Quick Answer
Gut tests are most useful when they answer a specific question, such as whether you have celiac disease, an infection, inflammation or trouble digesting lactose. Standard options include blood tests, stool tests, breath tests and, when needed, procedures like endoscopy or colonoscopy. Direct-to-consumer microbiome kits and IgG food sensitivity panels are popular, but experts say they are not ready to diagnose digestive problems or guide treatment on their own. The right test depends on your symptoms and history.
Who this is for: adults with digestive symptoms who are weighing gut tests, including at-home kits, and want to know what results can really show
Start With the Question, Not the Test
No single test measures overall gut health. Each test looks for something specific, so the most helpful starting point is a careful look at your symptoms, bowel habits, diet, medications and family history. That history often points to one or two tests that can actually change the plan.
Testing without a clear question can produce confusing or borderline results. Those results can cause worry without offering real answers.
Blood Tests
Blood work can screen for several conditions linked to digestive symptoms. A complete blood count can show anemia, and iron or vitamin B12 levels may point to trouble absorbing nutrients (see Ferritin and Iron). Thyroid tests can help when constipation or fatigue is part of the picture.
Celiac disease screening looks for antibodies that are often higher than normal in people with untreated celiac disease. Keep eating gluten before testing, because a gluten-free diet can change the results.[1] A positive screen is usually followed by an upper endoscopy with a small biopsy to confirm the diagnosis.[1]
Bringing past results and a symptom log to a visit can make testing decisions easier.
Stool and Breath Tests
Stool tests can look for infections, hidden blood and markers of inflammation in the intestines. They can help tell inflammatory conditions, such as Crohn’s disease or ulcerative colitis, apart from conditions like irritable bowel syndrome. Some stool tests are also used for colorectal cancer screening.
Breath tests measure gases made when bacteria ferment sugars. For lactose intolerance, you drink a measured amount of lactose and breathe into a container at set times over a few hours. Rising hydrogen along with symptoms makes the diagnosis more likely.[2] Similar breath tests are used to evaluate small intestinal bacterial overgrowth, though they are less precise.
Microbiome Kits and IgG Food Panels
At-home microbiome kits analyze a stool sample and report which bacteria are present. Microbiome research is growing quickly, but an international expert panel concluded in 2025 that there is not yet enough evidence to recommend routine microbiome testing.[4] The panel also advised that these tests be ordered by a licensed health care provider rather than self-ordered.[4]
IgG food sensitivity panels report reactions to dozens of foods. The American Academy of Allergy, Asthma & Immunology and the Canadian Society of Allergy and Clinical Immunology recommend against using IgG testing to diagnose food allergies or intolerances.[3] IgG to a food may simply be a normal response to eating it, so results can lead people to avoid foods they tolerate well.[3]
When a Scope Is the Right Test
Some questions can only be answered by looking directly at the digestive tract. Upper endoscopy and colonoscopy, performed by a gastroenterologist, can find ulcers, inflammation, sources of bleeding and polyps, and allow biopsies. They are typically recommended for red-flag symptoms or when other tests suggest a problem that needs a closer look.
Colonoscopy is also one option for routine colorectal cancer screening (see Preventive Screenings by Age).
How We Approach Gut Testing at Lake Forest Regenesis
Allana focuses on testing that answers a clear question about your symptoms. She reviews your history, bowel habits, diet and medications, then may order blood work, stool or breath testing when the results are likely to guide next steps. She explains what each result can and can’t show, including results from tests you have already done at home. If you need endoscopy, colonoscopy or specialist care, she refers you to a gastroenterologist.
When to See a Provider
Seek emergency care for vomiting blood, black or bloody stools with dizziness, or severe abdominal pain. Book a visit for digestive symptoms that last more than a few weeks, or for unintended weight loss, anemia, trouble swallowing, persistent vomiting or a lasting change in bowel habits. These red flags usually call for evaluation by a gastroenterologist, who can perform endoscopy or colonoscopy.
Not sure which gut test, if any, you need? Allana can review your symptoms and past results to help you choose testing that answers real questions.
Frequently Asked Questions
Can a microbiome test tell me which probiotic to take?
Not reliably yet. Research hasn't established how to match microbiome results to specific products, and probiotic effects vary by strain.
I already did an IgG food panel. Should I avoid everything it flagged?
Not necessarily. Bring the results to a visit. A provider can help you focus on foods linked to symptoms in your own experience and reintroduce others safely.
Does a normal test mean nothing is wrong?
A normal result rules out the specific thing that test checks. Ongoing symptoms still deserve attention, since conditions like irritable bowel syndrome are diagnosed mainly by symptom pattern.
Do I need to stop medications before a breath test?
Often, yes. Antibiotics, laxatives and some other medications can affect results, so follow the prep instructions and ask before stopping any prescription.
References
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Diagnosis of celiac disease. Read the article
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Diagnosis of lactose intolerance. Read the article
- American Academy of Allergy, Asthma & Immunology (AAAAI). The myth of IgG food panel testing. Read the article
- Porcari S, Mullish BH, Asnicar F, et al. International consensus statement on microbiome testing in clinical practice. Lancet Gastroenterol Hepatol. 2025;10(2):154-167. Read the study
This article is for general education and is not a substitute for individual medical advice. See our medical disclaimer.
