Vitamin D: doctors getting it wrong

OLYMPUS DIGITAL CAMERAGround Hog Day has come and gone, and it’s clear that winter isn’t going anywhere soon.  Days are a bit longer, and sun is a bit higher in the sky.  But even if you did expose some skin to the sun, it’s still not high enough to make any difference in your vitamin D production.  That process requires UVB light in the wavelength range of 270 to 300.  The most effective rays are in a very narrow range: 295-297 nm.  In the Northern Hemisphere, those intensities are only available in summer.  And only if you’re outside.  The rays can’t penetrate windows, or car windows.  And they’re blocked by sunscreen.

If you’re curious about sunlight intensity in your area, check out the United States EPA’s handy UV ray mapping tool.

Recently the physician-oriented online publication MedPageToday initiated a special blog dedicated to vitamin D.  It’s nice that these doctors have recognized the importance of a nutrient.  Unfortunately, they’re treating it like some novel new drug.  Does it prevent this?  Cure that?  No Big Picture understanding that vitamin D is a nutrient, and as such plays a role in numerous metabolic systems, interacting with numerous other nutrients.  All nutrients work together to keep us healthy.  When you build a house, all the pieces have to work together to make the house come out right.  The nails aren’t more important than the 2 X 4’s or the sheet rock or the shingles.

But doctors are trained to work with drugs, so they tend to see nutrients as drugs-lite.  The MedPageToday vitamin D blog reflects that prejudice.  Case in point: an ongoing study of omega-3 and vitamin D supplements is designed to see whether either or both of these supplements can prevent cancer or cardiovascular disease in women over 55 years old.  I’ve got the answer: neither.  Both cancer and cardiovascular disease are linked to a complex list of risk factors, including general diet, environmental exposures, lifestyle choices (exercise is a big one), genetics, type of fat, weight status, and on and on.

Another massive problem with this study: women older than 55 years already have decades of exposure to all those other risk factors.  They may still have those exposures.  Giving them a supplement isn’t going to reverse years of risks.  Unfortunately, when the data is published, the headlines will scream “Vitamin D ineffective against cancer.  Supplements are of no use.”  That’s the kind of junk conclusions you get when nutrition is medicalized.

Another post on the blog claims that vitamin D studies are futile because other studies have already “proved” it doesn’t prevent any of a laundry list of diseases.  Well technically I have to agree.  It’s a nutrient.  It isn’t likely to single-handedly prevent diseases.

But there is one very interesting post on pre-eclampsia.  In case you aren’t a Downton Abbey fan, eclampsia is the dreaded and unpredictable pregnancy complication that killed off Lady Sybil.  100 years later, we aren’t much closer to understanding why it happens, although proper monitoring during pregnancy means it can be diagnosed and treated more effectively.

This study examined blood samples taken from pregnant women in the mid-20th Century.  The samples had been preserved, and vitamin D assays were still considered accurate.  Results: women with sufficient vitamin D had a 40% lower risk for severe pre-eclampsia.  There was no difference for mild pre-eclampsia.

What might this mean?  That vitamin D cures or prevents eclampsia?  Not so fast.  While vitamin D could have a role to play, the study just found a link between status and risk for eclampsia.  Certainly, for plenty of other reasons, such as healthy fetal development, pregnant women should maintain a healthy vitamin D level, boosting intake appropriately if a blood test shows that they are deficient.

Vitamin D is one of many nutrients essential for human health.  If vitamin D levels are low, hundreds of metabolic systems will be adversely affected.  Other nutrients won’t work right.  And if other nutrients are out of whack, vitamin D may not work right, even if levels are sufficient.  The human body is extremely complex.  Thinking of any nutrient as a magic bullet drug for some disease will never ever work.

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