Background: People with severe substance use disorder (SUD) have a markedly higher burden of micronutrient deficiency compared to the general population. There is limited data available about vitamin B12 status among people with severe SUD. The aim of this study is to investigate vitamin B12 status and risk factors of deficiency related to substance use, opioid agonist therapy (OAT), as well as hepatitis C infection and liver fibrosis.
Method: We used a prospective cohort design. Participants were recruited from opioid agonist therapy (OAT) clinics or municipal health care clinics for SUD in western Norway. Participants were assessed by a research nurse and a structured interview as well as biochemical indicators and clinical data were collected annually. Data were collected between March 2016 and June 2020 and 2,451 serum vitamin B12 measurements from 672 participants were included for this analysis.
Results: The median serum vitamin B12 concentration of the study cohort was 396 (standard deviation (SD) 198) pmol/l at baseline, and 22% of the population had suboptimal serum vitamin B12 levels (<300 pmol/l) while 1.2% were deficient at baseline (<175 pmol/l). Eighty-one percent of the participants maintained their baseline vitamin B12 status in the subsequent assessment. No clear associations were seen with substance use patterns, but higher score of FIB-4 and younger age were associated with higher vitamin B12 levels.
Conclusion: The majority of patients have satisfactory serum levels of vitamin B12 and maintained their baseline vitamin B12 status in the subsequent assessments but about a fifth of the patients had suboptimal levels that might or might not be adequate for metabolic needs. No clear associations were seen with substance use patterns, but liver disease and younger age were associated with higher vitamin B12 levels.