Reference Number: 671
Year: 2025
Link: Link to original paper
Health: Gut Microbiome - Creating Healthier Bread to Support Optimal Gut Health
Nutrition: Vitamin D
Summary
ABSTRACT
This review explores the emerging term “gut-skin axis” (GSA), describing the bidirectional signaling that occurs between the skin and the gastrointestinal tract under both homeostatic and disease conditions. Central to GSA communication are the gut and skin microbiota, the microbial communities that colonize these barrier surfaces. By influencing diverse host pathways, including innate immune, vitamin D receptor, and Aryl hydrocarbon receptor signaling, a balanced microbiota contributes to both tissue homeostasis and host defense. In contrast, microbiota imbalance, or dysbiosis at one site, can lead to local barrier dysfunction, resulting in the activation of signaling pathways that can disrupt tissue homeostasis at the other site, potentially leading to inflammatory skin conditions such as atopic dermatitis and psoriasis, or gut diseases like Inflammatory Bowel Disease. To date, most research on the GSA has examined the impact of the gut microbiota and diet on skin health, but recent studies show that exposing the skin to ultraviolet B-light can beneficially modulate both the gut microbiome and intestinal health. Thus, despite the traditional focus of clinicians and researchers on these organ systems as distinct, the GSA offers new opportunities to better understand the pathogenesis of cutaneous and gastrointestinal diseases and promote health at both sites.
Summary of Findings
This paper explores how the gut and skin—two very different parts of the body—are actually deeply connected through a system called the “gut-skin axis.” Both the gut and skin are lined with protective cells and host large communities of microbes (bacteria, fungi, and viruses) that help keep us healthy. These microbes don’t just stay local—they send signals throughout the body that affect immune responses, inflammation, and even how other organs function.When the balance of microbes (called the microbiota) is disrupted—known as dysbiosis—it can lead to problems in both the gut and the skin. For example, an unhealthy gut microbiome can trigger inflammation that shows up as skin conditions like eczema, psoriasis, or acne. Likewise, skin problems may reflect deeper issues in the gut. This two-way communication is why researchers are paying more attention to how treating one area might help the other. The paper explains how the gut and skin share similar immune defences. Both have cells that detect harmful invaders and respond by producing protective substances. They also rely on tight junctions—special proteins that hold cells together and prevent leaks. If these junctions break down, it can lead to “leaky gut” or skin inflammation.One finding is that sunlight, especially ultraviolet B (UVB) light, can influence both gut and skin health. UVB exposure helps the skin produce vitamin D, which supports immune balance and strengthens barrier functions. It also affects gut microbes and may reduce inflammation in the digestive tract. This suggests that safe sun exposure could be a useful therapy for both gut and skin conditions.The paper also reviews how probiotics can improve skin health by first improving gut health. In animal studies, probiotics helped reduce skin inflammation, improve skin thickness, and increase protective molecules. Human studies show similar benefits for conditions like eczema, acne, and rosacea.Importantly, the authors highlight that many diseases—like inflammatory bowel disease (IBD), celiac disease, and rosacea—show symptoms in both the gut and skin. This overlap supports the idea that the gut-skin axis plays a role in disease development and could be a target for new treatments.
In summary, the gut and skin are connected through shared immune systems and microbial communities. When one is out of balance, the other can suffer too. By understanding this relationship, doctors and researchers may be able to treat skin and gut diseases more effectively, using tools like probiotics, dietary changes, and sunlight.Significance for the Baker
Through the BALM protocol we understand the impact of lifestyle factors as well as eating. Taking time in daylight is shown in this paper to influence the gut and skin health. The production of vitamin D from the impact particularly of UVB from sunlight is a useful adjunct to the intake of it through nutrients. Recipes that would encourage the outdoors intake of sunlight would be things like any of the focaccia recipes used at a picnic or pizza for a ‘bake your own pizza lunch’
