That afternoon slump. The bloating after lunch. The skin that won't clear up. What if they all have the same cause?

GutGuard explains how seven evidence-backed mechanisms in ultra-processed food can affect your gut barrier — the single-cell-thick lining that decides what gets into your bloodstream and what stays out. Backed by 40+ peer-reviewed studies.

The problem

53% of the average UK diet is ultra-processed food. Around 19 million UK adults are actively trying to avoid it, yet most can't identify it on a label. Your gut lining is a single cell thick, and something in your food is breaking it down.

Seven ways ultra-processed food can damage your gut

  • Emulsifiers: mucus disruption

    Surfactants like Polysorbate-80 and carboxymethylcellulose, added to foods such as oat milk and ice cream, can disturb the protective mucus layer lining your gut wall, letting bacteria drift closer to the cells beneath.

  • Refined seed oils: heated oil damage

    When repeatedly heated, sunflower, soybean and rapeseed oils can generate reactive aldehydes (acrolein, 4-HNE, formaldehyde) that may irritate gut tissue.

  • Refined carbs & sugar: metabolic disruption

    Refined carbohydrates and added sugar can drive rapid glucose spikes, increase liver fat production, and contribute to gut barrier dysfunction when they displace fibre.

  • Artificial sweeteners: microbiome disruption

    The evidence is mixed, but some controlled studies suggest saccharin and sucralose can shift the gut microbiome and may worsen glucose tolerance.

  • AGEs: glycation damage

    Advanced Glycation End Products, formed by very high dry heat, can accumulate in tissues, cross-link collagen, and activate inflammatory pathways.

  • Nitrites: genotoxic damage

    Sodium nitrite in bacon, ham and sausages can form genotoxic N-nitroso compounds during digestion. The World Health Organisation classifies processed meat as a Group 1 carcinogen.

  • Palatability engineering: overconsumption

    Flavour and spice systems are engineered to override your satiety signals. A landmark NIH study found people on ultra-processed diets eat around 500 extra calories per day without realising it.

Built on 40+ peer-reviewed studies

Across 7 evidence-backed mechanisms, with research published in Nature, Cell, BMJ, Lancet Oncology, Gastroenterology, PNAS and Cell Metabolism.

Read the science:

Get GutGuard

Scan any ingredient label with your camera and get instant, mechanism-by-mechanism analysis across all 7 mechanisms — so you know exactly what's in your food.

GutGuard is free to download and includes a limited number of free scans. For unlimited scans, GutGuard Pro is £5.99 per week or £49.99 per year (around £0.96 per week, roughly 84% cheaper than paying weekly).

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Frequently asked questions

How does GutGuard analyse food ingredients?

Point your camera at any ingredient label or paste a URL. GutGuard uses AI to identify every ingredient and analyse it against seven evidence-backed gut mechanisms, with context for where the evidence is strongest and where it is still emerging.

Is GutGuard medical advice?

No. GutGuard is an educational tool that helps you understand the scientific research on how food ingredients interact with your gut barrier. It is not a substitute for professional medical advice, diagnosis, or treatment.

How much does GutGuard cost?

GutGuard is free to download from the App Store and includes a limited number of free scans. For unlimited scans, GutGuard Pro is £5.99 per week or £49.99 per year. The annual plan works out at around £0.96 per week, roughly 84% cheaper than paying weekly.

How does ultra-processed food damage your gut?

Ultra-processed food can affect your gut through seven biological mechanisms: emulsifiers can disturb the protective mucus layer, heated oils can generate reactive aldehydes, excess sugar and refined carbs can disrupt barrier function and metabolism, some artificial sweeteners have mixed microbiome evidence, advanced glycation end products (AGEs) reflect high-heat processing, nitrites in processed meat can form genotoxic compounds, and palatability engineering can drive overconsumption. Over 53% of the average UK diet consists of ultra-processed food.

What is the gut barrier and why does it matter?

Your gut barrier is a single-cell-thick lining that separates your intestines from your bloodstream. It decides what nutrients get absorbed and what harmful substances stay out. When damaged by ultra-processed food ingredients, it can become permeable, allowing toxins and bacteria to enter the bloodstream, triggering inflammation linked to bloating, fatigue, skin problems, and chronic disease.

What are emulsifiers and why are they bad for your gut?

Emulsifiers like Polysorbate-80 and carboxymethylcellulose are surfactants added to processed foods to improve texture. Research published in Nature (Chassaing et al., 2015) showed they erode the protective mucus layer lining your gut wall, allowing bacteria to make direct contact with cells that were never meant to be exposed, triggering chronic low-grade inflammation.

Are artificial sweeteners bad for gut health?

Research published in Cell (Suez et al., 2022) found that saccharin and sucralose can impair glucose tolerance by disrupting gut microbiome composition in a two-week RCT. An earlier Nature study (2014) by the same team showed saccharin induced glucose intolerance through gut dysbiosis. Other studies have not replicated these effects, so the evidence is mixed and appears strongest for saccharin and sucralose.

Why is processed meat classified as a carcinogen?

The World Health Organisation's IARC classifies processed meat as a Group 1 carcinogen. Sodium nitrite in bacon, ham, and sausages can form N-nitroso compounds that damage DNA. The IARC analysis found about an 18% higher colorectal cancer risk per 50g daily serving, and a 2025 meta-analysis of 60 studies reported a hazard ratio of 1.21.

Is my data private with GutGuard?

Yes. GutGuard does not collect your name, email, location, or any personal identifiers. There are no user accounts and no way to identify who you are. Your analysis history is stored locally on your device. Scan records are saved on our server to improve analysis quality, but they are linked only to an anonymous session ID. Our analytics are aggregated and cannot identify individual users.