“Misleading” advertisements for Zoe and Huel featuring Steven Bartlett have been banned by the advertising regulator because the companies failed to disclose their commercial relationship with the celebrity entrepreneur.

The Advertising Standards Authority (ASA) is due to issue rulings that conclude Facebook adverts in which Bartlett endorsed the two nutrition businesses had “omitted material information” about their links to the 31-year-old, who is an investor in Zoe and a director at Huel.

Two adverts for Huel were “likely to mislead”, the regulator found, while a Zoe advert “was misleading”, according to rulings seen by The Times.

The adverts breached rules that govern non-broadcast advertisements, sales promotions and direct marketing communications and “must not appear again the complained about form”, the regulator will say in the rulings, which are expected to be published this week.

Zoe is a health testing and membership service that advises users on changing their diets. Huel is a food business that sells products including vitamin-enriched powders, drinks and snack bars.

Bartlett is a star of the BBC’s Dragons’ Den business show and a successful podcaster, author and social media personality.

The Zoe advert, seen by two complainants in February, featured Bartlett, with a quote from him saying: “If you haven’t tried Zoe yet, give it a shot. It might just change your life.”

The regulator said this was “reminiscent of how a customer might review a product, and how an independent testimonial might be presented”. His position as a backer of Zoe “was material to consumers’ understanding of the ad and relevant in making an informed decision,” the regulator said.

Zoe expressed dismay at the ruling. It had argued that when celebrities appeared in adverts, “the average consumer would understand there was a commercial relationship between the brand and the individual and did not need to know the exact nature of that relationship”.

It also argued that a requirement for specific disclosure would have a “wider impact on other brands and influencers” where they advertised on their own channels on social media.

A spokeswoman for Zoe said: “The ASA acknowledged that the ad was indeed ‘obviously identifiable’ as a marketing communication.”

She said that nothing in the rules or the ASA’s guidance suggested “it is necessary to go into granular detail about the precise nature of an ambassador’s commercial relationship with a brand. We believe the ad was compliant. We would welcome further guidance to bring clarity on the effect of this decision.”

In one Huel advert, seen by complainants in February, Bartlett was said to have described Huel’s “daily greens” as the company’s “best product”. The other showed an individual trying Huel on the basis that “I keep seeing this guy [Bartlett] all over the internet talking about Huel”.

The regulator acknowledged that the adverts were “obviously identifiable” as marketing but that many consumers would “interpret the ads as featuring a testimonial from Bartlett about one of Huel’s products”.

The ASA said: “Many consumers were unlikely to understand from the ads that Steven Bartlett had a financial interest in Huel’s performance. We considered that Bartlett’s directorship was material to consumers’ understanding of the ads, and so relevant for them in making an informed decision about the advertised product.”

Bartlett’s Flight Fund investment vehicle has invested in Zoe, and his Flight Story business is a shareholder in Huel. He has been a director of Huel since 2021.

The regulator also banned a podcast ad for Huel in 2022, in which Bartlett said during a segment on his highly successful The Diary Of A CEO show that he had “become hooked on” an iced coffee caramel-flavour Huel drink.

Huel and Bartlett were approached for comment.