18
votes
Resources on amount of noon sun for sufficient vitamin D production
I have taken supplements, but they are not very effective. Honestly, I don't want to rely on medication when our bodies are perfectly suitable with enough sunlight exposure.
I've been researching this for a while and can't find sources that show the difference according to latitude. I stupidly didn't bookmark what I read so what I say is based on what I've read but can't link to any of it :(.
- I gather there is research that around noon time sun exposure (e.g. 11am-3pm) results in greater production. The skin's processes are optimised for that time.
- I am very aware of the risks of skin cancer.
- I read in the UK about 13 minutes for 3 days a week, just between April and September is adequate for vitamin D levels year round.
- I live on the tropic of cancer so I'm expecting perhaps 7-10 minutes. Anything specific to that sub-tropical latitude would be greatly appreciated.
All advice is welcome, but links that I can read, compare and digest myself especially for different latitudes round the world would be perfect.
Does this calculator help? It's older (2011) but calculates for latitude, weather, skin type, to get the equivalent of 1000 IU vitamin D in an oral dose; explainer here.
That calculator is more than I could have hoped for. Thanks.
It doesn't specify what kind of clothing is assumed, so I assume it doesn't vary from a light t-shirt or even bikini in summer (since you can specify sand aka beach) to a coat, scarf, and beanie in winter.
For burning, I assume any amount of surface (1μm²) simply burns after the specified time, but the minimum time for synthesising the vitamin D? Does each part of your skin have its own supply and do you need to expose all of it? Surely not, so then the question still is: how much cm² of skin does one need to point at the sun for the specified amount of time, even by approximation?
You might look to the explainer (linked above) for some of the answers. The explainer also refers to their accompanying published article:
Webb, A. R., & Engelsen, O. (2006). Calculated Ultraviolet Exposure Levels for a Healthy Vitamin D Status. Photochemistry and Photobiology, 82(6), 1697. doi:10.1562/2006-09-01-ra-670
(The link in PubMed is broken because they have the incorrect year in their DOI, but this link will show you the paper.)
Just skimming, I believe the question about clothing is expose 25% of your skin:
And that's across your whole body, so:
For burning, I don't see that part on the calculator but I assume you mean their skin type selections? Might be a language translation issue but I thought those categories were weird, but the explainer points to Fitzpatrick skin types and the paper has a detailed chart on p. 1699 with a footnote that seems important to your query.
Oh, I had read the first ~half of the page as well as the output section at the very bottom, right below where it explains the skin area! And searching the page for "cloth" is not that effective when that's not the word used 😅 didn't think how else to describe clothing variation, but just skin percentage yeah. Thanks for pointing that out!
On the output screen there is "UV exposure in order to obtain a sunburn".
I also didn't understand the difference between pale caucasian and blonde caucasian (isn't that a hair color? Maybe not in Norway) but that's not what I meant about burning: for the time-to-sunburn that the output codes, I was saying that I assume it doesn't matter how much is exposed for it to get a sunburn; that the sunburn will simply happen on whatever surface has been exposed continuously for the amount of time specified.
According to that I only need 5 minutes where I live.
AFAIK this is one of these things where there's no single answer that is correct for every person. Each person produces a different amount of Vitamin D.
There's also lot's of evidence that the Vitamin D recommendations aren't high enough for some/many people. So if you're worried about it, I'd get some blood tests done regularly and monitor your levels.
E.g. I take 1 000 IU daily of D3 (+K2) of this supplement, and each time I have my blood done I'm still below recommended levels, even though the does I take is 2.5x my local recommendation.
That's a bit surprising and must be discouraging for you that your levels are still too low. I was taking D3+K2 but tablet form.
Hope it improves for you.
Exactly. I am on 150,000 iu per week. This gets my blood levels to the low end of the range. I read a paper that said this was a toxic dose.
I'm neither dark skinned nor living in high latitudes.
MsPiggleWiggle gave you the answer you were looking for. I would respectfully like to add that being outdoors may explain a good portion of the benefits of vit D levels.
Some of these benefits include:
Improved cognitive function: Spending time in nature has been shown to improve cognitive function, including memory and attention span.
Reduced stress: Being in nature can help reduce stress levels, leading to lower levels of anxiety and improved mood.
Increased physical activity: Being outdoors often involves physical activity, which has numerous health benefits, including lower risk of obesity, heart disease, and diabetes.
Better sleep: Exposure to natural light and fresh air can help regulate the body's circadian rhythm, leading to better sleep quality.
Boosted immune system: Exposure to sunlight and fresh air can help support a healthy immune system, reducing the risk of illness and infection.
Improved mental health: Spending time outdoors has been linked to improved mental health outcomes, including reduced symptoms of depression and anxiety.
Overall, spending time outdoors can provide a range of physical and mental health benefits beyond just vitamin D production.
Sounds like a vicious cycle too.
Less time outdoors -> lower vitamin D, worse sleep, lower physical and mental health -> less time outdoors ....
Keep in mind that the amount of sunlight you need and your skin cancer risk depends quite a bit on your skin color. (The visual difference in skin tone between type I and IV is not as much as between IV and VI, but the difference in safe sun exposure is quite dramatic). As far as how much sunlight is appropriate, it depends on a variety of environmental factors but ultimately following your intuition of how intense the sun seems and taking that into consideration with how sensitive your skin is to the sun is a reasonable approach since the environmental factors correlate with perceived sun intensity. You can also check your weather app for the UV index and see how much sun is appropriate for your skin type at each level.