A Kellogg’s advert that claimed its porridge had “30% less fat than most other porridges” has been struck down by the Advertising Standards Authority (ASA).

PepsiCo was one of 15 complainants who contacted the watchdog to challenge Kellogg’s nutritional assertions.

The ASA deemed the ad’s claim did not comply with the UK Code of Broadcast Advertising (BCAP) as it represented the product in its dry form when it should have related to the product once it had been prepared with milk.

Furthermore, the watchdog said it had not seen evidence that the products Kellogg’s used for comparison were representative of the category.

Kellogg’s said it based its claims on 100g of the dry product because consumers prepared porridge in different ways, using differing portion sizes as well as milk or water.

“The ASA’s decision is disappointing, especially considering that it was reviewed by three independent organisations,” said a spokesperson for the company. “We are committed to self-regulation and we will amend the advertisement.

“However, we believe that this decision makes it extremely difficult for companies to make lower fat, salt or sugar claims – we compared Special K Multi-Grain porridge with the top 75% of porridges sold in the UK, which goes further than EU legislation [on advertising].”

The ASA said the ad must not appear again in its current form and added that Kellogg’s must ensure that comparative nutrition claims complied with the BCAP in future.