Effect of apple vinegar intake on metabolic parameters and constipation in patients with schizophrenia treated with clozapine: a pilot study

Purpose: Clozapine is one of the drugs that cause the highest level of weight gain. Additionally, obese patients are at higher risk of developing various physical co-morbidities, such as type 2 diabetes and cardiovascular diseases. Forty-nine percent of patients on clozapine suffer from constipation. Apple vinegar (AV) had been assigned health benefits, such as weight loss, laxative properties, blood glucose lowering effects, and reducing the risk of heart disease. Our hypothesis was that AV would lower the mean glycated haemoglobin level and reduce the level of constipation. Material and methods: Pilot intervention study with a 12-week follow-up. All patients receiving clozapine treatment for schizophrenia at one outpatient clinic were eligible for inclusion. Intervention: Ten millilitres of AV diluted in 200 ml drinking water with breakfast and dinner. Results: Forty patients were suitable for inclusion and nine completed the intervention. Women had much higher-than-recommended body mass index. Scores for constipation were high. The reduction in constipation was of clinical interest (2.6 (p = 0.017)). However, there were no statistically significant differences in glycated haemoglobin, cholesterol, HDL, LDL or triglyceride levels. Patients with problems of constipation prior to the intervention experienced much better bowel habits and relief of their constipation. Conclusion: AV lower the constipation problems faced by patients with schizophrenia treated with clozapine. Further research, repeating this pilot study with a meaningfully larger sample size and randomized with placebo, is needed.