The Low-FODMAP Diet - is it really the answer for IBS?

If you have IBS, you've probably heard of the low-FODMAP diet.

It has become one of the most talked-about dietary approaches for managing IBS symptoms and for good reason. For some people, reducing FODMAPs can make a significant difference to bloating, abdominal pain, wind and changes in bowel habits but there's an important bit that often gets missed.

Low-FODMAP isn't supposed to be a diet you stay on forever.

And that's particularly important when we're thinking about the health of your gut and your health as you get older.

So, what exactly are FODMAPs? FODMAP stands for: Fermentable Oligosaccharides Disaccharides Monosaccharides And Polyols

It's quite a mouthful, hence the acronym!

FODMAPs are a group of short-chain carbohydrates that aren't always completely absorbed in the small intestine. When they reach the large intestine, they can be fermented by your gut microbes. For some people with IBS, this combination of fermentation, increased water in the gut and heightened sensitivity can contribute to symptoms such as:

Bloating Abdominal pain Wind and flatulence Diarrhoea Urgency Changes in bowel habits

This doesn't mean FODMAPs are “bad”. In fact, many FODMAP-containing foods are incredibly nutritious. The problem is that your individual gut may not tolerate certain amounts or combinations particularly well.

So is low-FODMAP the answer?

Yes… and no.

The low-FODMAP diet has good evidence for helping many people with IBS symptoms. Reducing high-FODMAP foods for a short period can sometimes provide valuable symptom relief and give you some breathing space while we investigate what else might be going on. But the long-term goal isn't to avoid FODMAPs.

And this is where I think it's important to understand what we're actually trying to achieve. Your gut bacteria need food too. Many FODMAP-containing foods contain different types of fermentable fibre and prebiotic carbohydrates that your gut microbes can use. When gut bacteria ferment certain fibres, they produce short-chain fatty acids (SCFAs) such as acetate, propionate and butyrate. These compounds have important roles in the gut and throughout the body.

Butyrate, for example, is an important energy source for cells lining the colon. So while reducing FODMAPs can help reduce symptoms, we don't want to remove fermentable foods from your diet unnecessarily or indefinitely. And this is particularly relevant to my approach to healthy ageing.

Diversity matters

One of the things I want to help my clients achieve is a varied diet. Different plant foods provide different types of fibre and other compounds for your gut microbes and dietary diversity is an important part of supporting a diverse and resilient gut ecosystem. If you remain on a highly restrictive diet indefinitely because you're frightened of symptoms, you can end up eating a much narrower range of foods than you actually need and as we age, we want to be doing the opposite.

We want to be eating a wide variety of nutrient-dense foods that provide the fibre, protein, vitamins, minerals and plant compounds that support our health.

So how long should you follow a low-FODMAP diet?

This is where things have changed from the old idea of simply going “low-FODMAP” and staying there. The diet is generally used as a short-term elimination phase, followed by systematic reintroduction and personalisation. The exact timeframe should depend on the individual, but you shouldn't remain on a strict low-FODMAP diet indefinitely.

Once symptoms have improved, the next step is to challenge and reintroduce FODMAP groups to discover which foods and quantities you can tolerate. This is actually one of the most important parts of the process.

The goal isn't: “I'm on a low-FODMAP diet.”

The goal is: “I know which foods my gut tolerates and I have as much variety in my diet as possible.”

In my experience, most clients often notice problems with foods such as onions, garlic, wheat-based products or lactose-containing dairy (and apples!).

But everyone's tolerance is different.

And it's important not to assume that a particular food is a problem simply because it appears on a high-FODMAP list.

Dose matters.

You may tolerate a small amount perfectly well but react when you eat a much larger portion. This is why a personalised approach is so useful.

Low-FODMAP doesn't automatically mean healthy and this is another important point. Just because something is low-FODMAP doesn't mean it's a nutritious food. There are plenty of highly processed, sugary foods that happen to be low in FODMAPs. You could technically follow a low-FODMAP diet while eating very little fibre, very few plants and a lot of ultra-processed food. That isn't going to support your gut or your long-term health.

The aim should always be to focus on nutrient density and variety, while adapting the carbohydrate sources to what your individual gut can tolerate.

Where does this fit into my approach?

For me, low-FODMAP sits within Step 1: CONSIDER and sometimes provides a useful temporary tool for getting symptoms under control.

But I don't want you to stay there.

The next step is ADD IN.

We gradually work towards increasing the variety of foods you can tolerate and supporting your gut microbiome. Then we can focus on REPLENISH & NOURISH, using nutrient-dense foods and, where appropriate, targeted therapeutic support.

And finally BALANCE — because stress, sleep and movement can all influence how your gut functions.

So low-FODMAP is a tool, not the destination.

The ultimate goal?

I don't want you to spend the rest of your life checking every ingredient against a FODMAP app. I want you to be able to sit down at a restaurant, eat with friends, enjoy a varied diet and feel confident about your food choices. And, importantly, I want your diet to provide the fibre, protein, plant diversity and nutrients that support your gut and your health as you age.

The goal isn't the lowest-FODMAP diet possible.

It's the most varied, nourishing diet your individual gut can comfortably manage. That's much more useful for your gut, and for healthy ageing.