Other studies have been done in humans and monkeys

BMJ 1996;312:1299 (18 May)

Letters

Other studies have been done in humans and monkeys

EDITOR,--Paul H A Steegmans and colleagues assert that theirswas the first study in humans to investigate the relation ofserum cholesterol concentration to metabolism of serotonin andthat only one study in monkeys has done so.¹ However, two studiesin humans bear on this issue, as does one study in primatesthat they fail to cite.

Ringo et al found a non-significant trend towards an increasedcerebrospinal fluid concentration of 5-hydroxyindoleacetic acid(a central metabolite of serotonin thought to gauge turnoverof serotonin) with high cholesterol concentration in psychiatricpatients and staff.² The 23% higher mean 5-hydroxyindoleaceticacid concentration in subjects with a high cholesterol concentrationis comparable in size, though not significance, to the 19% higher(arithmetic) mean peripheral serotonin concentration in Steegmansand colleagues' study. Anderson et al found significantly reducedplasma tryptophan concentrations in people placed on diets toinduce weight loss.³ Women, who were placed . . . [Full text of this article]