Tuberculosis (TB) is the second most common cause of death from infectious disease in the world, after deaths due to HIV. About a third of the world is infected by tuberculosis as detected by a TB skin test. Globally, new infections occur at a rate of one per second. In the past, cod liver oil and sunshine were mainstays of treatment.
However, most TB infections do not cause disease, as the body fights off the infection, and the infection is present but remains latent or asymptomatic. In 2007, there were an estimated 14 million chronic active, not latent, cases. In 2010, there were 8.8 million new cases of TB diagnosed, and 1.5 million deaths from TB, most of these occurring in developing countries.
Anything that would prevent TB skin tests from turning positive in a population at high risk is good evidence that substance is fighting the infection. Tuberculin conversion occurs if a patient who has previously had a negative tuberculin skin test develops a positive tuberculin skin test at a later date; it is evidence of an infection that may or may not be symptomatic.
In a double blind randomized controlled trial, researchers at Harvard, led by Dr Davaasambuu Ganmaa and supervised by senior author Professor Walter Willett, gave 61 Mongolian schoolchildren 800 IU of vitamin D/day for six months, and compared them to 58 children given placebo.
Ganmaa D, Giovannucci E, Bloom BR, Fawzi W, Burr W, Batbaatar D, Sumberzul N, Holick MF, Willett WC. Vitamin D, tuberculin skin test conversion, and latent tuberculosis in Mongolian school-age children: a randomized, double-blind, placebo-controlled feasibility trial. Am J Clin Nutr. 2012 Aug;96(2):391-6.
The treated children had a trend toward fewer conversions (P=.06) compared to placebo. Only one newly positive TB test occurred in those children who achieved a 25(OH)D of >20 ng/ml. Baseline 25(OH)D in these 12-15 year-old children averaged 7 ng/ml, with 82% of all children having levels below 10 ng/ml before the trial and mean levels falling to 4 ng/ml during January in the placebo group.
In a surprise finding, the treated children grew faster than the placebo children did (P=.0025). As the authors point out, this may explain the fact that children grow faster in the spring and summer.
Eight hundred IU per day only raised 25(OH)D levels by 13 ng/ml, so all children remained below 30 ng/ml after the study, and 60% of the treated children still had levels below 20 ng/ml after 6 months of 800 IU/day, a dose higher than that recently recommended by the U.S. Food and Nutrition Board.
Professor Willett (and a bunch of other experts) has previously recommended that you give your child enough vitamin D to obtain mid normal levels (50 ng/ml) and recommended 1,000 IU/day for every 25 pounds of body weight.
Cannell JJ, Vieth R, Willett W, Zasloff M, Hathcock JN, White JH, Tanumihardjo SA, Larson-Meyer DE, Bischoff-Ferrari HA, Lamberg-Allardt CJ, Lappe JM, Norman AW, Zittermann A, Whiting SJ, Grant WB, Hollis BW, Giovannucci E. Cod liver oil, vitamin A toxicity, frequent respiratory infections, and the vitamin D deficiency epidemic. Ann Otol Rhinol Laryngol. 2008 Nov;117(11):864-70. Review.