A handful of biotech companies are pursuing the development of microbiome drugs, and many prominent investors are placing their bets.

With $35 million series B funding led by Sequoia Capital, Whole Biome is on track to start selling a capsule for type 2 diabetes early next year. Whole Biome’s capsule helps patients restore gut bacteria, that when missing, impairs their immune systems.

In the last ten years, scientists have mapped the gut microbiome, the aggregate of bacteria living within human bodies, and identified the function of particular microbes.

Whole Biome claims it is leading the effort to identify novel bacteria and how they affect human health, using their proprietary data and analytical tools. Whole Biome’s co-founder and CEO Colleen Cutcliffe said in a statement that their product is able to “help naturally restore and improve one’s health.”

With the new funding, Whole Biome has now raised a total of $57 million, which will be used to commercialize its yet-to-be-named first product, and expand its clinical trials and research. Firms participating in the fundraising include True Ventures, Khosla Ventures, Mayo Foundation, AME Cloud Ventures and others. Sequoia Partner Roelof Botha joined Whole Biome’s board.

Whole Biome’s first product is labelled not as a therapeutic drug, but “medical food”, an FDA classification that requires less rigorous oversight, according to an Xconomy report. Cutcliffe told Xconomy that the microbes in its product are naturally occurring and found in abundance in healthy people, therefore meeting theFDA’s “generally recognized as safe” requirement for medical food.

Whole Biome also says it has done “double-blinded, placebo-controlled, randomized clinical trials”, and found the capsule highly effective without product-related side effects.

Whole Biome’s competitors’ products are in various clinical trial stages, giving the San Francisco company a clear lead, according to another Xconomy report.

Cambridge, Massachusetts-based Seres Therapeutics, currently valued at $135 million after its 2015 IPO , is at phase 3 of another clinical trial after its lead drug failed in 2016. Another San Francisco company, Second Genome, is testing a microbiome drug for nonalcoholic steatohepatitis (NASH). It raised $83 million in September. UBiome, also in San Francisco, suspended the sale of its microbiome self-testing kit after its offices were searched by the FBI in April over, according to the Wall Street Journal, dodgy billing practices.

Investors are confident Whole Biome will reach its target of rolling out its first product early next year.

“Whole Biome is creating novel, disease-targeting microbiome interventions that have the potential to improve the course of many of the significant health issues facing people today,” Sequoia’s Bartha said in a statement.