i was just listening to the new podcast on the healthy skeptic with kurt harris and he gave a pretty lengthy answer concerning his views on vitamin D supplementation. during his answer he touched on the differences in sunlight needed for vitamin D levels to be equal in light-skinned vs dark-skinned people. it's a subject that i've been wondering about for awhile in that being that, from a study i read recently, 97% of african americans are vitamin D deficient as opposed to 60-70% of white americans. i'm assuming that this is because it the uptake of vitamin d is much quicker in white americans- i believe 15-45 minutes of midday sun is needed- whereas african americans need somewhere in the range of 2-3 hours. being that on the east coast, it's pretty impossible for me to get anywhere near adequate sunlight during the winter so i supplement 2-3000iu a day on average. my question is, being that the uptake of sunlight is drastically different from lighter-skinned people, should the darker of us supplement more D than is generally recommended?
Edit: I've been supplementing with D3 since november and this is the first winter for as far back as i can remember that i haven't been anywhere near sick, even though seemingly everyone around me has gotten sick multiple times during the winter.
KGH is a radiologist. Radiologist dont treat people.......they read films and papers. That disclaimer should HAVE been made during the podcast. The recent trends in Vitamin D are being done by clinicians in the field. The clinical results are being published daily as are research protocols. Right now there really is no optimal range as far as I know but is based upon the diseases we are treating patients for. I personally see a ton of metabolic bone disease as a surgeon and therefore I treat it as I see fit based upon my experience and the best clinical data we have for my clinical practice. Kurt can see the effects of the treatment on the films. He can see the effects of clinicians who dont. Often he has no clue what context the patient or films are in because radiologists are not given a patients chart when they have a study. He does have good insights and he reads a lot more than most docs which is admirable. But I think you need to understand the biases before you generalize about any doc including moi. Always understand the context things are done in before you jump to a CONCLUSION.
At certain latitudes, for certain stretches of time, both whites and blacks get basically negligible amounts of D3 from the environment. There's less UVB, it's cloudier, we're outside less, we have only parts of our faces uncovered etc. For those periods of time, both blacks and whites, assuming all individual factors are the same, have the same requirements for vitamin D. As we near summer and more UVB is available and we are more willing and able to utilize it, the dietary need for vitamin D decreases for a white person at a much faster rate, so long as they're making an effort to get sun.
Controlling for differences in size etc., we can safely assume that any member of our species has the same biological need for vitamin D from all sources as any other.
The only way to make that determination is by getting tested a few times in a year and making the necessary adjustments.
Personally, this past spring/summer I took no vitamin d and made sure that I got 20-30 minutes of shirtless sun at or around solar noon every day. For the rest of the time I took 5000IU of D3. This resulted in a 25OHD level of 85ng/dl. I decided that this might be a bit high and adjusted downward to 4000IU currently. If I were identical in dimensions, diet, etc. but were black, I would have received less from the sunning, stored less in my fat and thus would have required more dietary vitamin d to reach that same level. It's also possible that storage was largely irrelevant and that 5000IU produces 85ng/dl in a person of my size due to the body's processing/breakdown of D. This would mean that there would be a racial difference for a short period of time, followed by a prolonged level of 85 or so.
One thing about vitamin D that I think isn't spoken of enough is that it's likely toxic if not consumed with the other fat solubles, especially where calcium is concerned. I think a person eating the SAD and taking 10000IU could accelerate the calcification of their arteries if they are deficient in K2 and A. If you eat a quarter pound of liver every week and butter, you're good though.
Did Harris mention at all any evidence like this:
Vitamin D Levels Have Different Effects on Atherosclerosis in Blacks and Whites, Study Finds
"In black patients, lower levels of vitamin D may not signify deficiency to the same extent as in whites," said the study's lead investigator
"However, we do not know all of its effects and how they may differ between the races. The bottom line is that racial differences in calcium handling are seen and black and white patients have differing risk for bone and heart disease. We should more clearly determine the effects of supplementing vitamin D in black patients with low levels based on existing criteria and should not assume that the effects of supplementation will be the same between the races."
You can also find a study on Pubmed Central (not confined to blacks) that shows benefit on outcomes when raising levels above the lowest quartile, but then benefit diminishes somewhat when raising to the highest quartile. IOW, don't take too much.
If it were me, I wouldn't take high doses because some guy on the internet says so. Good luck. From what I've seen, Harris regularly claims that he knows the truth of all nutrition. No one does.
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