason, some of the current fads, including at-home microbiome testing, are not routinely recommended by medical associations at this time.
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2. The gut–brain connection is real
There’s strong evidence that the gut and brain communicate constantly through neural, hormonal and immune pathways. Most people have experienced this, whether it’s butterflies in their stomach before a big event or digestive changes during periods of stress.
In my practice, I’ve seen how anxiety, depression and chronic stress can show up alongside gastrointestinal symptoms. The science is evolving when it comes to treating mental-health conditions by directly altering the microbiome. Early research into what are sometimes called psychobiotics (a subset of probiotics that may positively influence mood) is promising, but it’s not ready for routine clinical use and I always urge caution if purchasing products that are not Health Canada approved. For now, the most reliable ways to support the gut–brain connection are:
- Consistent sleep,
- Stress management,
- Regular physical activity,
- Healthy nutrition.
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3. What you feed your gut matters
This is one area where the evidence is strong and so it’s a big focus of my counselling for my patients: diet affects gut health. Fibre, in particular, is linked to lower risks of cardiovascular disease, type 2 diabetes and colorectal cancer, which is one of the most common and preventable cancers in Canada. Despite the benefits of fibre, most Canadians are getting about half of the recommended 25-30 grams of it per day. Beyond these positive benefits, fibre also:
- Feeds beneficial gut bacteria,
- Supports regular bowel function,
- Improves insulin sensitivity.
Plant diversity matters too. Diets that include a wider variety of plant foods, including vegetables, fruits, whole grains, legumes, nuts and seeds, are associated with a more diverse microbiome and better health outcomes. Ultraprocessed foods now make up nearly half of daily energy intake for Canadian adults, a shift with real consequences for gut and metabolic health.
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4. Some medications can affect gut health
Prescribed medications are often necessary and beneficial. The goal is not to avoid them, but to understand their effects and factor them in if new digestive symptoms arise. If you develop gastrointestinal changes when on a medication, consult your clinician, as they can help adjust the dose, timing or even the type of medication, if needed. Many commonly used medications affect the gut, including:
- Antibiotics, which disrupt the microbiome, usually temporarily;
- Proton pump inhibitors for acid reflux, which alter the gut environment;
- Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, which can irritate the gut lining;
- Antidepressants, which affect gut function through serotonin pathways;
- GLP-1 receptor agonists used for diabetes and weight management, which slow gastric emptying and can lead to nausea and changes in bowel habits.
5. Seek care for these gut symptoms
Digestive symptoms are common, but there are some specific signs that should never be ignored, including:
- Blood in the stool;
- Unexplained weight loss;
- Persistent abdominal pain;
- A significant or lasting change in bowel habits;
- Iron deficiency or anemia.
Colon cancer screening (either with colonoscopy or take-home fecal occult tests that check for blood in the stool that is not visible) is important. In provinces such as Ontario and Prince Edward Island, colorectal cancer screening now begins at the age of 45, down from 50. With rising diagnoses in younger adults, other provinces may follow. Early detection significantly improves outcomes.
“Gut health” may not be a precise medical term, but the symptoms it describes are very real. Most of what supports it comes down to the basics: what we eat, how we move, how we sleep and how we manage stress. And while digestive symptoms are common, they’re not something you have to just live with.
Dr. Sheila Wijayasinghe is a menopause-certified family physician practising at St. Michael’s Hospital in Toronto and the medical director of primary care outreach at Women’s College Hospital. She is also the resident health expert on CTV’s The Social and co-host of The Doc Talk Podcast.