Everything You Ever Wanted to Know About Vitamin D from the Expert, Dr. Michael Holick. How Much Do We Need? Why Is It So Hard to Get Enough? What About Breast-Fed Babies? Why Is It So Important for Good Health?

 

When it comes to good health, I pay very close attention to how the experts are taking care of themselves.

Dr. Michael Holick, the 62 year old Professor of Medicine, Physiology, and Biophysics at Boston University's Medical Center is probably THE world expert on Vitamin D & health--he's been studying Vitamin D for over 35 years.  When Holick talks--I'm listening!

What's his personal prescription for getting enough of this liquid gold?

1. 2000 IUs of vitamin D a day.

2. 3 glasses of milk a day = 300 IUs of Vitamin D

3. 400 IUs in his daily multivitamin

4. Between supplements & milk he's getting 2700 IUs a day

5.  He plays tennis & cycles outside in his free time.  He always wears sunscreen on his face--but leaves his arms & legs exposed--but he lives in Boston.  Sensible sun exposure on your arms & legs is the BEST way to build up your Vitamin D stores--10 minutes a day if you are fair-skinned, between the hours of 10-3, with sunscreen on your face, for 2-3 times a week. That ought to do it!

6.  What's his 25-hydroxyvitamin D level?  He's consistently in the 50-60 ng/mL range.  Just where you'd want to be to get all the health benefits of D.  30 ng/mL is the minimum and you can go all the way up to 100 & still be on the very safe side.

So, why am I writing about Vitamin D again?  There's just so much to say about it!  And besides, it's closing in on November--which means if you live north of Atlanta, Georgia there is no way you can get any vitamin D from the sun.  It's too high in the sky & the angle is too oblique.  By the end of the winter--if you aren't taking a Vitamin D supplement you are going to be deficient!  Not a good thing.

You can stand stark-naked on top of a building in Boston all day in February and get zippo Vitamin D!  So take that supplement & get some Real Sun in the summer!

Why Should I Care If I'm Sufficient or Deficient in Vitamin D?

I know, it sounds like snake-oil.  How can Vitamin D possibly have an effect on so many chronic diseases and conditions?

Simple--every cell and tissue in the body has a Vitamin D receptor--and all of them depend upon D for optimal health.  Here's just a sampling of the bad things that can happen if you aren't getting enough.

• Cardiovascular disease - increase risk of heart attack 142% if under 15 ng/mL
• Cancer - if you live in a northern latitude you have a higher risk of colorectal, breast, & prostate cancers.  Projected 50% risk reduction with over 1000 IUs a day.  Adequate Vitamin D actually inhibits cancer cell growth.
• Autoimmune Diseases
• Osteoporosis/fractures - study after study shows the necessity of Vitamin D to absorb calcium & build strong bones.  With sufficient Vitamin D you'll absorb 30% of the calcium in your diet.  Without Vitamin D, the absorption rate drops to 10-15%.  Although Dr. Holick recommends a Vitamin D level of 50 as the optimal number to prevent osteoporosis,  Dr. Heike A. Bischoff-Ferrari concluded that the minimum level of vitamin D to prevent hip and nonvertebral fractures in older adults should be at 75-80 nmol/l which is the equivalent of at least 32 ng/mL.  ("Optimal serum 25-hydroxyvitamin D levels for multiple health outcomes" in Sunlight, Vitamin D and Skin Cancer, edited by Jorg Reichrath, 2008)
• Respiratory infections & flu - Yes, believe it!  Your immune system hums with D. Cytokine & immunoglobulin production is regulated by Vitamin D.  2009 Archives of Internal Medicine article shows the higher the Vitamin D, the lower the risk of upper respiratory tract infections.
• Osteomalacia - generalized & isolated bone pain - it can vanish with adequate Vitamin D
• Arthritis - both rheumatoid & osteoarthritis
• Multiple sclerosis -risk increases the further one gets from the equator.  Studies show the risk is reduced for outdoor workers, and in people with higher levels of Vitamin D.
• Schizophrenia - risk diminished in infants supplemented with D in first year of life.
• Type 1 Diabetes - Finnish study showed an 80% reduction in developing Type 1 diabetes for infants receiving adequate Vitamin D supplementation.
• Dementia - both vascular and Alzheimer's
• Fibromyalgia is often a misdiagnosed Vitamin D deficiency causing generalized muscle aches & pains.
• Type 2 diabetes.  May exacerbate type 2 diabetes & impair insulin production.  Obesity, associated with type 2 diabetes,  prevents adequate Vitamin D absorption.

Why Are So Many of Us Vitamin D Deficient & What Gets in the Way of Absorbing Adequate Vitamin D?

• We're Indoors & Wear Sunscreen. We spend most of our time indoors & when we're outside we're slathered in sunscreen, or mostly covered up with clothes.  Dermatologists have been telling us to wear sunscreen & avoid the sun for almost 40 years.  An SPF 15 reduces Vitamin D absorption by 95-99%
• No Mid-day Sun. To get adequate Vitamin D from the sun you would have to be exposed to the sun in the peak hours of 10 am to 3 pm.
• It's a Vitamin D Deficiency Epidemic!  Vitamin D deficiency (a level under 30 ng/mL) is epidemic  in adults over 50 (over 70% of us); 50% of children are deficient; 42% of young adults are deficient; and Vitamin D deficiency even exists in California, Florida, Arizona, and Saudi Arabia.  Personally, I don't know a single friend who wasn't deficient when they were first tested.
• It's an Age Thing. Age decreases the ability of the skin to make Vitamin D.  A 20 year old makes 3 times more Vitamin D than a 70 year old.
• Dark Skin Color.  African-Americans need to be out in the sun 5-10 times longer to get enough Vitamin D.  They are walking around with a natural SPF of 15.  Many researchers believe that the excessively low levels of D in African Americans may be responsible for their higher rates of prostate cancer, hypertension, and diabetes.  For an interesting story of skin color & Vitamin D click here 
• Obesity.  The more you weigh, the less Vitamin D is getting into your blood stream.  Obese people can only utilize 50% of their Vitamin D--because it ends up in their body fat & can't get into their blood stream.  They need to get 2-3 times as much Vitamin D from the sun or supplements to bring their levels up to normal.
• Kidney disease & Liver Damage.  Either one will impair the body's ability to activate circulating Vitamin D.
• Certain Drugs Inhibit Absorption of Vitamin D.  Like anticonvulsants, bile acid sequestrants (for cholesterol), Tagamet, corticosteroids, and heparin.

How Do I Find Out What My Level of Vitamin D Is?

• Ask your doctor to order a simple, low cost 25-hydroxyvitamin D test for you.  It's the only way to know what your baseline is.  Then follow-up a few months later if you are deficient.
• For optimal health aim for Dr. Holick's goal of 50 ng/mL.  Absolutely get yourself up to 30 ng/mL.  You're safe up to 100 ng/ML.  And it's impossible to get too much Vitamin D from the sun--the body will regulate it.  With supplements you would have to take over 10,000 IUs/a day, for six months to have Vitamin D intoxication.  Lifeguards wearing no sunscreen have been tested--they have super-high levels, and no intoxication.
• Every 100 IUs of Vitamin D you take, you can figure it will raise your Vitamin D level by 1 point, assuming you are not obese--which necessitates increasing the level by 50% or more.
• For those who are very low in Vitamin D, under physician guidance, you may need to take 50,000 IUs of Vitamin D2  (yes, D2--is now confirmed to be just as good as D3) once a week for 8 weeks, then 50,000 IUs every 2 weeks "forever" after, according to Holick.

How Much Vitamin D Can I Get Naturally From the Sun?  What's Safe?

• You can get your Vitamin D from the sun, from April-September if you live north of Atlanta, Georgia, and it is the best source of Vitamin D.
• If you are sunbathing mid-day on Cape Cod in the summer, wearing a bathing suit, without sunscreen, and you have fair skin, you will get 10,000-20,000 IUs of Vitamin D in just 15 minutes of exposure. Do that 2-3 times a week and you'll build up a healthy storehouse.
• The body is able to store the Vitamin D it gets from the sun far longer than it can store the Vitamin D it gets from supplements.
• Mother Nature has designed the body to store the Vitamin D we get from the sun in our body fat, and release it when we aren't "making" any more.
• Our Vitamin D levels peak in the summer--but in you are barely Vitamin D sufficient at the end of the summer (a level of 30 ng/mL) you will deplete those stores in one month.  By the end of the winter, you will be severely Vitamin D deficient, unless you are taking a supplement.
• Sensible sun exposure.  Here's what Dr. Holick advocates.  10-15 minutes of exposure on arms & legs in the peak sun hours of 10 am - 3 pm, two or three times a week.  Use a sunscreen on your face, and after 10-15 minutes get out of the sun or slather up.   Overexposure can increase non-melanoma skin cancer.   10-15 minutes is not overexposure. 
• To get exact guidance on how long you would need to stay in the sun to get enough Vitamin D, based on where you live, your skin type, the time of day, & the time of year--take a look at Dr. Holick's book, The UV Advantage, or try Dr. James Dowd's online sun exposure calculator.
• Vitamin D from the sun & depression.  Although Vitamin D is known to lessen depression and boost the mood--unfortunately, only the natural kind from the sun has this effect.

What About Skin Cancer?  I Thought It Was Risky to Be Out in the Sun Without Sunscreen?

• The American Academy of Dermatologists is still not recommending that we go out in the sun without sunscreen for any amount of time. They are recommending we take supplements and eat fish.  But remember, Dr. Holick is only recommending short sun exposure with the face protected by sunscreen, and the truth of it is--melanoma, the most dangerous of skin cancers, is usually found in the unexposed parts of the body that never see sunlight.
• Interestingly, occupational sun exposure decreases the risk of malignant melanoma and lifetime sun exposure is associated with a lower risk for malignant melanoma.
• The Dermatological & Cancer Societies of Australia have recently changed their position on sun exposure.  Now that studies have shown that 30-50% of Australian's are Vitamin D deficient because the sunscreen campaigns have been so successful, the Aussies are rethinking "their sunscreen message".  Their new message:  Get sensible sun exposure.  Enough to get adequate Vitamin D, not too much to increase cancer.

Any Special Recommendations for Pregnant Women & Infants?

• Vitamin-D deficient infants will never attain their genetically preprogrammed bone density or height.  That's one scary thought!
• A Boston study looked at 40 mother-infant pairs--the moms took the recommended 400 IU/day Vitamin D in their prenatal vitamin and drank 2.3 glasses of milk a day--at birth, 76% of moms were Vitamin D deficient--81% of newborns were deficient.
• All pregnant women need get 1000 IUs a day in addition to the Vitamin D in their prenatal vitamin, and an additional 200 IUs from their diet, according to Holick.
• Higher Vitamin D levels decreased the likelihood of preeclampsia, and reduced the need for C-sections.
• Moms who got adequate Vitamin D during pregnancy reduced the risk of wheezing disorders in their children by 61%.
• Breast-feeding moms need to be vigilant that their babies are getting enough Vitamin D.  The breast milk of moms who are not getting enough Vitamin D has a paltry 25 IUs of Vitamin D per liter (1 quart, 2 ounces).  Not even close to the 400 IUs their babies need.  It would take 4000-6400 IUs/a day for a breast-feeding mom to get enough Vitamin D into her breast milk to meet the baby's requirement of 400 IUs a day.  But according to Holick, until more studies are done, "it's not something we're recommending."  Hopefully, we'll be able to in the near future."  In the meantime--breast-feeding moms need to make sure their babies are getting 400 IUs/a day of a Vitamin D supplement.

What Kind of Supplementation Does Dr. Holick Recommend?

• 1000-1500 IUs/a day for most children
• 1500-2000 IUs/a day for adults
• All pregnant women need get 1000 IUs a day in addition to the Vitamin D in their prenatal vitamin, and an additional 200 IUs from their diet.
• The American Academy of Pediatrics now recommends 400 IUs/a day for infants.
• In August 2009 Dr. Holick participated in an Expert Panel convened by the Institute of Medicine to work on new recommendations for Vitamin D--in light of all the research that has come out recently.  Expect new standards sometime around the Spring of 2010.

Can You Get Enough Vitamin D from Diet Alone?  Not Likely!

• The only food that contains Vitamin D, is oily fish, like wild (not farmed) salmon--clocking in at 500-1000 IU a serving.  See a Boston University breakdown of Vitamin D for various fish here.
• Cod Liver Oil is an OK source.
• Some foods are fortified, but at a typical 100 IUs a serving that's about 10 glasses of milk a day.

Want to learn more?

Listen to Dr. Holick and Dr. James Dowd on the People's Pharmacy

The American Academy of Pediatrics updated Vitamin D guidelines for infants & children

The Audio-Digest Family Practice Summary of "Vitamin D: the Vital Vitamin".  57(12): Mar. 28, 2009

NPR Transcript from the Living on Earth broadcast of "Skin Color and Vitamin D"

Why Is Vitamin D My Favorite Vitamin?  Let Me Count the Reasons

"Institute of Medicine Studies a Boost In Vitamin D".  AMA News April 20, 2009  

Gretchen Reynolds.  Phys Ed. Can Vitamin D Improve Your Athletic Performance?  New York Times Sept. 23, 2009

So, What About Me?

I try hard, but rarely succeed in taking 2000 IUs of D a day, plus about 400 IUs from Citracal calcium supplements, and maybe an additional 400 IUs from an occasional multivitamin or from fortified food.  I'm not often out in the mid-day sun--but when I am, don't tell anyone--I'm not wearing sunscreen.

I haven't been retested in over 2 years, when it was 33 ng/mL at the end of winter.  I plan to retest in January 2010.

Comments

[Steve Parker, M.D.]

Thanks for the comprehensive summary!

A study just in the last month linked low levels of vitamin D with falls in the elderly. Trust me, you don't want to be falling frequently when you're 75.

-Steve

[Evelyn Tribole MS RD]

Excellent synopsis and resources for vitamin D! Thank you.

--Evelyn Tribole, MS, RD

[JK]

As the others said, great post and resource. I found some "gummy" vitamin Ds for the girls, but they are only 400 IU. My girls like to swallow little pills--we used to have fish oil for them in pill form-- do you think I should get them 1,000 IU Vit Ds that they have to swallow? I think they can handle it. My 2,000 IU Vit Ds are very little. Hrm.

Again, thank you!

[Hank Roberts]

> the sun. It's too high in the sky &
> the angle is too oblique.

Too _low_ in the sky, during the months with short daylight.

Thanks for this heads-up. I'd started supplementing but nowhere near this amount.

Can you comment on whether there really are two different forms of Vitamin D available in supplements? There are some confusing claims (which I can probably find if this isn't familiar)

[The Healthy Librarian]

To JK:

Just to be clear: Those higher recommended levels for kids are Holick's recommendations. The new ones from the Institute of Medicine won't be out until 2010--maybe in the Spring. Be sure to read the American Academy of Pediatrics' recommendations, too.

That said--the 1000 is a total of everything kids get from their diet--like from supplemented foods & a multiple vitamin, and consider if you live somewhere in the lower latitudes & the kids get out in the sunshine--plus the vitamin D supplement. That's terrific that you found gummy vitamin D's.

D from the sunshine is the best--it can be stored, and you can never get too much.
Not sure this very helpful.

[The Healthy Librarian]

Thanks for the correction, Hank. In the winter--in the Northern hemisphere the sun's rays hit the earth at an oblique angle & is less concentrated, even at mid-day.
Also, not as concentrated in the Spring & Summer in the morning, and later afternoon hours.

If you mean by the two different types of D--D2 & D3--the claim had been that D3 was more beneficial, more absorbable than D2--but, it's recently proved to be incorrect.

Recent research by Dr. Holick showed that D2, was in fact as good as D3. Here's the link:

http://jcem.endojournals.org/cgi/content/full/93/3/677

But as with everything, I see that there continues to be controversy.

As for me--I still take D3. It's available, it's cheap, why not?

[Chris G.]

I hope some one will tell Dr. Michael Holick that his three classes of milk a day is not the optimal approach for long term health, given the ill effects of dairy.

Regardless, great post!

[The Healthy Librarian]

Hi Chris. I've had other off-blog replies that said the same thing! Don't know why a 60-something guy is still drinking milk--but, I'll overlook it because he's been a tireless leader/advocate in Vitamin D research back when people were ignoring its importance.

[Rachael]

I recently started supplementing my Vitamin D (and encouraging my family to do so) but I still have a few questions about supplementation- namely, absorption. What do we know about absorption of D from supplements? As I understand, many other vitamins (esp. water soluble) are excreted from the body very quickly. And some vitamins need to be taken with fats, or need to be taken in conjunction with other vitamins. What do we know about the optimal conditions of the absorption of Vitamin D?

[Christel B]

Hello,
I am so grateful to my new doctor for having discovered my Vitmain D deficiency. As a child growing up in Europe and Africa (I know, how could this happen in sunny Africa!), I used to suffer from tetany and severe muscle and joint pains. Doctors always said that my body did not absorb calcium althouhgt I ate plenty of dairy products. So they would put me on intense calcium and magnesium regimens every 6 months or so, and that would help for a while.
When I had my daughter 4 years ago,I suffered from preeclampsia and actually had a mini-stroke and full blown eclampsia a couple days after the delivery. It was horrible. But I am very grateful to have fully recovered and have a wonderful healthy 4 yr old. My blood pressure finally went back to normal 2 years after her birth. The excrutiating muscle and joint pains that I have experienced on and off my whole life had gotten much worse earlier this year. I was tested for lupus, fybromyalgia, osteoporosis etc... all came up normal. There were signs of major inflamation in my body because of extremly high and abnormal enzyme levels, but they couldn't figure out what caused it. So I was prescribeld medicne for the pain and inflamtion. Until one doctor decided to check my Vitamin D levels which were 13ng/ml. Severly deficient. Nobody had ever thought of that. Neither did I.
We stopped all other medications and I got on the 50,000iu once a week. I have never felt so good in my body. Within 3 weeks the pain and fatigue was gone. I have even started losing a little weight because I'm not as hungry anymore and I'm able to eat smaller portions and not crave sweets as much. After 3 months, I was tested again, my levels had gone up to 30ng/ml. I am on it for another 3 months again. My doctor wants my levels to be and stay at 50ng/ml.

When the spring and summer come around, I will seek to be outdoors more.
This has been a major breakthrough in my life. It seems like my Vitamin D deficiency was somewhat tied to all the major health issues I've had my whole life.

I wish Vitamin D levels were routinely tested as part of every American physicals and check ups. It is such a simple test that could truly change people's life for the better.

I could have been in chronic pain all my life, been on unnecessary medication and possibly suffered from more complications when all that was needed was the right dose of Vitamin D. Wow.

[The Healthy Librarian]

Christel,

What a frightening story--but thank goodness for your recovery! Just heard Dr. Bruce Hollis speak about vitamin D yesterday, and your experience absolutely concurs with his research & findings.

Thanks so much for sharing your happy-ending story. Sounds like you found an excellent doctor. 50 ng/ml seem to be the level that the vitamin D experts recommend

[Jen]

I have kidney stones and the stone clinic I got to wants me taking a women's multi vitamin and 1000 vitamin d no more. I'm guessing with kidney stones I should follow this nutritionist guidelines for now?