Linking vitamin D levels in children to asthma severity
Low maternal vitamin D intake during pregnancy is associated with asthma symptoms in early childhood.
Now, here are the results from the first study of the relationship between vitamin D blood levels in childhood and asthma severity.
First, the details.
- 616 asthmatic Costa Rican children between the ages of 6 and 14 years were studied.
- The relation between 25-hydroxyvitamin D levels (the major circulating form of vitamin D) and markers of allergy were compared.
And, the results.
- 28% of the children had insufficient blood levels of vitamin D (less than 30 ng/mL).
- Low vitamin D levels were significantly associated with higher total IgE and eosinophil counts (markers of allergic responsiveness).
- Increased vitamin D levels were associated with reduced odds of hospitalization, use of anti-inflammatory drugs, and increased airway responsiveness during the previous year.
The bottom line?
The authors concluded, “Vitamin D insufficiency is relatively frequent in an equatorial population of children with asthma. In these children, lower vitamin D levels are associated with increased markers of allergy and asthma severity.”
Lower vitamin D levels could be due to a lower socioeconomic level of the parents. However, Costa Rica has socialized healthcare and high literacy, which should offset this potential confounding factor.
It’s also possible that these kids just suffer from poor overall nutrition, or that children with asthma are spending too little time indoors and out of the sunlight, according to the authors.
In an accompanying editorial, researchers from the UK point out that in the absence of dietary supplementation, humans obtain about 90% of their vitamin D from sunlight exposure vs. 10% from diet. The increasing tendency to stay indoors and the promotion of sunshine avoidance to prevent skin cancer by covering up and using sunblock are the most likely reasons for inadequate vitamin D status.
“It is difficult to compensate for declining sunlight-derived vitamin D by dietary means alone because vitamin D is naturally present in very few foods (oily ï¬sh, ï¬sh liver oil, egg yolk), although in some countries margarine and/or milk are fortiï¬ed.”
Is this a case of unintended consequences following widely promoted but inadequately researched public health policy pronouncements by groups such as the American Academy of Dermatology?
4/23/09 15:25 JR
Ted Hutchinson said:
on December 28, 2009 at 6:05 am
Part of the trouble is that health professionals have not been keeping up with the latest research.
If we look at this study
25-hydroxyvitamin D is an agonistic vitamin D receptor ligand. At levels at or below 40ng/ml to 100nmol/l there is no measurable antiproliverative action by calcidiol. But at higher levels such activity is measurable.
It depends on the quantity of 25(OH)D3 available. The more calcidiol the more likely the vitamin D receptors will be activated.
Calcidiol does not have to be further hyrdoxylated to calcitriol in order to operate as a hormone. If you have a natural 25(OH)D3 status that allows human breast milk to flow replete with D3, around 60ng/ml then you have a chance and even more so around 80ng/ml to 200nmol/l.
We know from Developmental vitamin D deï¬ciency causes abnormal brain development and from Vitamin D supplementation during lactation to support infant and mother; we know that 6400iu/daily vitamin D3 at latitude 32 allows babies to be born vitamin D3 replete and able to obtain optimum amounts of vitamin D from their mothers breast milk.
30ng/ml is NOT an indication of vitamin D sufficiency.
Only when levels are above 60ng/ml can we begin to appreciate the ability of calcidiol 25(OH)D3 to act as the hormone that it is.
JR said:
on January 6, 2010 at 10:47 pm
Interesting, but I’m not sure it applies directly to this study.
My take is that this is one more piece in a growing volume of information supporting the widespread prevalence of vitamin D deficiency (even on the equator) and the diverse complications associated with the presence of that deficiency.
JR