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Vitamin D: Finding a balance

July 21, 2017

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photo of Emily S. Ruiz, MD, MPH

Emily S. Ruiz, MD, MPH, Contributor

Emily Ruiz, MD, MPH, is an Associate Physician at the Mohs and Dermatologic Surgery Center at Dana-Farber/Brigham and Women’s Cancer Center, an Instructor in Dermatology at Harvard Medical School and Director of the High-Risk Skin Cancer … See Full Bio
View all posts by Emily S. Ruiz, MD, MPH


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Antonio Kowatsch
September 17, 2017

Wouldn’t it make more sense to avidly apply sunscreen in order to minimize the vitamin D production so that one could substitute it with the respective vitamin D supplements? I mean, from a logical point of view this would be the better choice considering how many variables contribute to the “natural” vitamin D production. So many in fact that a regular person wouldn’t be able to infer his own recommended daily intake of “sunlight”.
There are just too many factors that one would have to account for in order to create a heuristic approximation for the optimal amount of time that one should be exposed to the sun (things like the skin complexion which are arbitrary by proxy to the layman). I appreciate the article for its informative nature but the advice given within seems to be non-compliant with the laws of logic, I am afraid.

Since we all require the same amount of vitamin D (more or less) and since people produce vitamin D at varying rates it would seem more reasonable to reduce the amount of arbitrarily generated vitamin D (by means of sunscreen, etc.) while substituting it with exactly measured vitamin D supplements.

September 6, 2017

sometimes allows naturally produced cancer cells to grow into dangerous tumors. Vitamin D deficiency is now an epidemic level immune suppressor.

Don Allen
September 5, 2017

I’ve been taking 2000 d3 i.u./day for the past couple of years since I found out I was deficient. Since then, my d levels went from 22 into the mid to high thirties. I’ve also been sure to get outside a little bit more, but high 30’s seems about as high as my levels go. While not deficient, it’s still pretty low. My doc says it’s because urban lifestyles tend to be indoor lifestyles. Given that, is there really a way to get sufficient vitamin d levels without supplements?


ismail avdas
September 5, 2017

K2 helps put the calcium in bones and keeps calcium from collecting in the blood, where it causes trouble such as plaque build up.

September 1, 2017

Vitamin D plays an immportant role overall health of an individual. If your body lacks enough Vitamin D, it will fail to absorb calcium it requires for strong bones. So make sure to include vitamin D rich foods and a lot of sun light. Good luck .

August 29, 2017

I am not pretty sure about the technical terms but I do face some problems due to vitamin deficiency, as I order the needed from coupons and will not consult any doctor but after reading this article I will surely consult the doctor for the actual rate and will follow the guided. Thank you, because this article gave me some information which is very useful for me to re think about my health

July 27, 2017

Vitamin D is so important because if acts like a support to the Immune system: Vitamin D and the Immune System But too much of it, can cause severe toxicity… unfortunalty some people especially those with Liver issues needs Vitamin D, but i guess, taking 5000 ui daily is enought for those with Vitamin D deficiency… But do not take any supplimentation without takng the advice of your doctor.

James A. Boatright
July 28, 2017

I believe that being replete in vitamin D is necessary for a strong immune system, but in itself does not always guarantee having a robust immune system. In mathematics this is called a necessary but not sufficient condition. Our modern environment and food, water, and medical systems expose us to many powerful immune suppressors which we must strive to avoid. Plasticizers, for example, are endocrine disrupting chemicals (EDC’s) which weaken our immune systems, making us more likely to catch a cold, flu, or other communicable disease or even to develop various cancers. We evolved relying upon our immune system to detect and repair or destroy incorrectly replicated cells in our bodies. A compromised immune system sometimes allows naturally produced cancer cells to grow into dangerous tumors. Vitamin D deficiency is now an epidemic level immune suppressor.

Julius Irozuru
July 27, 2017

For all who took their time to share their knowledge and experience, I am very very grateful.

I happen to be a 74-year old male with many health challenges who had been on Vitamin D2 50,000 units 1/wk for the past few years. Among my issues are Paget disease of bone (M88.9), Low back pain (M54.5), and Arthritis (M19.90).

I will now have to learn more about the difference between D3 and D2, and also K2.

Again, thanks.

James A. Boatright
July 27, 2017

Hello, Julius;
That 50kIU of D2 sounds like an old fashioned “bolus” dose of ergosterol, the plant form of vitamin D made by irradiating mushrooms. I would at least switch to an equivalent daily dose of vitamin D3, the human form of vitamin D. Your body can make D3 from the D2, but it is less efficiently utilized. Weekly or monthly bolus dosing is really only useful for your bone disease. Spreading the supplementation to an equivalent 7200 IU daily of D3 has many other possible health benefits besides calcium metabolism.
I have found that 15,000 IU/d of D3 helps alleviate my chronic lower back pain.

joy v. poskozim dds
July 25, 2017

I am disappointed that there is no mention of how Vitamin D also helps teeth. As it pertains to Rickets, children often obtain abscesses and severe tooth decay because they are excreting phosphates, not using phosphates to bond to calcium for strong tooth enamel.

Roger Stein
July 25, 2017

Presumably in response to a comment of mine yesterday (See Roger Stein, July 24, 2017, 5:37 PM) the writer of this blog amended her post by creating a link (in red) using the key words in dispute between us: “Most people need 1,000 to 1,500 hours of sun exposure throughout the spring, summer, and fall” to obtain the necessary amount of Vitamin D.

Clicking on her link, I was led to a 2012 article in a pharmacology journal entitled “Vitamin D: The ‘sunshine’ vitamin”. Scrolling down the article, I came to the section ‘Sources of vitamin D’, which contained a sentence which the writer of this blog apparently feels vindicates her position: “A major source of vitamin D for most humans is synthesized from the exposure of the skin to sunlight typically between 1000 h and 1500 h in the spring, summer, and fall. “

Let’s examine that sentence. First of all, what it actually says is that ‘a major source’ of vitamin D– not necessarily a SUFFICIENT source, and, ironically, OFTEN not a sufficient source– is from sun exposure, which is typically between 1000 hours and 1500 hours in the spring, summer, and fall. A few sentences later THAT SAME ARTICLE says “When an adult wearing a bathing suit is exposed to one minimal erythemal dose of UV radiation (a slight pinkness to the skin 24 h after exposure), the amount of vitamin D produced is equivalent to ingesting between 10,000 and 25,000 IU.” Does the writer of this blog realize that those two sentences need reconciling because without it they create a seeming paradox?

Why a seeming paradox? Since a slight pinkness to the skin 24 hours after exposure would, for a fair-skinned person, mean at most 20 minutes in the midday summer sun, the fact that that amount of exposure is equivalent to ingesting 10,000 and 25,000 IU of Vitamin D – many times the daily requirement– seems to implicitly contradict the ‘1000 to 1500 hours in the sun in spring, summer, and fall’ sentence of the article because–as I laid out yesterday in my first comment– if you divide 1000 hours by 270 days you get 3.7 hours a day, and using 1500 hours and fewer than 270 days you would dramatically increase the number of hours per day. To reconcile the two sentences I draw the following highly plausible inference: Most of the sun exposure in those 1000 to 1500 hours that a typical person receives is when he is mostly clothed and/or it is too early or too late in the day for the sunlight to generate much Vitamin D. And yet– ironically– the epidemiological studies that show the typical sun exposure in spring, summer, and fall is between 1000 and 1500 hours also show that, because of clothing covering the skin or the time of day, even that large number of hours in the sun is often not sufficient to supply enough vitamin D.

So what conclusions are to be drawn from all this? If you want to rely on the sun alone to supply you with your requirement of Vitamin D, you don’t need HOURS in the sun, just a few MINUTES, but you must choose those few minutes wisely as to time of day, and you must NOT be wearing a long-sleeved shirt and pants! As I said in my first comment, multiple sources make statements like this: “Generally, a fair-skinned person who’s out in the midday sun in shorts and a tank top for 10 minutes will generate 10,000 IU of Vitamin D.” But before you do that, carefully consider the risks of the various skin cancers highly correlated with sun exposure, including the often lethal (and always unpleasant) melanoma, not to mention — highly relevant to the vain among us– the aging effects on the skin of extensive sun exposure.

James A. Boatright
July 26, 2017

The article cited merely mentions that some vitamin D can be naturally produced in the skin by exposing it to sun for a few minutes between the hours of 10AM and 3PM (1000h and 1500h in typical European usage) during the spring, summer or fall seasons of the year. The clumsy wording is perhaps due to faulty translation.

Depending upon your skin type, 10 to 20 minutes of solar radiation exposure of most of your skin area 2 to 4 times per week when the sunlight containing high UV-B content provides adequate vitamin D for most people. As you tan, you should gradually increase your sunbathing time durations to continue making enough vitamin D. Always stop before obtaining a minimum erythemal dose of UV-A exposure (pinkness showing up 4 to 6 hours later). UV-B radiation does not penetrate glass or many plastics, so go outdoors for your vitamin D and other benefits of sunbathing.

July 25, 2017

It is important to note that people who are overweight have a more difficult time absorbing Vitamin D and therefore require a higher dose.

Vitamin D will also be absorbed better if taken with boron. One research study I read said that Vit D levels were 25% higher when taken with a boron supplement.

A chronic undiagnosed Vit D deficiency in me triggered Hashimoto’s Disease and early menopause at age 39. Thanks to an excellent Endocrinologist and my research on supplements, the disease is in remission.

James A. Boatright
July 25, 2017

I wish to thank the author, Dr. Emily Ruiz, for publishing this article rather courageously. She is a Dermatologist going against their established mantra of “No unprotected sun exposure for anyone, ever.” Dr. Michael F. Hollick, a respected researcher at Boston University, was kicked out of dermatology by the powers-that-be several years ago for recommending essentially what Dr. Ruiz is now recommending here–sensible (minimum erythemal dose) sun exposure of unprotected skin.

Muhammad Al-Khaldi
July 24, 2017

I was taking 10,000 IU of vitamin D-3 on daily basis for 2 years with a blood level around 90 ng/ml. For the last five years or so, I am taking 5,000 IU/day of vit D-3 for 5 days per week, and my vitamin level is around 60 ng/ml. I usually take the supplements just before breakfast.

I totally agree that we should be our own doctors. Most of the doctors around know little about vitamin D and its role in human health.

July 24, 2017

K2 helps put the calcium in bones and keeps calcium from collecting in the blood, where it causes trouble such as plaque build up.

Marie Capell
July 26, 2017

What is K2?

James A. Boatright
July 27, 2017

Yes, vitamin K2 (preferably in its MK-7 form) is an important co-factor with vitamin D3 and magnesium for proper calcium metabolism and bone health, especially with high doses of D3. MD’s using mega-doses of D3 to treat MS (successfully) monitor PTH levels in establishing individual D3 tolerances. Everyone needs to maintain at least some calcium ions circulating in their bloodstream for central nervous system functioning. [I am a physicist and not a physician.]

This MK-7 form of K2 is abundant in some fermented Japanese food which I cannot stand, but capsules of the extract are easy to take.

Magnesium supplementation is another matter though. I would look for a timed-release version of one of the more bio-available forms of magnesium. In any case, your magnesium tolerance will likely be limited by loose bowel problems.

roger stein
July 24, 2017

The writer of this blog describes herself as an MD and MPH. I assume she is both. But what she most certainly is NOT is a careful and conscientious MD and MPH, because she not only made a terrible– and DANGEROUS– mistake, but she has not corrected that mistake despite several commenters directing everyone’s attention to the questionable nature of her words!!

I’m referring to this sentence of her blog: “Your body produces vitamin D when the skin is exposed to sun, and it is estimated that most people need 1,000 to 1,500 hours of sun exposure throughout the spring, summer, and fall to obtain the necessary amount of vitamin D. ”

If you do the math in the way that is most favorable to the writer of the blog– i.e. the way that minimizes the amount of sun exposure– which is to take the LOWER limit of exposure (1000 hours) and the maximum number of days in ‘spring, summer, and fall’ which is 270, and divide 1000 by 270, you get 3.7 hours of sun exposure a day without sunscreen!!!!

Obviously– and this is confirmed by other sources– the 1000 to 1500 numbers she quotes refers to MINUTES per day NOT hours. Generally, a fair-skinned person who’s out in the midday sun in shorts and a tank top for 10 minutes will generate 10,000 IU of Vitamin D.

What an irony– a dermatologist trying to promote public health, through shocking carelessness makes a recommendation that would kill half the people she’s trying to help!!!

July 26, 2017

“makes a recommendation that would kill half the people she’s trying to help!!!” Really seems a bit over the top an excellent piece in the NYT “I BEG TO DIFFER; A Dermatologist Who’s Not Afraid to Sit on the Beach” just google it

July 24, 2017

The safe upper limit I believe is 10000 IU daily as set by the IOM . Similar to the max. amount a day achievable thur sun exposure which I believe is about 12000 IU a day. The guidelines where set only with regard to bone health and an inconvenient study suggest that people who tan live longer than those who do not .Nice critique of recommendations “J Bone Miner Res. 2011 Mar;26(3):455-7. doi: 10.1002/jbmr.328.
Why the IOM recommendations for vitamin D are deficient.
Heaney RP1, Holick MF.
Author information
From a previous blog post “Here’s something unexpected: Sunbathers live longer” Posted June 06, 2016, 9:30 am , Updated June 07, 2016, 12:06 pm
Robert H. Shmerling, MD, Faculty Editor, Harvard Health Publishing

James A. Boatright
July 25, 2017

I have taken at least 10,000 or 15,000 IU vitamin D3 supplement every day (depending on sun exposure) for the past 3 years with no problems. If I am recovering from an injury, I have taken 30,000 IU/d for a few months to promote healing. I just generally “feel better” at 80 to 120 ng/ml serum 25(OH)D3 levels.

Dana Holmes
July 24, 2017

Agree with Sherry’s and Gennaro’s comments re the need for D3, specifically, along with K2 for absorption. Additionally, the amount of time needed for sufficient Vit D absorption from the sun varies very widely based on latitude and skin color. It is irresponsible to generalize about this.

James A. Boatright
July 25, 2017

The photochemistry of vitamin D3 production within dermal tissue is quite involved. Adequate precursor cholecalciferol must be present and adequate UV-B radiation must penetrate below the melanin layers protecting against excess UV-A damage. If your sun shadow is shorter than your height, adequate UV-B radiation is getting through the atmosphere to make some vitamin D3 in your skin. The amount of melanin present in the exposed skin is a huge factor–both in vitamin D3 production and in determining the minimum erythemal (UV-A) radiation dose one should tolerate. Most individuals can make the equivalent of 10,000 to 20,000 IU of vitamin D3 before erythemal skin damage occurs in near overhead sun exposure.

Disappointed by doctors
July 28, 2017

Completely agree with you, Dana. It is VERY irresponsible to generalize. As well as not to paint the whole picture.

The whole picture is optimal blood levels are now considered to be 50-70, and 70-90 if you have chronic health conditions. By numerous doctors.

Additionally, supplementing > 4,000DUI/day is NOT what makes Vita D3 toxic. It’s effects on Calcium (needs K2 to balance it out), and blood levels that are >100 that are toxic (also because of effect on Calcium, btw).

Further, there are at least 2 MDs who think that because we shower every day, we wash away the chemical(s) produced by the skin to convert sun exposure to Vita D (As James A. Boatwright said, it’s a very complex system :).

I am very disappointed that Harvard isn’t on the cutting edge of this research as average Americans take what Harvard says as ‘gospel truth,’ when it’s obviously not.

I’m so grateful for the naturopaths, osteopaths, homeopaths and other holistic doctors who actually DO the research and the reading to stay current with the information.

R Tuck
July 24, 2017

What type of Vitamin D to supplement?

Parker Metcalf
July 24, 2017

…Take a Vit. D-3 supplement….very inexpensive and very effective…’ll need to take more that the “good Doctor” reccomends, however…i take 6500 units….my levels are 62 now. Don’t believe everything you read…..Vitamin D-3 is a hormone and is safe to take in amounts up to 7-10,000 units… your own due diligence……that’s where you’ll find the truth.

July 24, 2017

Recommended doses of Vitamin D seems to have been a controversial topic for several years. With regards to prostate cancer and vitamin D, I’ve read several studies that show a link between low vitamin D and prostate cancer, but have not read anything about high vitamin D and PCa until this article.
For example,

July 24, 2017

An Institute of Medicine committee also recommended the 4,000 IU limit (report from 7 years ago) and it reported levels of vitamin D above 10,000 IUs per day are known to cause kidney and tissue damage. My general practitioner was concerned that a nutritional coach (chiropractor) had me on 14,000 IU/day for the last six months. What’s interesting is that my blood test showed I was still in the reference range, albeit the high end. What is the role of blood testing in customizing dosage for the individual?

July 24, 2017

This is important to sort out. I was found to be severely deficient in vitamin D, to the point where it was deemed probably genetic. I have to take 10,000 units a day for my blood levels to be in a healthy range. Surely it must be the blood levels that matter, not the amount taken? If it is the amount taken, we must need a better way in which to take it to be sure our blood levels are healthy.

James A. Boatright
July 25, 2017

Dose response for vitamin D3 supplementation varies widely among individuals. Always use serum 25(OH)D3 levels as your guide to vitamin D3 sufficiency. Modern assays are very accurate and repeatable. The range recommended by grassrootshealth’s D-Action panel of expert clinical researchers is 40-60 ng/ml for the general population. After a prostate cancer scare, I have maintained my 25(OH)D3 levels between 80 and 120 ng/ml for the past three years. The warnings about toxicity and negative therapeutic value are overblown and based on faulty studies. The “not yet well clinically studied” comment is not strictly true. Historically, many vitamin D studies were “designed to fail” by the medical establishment, and they did.

Melville Jayathissa
July 24, 2017

TQ. Very helpful & informative article indeed! And a 2O17 web posting by the University of Queen Mary London researchers also says that globally Vitamin D heips prevent colds & the flu…echoed nearby there by Dr. Mercola’s website posting that Vitamin D is better than the flu vaccine!

J Lindholm
July 24, 2017

“most people need 1,000 to 1,500 hours of sun exposure throughout the spring, summer, and fall”


Kelly Lee
July 24, 2017

Is 1,000 to 1,550 hours of sunlight (25-30 per week) during the 9 months of Spring, Summer and Fall correct?

July 24, 2017

This article doesn’t really answer the question. The answer is 10-20 minutes depending on skin type and amount of skin exposed. Exposure beyond that will not give you more Vitamin D that day. After that, put on sunscreen

July 25, 2017

Your comment does not answer the question either.

Your location and the given UV index while out in the sun is critical as well as the skin exposure.

In the Northern parts of the US it is unlikely to get sufficient Vitamin D in ten or fifteen minutes of exposures most days of the year.

July 24, 2017

I’m > 65 y.o. caucasian man in good health.
In Jan. 2017, I was Taking 1000 IU/day, Vit. D OTC supplement
Vit. D level = 28

Then Increased supplement to 2000 IU/day
In July 2017, Vit. D level = 24

what’s your reaction and advice?

D. Hall, RD
July 24, 2017

Vitamin D is a fat soluble vitamin, meaning it will be better absorbed if taken with a little fat – think nuts or nut butters, oils, avocado, low-fat instead of non-fat dairy, etc.

Sheri Margulies-Semel
July 24, 2017


Learned the hard way
July 28, 2017

Fred, you’re not taking enough at those low levels. The RDA is WAY low on this one (but they kinda have to be because they don’t know anyone’s blood levels). I was given 50,000 dui/day for 2 months when my levels were as low as yours. Recommended dosage by numerous doctors is 4-6,000/day depending on your size…or health level. And even more depending on your chronic conditions.

Take Vita K2 so your Calcium doesn’t get out of whack. 100-200mg/day depending on how much Vita D you take.

I promise once you get your blood levels up to about 50ng you’ll start to feel like a whole new person- happy, energetic, healthy.

Supplementing > 4,000DUI/day is NOT what makes Vita D3 toxic. It’s effects on Calcium (needs K2 to balance it out), and blood levels that are >100 that are toxic (also because of effect on Calcium, btw).

July 24, 2017

Any comment on the recent research that says that vitamin D RDA amounts were based upon a statistical error and the correct amounts to supplement (or get naturally) are quite a bit higher in order to avoid deficiency?


Jana Perinchief
July 24, 2017

Dr. Michael Greger has a good video on this topic:

Gennaro Gallo
July 24, 2017

Hi Brad,

In that regard I think 5,000 UI is still safe. And I would always add Vit. K2 while supplementing.


Commenting has been closed for this post.

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