Genotoxicity of Coffee, Coffee By-Products, and Coffee Bioactive Compounds: Contradictory Evidence from In Vitro Studies

Abstract

Coffee and coffee by-products, such as coffee cherries, coffee flowers, coffee leaves, green beans, roasted coffee, instant coffee, spent coffee grounds, and silverskin, contain a complex mixture of bioactive compounds that may exhibit both genotoxic and antimutagenic effects. This article evaluates in vitro studies on the genotoxic potential of coffee and coffee by-products, with a focus on different preparation methods, roasting processes, and key chemical constituents. Furthermore, given the growing interest in utilizing coffee by-products for novel food applications, this review sought to identify knowledge gaps regarding their safety. The impact of metabolic activation, particularly the role of enzymatic detoxification and bioactivation, was examined to better understand the effects on genetic material. The findings suggest that while certain compounds in coffee can induce DNA damage under specific conditions, the overall evidence does not indicate a significant genotoxic risk to consumers. However, further studies, particularly in vivo and human studies, appear necessary to ensure the requirements of novel food applications for some coffee by-products.

Keywords: Ames test; DNA damage; antimutagenicity; bioactive compounds; coffee; coffee by-products; comet test; food safety; genotoxicity; micronucleus test; roasting process.

Figure 1

Chemical structures of key coffee constituents. Structures were obtained from ChEBI database, EMBL-EBI, Creative Commons License (CC BY 4.0).

Figure 2

Potential in vitro genotoxic effects of coffee constituents.

Figure 3

Molecular targets in the Nrf2 pathway for coffee compounds: chlorogenic acid, kahweol, and N-methylpyridinium. Reprinted with permission from Ref. [119]. Copyright 2013, John Wiley and Sons.