104 companies sell DNA-based diet advice. Nearly half won't say which genes they read

The pitch for consumer nutrigenetic testing is that your genome contains dietary instructions and a cheek swab can read them out. A scoping review published in Advances in Nutrition on 17 June went looking for what the market is actually selling, and produced the first systematic map of it [s1].

What the review counted

The authors searched the internet for companies providing direct-to-consumer tests that come with nutritional recommendations, excluding non-human tests, paediatric tests, and any test requiring a health practitioner to order it [s1]. The review was prospectively registered with the Open Science Framework [s1].

They found 104 companies offering 204 nutrition-related testing panels [s1]. Mean cost was US$234 [s1]. North America was the most common continent of company registration [s1].

The disclosure gap

Only 56 of the 104 companies — 54% — publicly disclosed which genes they use to generate their nutritional recommendations [s1].

That single figure carries most of the review's weight. Nearly half the market sells a genetics-derived recommendation without saying what genetics it derived it from. A consumer cannot evaluate the claim, a dietitian cannot check it against the literature, and a researcher cannot replicate it. The recommendation arrives as an assertion with a scientific-sounding provenance and no way to inspect the provenance.

The gene count

The review identified 3,309 unique genes across the testing panels [s1]. The most commonly reported nutrition categories were micronutrients (1,593 genes), cardiovascular health (1,446 genes) and weight loss (1,383 genes) [s1].

Three thousand three hundred and nine is not a number that suggests convergence on a small set of well-characterised variants. It suggests companies drawing from very different gene lists to answer superficially similar questions. Two panels sold as "personalised nutrition" may share almost no genetic basis, and a consumer comparing them has no way to know.

What happens after the result

Post-test support was provided by 55 of the 104 companies — 53% [s1]. Of those, 33 charged extra for it [s1]. The qualifications of the people providing that support varied greatly [s1].

So roughly half of companies offer no support in interpreting a result, and of those that do, a majority charge separately, with no consistent standard for who is doing the interpreting.

The review's conclusion

The authors describe the expanding nutrigenetics market as continuing to be unregulated, with high variability in offerings [s1]. With thousands of unique genes linked to nutrition recommendations, they write, it is challenging for healthcare practitioners and consumers to keep pace, and evidence analysis and resources are required to support practitioners in giving evidence-based guidance and to protect consumers' interests [s1].

Note what the review does not claim. It did not test whether any panel's recommendations are correct, whether the gene-diet associations they rest on are replicated, or whether following the advice changes any health outcome. It is a market map, not an efficacy assessment. Its finding is about the structure of what is being sold — the price, the opacity, the sprawl — and that is the part a prospective buyer can actually see.

Where this sits in the wider consumer-testing market

Nutrigenetics is one segment of a larger direct-to-consumer diagnostics market. A narrative review in the Journal of General Internal Medicine published on 5 January 2026 describes that marketplace — direct-to-consumer genomics, broad laboratory panels, wearable sensors and whole-body imaging — as outpacing the evidence supporting it, and reports that low-value diagnostics account for over $100 billion in annual downstream costs in the United States, while exposing patients to false-positive cascades, anxiety and bias [s2].

The review's own framing of the demand side is the same one the nutrigenetics authors give: consumer demand for autonomy in their own health care is driving the rise of personal genetic testing [s1]. That demand is not irrational. The gap the two papers identify is between what people are buying autonomy over and what the tests can actually tell them.

What to watch

Whether disclosure of the gene panel becomes a market norm or a regulatory requirement — it is the single change that would make independent evaluation possible. Whether professional nutrition bodies publish appraisals of the specific gene-diet associations in commercial use. And whether the mean price holds at around $234 [s1] as the market grows, or falls in the way consumer genotyping prices did.

Sources

1. [s1] A Scoping Review of Direct-to-Consumer Nutrigenetic Testing: Mapping Genes and Associated Nutrition Recommendations. Advances in Nutrition, published online 17 June 2026. https://doi.org/10.1016/j.advnut.2026.100687
2. [s2] Critically Appraising the Wellness Movement: Cost Without Value, A Narrative Review. Journal of General Internal Medicine, published online 5 January 2026. https://doi.org/10.1007/s11606-025-10099-3