Pyruvate and Lactate in Human Blood and Saliva in Response to Different Carbohydrates

Abstract

The possibility of using parotid saliva as a tool in measuring metabolic response to carbohydrates was investigated. Seven young women were given seven different carbohydrates (cornstarch, fructose, glucose, lactose, potato starch, sucrose, and wheat starch) and responses in pyruvate and lactate levels in blood and saliva were determined at 1 and 2 hours afterward. The responses in the blood were reflected in the saliva. There were significant increases in pyruvate levels in both blood and parotid saliva at 1 hour after fructose and sucrose. There were significant increases in lactate levels in both blood and parotid saliva at 1 hour after fructose, lactose, and sucrose. Significantly higher levels of lactate in blood and saliva persisted at 2 hours after lactose and sucrose. Significant correlations were detected between pyruvate in parotid saliva and pyruvate in blood at 1 hour after sucrose and between lactate in parotid saliva and lactate in blood at 1 hour after fructose and sucrose. There were no changes in lactic dehydrogenase (LDH) activity in serum after any of the carbohydrates. Lactate/ pyruvate ratios were significantly higher in blood and saliva at 1 hour after fruc tose and sucrose. Data suggest that the increased lactate/pyruvate ratio in saliva as well as in blood can be used as an index to assess the potential for lipogenesis from different carbohydrates in human subjects. J. Nutr. 102: 661-666, 1972.