If you have heard about gut microbiome testing and are trying to figure out whether it is worth doing, whether the version marketed in Japan is different from Biome or ZOE, or whether the results actually change anything a doctor would recommend, this article is the one to read first.
We use Mykinso, Japan’s largest and most peer-reviewed consumer gut microbiome test, in the BIOTOPE Clinic workflow — and we are careful about what it can and cannot tell us. This guide walks through the test honestly for Japanese patients living abroad and English-speaking readers in Tokyo.
Two framings up front. First, Mykinso is an assessment, not a diagnosis. It is not classified as a medical device in Japan, and no consumer gut microbiome test anywhere in the world is currently approved to diagnose a disease.
Second, the strongest reason to consider Mykinso specifically — rather than one of the American or British options — is that it is built on a Japanese reference cohort of roughly 250,000 samples. If you are a Japanese person tested against a Western reference population, the reading will systematically look “unusual” in ways that reflect ethnicity, diet, and geography rather than anything about your health.
What Mykinso is
Mykinso is developed by Cykinso, Inc. (株式会社サイキンソー), a Tokyo microbiome company founded in November 2014 as an Osaka University Research Institute for Microbial Diseases spinout. The consumer product launched in November 2015 as Japan’s first at-home direct-to-consumer gut microbiome test. The current consumer version, Mykinso Gut V2, was released on 23 January 2024 and doubled the number of report items from 10 to 20.
There are two lines you should know about:
- Mykinso Pro — the clinical version used by medical institutions. Adds a physician dashboard, patient case management, a free registered-dietitian phone consultation (“腸活ご相談コール”), and a printed report booklet designed to be handed to the patient on a follow-up visit. BIOTOPE uses the Pro version ¥33000 tax-included.
The underlying method is 16S rRNA gene sequencing. Specifically, Mykinso amplifies the V1–V2 region of the 16S rRNA gene, sequences it on the Illumina MiSeq platform, and classifies organisms at the genus level against the Cykinso reference cohort.
That method has technical trade-offs — it does not read species or strain level, and it does not tell you whether a bacterium is active or dormant — but for population-scale comparison it is the industry standard.
Why the reference cohort matters
This is the single most important thing to understand before ordering any gut microbiome test.
Every microbiome test compares your sample to a reference population. The reference decides what “average,” “high,” and “low” mean for every genus reported. Japanese guts differ meaningfully from Western guts on several key genera.
The Cykinso team, in their 2021 peer-reviewed cohort paper (Watanabe et al., Bioscience of Microbiota, Food and Health, PMID 33996369), found that Japanese individuals have higher baseline levels of Bacteroides, Faecalibacterium, and Bifidobacterium than Western reference populations — with sex differences in Akkermansia (higher in women) and Prevotella (higher in men), and an age-related decline in Actinobacteria.
The practical consequence is that a Japanese person tested against a Western cohort will consistently register as an outlier on genera that are entirely normal for their population. Reports get flagged in ways that do not reflect a real anomaly, and downstream recommendations skew toward correcting things that are not actually off. Testing against a Japan-specific reference removes that source of noise, which is why we prefer Mykinso for our Japanese-abroad patients.
What the Gut V2 report measures
The current 20-item report is structured around the following categories:
- Overall grade — a proprietary A–E score benchmarked against the Japanese reference cohort.
- Bacterial diversity — alpha-diversity measured with the Shannon index and observed genera count, ranked against the healthy reference subset.
- Firmicutes / Bacteroidetes ratio (F/B) — historically labelled as an “obesity ratio.” We flag this specifically in the discussion below — the F/B ratio has become controversial in the recent literature.
- Phylum-level composition — full breakdown across Bacteroidetes, Firmicutes, Actinobacteria, Proteobacteria, Fusobacteria, Verrucomicrobia and adjacent phyla.
- Beneficial bacteria (6 items) — including Bifidobacterium, lactic-acid producers (Lactobacillales), butyrate producers (Faecalibacterium, Roseburia, Eubacterium, and adjacent Lachnospiraceae / Ruminococcaceae members), equol producers, and broader short-chain-fatty-acid producers.
- Bacteria requiring attention (4 items) — for example, Fusobacterium, oral-origin translocated genera such as Streptococcus, and Gammaproteobacteria-class markers.
- Actionable output — the top three improvement priorities plus diet and lifestyle guidance, integrated with a lifestyle questionnaire.
- Longitudinal tracking — repeat testing plotted against your own baseline over time.
What the evidence supports — and what it does not
Because this is a topic where marketing and science do not always overlap, we think it is important to lay out where the microbiome literature is firm and where it is still exploratory.
| Clinical context | Evidence strength | What that means for a Mykinso reader |
|---|---|---|
| Recurrent Clostridioides difficile infection | Strong | Prospective randomized trials support fecal microbiota transplant and standardized microbiome therapeutics (SER-109, RBX2660) for recurrence prevention. This is a hospital-level intervention, not a consumer-test use case, but it is why the microbiome field has clinical credibility at all. |
| Inflammatory bowel disease (Crohn’s, UC) | Moderate | Recent systematic reviews consistently show reduced alpha and beta diversity and depletion of butyrate producers (Faecalibacterium, Roseburia, Eubacterium). Mykinso can describe those patterns; it does not diagnose IBD, and it should not delay a gastroenterology referral if you have persistent GI symptoms. |
| Obesity / metabolic syndrome | Correlational; F/B ratio contested | The F/B ratio has been reported as a marker of obesity for years, but multiple 2023–2024 meta-analyses and reviews have questioned whether it is a reliable individual biomarker. Take the F/B line on your report as informative context, not a verdict on body composition. |
| Depression, anxiety, gut–brain axis | Emerging | The Cykinso team’s own 2024 paper (Masamura et al., PMID 39364125, n=457) found no global compositional shift by CES-D depression severity score — but did flag candidate taxa (Bifidobacteriaceae, Streptococcaceae, Veillonellaceae) worth further study. Do not expect a microbiome test to explain, diagnose, or treat mood symptoms on its own. |
| Maternal mental health, parenting stress | Emerging | The Osaka–Kyoto–Cykinso collaboration (Matsunaga et al., Communications Biology, 2024, PMID 38424440) linked alpha/beta diversity to parenting-stress risk and identified resilience-associated taxa (Blautia, Clostridium, Eggerthella). Interesting; not clinically actionable yet. |
| Atopic dermatitis, allergy, IBS, autism, cancer risk | Correlational / exploratory | Signal exists in each of these areas. None is at the point where a genus-level 16S readout is a diagnostic or treatment guide. |
| Diagnostic classification of any disease | Not yet — anywhere | As of 2026, no 16S rRNA gene microbiome test — Mykinso included — has regulatory approval as a diagnostic device for any condition in any jurisdiction. |
The bottom line: microbiome testing is a legitimate scientific tool that gives you a snapshot of your gut community, and Mykinso happens to be an unusually well-referenced version of that tool for a Japanese population.
What it is not is a device that diagnoses IBS, autoimmune disease, colon cancer, depression, or metabolic disease. Any clinic that claims otherwise is not respecting either the science or Japan’s medical-advertising rules.
Peer-reviewed Cykinso publications
One reason we prefer Mykinso over some of the consumer competitors is that the Cykinso team publishes their methodology and reference-range work in peer-reviewed journals. For readers who want to look at the primary sources rather than a marketing page, the most useful ones are:
- Watanabe et al., 2021 — the reference-range paper. 5,843 Japanese samples, 1,319-subject healthy reference subset; established Japan-specific ranges for 11 microbial indices. Open access at PMC8099632.
- Watanabe et al., 2024 — gut microbial stability in 3,361 older Japanese adults. Uses SparCC network inference and generalized Lotka–Volterra modeling. Open access at PMC10767323.
- Masamura et al., 2024 — microbial composition versus depressive symptom severity (n=457). Open access at PMC11444865.
- Matsunaga et al., 2024 — Communications Biology (Nature Portfolio). Maternal mental health and gut microbiome. Open access at PMC10904874.
- Kubo et al., 2021 — methodological benchmark of V1–V2 versus V3–V4 primer sets on Japanese samples. Open access at PMC8272389.
How Mykinso compares to Viome, ZOE, and other consumer tests
Patients often come in having considered a US or UK product first. The differences matter, so here is a straightforward comparison.
| Product | Method | Resolution | Price (2026) | Reference cohort |
|---|---|---|---|---|
| Mykinso (Cykinso, Japan) | 16S rRNA V1–V2, Illumina MiSeq | Genus | ¥19,800 (~US$130) | ~250,000 Japanese samples — the largest Japan-specific commercial cohort |
| Viome (US) | Metatranscriptomic RNA sequencing | Species/strain + microbial activity | US$249–399 | Western-heavy |
| ZOE (UK) | Shotgun metagenomics (CGM component removed in September 2025) | Species | £299 (~US$380) | UK / US-heavy |
| Ombre (formerly Thryve, US) | 16S rRNA | Genus | US$99–179 | US-heavy |
| BIOHM (US) | 16S + fungal ITS | Genus | ~US$130 | US-heavy |
A few honest observations on that table:
- Viome’s metatranscriptomic method reads more than 16S can, in theory. Whether that extra resolution changes clinically useful advice is still an open question in the literature.
- ZOE’s original personalized-nutrition strength depended in part on its continuous glucose monitoring component, which was discontinued in September 2025. The product is different now than it was in 2022–2024 reviews you may have read.
- The now-defunct uBiome (US) is worth mentioning as a cautionary tale — the company filed for bankruptcy in 2019 amid federal fraud charges against its founders. Consumer microbiome testing does not have a perfect corporate track record globally; buying from a peer-reviewed, still-operating Japanese lab is not a trivial advantage.
What the test is not
Under Japan’s Pharmaceutical and Medical Devices Act (薬機法), Mykinso is not classified as a diagnostic medical device. It is a health-check / lifestyle service (健康チェック / 生活習慣サービス). This is not a technicality; it is a statement about what the test is legally allowed to be used for. In practical terms:
- Clinics can describe the report, correlate patterns with your lifestyle and diet, and recommend dietary or probiotic changes based on peer-reviewed microbiome research.
- Clinics cannot use the test to diagnose IBS, IBD, colorectal cancer, depression, autism, or any named disease.
- Clinics cannot claim the test predicts, prevents, or cures disease.
- Clinics cannot make quantitative risk statements (“30% higher risk of X”) that are not present in the report itself.
You will not hear any of that language from us. Where your report and symptom picture point to a genuine disease workup, we refer — to a gastroenterologist for IBD-pattern findings, to your primary care team for metabolic concerns, and so on.
How the test actually works — step by step
- Clinic intake. On the first visit you complete the Mykinso Pro questionnaire (lifestyle, diet, bowel habits, medications, physical condition) and sign the consent form.
- Take-home stool kit. The Cykinso kit is a small preservative-filled container plus a return envelope. The sample is stable at room temperature until it is mailed back.
- Return the sample by Japan Post. Prepaid postage is included in most cases. Overseas patients and patients traveling should check the specifics — Cykinso ships to Japanese addresses only, and international return-post is not straightforward, so we usually time the sampling to happen in Japan.
- Laboratory processing at Cykinso. DNA extraction, V1–V2 PCR amplification, MiSeq sequencing, bioinformatic analysis against the Japanese reference cohort.
- Result delivery in about 4–6 weeks. Delivered via the patient portal as a PDF, plus a printed booklet on Pro. Note that the report itself is in Japanese — the doctor consultation is where English-speaking patients get their interpretation and plan.
- Follow-up consultation. Discussion of the report, targeted diet and lifestyle plan, probiotic recommendations if indicated. Pro patients can also use the free registered-dietitian phone line for follow-up questions.
Who this test tends to help — and who should skip it
Mykinso tends to be genuinely useful when:
- You have chronic but non-alarming digestive symptoms (bloating, irregularity, food-mood interactions) and want a structured way to look at what your gut community looks like.
- You are considering probiotic or prebiotic products and want the recommendation to be grounded in your actual composition rather than generic marketing.
- You are Japanese, living abroad, and have been offered a Viome or ZOE test — a Japan-referenced version is more informative for you.
- You are combining nutrition therapy work (see our orthomolecular nutrition therapy overview) with gut health and want both angles on the same visit.
It is not the right first step when:
- You have red-flag GI symptoms — bleeding, unintentional weight loss, persistent severe pain, or a family history of colorectal cancer. Those need a gastroenterologist first, not a lifestyle test.
- You are hoping to diagnose IBS, IBD, colorectal cancer, autism, or a psychiatric condition. Mykinso is not that tool.
- You have already had a normal microbiome test within the past 6–12 months and no meaningful lifestyle change has happened since. The gut community is relatively stable over short intervals.
Related BIOTOPE articles
- Adult acne and rosacea — the gut–skin connection. If your reason for testing is skin, this is the companion piece.
- Gut microbiome testing in Tokyo — a general overview. Broader context on gut testing beyond a single brand.
- Winter immunity — a nutritional guide. Where gut health meets seasonal immune function.
- Hashimoto’s thyroiditis and nutritional support. If autoimmune features are part of the picture.
- Orthomolecular nutrition therapy at BIOTOPE. The pillar article on the broader nutrition-medicine framework that a Mykinso result often feeds into.
Frequently asked questions
Is Mykinso covered by Japanese health insurance?
No. It is a self-pay (自由診療) service. This applies to the consumer version and to the clinic-ordered Pro version.
Can the kit be shipped to me overseas?
Cykinso ships to Japanese addresses only, and international return-post is not reliably supported. In practice, Japanese-abroad patients time the sampling to a visit home. We can also coordinate the intake around a Japan trip so a single visit covers the questionnaire, the sample, and the eventual follow-up.
Is the report in English?
The doctor consultation at BIOTOPE is where English-speaking patients get their interpretation and plan. If English-language documentation is essential, tell us at intake and we will prepare a written English summary for you.
How often should the test be repeated?
For most patients, a follow-up test at 6–12 months makes sense if a real lifestyle or supplementation change is underway. Testing more frequently than that rarely adds useful information, because the gut community is relatively stable over shorter intervals unless there has been an antibiotic course or a major dietary shift.
What happens if the report flags “bacteria requiring attention”?
The result is a starting point for discussion, not a diagnosis. Depending on which genera are flagged and how your symptom picture reads, next steps range from dietary adjustments and probiotic recommendations to — where clinically appropriate — a referral to a gastroenterologist for further workup.
Will you also recommend probiotic supplements?
Where the composition and symptoms line up with a category the literature supports (for example, low butyrate producers with mild digestive complaints, or low Bifidobacterium with recent antibiotic exposure), yes — usually a specific strain rather than a generic product. Where the report does not point to a clear intervention target, we do not add a supplement just to have something to prescribe.
The next step
If you are considering Mykinso and want a clinician who reads the report in the context of your medical history rather than a generic template, BIOTOPE CLINIC in Shirokanedai is a straightforward option. Dr. Jun Karibe, MD, sees patients in Japanese and English, and the Mykinso Pro workflow is set up for both intake in Japan and remote follow-up for patients based abroad.
You can book or ask a question at BIOTOPE CLINIC — Shirokanedai, or reach us on LINE in Japanese or English. Mykinso is a lifestyle and wellness assessment, not a diagnostic test. If you have a diagnosed medical condition or red-flag symptoms, please consult your primary care physician first.
References
- Watanabe S, et al. A cross-sectional analysis from the Mykinso Cohort Study: establishing reference ranges for Japanese gut microbial indices. Biosci Microbiota Food Health. 2021. PMID 33996369. PMC8099632.
- Watanabe S, et al. Gut microbial stability in older Japanese populations: insights from the Mykinso cohort. Biosci Microbiota Food Health. 2024. PMID 38188657. PMC10767323.
- Masamura Y, et al. Differences in the human gut microbiota with varying depressive symptom severity scores. Biosci Microbiota Food Health. 2024. PMID 39364125. PMC11444865.
- Matsunaga M, et al. Intestinal microbiome and maternal mental health: preventing parental stress and enhancing resilience in mothers. Communications Biology. 2024;7:235. PMID 38424440. nature.com/articles/s42003-024-05884-5.
- Kubo R, et al. Benchmark of 16S rRNA gene amplicon sequencing using Japanese gut microbiome data from the V1–V2 and V3–V4 primer sets. 2021. PMID 34246242. PMC8272389.
- Cykinso, Inc. corporate information. cykinso.co.jp.
- Mykinso consumer product overview. mykinso.com/about.
- Mykinso Pro clinical product overview. pro.mykinso.com.
- Mykinso Gut V2 launch press release (23 January 2024). prtimes.jp announcement.
- PMDA — medical-device applicability guidance. pmda.go.jp guidance.
- Ministry of Health, Labour and Welfare (Japan). Pharmaceutical and Medical Devices Act (薬機法).
