LACTATE AND PH IN FECES FROM PATIENTS WITH COLONIC ADENOMAS OR CANCER

Earlier studies have reported that faecal pH is more alkaline in patie nts with colonic cancer, indicating a reduction in colonic carbohydrat e fermentation to organic acids. The pH of faeces from 11 pre and 14 p ostoperative, selected colonic cancer patients without intestinal obst ruction, major loss of appetite or weight, not treated with antibiotic s, and without signs of dissemination or recurrence of the cancer, did not differ, however, from faecal pH in 17 patients with previous colo nic adenomas removed by polypectomy and faecal pH in 17 age matched (m ean 61 years) healthy controls (mean (SE) 7.03 (0.10), 7.15 (0.11), 7. 20 (0.12), 7.11 (0.12) respectively; p=0.82). Faecal pH in 20 younger (mean 32 years) healthy controls tended to be lower (6.89 (0-07) compa red with the older age matched control group (p<0.06). Faecal concentr ations of D-, L- or total D+L-lactate did not differ between the patie nts with present or previous colonic cancer, adenomas, and the healthy controls (D+L-lactate mean (SE) 3-2 (0-5),3-1 (0.3), 3.5 (0.7), 4.1 ( 1.0) mmol/l respectively; p=0.72), and the production pattern of lacta te from different carbohydrates (glucose and dietary fibre) in 16.6% f aecal homogenates was similar in all the three groups of patients and the healthy controls. Faecal pH was changed within days by modificatio ns of the diet. An enteral diet free of fibre, starch, and lactose inc reased faecal pH within three days, whereas pH decreased when the colo nic load of carbohydrates was increased by lactulose. Therefore, the r eported alkaline faecal pH in patients with colonic cancer may reflect short term reductions in dietary intake and colonic fermentation seco ndary to the presence of the cancer, especially in patients with advan ced disease, rather than long term differences in the precancer dietar y habits.