Natural production of vitamin D without sun

This page was created 17/01/26

This page was last modified 24/02/26

A huge work in progress, in one of the most fascinating areas of science.

In some countries, it is not feasible for the body to create much Vitamin D due to the weak sun. But this vitamin is essential to our life and bodily function, so how come some people apparently "didn't get it"?

Well, actually it turns out that you can produce Vitamin D without sunlight at all!

40° above the equator, it becomes very hard for the body to convert sunlight into vitamin D. So how does the body create vitamin D when it does not receive enough sunlight?

The biophoton theory

When exposed to cold temperatures (commonly also found 40° above the equator), the body can internally glow and produce Vitamin D without sunlight. Let me explain:

Very recently, there have been a few studies showing a link between cold exposure (such as ice baths or cryotherapy, or just being exposed to the cold outside) and the increase of Vitamin D levels. This is caused (theoretically, not yet proven), by the internal glowing of cells. Human cells actually do emit a very faint light as a byproduct of metabolic processes, specifically from the mitochondria. This glow is about 1,000 times too dim for our eyes to see, but it can be detected by some very sensetive cameras. Researchers suggest that when you are exposed to the extreme cold, your mitochondria, especially in brown fat, work a lot to produce heat. This creates the "biophotons" (very weak photon emissions) in the UVB range (same wavelength as sunlight), which in turn hits cholesterol molecules inside the cell. This process converts the biophotons into Vitamin D

Of course, this is all just "theory", but it seems very believable and grounded in proof to me.

Whole-Body Cryotherapy Affects Blood Vitamin D Levels in People with Multiple Sclerosis.

A 2025 study published in the Journal of Clinical Medicine (Ptaszek et al.) found that patients with Multiple Sclerosis who underwent 20 sessions of whole-body cryotherapy saw a significant increase in their blood Vitamin D levels, even without extra sun exposure.

Patients with Multiple Sclerosis (MS) underwent 20 sessions of whole-body cryotherapy (3 minutes at -130°C). Their blood tests showed a 30% increase in serum 25-hydroxyvitamin D [25(OH)D] levels. A group of healthy women also saw an increase, though it was smaller (around 8%) and not as significant. The participants did not increase sun exposure or change their diet, meaning that this increase was 100% from producing or releasing the Vitamin D.

The theory is that when you are in an ice bath, your Brown Adipose Tissue (BAT) (fat that is full of mitochondria) increases up to maximum capacity. Research suggests that this intense mitochondrial activity produces biophotons in the UVB spectrum (290 - 315 nm).

If these UVB biophotons hit cholesterol molecules (7-Dehydrocholesterol) inside the brown fat cell, they could theoretically trigger the same photochemical reaction that happens on your skin under the sun, creating "Pre-Vitamin D" entirely inside the body.

The only issue is that these photons are really weak and could thus not be strong enough to increase the Vitamin D levels by 30%.

Other theories as to why this could happen

Vitamin D is stored in the bodys fat tissues. When entering a cold nvironment, the body burns the fat tissues and could release Vitamin D from fat ells into the blood, causing the levels to increase.

Cold exposure could make the liver and kidneys more efficient at converting inactive Vitamin D into its active form.

Over 65% of your body's Vitamin D is stored in your fat cells (adipose tissue). When you are exposed to extreme cold, your body initiates thermogenesis - it begins burning fat to create heat.
Cold triggers the release of norepinephrine, which activates lipolysis (the breakdown of fat). As the fat cells shrink or release fatty acids for fuel, the Vitamin D "trapped" inside them is released into the bloodstream.
Cold exposure has been shown to modulate Parathyroid Hormone (PTH). PTH is the mechanism for the kidneys to convert inactive Vitamin D into its active, hormonal form (1,25-dihydroxyvitamin D). It is possible that the "shock" of the cold recalibrates this system, making the conversion of existing Vitamin D more efficient.

Whichever theory is right or wrong, that does not matter. What matters is that you can increase your Vitamin D levels through cold exposure.

I hope that the biophoton theory is right though. This would mean that the body creates its own Vitamin D rather than using its stored Vitamin D (stored in fat tissue).

Feel free to share ideas by contacting me.

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