We know that air pollution decreases vitamin D levels in adults, adolescents and children, but we know nothing of its effects on newborn infants. It is generally assumed that the fickle UVB photon, which can be thought of as a ping pong ball, bouncing off clouds, buildings, sand, water, and snow, also bounces off air pollution. In fact, UVB monitoring stations consistently show air pollution cuts down on UVB penetration to the ground.
A collaborative French study led by Dr. Nour Baiz recently looked at infant (cord blood) vitamin D levels and wanted to see if there was an association with the air pollution indices of where the women lived during their pregnancy.
Baïz N, Dargent-Molina P, Wark JD, Souberbielle JC, Slama R, Annesi-Maesano I; the EDEN Mother-Child Cohort Study Group. Gestational Exposure to Urban Air Pollution Related to a Decrease in Cord Blood Vitamin D Levels. J Clin Endocrinol Metab. 2012 Aug 17. [Epub ahead of print]
The first striking finding was the extremely low vitamin D levels in French infants despite the fact all the mothers received a 100,000 IU dose of vitamin D to begin their last trimester. Twenty-eight percent of the infants had levels less than 10 ng/ml, 47% had levels lower than 15 ng/ml and 85% had levels lower than 30 ng/ml. One infant of a brave mother who must have sunbathed or supplemented had a level of 60 ng/ml.
The second finding was the same as for adults and children: the more the air pollution, the lower the vitamin D levels in infants. The association was the strongest in women in their last trimester. The authors state, “The impact of air pollution exposure during the last trimester of gestation is all the more important because maternal supply of vitamin D decline gradually in pregnancy and reaches its lowest level in the third trimester.”
Is that true in the natural state? The recent Luxwolda paper found just the opposite in equatorial populations, where vitamin D levels spiked during pregnancy, especially during the last trimester, reaching about 60 ng/ml, probably by recruiting stores in muscle and fat for the pregnancy. This study shows how vitamin D depleted pregnant women in Europe and the USA really are.
One hundred thousand IUs in late pregnancy failed to keep vitamin D levels sufficient because 100,000 IU is enough for only a couple of weeks of pregnancy.
Again, if you are thinking of getting pregnant, you and your partner should first take 5,000 IU/day for a year. Then take 5,000 IU the first two trimesters and 6,000 IU/day the final trimester. Continue to take 6,000 IU/day when you breast feed, because any less and your infant needs to supplement. I also think sunbathing when pregnant is a good idea. Soon enough you should have some more sunshine in your life, a happy healthy baby.