That HIGHLY depends on the climate. 5 minutes in direct sunlight in a t-shirt was referencing someone around the equator under optimal conditions I believe.
As an example, here in belgium, it is often cloudy and rainy for weeks or months at a time, combined with winter sun being significantly less effective at generating vitamin D just due to passing through much more of the atmosphere.
The majority of central and northern European countries, along with most people above Missouri or so in America, especially in the midwest will not get enough vitamin D from the above reasons along with the fact that wearing a T-shirt just isn’t feasible, and people will be often fully covered outside of their face. That means that possibility of absorption is extremely low. Studies have shown that many or most people in these areas are vitamin D deficient through the winter.
Also the “standard recommendation” for vitamin D has been suggested by a few studies to be significantly too low (>2x higher daily dosage needed before deficiency), but that is getting into less supported theories. Though there isn’t much funding for those types of studies, so who knows.
Yes, the D data is incomplete and mostly done in sunny climates, the reference range for vitamin D in blood is also based in iirc Spain or that climate, so it might be that slightly defficient in colder climates is a-ok. Plus it is hard to separate bogus claims when it comes to D, since people want to implicate it in everything from immune compromise to why your nanas cookies don’t taste too good.
That said, 5 minutes out in direct sun is probably a fair recommendation because most people will likely spend more than 5 minutes out if they have made it there. I think the recommendation is more about the climate / weather conditions rather than “take off your clothes for 5 mins in the winter”. If you have to go out more covered (i.e. long sleeves, pants) for the majority of a month, you will want to supplement. If you are unsure can always check serum levels.
Personally I take more than 1k IU, but I will stick to official recommendations when giving advice.
That HIGHLY depends on the climate. 5 minutes in direct sunlight in a t-shirt was referencing someone around the equator under optimal conditions I believe.
As an example, here in belgium, it is often cloudy and rainy for weeks or months at a time, combined with winter sun being significantly less effective at generating vitamin D just due to passing through much more of the atmosphere.
The majority of central and northern European countries, along with most people above Missouri or so in America, especially in the midwest will not get enough vitamin D from the above reasons along with the fact that wearing a T-shirt just isn’t feasible, and people will be often fully covered outside of their face. That means that possibility of absorption is extremely low. Studies have shown that many or most people in these areas are vitamin D deficient through the winter.
Also the “standard recommendation” for vitamin D has been suggested by a few studies to be significantly too low (>2x higher daily dosage needed before deficiency), but that is getting into less supported theories. Though there isn’t much funding for those types of studies, so who knows.
Yes, the D data is incomplete and mostly done in sunny climates, the reference range for vitamin D in blood is also based in iirc Spain or that climate, so it might be that slightly defficient in colder climates is a-ok. Plus it is hard to separate bogus claims when it comes to D, since people want to implicate it in everything from immune compromise to why your nanas cookies don’t taste too good.
That said, 5 minutes out in direct sun is probably a fair recommendation because most people will likely spend more than 5 minutes out if they have made it there. I think the recommendation is more about the climate / weather conditions rather than “take off your clothes for 5 mins in the winter”. If you have to go out more covered (i.e. long sleeves, pants) for the majority of a month, you will want to supplement. If you are unsure can always check serum levels.
Personally I take more than 1k IU, but I will stick to official recommendations when giving advice.