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Retinoic acid peaked at noon
Quote from
dan on July 17, 2020, 5:11 pm
"All-trans retinoic acid showed a significant systematic variation throughout the day, with a peak before lunch and lower concentrations in the morning and in the afternoon. There was no obvious correlation with meals or with other hormonal circadian variation..." https://sci-hub.tw/10.1080/003655102321004521
Here are the approximate values of retinoic acid from their chart:
8:00 4.5 nmol/L
10:00 5 nmol/L
12:00 5.5 nmol/L
14:00 4.75 nmol/L
16:00 4 nmol/L
18:00 4 nmol/L
Note that commercially available Vitamin A blood tests measure retinol, not retinoic acid. In the study, retinol levels didn't vary with the time of day. Also retinol levels are about 500 times higher than retinoic acid levels so they're not directly comparable.
"All-trans retinoic acid showed a significant systematic variation throughout the day, with a peak before lunch and lower concentrations in the morning and in the afternoon. There was no obvious correlation with meals or with other hormonal circadian variation..." https://sci-hub.tw/10.1080/003655102321004521
Here are the approximate values of retinoic acid from their chart:
8:00 4.5 nmol/L
10:00 5 nmol/L
12:00 5.5 nmol/L
14:00 4.75 nmol/L
16:00 4 nmol/L
18:00 4 nmol/L
Note that commercially available Vitamin A blood tests measure retinol, not retinoic acid. In the study, retinol levels didn't vary with the time of day. Also retinol levels are about 500 times higher than retinoic acid levels so they're not directly comparable.
Ourania has reacted to this post.
Quote from
Ourania on July 17, 2020, 7:28 pm
Extremely interesting @dan! The link does not open for me. Does it say anything about what happens at night?
Extremely interesting @dan! The link does not open for me. Does it say anything about what happens at night?
Quote from
dan on July 17, 2020, 8:06 pm
Extremely interesting @dan! The link does not open for me. Does it say anything about what happens at night?
Another link is https://pubmed.ncbi.nlm.nih.gov/12512741/
They only measured one day, from 8am to 6pm. Maybe they thought six blood draws in a day was bad enough.
Extremely interesting @dan! The link does not open for me. Does it say anything about what happens at night?
Another link is https://pubmed.ncbi.nlm.nih.gov/12512741/
They only measured one day, from 8am to 6pm. Maybe they thought six blood draws in a day was bad enough.
Quote from
Ourania on July 17, 2020, 10:03 pm
Thank you @dan.
This release of RA for noon could be timed to get a maximum conversion to vit D, or to make sure a maximum of RA is disposed of at a time it can do less damage because the sun will take care of it?
Inversely, more accumulation of RA would happen if this circadian effect is stopped because people don't go out at this time?
Or because te circadian clock is not running right. If you are exposed to blue at the time red should be on?
It would explain why red LEDs seem to have an effect.
Thank you @dan.
This release of RA for noon could be timed to get a maximum conversion to vit D, or to make sure a maximum of RA is disposed of at a time it can do less damage because the sun will take care of it?
Inversely, more accumulation of RA would happen if this circadian effect is stopped because people don't go out at this time?
Or because te circadian clock is not running right. If you are exposed to blue at the time red should be on?
It would explain why red LEDs seem to have an effect.
Quote from
dan on September 2, 2020, 2:51 pm
I found a different study that found a Vitamin A peak time around 4 p.m. not noon:
Daily rhythm of circulating fat soluble vitamin concentration (A, D, E, and K) in the horse. https://www.jcircadianrhythms.com/articles/10.1186/1740-3391-2-3/
I found a different study that found a Vitamin A peak time around 4 p.m. not noon:
Daily rhythm of circulating fat soluble vitamin concentration (A, D, E, and K) in the horse. https://www.jcircadianrhythms.com/articles/10.1186/1740-3391-2-3/
Uploaded files:puddleduck has reacted to this post.
Quote from
lil chick on September 3, 2020, 5:18 am
4 pm is when fevers spike (as dr. mom you can quote me on that)
4 pm is when fevers spike (as dr. mom you can quote me on that)
