Study on Narrow band UVB Light’s Effect on the Microbiome


Sunlight has long been recognized for its potential health benefits, notably the synthesis of Vitamin D in the skin. However, emerging research suggests that the benefits extend far beyond just Vitamin D. A groundbreaking study titled "Skin exposure to narrow band ultraviolet B light modulates the human intestinal microbiome" presents compelling findings that narrow band UVB light not only affects our skin but also our gut health. In this blog post, we will delve into the study to uncover how Narrow band UVB light has a profound effect on the microbiome and explore its ramifications for human health.

Skin Exposure to Narrow Band Ultraviolet (UVB) Light Modulates the Human Intestinal Microbiome

What is Narrow band UVB Light?

Narrow band UVB light is a specific range of ultraviolet light that has a wavelength of 311-312 nm. It is distinct from the broad-spectrum UV light in that it is a focused form of UVB. The most common sources of Narrow band UVB light are sunlight and medical UV lamps designed for therapeutic use.

Source of Light Wavelength Range
Sunlight Broad Spectrum
Medical UV Lamp Narrow band UVB

The Microbiome: A Quick Primer

The term "microbiome" refers to the complex community of microbes—bacteria, fungi, protozoa, and viruses—that live in and on our bodies. These microbial communities play a crucial role in various bodily functions, including digestion, immune system function, and even mental health.

  • Digestion: Microbes break down complex carbohydrates and aid in the absorption of nutrients.
  • Immune System: The microbiome helps in the formation of a barrier against pathogens.
  • Mental Health: Emerging research suggests a gut-brain axis that affects mood and mental well-being.

The Human-Sun Connection

Traditional understanding emphasizes the sun's role in Vitamin D production in the skin. Vitamin D is essential for bone health, immune function, and various metabolic processes. However, the benefits of sunlight exposure seem to be more multifaceted, impacting skin health, mood, and as the study reveals, even the gut microbiome.

The Study in Detail

Details: Skin Exposure to Narrow Band Ultraviolet (UVB) Light Modulates the Human Intestinal Microbiome

Research Questions

The study aimed to examine the following:

  • Does skin exposure to narrow band UVB light have an effect on the human intestinal microbiome?
  • Is there a change in the levels of serum 25 hydroxy vitamin D post-exposure?


The researchers conducted a thorough examination involving human subjects. Participants were exposed to narrow band UVB light, and their serum 25 hydroxy vitamin D levels were measured. A comprehensive analysis of their intestinal microbiome was conducted both before and after the exposure.

Key Findings

The study unearthed significant revelations:

  1. Individuals with low serum 25 hydroxy vitamin D levels showed a change in their intestinal microbiome after exposure to narrow band UVB light.
  2. An increase was observed in 25 hydroxy vitamin D levels post-exposure.
  3. Introduction of a new concept: "skin-gut axis."
Key Finding Implication
Change in microbiome Potential impact on digestive health and immune system
Increase in 25 hydroxy vitamin D levels Enhanced Vitamin D synthesis
Concept of "skin-gut axis" Interconnectedness of skin and gut health


This suggests that narrow band UVB exposure could potentially be utilized to promote intestinal homeostasis and overall gut health. There is also the implication that various intestinal or microbiome-related health issues might benefit from UVB therapy, introducing a novel "skin-gut axis."

Why This Study is Groundbreaking

The general discourse around sunlight exposure rarely, if ever, discusses its potential effects on the microbiome. This study is the first of its kind to propose and demonstrate the existence of a skin-gut axis.

Debunking Common Myths

  • Myth: All UV light is harmful and should be completely avoided.
  • Fact: Controlled and moderate exposure to narrow band UVB light has health benefits.

Cautionary Note

Although these findings are revolutionary, it is important to approach them with caution. Narrow band UVB light exposure also carries risks, such as the potential for skin cancer. More research is needed to validate these findings fully.


The study on narrow band UVB light's impact on the microbiome adds a fascinating layer to our understanding of the multifaceted benefits of sun exposure. While there is a need for further research, the concept of a "skin-gut axis" opens new avenues for promoting intestinal homeostasis and overall health. Consider incorporating safe sun exposure or medical UVB light therapy into your routine but always consult your functional healthcare provider for personalized advice.


What is the microbiome?

  • It's the community of microbes that live in and on our bodies.

How does narrow band UVB light differ from broad-spectrum UV light?

  • Narrow band UVB has a specific wavelength range of 311-312 nm, whereas broad-spectrum UV covers a wider range.

    Feel free to dive deeper into each section and ask any questions you might have. Your gut health might thank you for it!

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