Microbiome testing companies have become a thing, offering consumers a chance to see a snapshot of the billions of microbes that reside in their bodies. Some promise even more from a swab: personalized advice on how to improve your health.

“Take control of your gut bacteria to help with weight management, fitness, skin health and more!” says Thryve’s website. Meanwhile, Viome, launched with $21 million in startup funding last year, promises to help people “discover what’s happening inside your gut and get a personalized action plan to fix it,” using technology “developed for National Security.” Their competitor uBiome has a vaguer sales pitch, saying customers will “learn” and “discover” more about their microbiome — and it may have good reason to keep it simple.