Histamine plays an important role in the development of symptoms in allergic, infectious, neoplastic and other diseases. Empirical findings have suggested beneficial effects of ascorbic acid supplementation in those diseases, and these effects are assumed to be related to a possible decrease in systemic histamine concentration. In the present study, we systematically investigated for the first time the effect of 7.5 g of intravenously administered ascorbic acid on serum histamine levels (as detected by ELISA) in 89 patients (19 with allergic and 70 with infectious diseases). When all patients were grouped together, there was a significant decline in histamine concentration from 0.83 to 0.57 ng/ml×m2 body surface area (BSA, p<0.0001). The decrease in serum histamine concentration in patients with allergic diseases (1.36 to 0.69 ng/ml×m2 BSA, p=0.0007) was greater than that in patients with infectious diseases (0.73 to 0.56 ng/ml×m2 BSA, p=0.01). Furthermore, the decline in histamine concentration after ascorbic acid administration was positively correlated with the basal, i.e. pre-therapeutic, histamine concentration. Intravenous infusion of ascorbic acid clearly reduced histamine concentrations in serum, and may represent a therapeutic option in patients presenting with symptoms and diseases associated with pathologically increased histamine concentration.

The nitrate and nitrite levels of 75 gastric juice samples from young and healthy fasting volunteers were examined. For both parameters a dependence on the specific pH value of the secretion was detected. The rise of the nitrite level from normal 0.1 ppm in the acid to 1.4 ppm in the neutral range can be explained by the activity of the bacterial flora even in the healthy stomach, which has already been demonstrated earlier. The hitherto existing theory that nitrate originates exclusively from the salivary glands, and if not reduced to nitrite by bacteria in the mouth cavity, is brought into the stomach via swallowed saliva only, does not explain the observation that there is a rise in nitrate concentration in neutral juice, too. Further investigations have to be made to see whether there are other endogenous sources of nitrate except the salivary glands in the gastrointestinal tract. The environmental pollutant nitrate must be paid more attention to in future.

No abstract