Colonic lactate metabolism and D-lactic acidosis.
D-Lactic acidosis is seen in patients with intestinal bypass or short bowels in whom colonic produced D-lactate accumulates. An intestinal bypassed patient with D-lactic acidosis had higher fecal D-lactate (122.4 mmol/liter) and L-lactate (90.1 mmol/liter) than described before in humans. D-Lactate fluctuated between 0.5 and 3.1 mmol/liter in plasma (normal < 0.1 mmol/liter) and between 1.1 and 52.8 mmol/liter in urine (normal < 0.7 mmol/liter) within a few hours, indicating that the human organism do metabolize and excrete D-lactate. The patient with D-lactic acidosis had a 10-fold increased DL-lactate production from glucose in fecal homogenates compared to 14 healthy controls and a patient with intestinal bypass, who did not have D-lactic acidosis. A 67% carbohydrate (starch)-enriched diet resulted in a minor elevation of fecal and plasma lactate, whereas 50 + 100 + 150 g of ingested lactose increased D-lactate in feces (84.0 mmol/liter) and plasma (2.3 mmol/liter) considerably in the patient with D-lactic acidosis. Intestinal prolongation (22 cm ileum) had a temporary effect on fecal and plasma D-lactate, but intestinal continuity was reestablished 26 months later because D-lactic acidosis recurred (plasma 8.6 mmol/liter, urine 101.3 mmol/liter). Large amounts of lactulose (160 g/day) to 12 normal individuals increased D-lactate to 13.6 +/- 3.5 mmol/liter in feces, but never increased D-lactate in plasma or urine. The in vitro fermentation of glucose in fecal homogenates increased DL-lactate, which disappeared after complete metabolization of the glucose. L-Lactate was converted to D-lactate and vice versa, and both were degraded to the short-chain fatty acids acetate, propionate, and butyrate. An infrequent, but elevated ability of the colonic flora to produce lactate may be a prerequisite for D-lactic acidosis to occur and may explain why the syndrome is so seldom seen even in patients with intestinal bypass or short bowels. The suggestion that D-lactate is not metabolized and hence accumulates is probably not valid.
Department of Medicine A, Rigshospitalet, University of Copenhagen, Denmark.
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D000140:Acidosis, Lactic / Q000178:diet therapy / Q000209:etiology / Q000378:metabolism*; D000328:Adult; D000704:Analysis of Variance; D001644:Bifidobacterium; D003106:Colon / Q000378:metabolism*; D005232:Fatty Acids, Volatile / Q000032:analysis; D005243:Feces / Q000737:chemistry / Q000382:microbiology; D005260:Female; D006801:Humans; D007773:Lactates / Q000032:analysis / Q000378:metabolism*; D007792:Lactulose; D008297:Male; D008875:Middle Aged; D012778:Short Bowel Syndrome / Q000150:complications / Q000178:diet therapy / Q000378:metabolism
D005232:Fatty Acids, Volatile; D007773:Lactates; D007792:Lactulose