Hi Dr. Holick ,
I work at a health store in the Twin Cities area and often recommend Vitamin D3 to our customers telling them that 2,000 iu’s min. are need to be taken daily. I have read that that amount is far short. What is a good amount to recommend to most customers? I’m sure it’s best to get it from the sunlight. In the winter months when it’s below zero that is very difficult. Is it true after being in the sun you should not shower for 2-4 hours for best absorption

Thanks,
J

Dear J,
2000 IU/d is fine. You cannot wash vitamin D off your skin because it is made in the living skin cells.
Best, Michael

Dear Dr. Holick,

I have never heard of you or your expertise before I opened an
email from “Bottom Line” books. They mentioned your name and your prestigious works concerning preventing cancer. I am aware Sir that you are an extremely busy physician but I have been an extremely ill person who could use some reassurance.

In short, I was diagnosed with rheumatoid arthritis at the age of
16, have had three hip arthroplasty’s the last of which the pelvis was
severely fractured, 2007 and had to have bone and tissue grafting.. One
thing that really disturbed me is the fact that I had mirco-calcifications removed from my breast two yrs. ago. The attending surgeon accidentally struck a major artery and I hemorrhaged on the table, therefore having to halt the procedure. They tried to assure me that they had taken out all the micros before the bleeding. I’m wary though; am due for my yearly mammogram in two months. Does ingesting Vitamin D cause microcalcifications in the breast? I would like to drink more milk for the Vitamin D benefit but am not sure if this is wise.

Thank you sincerely for taking time to read this and I’ll be delighted if you can reply.

Thanks,
–

Dear –

Vitamin D will not cause micro calcifications in the breast. Milk is a
good source of calcium but has very little vitamin D. typically only
about 100 IU in 8 ounces. I would recommend that you take a multivitamin
along with a 1000 IU Vitamin D supplement a day. That is what I do.

Best, Michael

Dear Dr. Holick,

I’m sorry if I’m imposing, but I read online that you are the foremost authority on vitamin D. My daughter has just learned she’s pregnant and began taking a prenatal vitamin that claims to provide all the necessary vitamin D but it’s less than 2,000 units. I heard Dr. Oz on Oprah say that non-pregnant women should be taking 4,000 units per day. Can you tell me what you recommend for pregnant women?

Thank you very much for your help. We really appreciate it.

Thanks,
K

Dear K,

I recommend that all pregnant women take their prenatal vitamin along with a 1000 IU vitamin D. supplement once a day. It is probably even safe to take 2000 I U. of vitamin D a day.

We reported that most pregnant women taking a prenatal vitamin are vitamin D deficient. Thus the 1000 IU of vitamin D in addition to the prenatal vitamin should help provide both the woman and her fetus a reasonable amount of vitamin D. I do not see a need for pregnant women to be taking 4000 IU of vitamin D a day. However this may be valuable for lactating women since the Vitamin D then enters into their milk and satisfies the infant’s requirement.

Best, Michael

Dear Dr. Holick,

Is there an approximate serum level of 25-OH-D3 above which the immune system of the average healthy adult starts to become mildly suppressed?

Thank you very much,
L, M.D.

Dear L,
In my opinion NO.
Best, Michael

Dear Dr. Holick,
I have been reading online that Vitamin D3 is more effective than D2 in raising serum 25(OH)D concentrations and maintaing those levels for a longer time due to their superor affinity for Vitamin D binding proteins in plasma. Coming from a Chronic Renal Disease perspective, what is the clinical signifigance of ordering a Vitamin D2 vs. Vitamin D3 level for renal patients. Does it help in adjusting doses or seeing the efficacy of the Rocaltrol supplimentation,help to assess the severity of kidney disease, and is it affected by other levels other than Calcium ? why would you order one over the other?
Your assistance in answering these questions would be greatly appreciated, I just read your recent arlitcle and am a little confused since it seemed to me that you felt Vit D2 supplimentation was just as effective as D3 in raising the 25(OH)D concentrations.

Thank you,
K

Dear K,
Vitamin D2 is as effective as D3 when given daily. We have completed a 6 year study showing the 50,000 IU vitamin D2 was effective in maintaining serum 25(OH)D levels 40-50 ng/ml.
Best, Michael