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Food additives and your gut: what the science really says

2 March 2026

By The Gut Health Doctor Team

Dr Megan Rossi in a lab looking through a microscope

You’re trying to do everything “right” for your gut. You’ve added more fibre. You’re eating more plants. Maybe you’ve introduced kefir or a targeted probiotic. You’re reading labels more carefully.

And then suddenly, additives are the new enemy. Scroll social media, and it sounds simple: “chemicals” are damaging your microbiome. Headlines warn of hidden emulsifiers. Packaging shouts “no nasties” as if that alone makes a biscuit gut-friendly. It leaves you wondering whether, despite your best efforts, you’ve been getting it wrong all along.

Food additives, commonly referred to as E-numbers, have become a major flashpoint in the gut health conversation. Some research suggests certain additives may affect the gut barrier or microbiome. At the same time, the evidence is far more nuanced than many headlines imply, and context matters, especially for people living with conditions such as Crohn’s disease.

So what’s hype, what’s supported by evidence, and what actually matters for your gut? Let’s unpack it.

What do we really mean by “chemicals” in food?

The word chemical is often used as shorthand for something harmful, but it’s misleading. Everything we eat is made of chemicals. Water is a chemical. Fibre is a chemical. Vitamins and minerals are chemicals.

In the context of food, additives are substances added to improve safety, stability, shelf life, texture or consistency. They help prevent spoilage, maintain colour, stop separation and keep foods safe to eat for longer. Realistically, most of us rely on them to some degree; very few people make everything from scratch.

Additives span a wide range of categories, including preservatives, antioxidants, sweeteners, colourings and emulsifiers. But this is where nuance matters. Each class behaves differently in the body. And within those classes, each individual additive – of which hundreds are approved by health authorities – has its own structure, metabolism and potential effects on the body.

Lumping them together as a single group overlooks the complexity of how the gut responds to different compounds, and how those compounds interact within the foods that contain them.

The more useful question isn’t simply whether a food contains additives, but which ones, in what amounts, how frequently they’re consumed, and by who.

How additives interact with the gut

Most approved food additives are either broken down during digestion or pass through the gut without causing an issue. But new research suggests that some interact more closely with the gut lining or with our gut microbes than previously thought.

Emulsifiers are one such group. They’re used to keep ingredients, specifically fat and water, mixed together in products like sauces, spreads, ice cream and certain baked goods, preventing separation and maintaining texture.

A landmark animal study back in 2016, led by one of our colleagues, Prof Benoit Chassaing, showed that certain emulsifiers alter the composition of the gut microbiome, thin the protective mucus layer that lines the gut, and influence immune responses. These findings raised an important clinical question: could emulsifiers have a greater impact on people whose gut lining is already vulnerable or inflamed?

Who should pay most attention to this research?

The strongest evidence to date on emulsifiers relates to people with inflammatory bowel disease, specifically Crohn’s disease, where the gut lining is already compromised. Of the 60+ emulsifiers currently approved for use, it remains too early to determine which specific ones may be driving the effects observed in research.

Importantly, emulsifiers are not a uniform group. Some, such as lecithin (which occurs naturally in foods like eggs and soy) are not currently thought to pose concern based on the available evidence.

For the general adult population, the picture is far less clear. There is currently no robust human data showing that emulsifiers are harmful to healthy adults when consumed occasionally as part of a varied diet. Whether the developing digestive tract of infants may be more vulnerable is another important and evolving area of research.

What about other additives?

Emulsifiers aren’t the only group under scrutiny.

Food colourings – a history of caution

Food colours are a useful place to start. Several have been restricted or banned over the years after safety concerns emerged. In the UK and EU, for example, titanium dioxide (e171) found in things like chew gum were banned in 2021 and others like Sunset Yellow FCF (e110) now require warning labels following evidence suggesting potential links with behavioural changes in children.

This history matters because it shows that additive safety is not static. Regulatory decisions evolve as new data emerge, and when credible concerns arise, policy can and does change.

Sweeteners – more than just “no calories”

More recently, research has turned its attention to non-nutritive sweeteners.

A landmark intervention study showed that sweeteners such as saccharin, sucralose and even stevia – despite containing little to no calories – can alter the gut microbiome in some people. In certain participants, these changes were also associated with altered blood glucose responses. That’s notable, because these compounds are not sugar and would not be expected to impact blood glucose.

What’s particularly interesting is the variability. Not everyone responds in the same way. Some people show measurable metabolic changes, while others do not. This reinforces a key theme in gut health – responses are often individual, shaped by baseline microbiome composition and overall diet.

There are also behavioural considerations when it comes to sweeteners. Regularly consuming high levels of intense sweeteners may maintain or increase our preference and cravings for very sweet tastes, which can influence overall diet quality over time.

Preservatives – emerging observational data

Preservatives are another group attracting attention. A recent large observational study reported associations between intakes of certain preservatives and increased cancer risk. However, it’s important to approach these findings with nuance.

Observational research can identify associations, but it cannot prove causation. Although researchers attempt to adjust for overall diet and lifestyle factors, it is difficult to fully separate the effects of specific additives from the broader dietary patterns in which they are eaten.

Dose is also likely a key factor. In many cases, the risk associations were largest with the greatest intakes. That is very different from showing harm at occasional levels of consumption.

Ultimately, intervention studies are needed before we can really understand what’s going on.

Why cutting everything out isn’t the answer

When headlines spotlight single ingredients, it can nudge people towards overly restrictive eating. But that approach often backfires.

Over-restriction can narrow diet diversity, reduce fibre intake and, over time, negatively impact the gut microbiome. It can also increase stress around food, which in itself can aggravate gut symptoms. And for many people, strict rules aren’t sustainable, often leading to cycles of avoidance and binge eating.

A more effective approach is awareness without fear. That means understanding where certain additives – particularly emulsifiers and sweeteners – tend to appear, reducing reliance on ultra-processed foods where it’s realistic to do so, and building your diet around whole and minimally processed foods most of the time. Not perfectly, just consistently.

A practical, gut-supportive approach to additives

It can be helpful to play food detective in the supermarket while you’re getting familiar with what’s in your weekly staples. But you don’t need to analyse every label or eliminate all packaged foods. Instead, anchor your decisions in what we know so far:

1. Go for whole
The simplest way to moderate additive intake is to centre your meals around the Super Six, along with oily fish and fermented dairy (think kefir and aged cheese). These foods naturally support microbial diversity, fibre intake and gut barrier health – without the need for rigid food rules.

2. Look at overall exposure
Remember it’s about regular exposure, rather than occasional intake. If more than 50% of your meals are from packets, it’s worth reviewing the labels and choosing the brands with less additives. The perfect example is with wraps; some brands contain no additives, while others contain at least four.

3. Scrutinise your sweeteners
Frequent reliance on non-nutritive sweeteners may maintain a strong preference for very sweet tastes and influence microbial composition. If sweetened drinks or products appear multiple times a day, it may be worth gradually reducing reliance and retraining your palate. Try some of our recipes sweetened naturally with whole fruit instead, like these fibre:protein mango pancakes or this berry, chocolate and nut butter bark.

4. Be emulsifier-aware
If you live with Crohn’s disease or ongoing gut inflammation, being more emulsifier-aware may be worthwhile. In this context, a short-term, structured reduction in emulsifier intake, guided by an additive-expert dietitian like Amy Buckley at The Gut Health Clinic, can help assess whether symptoms or inflammation improve while keeping the diet nutritionally balanced.

Takeaway

Food additives are not all created equal. Their impact on the gut depends on the specific compound, the dose, the frequency of intake and the person consuming them. While several categories – including sweeteners, emulsifiers and preservatives – are under active investigation, this does not mean blanket avoidance is necessary for everyone. It does, however, remind us that context matters and that gut health is influenced by more than just fibre.

It’s understandable that the noise around food additives can feel unsettling, and yes, the science is still evolving, but there is reassurance in the process. As we’ve seen historically, when evidence becomes strong enough, policies and recommendations change. Researchers, including our own team, continually review emerging data, and guidance evolves accordingly. We’ll keep following the science and sharing updates with you.

Ultimately, a gut-nourishing diet isn’t about perfection or fear. It’s about balance and perspective. Stay aware, not alarmed and remember that your gut health is shaped far more by your consistent habits than by any single ingredient.