Carcinoid Tumours and Pineapples

SIR,-h a letter to the Editor in this Journal, West (1960) claims that he has found only traces of indole derivatives in pineapples, and that Foy and Parratt (1960) found likewise. In fact, Foy and Parratt claim that they found none. I find quite high levels in Australian pineapples (25 pg./ml. in canned juice) and have the confirming finding of raised indole excretion after the ingestion of pineapple juice (Bruce, 1960). My result is confirmed by Sjoerdsma (personal communication) working with canned pineapple juice available in Maryland, and in which he claims to have detected 35 pg./ml. The possible reasons for this discrepancy seem to be twofold : (1) the geographical or ripeness differences in the fruit, and (2) differences in extraction procedures or in chromatographic, bioassay or colorimetric methods. I have written to Dr. West with a view to resolving the differences, and suggesting the exchange of samples and assay methods. I shall communicate my result to this Journal as soon as possible.