Objective: To investigate the nutrition education provided by primary-care physicians (PCP). Design: An integrative review was used to examine literature on nutrition care provided by PCP from 2012 to 2018. A literature search was conducted in MEDLINE, PubMed, Cumulative Index of Nursing and Allied Health Literature (CINAHL) and Scopus using key search terms. Setting: USA, Netherlands, Germany, Denmark, UK, Lebanon, Australia and New Zealand. Participants: Primary-care physicians. Results: Sixteen qualitative and quantitative studies were analysed thematically using meta-synthesis informed by the COM-B model of behaviour (capability, motivation and opportunity), to understand the influences on PCP behaviours to provide nutrition care. PCP perceive that they lack nutrition capability. While PCP motivation to provide nutrition care differs based on patient characteristics and those of their own, opportunity is influenced by medical educators, mentors and policy generated by professional and governmental organisations. Conclusions: The development of PCP capability, motivation and opportunity to provide nutrition care should begin in undergraduate medical training, and continue into PCP training, to create synergy between these behaviours for PCP to become confident providing nutrition care as an integral component of disease prevention and management in contemporary medical practice.