The Wisdom of Chinese Medicine in Sunlight

The Wisdom of Chinese Medicine in Sunlight

At the heart of Traditional Chinese Medicine (TCM) lies the philosophy of “the unity of man and nature” (天人合一). Our bodies are not separate from the environment; rather, we are a part of nature’s cyclical flow. For this reason, ancient wisdom has long emphasized the importance of living in harmony with the natural world—waking with the sun, resting when night falls, and drawing life energy from sunlight. These are all ways of maintaining health according to the principles of TCM.

For thousands of years, Chinese medicine has regarded sunlight as a vital source of life energy. But what exactly is this energy, and how does it function within our bodies?

Today, modern science is uncovering fascinating answers through the study of a compound called cholesterol sulfate, which may hold the key to unlocking ancient wisdom—offering us a clearer understanding of the foundational principles of Traditional Chinese Medicine.


Yang Qi (阳气): The “Flame of Life” from the Sun
In TCM, Yang Qi (阳气) is the warm, activating, and life-giving force—like the sun illuminating and energizing the body. When Yang Qi is abundant and strong, the body functions efficiently. But when it is deficient, we may feel sluggish, cold, and experience a general decline in physiological functions.

Thus, TCM practitioners have always encouraged exposure to morning sunlight as a way to replenish Yang Qi. But how does modern science explain this?

When the skin is exposed to sunlight—especially UVB radiation—a natural process occurs, in which enzymes convert cholesterol in the skin into cholesterol sulfate. This aligns with the role of Yang Qi, which is to promote the generation and transformation of substances within the body.


Qi Moves Blood (气行血): The Vital Flow of Life
A fundamental TCM theory states: “Qi moves blood” (气行血). This means Qi is the driving force that propels blood to flow smoothly throughout the body, nourishing all cells. When Qi, particularly Yang Qi, is deficient or stagnant, blood becomes thick and sluggish, leading to conditions such as blood stasis (血瘀)—a root cause of various cardiovascular disorders.

In treatment, TCM therefore often focuses on boosting Yang to support healthy blood circulation.

Here again, cholesterol sulfate provides a molecular explanation:
This compound acts as a natural surfactant in the blood, reducing its viscosity and enhancing the flow of red blood cells through tiny capillaries. Sunlight stimulates the synthesis of cholesterol sulfate in the skin, which then physically helps improve blood circulation—offering modern confirmation of the TCM concept that “Qi moves blood.”

Kidney Yang Governs the Bones (肾阳主骨): The Dual Action of Sunlight
In TCM, the kidneys (肾) are seen as the foundation of life, and Kidney Yang (肾阳) is the “inner fire” that governs the bones (主骨)—ensuring they grow strong and remain healthy.

In the past, it was commonly believed that sunlight simply helped produce vitamin D for bone health. But recent scientific studies have revealed a more complex—and awe-inspiring—mechanism that aligns beautifully with the TCM view of Kidney Yang as a “governing force.”

When UVB rays strike the skin, two vital processes are triggered simultaneously in the same location:

7-dehydrocholesterol is converted into Vitamin D3, and
Cholesterol is converted into cholesterol sulfate.
This co-creation of two essential compounds under the same energy source (sunlight) reflects the holistic nature of Kidney Yang’s governing role—not just in producing vitamin D, but in orchestrating the entire system of bone nourishment. Kidney Yang doesn’t merely "initiate" a single function—it governs a coordinated and intelligent process, from synthesis to efficient delivery, ensuring the body’s needs are met.

This seamless integration is a clear illustration of the TCM concept of “governance” (主)—where regulation and coordination, not just creation, are key.


Conclusion: Ancient Wisdom Meets Modern Light
Modern scientific discoveries do not negate ancient wisdom—they illuminate it.
The sunlight-driven production of cholesterol sulfate, which supports blood circulation, and the co-creation of vitamin D and its "delivery partner" for bone health, beautifully confirm that the human body is a truly integrated system—working in harmony with nature.

So, the next time you step into the morning sun, remember:
You’re doing far more than getting your daily dose of vitamin D.
You are replenishing your Yang Qi, empowering your blood to flow smoothly through the vessels, and strengthening your Kidney Yang to support healthy bones.

This is the way of health—affirmed by both ancient wisdom and cutting-edge science alike.


Written by:

李成俊 中医师
TCM. Dr. Tseng Chun Lee