Vitamin D news update

photo by DBduo Photography via Flickr

Vitamin D is in the news.  Not new research, but rather issues concerning doses, supplements and blood test accuracy.  According to a report from ConsumerLab, as the demand for vitamin D testing took off around 2007, the test in use at the time sometimes gave results that were too high.  Meaning people may have thought their levels were OK when they actually weren’t.  In recent years, faster and less expensive tests were developed, but the new study suggests these may give results that are too low.  Meaning: people think they’re deficient when they aren’t.  The new tests were compared to the gold standard, known as “liquid chromatography/tandem mass spectrometry” or LCMS.  One of the newer tests found deficiency most than twice as often as LCMS, and the discrepancies were more common when samples contained vitamin D2, vs. vitamin D3.  What to do?  If you’re taking D2 (ergocalciferol), and your tests come out low, ConsumerLab suggests retesting using the LCMS method.  Switching to a D3 supplement may also be advisable, as that is generally thought to be better absorbed.  Certainly this is a concern for studies of vitamin D status, since inaccurate testing could skew results.

Another study examined vitamin D absorption, depending on when the supplements were taken.  Results: taking vitamin D on an empty stomach, as some people do when rushing out the door in the morning while swallowing a handful of pills, is a waste.  Even adding a small amount of food wasn’t that helpful.  What really boosted absorption was taking vitamin D with a large meal, such as dinner in the evening.  Absorption went up almost 60%.  So if you were found to have low blood levels (by a reliable test), and you’ve been taking D, and your blood levels aren’t improving, maybe you need to change your timing and take vitamin D with dinner.

Finally, obesity makes vitamin D deficiency more likely, and makes it harder to get blood levels to normal.  As ConsumerLabs points out, the rule of thumb for supplementation for normal weight people is every 100 IU of D will raised blood levels by about 1 ng/ml.  But for obese people, that figure is 200 IU to raise levels 1 ng/ml.  Twice as much.  Why?  Vitamin D is fat soluble, and so it will tend to sequester with fat molecules, in fat tissue, effectively removing it from circulation.  One solution: lose weight.

The Office of Dietary Supplements has more information about vitamin D here.

While we’re on the topic of supplements, an inspection report of supplement manufacturers done by the FDA shows that half of inspected companieshave serious lapses in manufacturing standards.   Some companies don’t even have standard formulations.  One firm was packaging protein powders in a rodent infested building.  Yuck!  Another company sold liquid supplements with toxic levels of selenium, which poisoned 200 people.  According to Daniel Fabricant, head of head of the FDA’s Division of Dietary Supplement Programs:

 “It’s downright scary…. At least half of industry is failing on its face.”

Where do vitamin D supplements fit in this scenario?  ConsumerLabs recently tested vitamin D supplements for purity and label accuracy.  While most supplements passed, some were found to contain lead, and others did not contain the stated amount of vitamin D.  In one case, a children’s formulation contained 2-1/2 times the stated dose, which could certainly be a problem.

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