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.

IMPACT:

When ingested several times daily the repeated exposure to carcinogenic levels of acetaldehyde may contribute to esophageal carcinogenesis.

• Authors: Mikko T Nieminen, Lily Novak-Frazer, Rebecca Collins, Sonja P Dawsey, Sanford M Dawsey, Christian C Abnet, Russell E White, Neal D Freedman, Michael Mwachiro, Paul Bowyer, Mikko Salaspuro, Riina Rautemaa
• Journal: Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology (Cancer Epidemiol Biomarkers Prev) Vol. 22 Issue 1 Pg. 69-75 (Jan 2013) ISSN: 1538-7755 [Electronic] United States
• PMID: 23155139 (Publication Type: Comparative Study, Journal Article, Research Support, N.I.H., Intramural, Research Support, Non-U.S. Gov't)

Chemical References

• Ethanol
• Acetaldehyde

Topics

• Acetaldehyde (adverse effects)
• Animals
• Candida (growth & development)
• Carcinoma, Squamous Cell (epidemiology, etiology)
• Colony Count, Microbial
• Developing Countries
• Esophageal Neoplasms (epidemiology, etiology)
• Ethanol (adverse effects)
• Female
• Fermentation
• Humans
• Incidence
• Kenya (epidemiology)
• Lactobacillus (growth & development)
• Male
• Milk (adverse effects, chemistry)
• Risk Assessment
• Sampling Studies
• Yeasts (growth & development)