There are many Vitamin D metabolites that differ in water solubility, how long they last, and their ability to be reactivated in tissues when needed This means your body can store Vitamin D in different forms, keep it circulating longer, and reactivate it on demand, hence Vitamin D status isn’t just about new production, but also how well your system manages and taps into these reserves Because of this, someone with strong metabolic and circadian rhythms can stay Vitamin D sufficient longer, even with little sun, by cycling and reusing stored forms efficiently On the flip side, if those pathways are disrupted, your body will likely struggle to access or convert those stored metabolites, leading to deficiency even if you technically have plenty in the bank Skin type absolutely matters, but mainly upstream, at the level of how much Vitamin D you can make and store in the first place, not so much in the downstream recycling Darker skin makes Vitamin D more slowly because higher eumelanin blocks UV-B more effectively, but once D3 is produced and metabolized, the sulfation, storage, and recycling pathways work similarly Lighter skin can build up stores faster with less UV-B exposure, but if circadian rhythms or metabolic health are poor, they can burn through or fail to mobilize those stores just as easily This is such a game changing and refreshing narrative involving Vitamin D3 acquisition and storage

For many, this is true