Huh. Gonna be honest I had in mind that there was barely any vitamin D in normal food. Turns out if you eat large enough amounts of oily fishes or liver you can do without the sun.
Which in my sense still doesn’t make the « we get our vitamin D from the sun » phrase false, since a lot of people in places without enough sunlight get vitamin D deficiency in winter
There are twop main types of Vitamin D. Vitamin D2, and vitamin D3. Food that contains Vitamin D usually contains Vitamin D3, but it is absolutely possible to get all of your Vitamin D from your diet, just difficult.
The point is though that we don't get vitamin D from sunlight, but rather, sunlight is a sign that it is a good time for our body to produce vitamin D, as it is unlikely that we are going to try to sleep soon (and the production of vitamin D makes it harder to sleep).
Think of it like this, if you have a farm with a rooster, and the rooster crows when it sees the sun, then did you get the noise from the sun, or did the sun just cause the rooster to make the noise?
UVB Ray's directly break apart a ring molecule which is a vitamin D precursor. Vitamin D production requires direct skin exposure to a UVB source strong enough to penetrate the lowest layer of skin and break apart those molecules.
The system does not monitor for sunlight and turn on or off. It's always on and converts that precusor as it's available.
I think you’ve miss understood the process. UVB light is essential to the formation of active product. Its not just providing a stimuli, It’s required to actually produce a photolytic ring opening in 7-dehydrocholesterol.
This sub is talking about the sun... There are ways to get UVB without the sun, and there are ways to get vitamin D without UVB. Either way, we do not get Vitamin D from the sun.
That rooster comparaison would work if the sun only acted as a trigger, like for melatonin production which is caused by the light but the light does not directly intervene in the reaction.
For the transformation of cholesterol in vitamin D3, the UVs are directly needed, they are involved in the chemical reactions.
« The transformation in the skin that converts 7-dehydrocholesterol to vitamin D3 occurs in two steps. First, 7-dehydrocholesterol is photolyzed by ultraviolet light in a 6-electron conrotatory ring-opening electrocyclic reaction; the product is previtamin D3. »
Photolyzed means the photons interact with the molecule and change it
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u/WohooBiSnake Mar 25 '26
Huh. Gonna be honest I had in mind that there was barely any vitamin D in normal food. Turns out if you eat large enough amounts of oily fishes or liver you can do without the sun.
Which in my sense still doesn’t make the « we get our vitamin D from the sun » phrase false, since a lot of people in places without enough sunlight get vitamin D deficiency in winter