Q&A with Dr. Megan Rossi: Tips for a Healthier Gut and Immune System

What are the links between our digestive and immune health?

We know that around 70% of your immune cells live in the gut. The gut and immune system are in constant communication through the gut: immune axis, which is why people with better gut health seem to have more resilient immune systems. This caught the attention of the general public during the COVID-19 pandemic, as those who had more diverse microbiomes experienced a lower risk of serious illness and better recovery if they contracted the virus. Meanwhile, research has also shown that gut diversity is linked to fewer or milder cold and flu contractions too, as well as broader beneficial health factors.

How can Canadians change their nutrition to help improve immune health?

We’ve always known that plants are important to our overall health and wellbeing. But until recently, we didn’t truly understand the full power – and influence – of plant-based diversity on our gut microbiome and the subsequent impact this can have on our immune health through the gut’s clever connections.

We still have a lot to learn in this area, but from what we know so far, the best thing we can do for the 40 trillion microbes living in our gut is to feed them with variety across the Super Six plant groups – vegetables, fruits, wholegrains, legumes, nuts and seeds, and herbs and spices. As each bacteria performs a different function, they will favour a different type of plant ‘fuel’ to flourish. The microbes in your gut feed on the fibre you eat that is not digested in the small intestine, and this acts almost like a fertiliser, creating a more diverse microbiome that can support your immune health as well as your skin, metabolism, mental wellbeing and more.

To do this, I recommend increasing your plant diversity, with a goal of 30 or more different types of plants each week from across the Super Six. This is based on several research studies that I tested out in clinic with great success. We are looking to validate this concept in a clinical trial at King’s and while this target might sound overwhelming at first, it’s actually a lot cheaper and easier than you might think.

Start by increasing your intake by 10 plant points per week to help build up your fibre fitness (i.e. how efficiently your body digests fibre), and make sure you’re drinking plenty of water for the full fibre benefits. Remember, it’s normal to experience a little bloating when initially increasing your fibre intake – it’s a sign of a well-fed gut microbiome. However, if you are experiencing burdensome bloating which discourages you from increasing your plant diversity, I’ve developed a digestible on-demand Bloating Masterclass with advice and practical strategies to help you beat bloating for good.

As an exclusive offer for Toronto Star readers, you can use the discount code TORONTO10 for 10% off Dr Megan Rossi’s Bloating Masterclass.

What are habits you recommend for anyone on a gut health journey?

Instead of sticking to the same recipes – or shopping list – on a weekly rotation, think about what you’ve eaten today so far and where you can add some plant points I mentioned above. Could you level up your morning porridge by switching half of the oats for cooked quinoa or topping it with mixed berries and seeds instead of the single varieties? Could you swap some of the meat in your weekly bolognese for some fibre-rich lentils? You might even want to get curious about the plants available to you. When you can, spend some extra time checking out the fruits and vegetables in your nearest supermarket – particularly the ones that don’t usually end up in your basket! Or even spend a morning browsing a local Farmer’s Market for some alternative options from local suppliers. Once you start seeking out diversity, it will almost become second nature. I see this regularly with my clinic patients, and these changes have been transformative for them.

What is important to keep in mind when selecting products for good gut health?

You don’t need to take supplements for general good gut health—those backed by scientific research are condition-specific. So, if you’re looking at general health, I’d focus on getting enough plant-rich diversity into your diet, which acts as a fertiliser for the good gut bacteria, helping them flourish.

There are some cases where you may want to introduce probiotics (live beneficial bacteria) to your medicine cabinet, but only if used correctly. While there is no evidence to suggest that the ‘everyday’ probiotic product that you see on the shelves today will improve your gut health,  there are a number of condition-specific probiotics that can help in the management of specific symptoms or conditions. But here is the thing: you need to take the right strain (i.e. type of bacteria), at the right time (i.e. if you need to go on antibiotics, for instance), and you need to take it in the right way (i.e. for the right length of time and dose). For example, research has shown that if you need to take antibiotics then taking the probiotic Lactobacillus rhamnosus GG throughout and for a week afterwards significantly reduces your risk of antibiotic-associated diarrhoea, which affects as many as one-third of patients. There are also several other evidence-backed probiotics available for female health, infant colic and cold and flu, to name a few. I am passionate about dispelling probiotic myths and helping to educate people about the science behind probiotics (my PhD was on this topic after all!). This is why I’m running a free educational webinar on probiotics later this year, and people can sign up here.

Other supplements on the market can also help with condition-specific issues. For example, psyllium husk can support bowel movements for those struggling with constipation and also help to manage symptoms of diarrhoea. Meanwhile, peppermint oil may help relieve IBS-related issues, including cramps, bloating, and flatulence.