The account includes digital marketing as well as advertising. Before its merger with Adam & Eve this summer, DDB London lost the global advertising account for the brand (known as Becel in other markets) to Lowe Worldwide in September 2011.
DDB had won the global account for Flora and Becel from Bartle Bogle Hegarty (BBH) in 2009.
The agency, which is understood to be up against TBWA for Flora, is also contending with a review by rival healthy spread brand Benecol as part of Johnson & Johnson's £1.7bn global rethink. Benecol was an Adam & Eve client prior to the merger with DDB London.
A Unilever spokesman said: "We can confirm that we are conducting a review of the creative agency services for our Flora brand in the UK. This is in line with our policy to review agency appointments every few years. We will announce the outcome in due course."