The number of bacteria living on and in the body of the average healthy adult human are estimated to outnumber human cells by a ratio of anywhere from 3:1 to 100:1. Commensal bacteria provide numerous benefits to their host including production of vitamins and antimicrobial substances that are essential in maintaining the delicate balance between helpful colonies and pathogenic overgrowth.
There is a school of thought that posits lactate-producing bacterial species will cause ill-health rather than promote health, particularly for patients suffering Chronic Fatigue Syndrome and Short Bowel Syndrome. Today Belinda Reynolds explores the pathogenesis of D-Lactate and reveals it may not be the culprit first thought, but rather a victim of circumstance.
Research explored in this podcast
Increased D-lactic acid intestinal bacteria in patients with chronic fatigue syndrome
Patients with chronic fatigue syndrome (CFS) are affected by symptoms of cognitive dysfunction and neurological impairment, the cause of which has yet to be elucidated. However, these symptoms are strikingly similar to those of patients presented with D-lactic acidosis. A significant increase of Gram positive facultative anaerobic faecal microorganisms in 108 CFS patients as compared to 177 control subjects (p<0.01) is presented in this report. The viable count of D-lactic acid producing Enterococcus and Streptococcus spp. in the faecal samples from the CFS group (3.5×107 cfu/L and 9.8×107 cfu/L respectively) were significantly higher than those for the control group (5.0×106 cfu/L and 8.9×104 cfu/L respectively). Analysis of exometabolic profiles of Enterococcus faecalis and Streptococcus sanguinis, representatives of Enterococcus and Streptococcus spp. respectively, by NMR and HPLC showed that these organisms produced significantly more lactic acid (p<0.01) from 13C-labeled glucose, than the Gram negative Escherichia coli. Further, both E. faecalis and S. sanguinis secrete more D-lactic acid than E. coli. This study suggests a probable link between intestinal colonisation of Gram positive facultative anaerobic D-lactic acid bacteria and symptom expressions in a subgroup of patients with CFS. Given the fact that this might explain not only neurocognitive dysfunction in CFS patients but also mitochondrial dysfunction, these findings may have important clinical implications.
D-lactate in human and ruminant metabolism
D-Lactate is normally present in the blood of mammals at nanomolar concentrations due to methylglyoxal metabolism; millimolar D-lactate concentrations can arise due to excess gastrointestinal microbial production. Grain overload in ruminants, short-bowel syndrome in humans, and diarrhea in calves can all result in profound D-lactic acidemia, with remarkably similar neurological manifestations. In the past, D-lactate was thought to be excreted mainly in the urine, and metabolised slowly by the enzyme D-α-hydroxy acid dehydrogenase. More recent studies reported that mammals have a relatively high capacity for D-lactate metabolism and identified a putative mammalian D-lactate dehydrogenase. A growing body of literature is also emerging describing subclinical elevation of D-lactate as an indicator of sepsis and trauma. This article describes advances in the understanding of D-lactate metabolism, D-lactic acidosis in ruminants and humans, and subclinical elevation of D-lactate.
Belinda Reynolds is a dietitian and Education Manager at BioCeuticals. She graduated with an Honours Degree in Nutrition and Dietetics, and has been involved in the complementary medicine industry for over 15 years. Her key interests are immune modulation, the human microbiome and the impact they have on overall health.