Dietary Modulation of Bacteriophages as an Additional Player in Inflammation and Cancer

SIMPLE SUMMARY: The role and function of bacteriophages (phages) in the intestine, its health and microbial homeostasis has been underestimated so far. This interdisciplinary review highlights the effect of dietary compounds on phages and puts this into perspective with putative contributions of phages to gastrointestinal diseases, specifically inflammation, infection, and cancer. The review discusses novel fields of opportunities in this context. These include, but are not limited to, perspectives how a better understanding of modulating the activity of specific phages by particular nutritional components may contribute to reorganizing the microbial network, thus supporting in the combat, or even prevention, of inflammation or even cancer in the gut. ABSTRACT: Natural compounds such as essential oils and tea have been used successfully in naturopathy and folk medicine for hundreds of years. Current research is unveiling the molecular role of their antibacterial, anti-inflammatory, and anticancer properties. Nevertheless, the effect of these compounds on bacteriophages is still poorly understood. The application of bacteriophages against bacteria has gained a particular interest in recent years due to, e.g., the constant rise of antimicrobial resistance to antibiotics, or an increasing awareness of different types of microbiota and their potential contribution to gastrointestinal diseases, including inflammatory and malignant conditions. Thus, a better knowledge of how dietary products can affect bacteriophages and, in turn, the whole gut microbiome can help maintain healthy homeostasis, reducing the risk of developing diseases such as diverse types of gastroenteritis, inflammatory bowel disease, or even cancer. The present review summarizes the effect of dietary compounds on the physiology of bacteriophages. In a majority of works, the substance class of polyphenols showed a particular activity against bacteriophages, and the primary mechanism of action involved structural damage of the capsid, inhibiting bacteriophage activity and infectivity. Some further dietary compounds such as caffeine, salt or oregano have been shown to induce or suppress prophages, whereas others, such as the natural sweeter stevia, promoted species-specific phage responses. A better understanding of how dietary compounds could selectively, and specifically, modulate the activity of individual phages opens the possibility to reorganize the microbial network as an additional strategy to support in the combat, or in prevention, of gastrointestinal diseases, including inflammation and cancer.