Bloating that builds through the day, a bowel habit you plan around, foods that used to be fine. Digestive discomfort usually reflects change across fermentation, transit, the gut barrier, the gut-brain axis, digestive capacity and sex hormones.
The symptom won’t tell you which of these is driving it. A vivaINSIGHT test narrows it down. One at-home collection reads your gut microbiome, metabolites and lifestyle to show where your biology has drifted furthest from optimal.
Your first result is a baseline snapshot of your Biological Drift. Make a change, such as more fibre or different meal timing, then test again to see whether your markers are moving the right way.
Digestive discomfort is a symptom, not a diagnosis. It tends to appear when several systems drift at once: how much gas your microbes make, how quickly it moves, how sensitive the gut wall is to being stretched, and what your hormones are doing that week.
Get coeliac serology first. Both the blood test and the biopsy lose sensitivity once gluten is out of your diet, so a self-directed gluten-free trial can make a lifelong diagnosis much harder to confirm later.[5]
The same symptom (bloating) comes from at least four different mechanisms, and the fix for one makes another worse.
Fibre you cannot digest is food for microbes that can, and gas is the by-product. That is normal biology, but the volume depends on which fibres you eat and which organisms you are carrying. Of the dietary approaches tested in irritable bowel syndrome, a low FODMAP diet has the most evidence for bloating and distension, and it is designed as a short elimination followed by structured reintroduction rather than a way of life.[1][2][3]
Gas only distends you if it cannot leave. Methane produced by gut archaea is associated with slower transit, and slower transit gives fermentation more time to run, which is why adding fibre to a slow gut can make bloating worse before it makes it better. Thyroid function sets the background pace.[4][10]
A single cell layer separates what you eat from your immune system. Coeliac disease is the version of this we can test for definitively, and it is routinely missed for years, which is why serology belongs at the start of the work-up, taken while you are still eating gluten.[5]
The gut and the brain talk constantly, through the vagus nerve, immune signalling and microbial metabolites including the short-chain fatty acids produced when fibre is fermented. This is why stress changes your bowel habit within hours, and why two people with identical gas volumes can report completely different pain.[6][7]
Before anything reaches your microbes it has to be broken down: by stomach acid, by bile, and by pancreatic enzymes. When any of those falls short, more undigested material arrives in the colon and the fermentation load rises. Feeling heavy or over-full within minutes of starting a meal points here rather than at fibre.
There are oestrogen and progesterone receptors along the gut. Irritable bowel syndrome affects around twice as many women as men in Western countries, and rectal sensitivity has been shown to change across the cycle in women with IBS but not in healthy controls. If your symptoms have a monthly rhythm, that rhythm is the finding.[8][9]
Biological Drift is the gradual, usually invisible shift in your biology away from your own baseline over time.
In the gut, drift has a specific shape. Symptoms lead to cutting foods out; a narrower diet supports fewer microbial species; lower diversity means less butyrate and a less resilient barrier; and the list of foods you react to gets longer.
Higher habitual fibre intake is associated with greater abundance of the fibre-fermenting organisms that make butyrate.[3]
DRIFT TIMELINE
Biological Age50
61 / 100
64 / 100
66 / 100
67 / 100
69 / 100
WHAT YOU'D NOTICE
The list of safe foods is now short enough to plan around, and eating out takes thought. This is often when people ask for tests and are told everything is normal.
Illustrative direction of change drawn from published research, shown as vivaINSIGHT scores out of 100 against your own baseline. Not patient data, and not a prediction for any individual.
Gut symptoms are the area where guesswork is most common and least useful, because four different mechanisms produce the same complaint. vivaLAB's testing tells them apart.
vivaINSIGHT is tri-layer: two lab-tested molecular layers (microbiome and metabolites) plus a structured lifestyle assessment, all from home. Blood markers are covered separately with your GP.
Markers are scored against ideal ranges rather than the broad "not yet abnormal" reference band, then cross-referenced across layers. The pattern determines the sequence of actions.
All three layers captured on the same day, so the picture is internally consistent.
Our algorithms weight the markers furthest from optimal and read them across layers.
A nutrition plan and supplement recommendations tied to your markers, highest-leverage change first.
vivaBALANCE 360 tests in month 1, month 4 and month 10. Track the impact of your changes from test to test.
The systems behind this symptom change slowly and usually without obvious signs. Slow changes are often missed which is why testing and tracking over time is important.
Associations described in published literature. Testing identifies and tracks markers; it does not diagnose, treat, cure or prevent any disease.
One at-home collection. Three layers. A plan built on your own numbers. With vivaBALANCE 360 you test in month 1, month 4 and month 10, so you can see whether it worked.
Written by the vivaLAB science team. Clinically reviewed by Dr Andrew O'Brien, PhD, MBA, Executive Chairman, Co-Founder, vivaLAB. Last reviewed 28 September 2026. Next review March 2027.
Blood in your stool or black stools, unintended weight loss, a persistent change in bowel habit lasting more than six weeks, difficulty swallowing, persistent vomiting, pain that wakes you at night, unexplained iron-deficiency anaemia, or a family history of bowel cancer should be discussed with your GP promptly rather than investigated at home.
Persistent bloating usually reflects one of a small number of measurable things: how much gas your microbes produce from the fibre you eat, how fast that gas moves through you, how sensitive your gut wall is to being stretched, and where you are in your cycle. Testing across layers separates a fermentation problem from a transit problem, and both from a sensitivity one.
Not before coeliac testing. Coeliac serology and biopsy both lose sensitivity once gluten is removed from the diet, so a self-directed gluten-free trial can make a lifelong diagnosis much harder to confirm. Ask for tissue transglutaminase IgA with total IgA while you are still eating gluten normally.
Your GP can test coeliac serology with total IgA, ferritin and iron studies, full blood count, hs-CRP, vitamin D, B12 and folate, and TSH. vivaLAB does not collect blood; vivaINSIGHT adds your gut microbiome, metabolites and a structured symptom history, which is what separates the common causes from each other.
Of the dietary approaches studied in irritable bowel syndrome, a low FODMAP diet has the most evidence, particularly for bloating and distension. It is designed as a short elimination phase followed by structured reintroduction, not as a permanent way of eating, because long-term restriction narrows the fibre diversity your microbes depend on.
Biological drift is the gradual, usually invisible shift in your biology away from your own baseline over time. It usually happens inside normal reference ranges, which is why standard results can read as fine. One test gives you a baseline; a second shows the direction of change.
Timeframes vary by cause. A fermentation or transit change can shift within two to four weeks, while rebuilding microbial diversity and iron stores takes months. This is why it's important to maintain testing over an extended period so you can track symptoms, any changes resulting from the inputs you make, and your biological drift.
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Every numbered claim on this page links to a record in PubMed, the US National Library of Medicine’s index of biomedical literature.
Efficacy of dietary interventions in irritable bowel syndrome: a systematic review and network meta-analysis. 2025. PMID 40258374
Systematic review: quality of trials on the symptomatic effects of the low FODMAP diet for irritable bowel syndrome. 2017. PMID 28440580
Association of dietary fibre intake and gut microbiota in adults. 2018. PMID 30355393
Methanogens, methane and gastrointestinal motility. 2014. PMID 24466443
ACG clinical guidelines: diagnosis and management of celiac disease. 2013. PMID 23609613
Short chain fatty acids: microbial metabolites for gut-brain axis signalling. 2022. PMID 35066114
Gut microbiota-derived short chain fatty acids act as mediators of the gut-brain axis targeting age-related neurodegenerative disorders: a narrative review. 2023. PMID 37897083
Gender-related differences in irritable bowel syndrome: potential mechanisms of sex hormones. 2014. PMID 24944465
The menstrual cycle affects rectal sensitivity in patients with irritable bowel syndrome but not healthy volunteers. 2002. PMID 11889064
Hypothyroidism. 2017. PMID 28336049
