The FLAM study was set up in order to assess the effectiveness of FV vouchers allowed to low-income households, on their FV consumption. The aim of the present study was to investigate issues associated with conducting interventional trials in disadvantaged populations using the FLAM study as an example of reaching target populations and recruitment difficulties. Families were recruited in Saint-Denis city (North Paris suburb), via social and municipal structures. Main interest variables in the study (food consumptions) were collected using face-to-face food interviews, either at home or municipal facilities. A qualitative analysis was performed among people who refused to participate in order to understand the barriers to participation. A total of 95 parents-child pairs were included from May 2015 to May 2016. The families were mostly in precarious situation (63.3%), and most of parents were unemployed (71.3%). Almost the two third of children and 79.4% of parents were small consumers of FV (less than 3.5 servings per day). Several reasons for non-participation were reported including time constraints, understanding and mistrust issues. Though using facilitating strategies, we recruited fewer participants than expected. The population finally included was mainly made of precarious families with a low consumption of FV. These results highlight the importance of identifying effective facilitating strategies to improve recruitment in disadvantaged populations. ClinicalTrial.gov no. NCT02461238, on June 3, 2015, retrospectively registered.