Is there any research out there which links moderate amounts of vitamin D (such as the recommended dosages on vitamin D supplements) to any negative effects at all?

Is there any research to indicate that a lack of urushiol has negative effects, similar to how we know that a lack of vitamin D has negative effects?

If not I don't really see the connection

It's not a prescription drug, so I'm not really sure what 'self-medication' means; I self-medicate with caffeine, might eat an orange and self-medicate vit C later, etc.

NHS (UK) guidance:

> Government advice is that everyone should consider taking a daily vitamin D supplement during the autumn and winter.

> People at high risk of not getting enough vitamin D, all children aged 1 to 4, and all babies (unless they're having more than 500ml of infant formula a day) should take a daily supplement throughout the year.

(People at high risk = for example darker skin, or indoor jobs.)

Vitamin D deficiency (and while we're at it, B12 deficiency and iron deficiency) are real deficiency issues that have risen in numbers across Western societies for quite the time now - IIRC, a large contributor is our change in diets and living habits.

Basically, we're spending far less time working out in the open so our body doesn't generate vitamin D on its own in sufficient quantities, and the trend towards highly processed, nutritionally inflexible diets on one side and vegetarianism/veganism on the other side leads to a whole host of malnutrition issues.

Unfortunately, the "malnutrition" levels in bloodwork are mostly calibrated on white European males... so similar to BMI [1] and a few medications and diseases [2], there is a "vitamin D paradox" in Black people who seem to not be that sensitive to lower vit-D levels than White people [3].

Human bodies and genetics are fascinating, even if you're not an expert in it.

[1] https://pubmed.ncbi.nlm.nih.gov/9877251/

[2] https://academic.oup.com/ehjcvp/article/8/7/738/6644872

[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5954269/

There is lots of research saying that vitamin D deficiency causes problems, and the deficiency is more common than you'd expect. Other health conditions and habits can lead to a deficiency.