BACKGROUND: Supportive interventions for enhancing dietary intake in malnourished or nutritionally at risk adults are frequently recommended. A recent systematic review of randomised controlled trials identified limited and poor quality evidence to support their use. Observational studies have been shown to compliment and extend their evidence. This review aimed to synthesise evidence from nonrandomised studies aiming to improve nutritional intake in nutritionally vulnerable individuals and to describe their effects on cost, nutritional, clinical and patient centred outcomes. METHODS: Systematic searches of 10 electronic databases were undertaken to May 2013. Reference lists of identified studies and systematic reviews were scrutinised and hand searching of relevant meeting abstracts was undertaken. Titles and abstracts were reviewed, data extracted by two research-ers working independently and summarised using a structured narrative format. RESULTS: Forty-one studies (n = 3751 participants) were identified for inclusion. Interventions identified included changes to the organisation of nutritional care (n = 15), changes to the feeding environment (n = 11), modification to meals (n = 6), supplementation of meals (n = 7) and recipients of home delivered meals (n = 2). Eighteen of 23 studies reported improvements in nutritional intake; however, effects on nutritional status, clinical outcomes and costs were reported in few studies and findings were inconsistent. Eighteen studies reported patient experience, highlighting benefits to nutritional status most commonly as judged by the carers but the methods used lacked rigour. CONCLUSIONS: This systematic review describes a range of interventions that may be implemented in clinical practice. A limited range of outcomes are reported and it is difficult to draw any meaningful conclusions on the effect of the different methods.