Friday, December 3, 2010

winter and vitamin D

I have been getting a few emails about vitamin D;  I'm sure it's generated by all of the press about the changing recommended levels, levels of exposure and how important it is for our health.

Vitamin D, known as the "sunshine vitamin" is a fat-soluble vitamin produced in the skin by exposure to ultraviolet (UV) type B rays.  Fatty fish and eggs are a good food source of vitamin D and it is often added to milk.  I have a personal theory that part of the reason behind the epidemic of vitamin D deficiency is that our parents were forced to take cod liver oil by their parents.  They hated it so much they decided not to give it to their kids.  The science of the times did not recognize how important cod liver oil was and it was considered "old fashioned."  As a result I, and many others of my generation, grew up not taking it.  So we didn't give it to our kids.  While I'm not sure how much scientific veracity there is to that theory it certainly seems to fit the current situation.  Decreased cod liver oil consumption combined with reduced sunshine/increased sunscreen and suddenly many people, including pregnant women and their infants, are deficient.

Why all of the scientific attention to vitamin D lately?  It's very important to our health.  Not only does it help support our bone structure, it's vital to immune system health, increasing activity of our natural killer cells and macrophages.  Many studies now show that it may help protect against cancer, cardiovascular disease and there are even suggestions that vitamin D deficiency may be a contributing factor to increased influenza rates during the winter months.

One question I recently received about vitamin D:

"I was taking 400 IU but a while back started reading about re-examined attitudes toward D and upped it to 2,000 IU.  Then I thought that might be too much so I am currently taking 1,000 IU.  Your thoughts?"

Here's a little information to help you understand vitamin D better.  

I believe, and the studies support, that we do not get enough and that the levels set by the government are too low.  If you wear sunscreen you need to be aware that SPF8 and over will effectively block UV-B; this means your body cannot synthesize D from sunlight.

If you do not get enough outdoor exposure, are over 60 years of age (our ability to synthesize D decreases as we age), and/or live in northern latitudes you are probably not getting enough vitamin D.  Someone who lives in New England or further north generally does not get sufficient vitamin D during the winter months and can become deficient.  Especially if they did not have sufficient stores to begin with.

How to find out if you need more?  You need to get a blood test.  It is important to get the 1,25 OH-dihydroxy,  not the 25(OH) vitamin D to find out what your levels are.   Taking 2,000 IU per day is not an unreasonable amount especially in the winter.  

Osteomalacia (vitamin D deficiency) is often treated with 5,000-50,000 IU for three to six months.  Once a good level is reached doctors usually drop people to 1,500-2,000 per day.  Most doctors aim for at least 30-40 ng/dL (nanograms per deciliter) although many Functional Medicine practitioners prefer a level of 50-60 ng/dL.  It is important to note that too much vitamin D can be just as bad for you as too little, which is why it is important to get tested and know what your levels are.

When you take vitamin D is it best to take it as vitamin D3 (cholecalciferol) combined with K2 which is the most effective form.  D2 (ergocalciferol) is not as effective.  I personally prefer to take a sublingual D3/K2 liquid formulation to make sure that I am getting the best possible absorption.

The very best way to get your vitamin D?  Get sunshine.  Whenever possible get 15-20 minutes per day before you put on your sunscreen.  

Other resources which provide good information about vitamin D:

Dr. Holick's YouTube video on Vitamin D 
The Vitamin D Council

1 comment:

Anonymous said...

PROFESSOR Frank Garland, and his brother, Cedric, recommend [...] taking 50,000 units of vitamin D per week for eight to twelve weeks followed by maintenance on 1,000 to 2,000 units a day”.
ACCORDING Cedric F. Garland, Dr. P.H., FACE, Department of Family and Preventive Medicine and Moores Cancer Center of the University of California, San Diego (UCSD), “It is projected that raising the minimum year-around serum 25(OH)D level to 40-60 ng/ml (100-150 nmol/L) would prevent approximately 58,000 new cases of breast cancer and 49,000 new cases of colorectal cancer each year, and three quarters of deaths from these diseases, in the US and Canada.”
Plasma vitamin D and mortality in older men: a community-based prospective cohort study.
“There was a U-shaped association between vitamin D concentrations and total mortality. An approximately 50% higher total mortality rate was observed among men in the lowest 10% (<46 nmol/L) and the highest in the highest 5% (>98 nmol/L [or 39 ng/ml]) of plasma 25(OH)D concentrations compared with intermediate concentrations. Both high and low concentrations of plasma 25(OH)D are associated with elevated risks of overall and cancer mortality.
Dr. Frank C. Garland, 1950-2010
“Tuesday, August 17 at UCSD Thornton Hospital after contending with a nearly year-long illness.“

“African Americans … are more likely to be vitamin D deficient due to their darker skin pigmentation’s ability to block the sun’s rays”
It is not true that melanin blocks the wavelengths which synthesize vitamin D . The value of melanin as a sunscreen (2010).
“epidermal melanin is not a neutral density filter providing no or minimal protection for the induction of erythema at 295 and 315 nm and some protection at 305 and 365 nm”
It does block 305nm but around that wavelength is the most damaging A UVB Wavelength Dependency for Local Suppression of Recall Immunity in Humans Demonstrates a Peak at 300 nm. also see Erythema curve. Note the relative danger curve ( yellow) peaks at around 305nm
T the blocking of a limited spectra of vitamin D synthesizing UVB doesn’t matter the other wavelengths get through. Blood vitamin D levels in relation to genetic estimation of African ancestry “found novel evidence that the level of African ancestry [rather than skin pigmentation] may play a role in clinical vitamin D status”.
There is a negative feedback system; evolution has has got vitamin D levels just right
Klotho protein deficiency and aging.
“α-Klotho protein is shown to function in the negative feedback regulation of vitamin D3 synthesis These observations indicated that abnormal vitamin D3 metabolism is the main cause of aging phenotypes.″
Klotho was named after one of the Moirae or fates, supplementing vitamin D is indeed a fateful step.

Many people of tropical ancestry have a optimum homeostasis of vitamin D which is below the new IoM levels, but if they're wise they'll not take supplements