Consumption of Low-Dose of Ethanol Suppresses Colon Tumorigenesis in 1,2-Dimethylhydrazine-Treated Rats

Low-Dose Alcohol-Induced Inhibition of Mouse Orthotopically Transplanted Tumors Is Associated with T-Cell Response

INTRODUCTION

The effects of low-dose alcohol consumption on colorectal cancer development are not well understood. Epidemiological studies have reported that people who consume small amounts of alcohol have lower mortality rates than both nondrinkers and heavy drinkers. This phenomenon has been labeled the "J-curve effect" of alcohol. This study examined the effects of low-dose alcohol (0.5%, 1%, and 2%) on tumor growth in a transplant colon cancer model.

METHODS

BALB/c and BALB/c nude mice were used to analyze T-cell immunity. Syngeneic CT26 murine colon cancer cells were implanted into the cecal wall, and the resulting T-cell immune effects were monitored.

RESULTS

The growth of orthotopic tumors was markedly inhibited upon ingestion of low-dose (0.5%) alcohol compared with that in the control mice. In contrast, cells from the same line were injected into the cecal wall of nude mice, and tumor growth inhibition was not observed. Histopathological and RNA sequence analyses were performed to elucidate the mechanisms underlying tumor growth inhibition. An increase in tumor CD8+ T lymphocytes and changes in cytokine levels were observed. Microbiome analysis using 16S rRNA gene sequencing of cecal contents was performed and revealed Mucispirillum schaedleri and Clostridium cocleatum showed decreased and increased abundance, respectively, in the alcohol group.

DISCUSSION/CONCLUSION

Ingesting a threshold amount of alcohol results in the infiltration of T lymphocytes, which may enhance immune responsiveness in mouse colorectal cancer models.

Effects of Regular Low-Level Alcohol Consumption in Healthy Individuals: A Randomized, Double-Blind, Placebo-Controlled Crossover Study

The effects of alcohol consumption on health are suggested to depend on the amount of alcohol consumed. We investigated the objective and subjective health effects of the daily consumption of a small amount of alcohol in healthy individuals using a randomized, double-blind, placebo-controlled crossover study. Accordingly, 15 male and 27 female Japanese adults with average or lower general well-being schedule (GWBS) scores were asked to consume a beverage with 0.5% (v/v) alcohol (~4 g of alcohol a day; test beverage) and a placebo beverage two times daily for 4 weeks each. Regular low-level alcohol consumption significantly decreased the serum liver function indexes (aspartic aminotransferase, alanine aminotransferase, and lactate dehydrogenase) before and after consumption (p = 0.034, 0.033, and 0.013, respectively). The small amount of alcohol did not affect the participants’ GWBS scores; however, a stratified analysis with poor subjective well-being revealed that these changes differed significantly between low-level alcohol consumption and placebo-treated subjects (16.0 vs. 11.5, p = 0.041). In addition, changes in serum testosterone levels demonstrated a higher trend in the group that received the test beverage compared with the group that received the placebo beverage (p = 0.051). Daily low-level alcohol consumption may have positive effects on liver function and subjective well-being.