Gene Expression

Association Between Serum 25-Hydroxyvitamin D Level and Upper Respiratory Tract Infection in the Third National Health and Nutrition Examination Survey:

The median serum 25(OH)D level was 29 ng/mL…and 19%…of participants reported a recent URTI [recent respiratory tract infections]. Recent URTI was reported by 24% of participants with 25(OH)D levels less than 10 ng/mL, by 20% with levels of 10 to less than 30 ng/mL, and by 17% with levels of 30 ng/mL or more…Even after adjusting for demographic and clinical characteristics, lower 25(OH)D levels were independently associated with recent URTI (compared with 25[OH]D levels of 30 ng/mL: odds ratio [OR], 1.36; 95% CI, 1.01-1.84 for <10 ng/mL and 1.24; 1.07-1.43 for 10 to <30 ng/mL). The association between 25(OH)D level and URTI seemed to be stronger in individuals with asthma and chronic obstructive pulmonary disease (OR, 5.67 and 2.26, respectively).

Some caution from ScienceDaily:

The authors stress that the study’s results need to be confirmed in clinical trials before vitamin D can be recommended to prevent colds and flu. “We are planning clinical trials to test the effectiveness of vitamin D to boost immunity and fight respiratory infection, with a focus on individuals with asthma and COPD, as well as children and older adults – groups that are at higher risk for more severe illness,” Ginde says. “While it’s too early to make any definitive recommendations, many Americans also need more vitamin D for its bone and general health benefits. Clinicians and laypeople should stay tuned as this exciting area of research continues to expand.”

The overused chestnut that correlation imply causation is important to keep in mind here. But, causation does entail correlation, so this is a place to start. A few years ago I was diagnosed with Vitamin D deficiency (serum levels below 10 ng/mL). This is not surprising as I have dark skin and live in a region with low levels of radiation. Since that point I’ve been taking supplements and my blood serum is now within the normal range (Carlson has 360 2000 IU tablet packages, so this isn’t even a major expense). I also have had a history of nearly ubiquitous minor respiratory problems. Since I started taking the supplements I can report that these are not nearly as much of an issue, though I have had bronchitis a few times (bacterial infections). It seems likely that most dark-skinned people in northern climes have Vitamin D deficiency, so if the correlation does pan out to be a causation then micronutrient supplementation would be a quick way to increase median levels of public health.


  1. #1 jay
    February 24, 2009

    My wife has had breathing difficulties for a couple of years (including a couple of hospital stays), with prescripion inhaler use a couple of times a day.

    Recently she went to a different doctor who notices that her D levels were low and prescirbed enhanced dosages. Her use or the rescue inhaler has decreased substantially.

  2. #2 razib
    February 24, 2009

    Her use or the rescue inhaler has decreased substantially.

    same experience for me. though to be fair, i’ve also taken other steps such has habitually washing my hands for at least a minute when i come home from being out, etc. but i used to regularly use my inhaler overnight, so it wasn’t just recurrent infections but the basal state of the bronchi.

  3. #3 Sandgroper
    February 25, 2009

    Razza – Somewhat off topic, but I meant to report back on it – I know two people who have been suffering long term chronic depression, including my sister who also suffers from asthma and other recurrent respiratory problems.

    In both cases, some months ago their doctors had them tested and found they were Vitamin D deficient and prescribed supplements, and in both cases they have reported that they are no longer suffering from depression. No indication yet whether my sister will notice any improvement in her respiratory condition.

    Sample of two.

  4. #4 Pete
    February 25, 2009

    Beware, the ‘normal range’ is 16.0 to 74.0 ng/ml so if you are at the low end of normal you can still have a shortage. The parathyroid normally starts behaving correctly at about 40 to 50ng/ml so above this is where you want to be.

  5. #5 Sandgoper
    February 25, 2009

    Thanks Pete, I have passed that on.

  6. #6 Kajducker
    March 3, 2009
  7. #7 Mills
    November 6, 2009


    That piece of research (a pre-conference review to be precise) stands alone and both it and the ‘Marshall Protocol’ that it promotes have been discredited (see

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