I’ve wondered whether vitamin D is a real time signal within the circadian rhythm regulation system. Perhaps it is released in response to sunlight in order to let other parts of the system know it is daytime.
If it were like this, bulk dosing would be expected to be better than nothing (“maximum daytime!!!! Followed immediately by a very long slow sunset at whatever curve it is cleaned up in the body), but it would be better to dose continuously in real time at a level and body location(s) that would simulate the range of sunlight throughout the day.
Can anyone professionally familiar with the research in this area comment?
Isn’t vague mixed evidence of a small, limited effect pretty much what you’d find if it it did basically nothing in aggregate?
This article aside, there are a number of very well established benefits of vitamin D. I think “mixed evidence of small limited effect” is not a phrase that is reflective of current knowledge.
I found that taking a specific brand of Vitamin D (the Genestra D-mulsion in particular) right before bed was guaranteed to give me vivid dreams. I've had half a dozen friends try it, with every single one reporting similar results.
Supplementing any "large" amount of either Vitamin D or Bs really messes with my sleep. It makes it harder to fall asleep and I get crazy dreams (and sometimes hallucinations in bed too)
I've heard not to take vitamin D right before bed because it will kinda keep you up. Maybe the vitamin D as a stimulant is what's gives you the extra dream awareness.
I checked the ingredients. That is because it contains glycerin. Which is a great and safe supplement to take for anyone with sleeping issues. But will cause very vivid dreams at the start. D3 will not by itself have a huge effect on dreams.
This is such a weird fact that I googled it and sure enough it is widely noted!
That's interesting. I know vitamin D can improve sleep quality in people who are deficient, and sleep quality helps with dream recall -- I wonder if that's the mechanism or it's something else.
A cursory search shows lots of redditors taking Vitamin D (some of them way, way too much btw) and having wild dreams too.
I take 800IU D3 a day and haven't personally noticed anything.
What is way too much? I take around 4000IU per day. Which just about brings my blood levels into the “green” area in blood testing.
My dose is very low -- this guy was taking 50,000IU a day, which is usually the amount prescribed for someone to take once a week.
Your 4000IU isn't too much. Lots of the brands you see in stores are 5k for daily supplementation.
FWIW: my functional provider recently noted low levels in my labs and I was already taking 2K IU daily. She bumped me up to 6K UI daily.
That is actually a low dose.
Yeah, I showed a really mild deficiency in my work so they just suggested adding a low daily dose for me. I wouldn't expect to have had any side effects.
I was very deficient and they gave me 50k UI per day prescription vitamin D3 for 60 days. Sure enough I was high-normal on my next test. 800ui is likely not enough to have any effect unless you consistently take it for years.
Spicy food and dehydration do wonders for me!
It’s interesting that his doctor wouldn’t prescribe a vitamin D supplement because it would supposedly be too expensive for the health care system. Fortunately, vitamin D supplements are generally inexpensive to buy. I doubt I’d ever get a prescription for one, they’d probably just tell me to pick some up at the pharmacy downstairs.
That will be why the doc tells you it's too expensive, because over the counter is cheap. It's not that they can't afford it, but in the UK there is a standard prescription price. It's under £10 per prescription for any drug that prescribed, but it's a flat fee. So if they prescribe something that costs less than the prescription charge it makes no sense for the patient.
There's a standard perscription price in England, not the UK. in Scotland and Wales there's 0 charges to the patient
Mushrooms exposed to UV convert egosterol to vitamin D - an almost identical mechanism found in our skin
Cool fact, but so what?
Well, mushrooms when exposed to UV convert egosterol to vitamin D - an almost identical mechanism found in our skin.
>For me, that means topping up with a supplement. The UK government advises everyone in the country to take a 10-microgram vitamin D supplement over autumn and winter
My last blood test showed I was slightly deficient in vitamin D - my doctor recommended a 50 microgram (2000 IU) supplement. My next test to see how well it' working isn't for a few more months.
Good article, but it does not cover toxicity; you can take too much vitamin D and this has very negative affects. Usually a multivitamin is enough for supplementing; taking extra is where you can run into issues; consult your Doctor.
Evidence that multivitamin d is useful?
> At a checkup a few years ago, a doctor told me I was deficient in vitamin D. But he wouldn’t write me a prescription for supplements, simply because, as he put it, everyone in the UK is deficient. Putting the entire population on vitamin D supplements would be too expensive for the country’s national health service, he told me.
Ugh. It's amazing how incompetent medical systems are. I was also deficient in vitamin D and my doctor wrote a prescription. When I did the math, the cost was something like >$.10 per 1000IU. But if I bought the vitamins from a normal store, I would pay <$.01 per 1000IU. Since a person lacking sunlight only needs 1000IU, the price for giving everyone in the UK Vitamin D would be <$700k/day. And probably much less since most people won't need this high of a dose and bulk quantities would be cheaper.
For healthy people, taking extra vitamins is pointless, but giving them to people who are deficient in vitamins is one of the cheapest health interventions for the benefits.
PSA: if you're feeling off, make sure your doctor checks your various vitamin levels and see if cheap OTC vitamins help.
From a strictly biomedical point of view, mild vitamin D deficiency is trivial to correct and supplementation is indeed one of the lowest-cost interventions we have. But large health services often optimize around procurement, prescribing ceilings, and clinical workload rather than marginal benefits. In that logic, pushing people toward OTC supplements is simply cheaper to administer, even if it looks absurd from the outside.
There’s also a less-discussed layer: population screening for micronutrients tends to be episodic rather than continuous, and the thresholds for “deficiency” versus “insufficiency” have shifted over the years. Some clinicians quietly adopt a pragmatic stance - if the risk is low and the intervention is cheap, they’d rather patients self-supplement without pulling the system into it.
The general point still stands, though. If someone has persistent fatigue, mood changes, sleep disruption, or immune irregularities, checking basic micronutrient status is a reasonable first step. A small, targeted correction often produces disproportionate improvements, even if it sits outside the more glamorous parts of medicine.
Too add to this, if anyone is considering looking for otc vitamin supplementation, please check to see if the brand you're interested in has been lab tested. Heavy metals have been found in cheap stuff before in the US and the government isn't really screening for this stuff proactively.
If you consider the deficiency a national health issue, you can even subsidize a nation scale production reducing the cost even more. From a state perspective, that should be chump change considering the nation-wide effects.
During the Pan I took a lot of VitD. It started giving me the feeling that my heart was beating out of my chest, so I stopped.
Vitamins A, D, E and K can be overdosed… But for vitamin D to be toxic you would have to veer quite far from the posology.
How much Vitamin D? Vitamins are good but as with many things, the poison is in the dosage. You can definitely take too much of it.