The new strategy, which was introduced by D'Arcy following its reappointment at the beginning of the year, saw the Tetley Teafolk ditched in favour of a campaign stressing the drink's health benefits.
However, the strategy has been thrown into doubt as the ASA and the ITC have upheld complaints made by the Food Commission against two poster executions.
The first complaint objected to the claim that "Tetley is rich in antioxidants that can help keep your heart healthy", as it misleadingly implied that drinking tea had proven health benefits.
The second objection was made on the basis that the "Go on, live a lot" execution misleadingly implied that drinking tea could prolong the drinker's life.
The ruling caps a frustrating week for Tetley's marketing department, following the decision by Publicis to fold D'Arcy London, the recently reappointed incumbent, into its fellow Publicis subsidiary, Leo Burnett.
Nick Kilby, the Tetley GB marketing and development director, said: "There is a wealth of evidence to support the link between antioxidants in tea and the maintaining of a healthy heart and it's a great shame that we're not going to be able to tell people about it directly."
While Kilby stressed that Tetley is keen to avoid repeat rulings in the future, he is adamant that this development will not lead to a total change in the brand's advertising strategy. He said: "We're going to augment the message and find different ways of expressing it. Our campaign will continue on a number of fronts, and will continue in a similar vein - associating Tetley with whole-hearted living."