Diet Therapy of Obstructive Sleep Apnea Syndrome Treated with Positive Airway Pressure: A Systematic Review of Randomized Controlled Trials

The positive airway pressure (PAP) is a gold standard in therapy for obstructive sleep apnea (OSA) patients, though weight loss is among the most effective supportive therapeutic methods. The aim of the study is to conduct a systematic review of randomized controlled trials (RCTs) of diet therapy interventions for OSA patients treated with PAP. The systematic review was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and registered in the International Prospective Register of Systematic Reviews (PROSPERO) database (CRD42023398374). The 1436 records were screened and five records were included identified as RCTs available within PubMed and Web of Science databases until 1 February 2023. Two researchers independently conducted identification, screening, inclusion, and evaluation of RCTs, using the revised Cochrane risk-of-bias tool for randomized trials. The studies were conducted in groups with patients treated or intended to be treated with CPAP, while patients with moderate-to-severe or severe OSA were included. Within all included studies, an experimental diet was compared with a control group; however, various interventions were applied, including dietary intervention, which was compared with no intervention, and dietary and physical activity intervention, which was only compared with general advice. The applied intervention included various dietary approaches, such as various energy deficits or dietary health-promoting behaviors. The monitored variables included apnea-hypopnea index (AHI), sleep time, sleep efficiency, sleep latency, oxygen desaturation episodes, oxygen saturation, OSA type, Epworth Sleepiness Scale score, Pittsburgh Sleep Quality Index, and quality of life. For the majority of studies, some concerns were defined for the risk of bias; however, for one study the risk was high. Three studies supported the positive influence of diet therapy, one study somewhat supported it and one study did not support it. It may be stated that for excessive body mass individuals, even if PAP is applied, the diet therapy should be included in order to reduce body mass, reduce the symptoms of OSA, and improve the quality of life. This therapeutic option should be applied, even if no effect on OSA is noted, as body mass reduction have multiple positive effects, which may also influence the quality of life.