4 ms·

> I suggest vitamin D 2000 IU a day Anyone know how long I'd need to stand in the sun to get the equivalent of this? I live in the tropics.

someotherperson 5y ago
Keep in mind the only thing tested is Vitamin D3 supplementation, it's not the same as synthesizing Vitamin D3 through sunlight. It might be worth reading the paper to see if sunlight exposure was even controlled for. To answer your question, though, it depends on your skin tone and your location. It could be about 5 minutes if you're very fair skinned.
- stjohnswarts 5y ago
  Of course it's not the same. However people are people for the most part. I was low, and I'm sensitive to the sun and don't like being out in it, so I supplement with D and my doc tells me I'm perfectly healthy and vitamin D levels are normal. Supplements can work too.
krona 5y ago
It's not that simple. The angle of the sun needs to be such that the UV B isn't absorbed by the atmosphere. I believe the dminder app can track this and account for other things like altitude.
- markdown 5y ago
  > The angle of the sun needs to be such that the UV B isn't absorbed by the atmosphere. I'm in the tropics, so this shouldn't be a problem, should it?
  - krona 5y ago
    You should be able to get UV B all year, but only between maybe 10am and 2pm (rough guess).
8fingerlouie 5y ago
Nobody really knows, but the general advice is to get "10-15 minutes of sun every day, when your shadow is shorter than you". The above is probably enough if you're caucasian, but add a bit of color and you'll need more time. Also, UV-B rays needs to be able to penetrate the atmosphere, which is why the shadow part is there. I live at 56 degress north, and the shadow thing becomes a problem from around September to April. First of all, the sun doesn't rise above 50 degress until late april, and it also needs to be visible, which it usually isn't for long.
o_m 5y ago
If you use sunscreen every time you go outside then you might be vitamin D deficient
jrapdx3 5y ago
As other comments say, duration of exposure depends on time of year, distance from equator, level of skin pigmentation, etc. One other factor I didn't see mentioned (or I just missed it) is amount of skin area exposed to sunlight. Generally it's recommended to protect sensitive skin of face/neck. Exposed limbs, trunk are somewhat less vulnerable to sunlight injury (but varies with skin type). When sunlight has little penetration of layers of clothing it obviously doesn't cause Vit D synthesis in skin. In northern US/Canada, European countries, vit D supplementation is more reliable, possibly safer re: cancer risk. However a lot about Vit D remains controversial. It's still unclear what the optimum target range is (as measure by blood level), and just how much Vit D is too much. As it is now, lots of expert opinions but no consensus in in sight. Finally Vit D accumulates/declines gradually. High doses (50k units) are used in deficiency states, normalization of blood level typically takes a few months. Well worth doing for sake of bone health, and other body systems too. In Vit D insufficiency (low but not as low as deficiency) OTC Vit D is probably enough, but people should ask their healthcare providers about what form and dose are best.
m0llusk 5y ago
This is complex to evaluate. Another issue is that absorbing UV to create Vitamin D happens not within the body but at the skin. Because of this washing and scrubbing thoroughly just after sun exposure can reduce or eliminate generation of Vitamin D. What is considered ideal is to get sun exposure during the day and then avoid showering until the next morning to allow the skin to do its work.
sooheon 5y ago
2000 IU is an almost arbitrary number anyways. The precise input is obviously less important than the resulting serum levels, quantifiable by a simple blood test measuring 25-hydroxy D. A recent meta-analysis of 32 studies (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4103214/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4103214/) recommended >30 ng/mL 25(OH)D for lower all-cause mortality risk. Just get a blood panel in the summer/winter.
orangepurple 5y ago
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7468901/pdf/nutrients-12-02237.pdf https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7468901/pdf/nut... “Sensible sun exposure” is the practice of obtaining the minimum sun exposure required for adequate vitamin D synthesis followed by application of sunscreen or clothing coverage; and is often characterized as sun exposure of 5–30 min, two–three times per week to the arms, legs and torso during 10:00 h to 15:00 h [2,30]. The specific duration required within this time frame is dependent on skin type, previous tanning, latitude, season and environmental conditions. The minimal erythemal dose (MED), or the minimum quantity of UVB that induces a slight erythema 16–24 h post exposure, is a common dosage employed for sensible sun exposure guidelines [31]. The standard erythemal dose (SED) is a standardized method for quantifying erythemal UV radiation (UVR) dose and is becoming more commonly used because the MED varies from person to person even within the same skin type. The SED is defined as 100 J/m2 [32]. For adults with a fair complexion, one MED is equal to about 10–12 min of full body exposure during peak summer sun for all skin types [33]. One MED may be considered equivalent to ~2.5 to 3.5 SEDs depending on skin type [34].
stjohnswarts 5y ago
You should get tested first, chances are you don't need supplements if you live in the tropics and spend much time at all out in the sun. If you're a vampire like me (I rarely go out much during the day, my car is even in the garage :) ) you might need supplementation though. If you're an active person outdoors a lot the chances you need supplements are unlikely. Go to a doctor and get some blood tests, they can spot all kinds of deficiencies and tell you how normal things look

someotherperson 5y ago

Keep in mind the only thing tested is Vitamin D3 supplementation, it's not the same as synthesizing Vitamin D3 through sunlight. It might be worth reading the paper to see if sunlight exposure was even controlled for. To answer your question, though, it depends on your skin tone and your location. It could be about 5 minutes if you're very fair skinned.

stjohnswarts 5y ago
Of course it's not the same. However people are people for the most part. I was low, and I'm sensitive to the sun and don't like being out in it, so I supplement with D and my doc tells me I'm perfectly healthy and vitamin D levels are normal. Supplements can work too.

krona 5y ago

It's not that simple. The angle of the sun needs to be such that the UV B isn't absorbed by the atmosphere. I believe the dminder app can track this and account for other things like altitude.

markdown 5y ago
> The angle of the sun needs to be such that the UV B isn't absorbed by the atmosphere. I'm in the tropics, so this shouldn't be a problem, should it?
- krona 5y ago
  You should be able to get UV B all year, but only between maybe 10am and 2pm (rough guess).

8fingerlouie 5y ago

Nobody really knows, but the general advice is to get "10-15 minutes of sun every day, when your shadow is shorter than you". The above is probably enough if you're caucasian, but add a bit of color and you'll need more time. Also, UV-B rays needs to be able to penetrate the atmosphere, which is why the shadow part is there. I live at 56 degress north, and the shadow thing becomes a problem from around September to April. First of all, the sun doesn't rise above 50 degress until late april, and it also needs to be visible, which it usually isn't for long.

o_m 5y ago

If you use sunscreen every time you go outside then you might be vitamin D deficient

jrapdx3 5y ago

As other comments say, duration of exposure depends on time of year, distance from equator, level of skin pigmentation, etc. One other factor I didn't see mentioned (or I just missed it) is amount of skin area exposed to sunlight. Generally it's recommended to protect sensitive skin of face/neck. Exposed limbs, trunk are somewhat less vulnerable to sunlight injury (but varies with skin type). When sunlight has little penetration of layers of clothing it obviously doesn't cause Vit D synthesis in skin. In northern US/Canada, European countries, vit D supplementation is more reliable, possibly safer re: cancer risk. However a lot about Vit D remains controversial. It's still unclear what the optimum target range is (as measure by blood level), and just how much Vit D is too much. As it is now, lots of expert opinions but no consensus in in sight. Finally Vit D accumulates/declines gradually. High doses (50k units) are used in deficiency states, normalization of blood level typically takes a few months. Well worth doing for sake of bone health, and other body systems too. In Vit D insufficiency (low but not as low as deficiency) OTC Vit D is probably enough, but people should ask their healthcare providers about what form and dose are best.

m0llusk 5y ago

This is complex to evaluate. Another issue is that absorbing UV to create Vitamin D happens not within the body but at the skin. Because of this washing and scrubbing thoroughly just after sun exposure can reduce or eliminate generation of Vitamin D. What is considered ideal is to get sun exposure during the day and then avoid showering until the next morning to allow the skin to do its work.

sooheon 5y ago

2000 IU is an almost arbitrary number anyways. The precise input is obviously less important than the resulting serum levels, quantifiable by a simple blood test measuring 25-hydroxy D. A recent meta-analysis of 32 studies (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4103214/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4103214/) recommended >30 ng/mL 25(OH)D for lower all-cause mortality risk. Just get a blood panel in the summer/winter.

orangepurple 5y ago

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7468901/pdf/nutrients-12-02237.pdf https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7468901/pdf/nut... “Sensible sun exposure” is the practice of obtaining the minimum sun exposure required for adequate vitamin D synthesis followed by application of sunscreen or clothing coverage; and is often characterized as sun exposure of 5–30 min, two–three times per week to the arms, legs and torso during 10:00 h to 15:00 h [2,30]. The specific duration required within this time frame is dependent on skin type, previous tanning, latitude, season and environmental conditions. The minimal erythemal dose (MED), or the minimum quantity of UVB that induces a slight erythema 16–24 h post exposure, is a common dosage employed for sensible sun exposure guidelines [31]. The standard erythemal dose (SED) is a standardized method for quantifying erythemal UV radiation (UVR) dose and is becoming more commonly used because the MED varies from person to person even within the same skin type. The SED is defined as 100 J/m2 [32]. For adults with a fair complexion, one MED is equal to about 10–12 min of full body exposure during peak summer sun for all skin types [33]. One MED may be considered equivalent to ~2.5 to 3.5 SEDs depending on skin type [34].

stjohnswarts 5y ago

You should get tested first, chances are you don't need supplements if you live in the tropics and spend much time at all out in the sun. If you're a vampire like me (I rarely go out much during the day, my car is even in the garage :) ) you might need supplementation though. If you're an active person outdoors a lot the chances you need supplements are unlikely. Go to a doctor and get some blood tests, they can spot all kinds of deficiencies and tell you how normal things look