title: Alcohol and acetaldehyde in African fermented milk mursik--a possible etiologic factor for high incidence of esophageal cancer in western Kenya.
abstract: BACKGROUND
  Esophageal cancer is unusually frequent in Western Kenya, despite the low prevalence of classical risk factors such as heavy drinking and tobacco smoking. Among Kenyans consumption of fermented milk is an old tradition. Our hypothesis is that alcohol and acetaldehyde are produced during the fermentation process and that their carcinogenic potential contributes to the high incidence of esophageal cancer.
  
  
  METHODS
  Eight samples of mursik milk starter cultures were collected from different Kalenjin families in the Rift Valley province, Western Kenya. A protocol provided by the families was used for milk fermentation. Ethanol and acetaldehyde levels were measured by gas chromatography. The microbial flora in starter cultures was identified by 16S and 18S sequencing.
  
  
  RESULTS
  7/8 starter cultures produced mutagenic (>100 μmol/L) levels of acetaldehyde and 4/8 starter cultures produced more than 1,000 μmol/L of acetaldehyde. The highest alcohol levels (mean 79.4 mmol/L) were detected in the four fermented milks with highest acetaldehyde production. The mean number of microbial species in the starter cultures was 5 (range 2-8). Yeasts were identified in all starter cultures (mean 1.5 species/milk) but their proportion of the total microbial count varied markedly (mean 35%, range 7%-90%). A combination of yeast and lactobacilli, especially Candida krusei with Lactobacillus kefiri, with the exclusion of other species, seemed to correlate with higher acetaldehyde and ethanol levels.
  
  
  CONCLUSIONS
  Significant levels of ethanol and acetaldehyde were produced during mursik fermentation.
  
  
  CONCLUSIONS
  When ingested several times daily the repeated exposure to carcinogenic levels of acetaldehyde may contribute to esophageal carcinogenesis.
authors.affiliation: Research Unit on Acetaldehyde and Cancer, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
authors.forename: Mikko T
authors.initials: MT
authors.lastname: Nieminen
authors.forename: Lily
authors.initials: L
authors.lastname: Novak-Frazer
authors.forename: Rebecca
authors.initials: R
authors.lastname: Collins
authors.forename: Sonja P
authors.initials: SP
authors.lastname: Dawsey
authors.forename: Sanford M
authors.initials: SM
authors.lastname: Dawsey
authors.forename: Christian C
authors.initials: CC
authors.lastname: Abnet
authors.forename: Russell E
authors.initials: RE
authors.lastname: White
authors.forename: Neal D
authors.initials: ND
authors.lastname: Freedman
authors.forename: Michael
authors.initials: M
authors.lastname: Mwachiro
authors.forename: Paul
authors.initials: P
authors.lastname: Bowyer
authors.forename: Mikko
authors.initials: M
authors.lastname: Salaspuro
authors.forename: Riina
authors.initials: R
authors.lastname: Rautemaa
mesh_terms: D000079:Acetaldehyde / Q000009:adverse effects*; D000818:Animals; D002175:Candida / Q000254:growth & development; D002294:Carcinoma, Squamous Cell / Q000453:epidemiology / Q000209:etiology; D015169:Colony Count, Microbial; D003906:Developing Countries; D004938:Esophageal Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D000431:Ethanol / Q000009:adverse effects*; D005260:Female; D005285:Fermentation; D006801:Humans; D015994:Incidence; D007630:Kenya / Q000453:epidemiology; D007778:Lactobacillus / Q000254:growth & development; D008297:Male; D008892:Milk / Q000009:adverse effects* / Q000737:chemistry; D018570:Risk Assessment; D012494:Sampling Studies; D015003:Yeasts / Q000254:growth & development
chemical_list: D000431:Ethanol; D000079:Acetaldehyde