The goal of a study published in The Journal of Nutrition, Health & Aging  was to assess the tolerance and potential nutritional consequences of long-term repeated doses of polyethylene glycol (PEG) in the elderly with chronic constipation as compared to lactulose. This was a single-blinded, randomized, multicenter, parallel group comparative study, wherein participants were community-dwelling patients and nursing home residents aged 70 years and older with a history of chronic constipation. Among the patients selected, 118 received PEG and 127 were given lactulose for six months. The findings showed that the proportion of patients receiving PEG with abnormal levels of electrolytes, nutritional markers or vitamins did not significantly change in the six months after initiating laxative treatment; this result did not differ between the two groups. On a D-xylose challenge test, the proportion of patients with abnormally low xylosaemia (suggesting malabsorption) varied from 24.6% at baseline to 35.8% after six months in the PEG group and from 29.1% to 42.4% in the lactulose group. Meanwhile, the percentage of patients with poor nutritional status varied from 8.5% at baseline to 9.8% after 6 months in the PEG group and from 3.9% to 5.0% in the lactulose group. No changes in stool fat or total or soluble stool nitrogen were observed in the few patients for whom stool analysis was performed. Furthermore, a significantly higher stool frequency and improved stool consistency were observed in the PEG group compared to the lactulose group at each monthly evaluation period. The results suggested no clinically relevant changes in biochemical and nutritional parameters and no unanticipated treatment-related adverse events after six months of treatment with PEG, demonstrating good clinical tolerance of PEG among elderly patients with constipation. It was stated that this tolerance was associated with a better clinical efficacy of PEG compared to lactulose.