Low Zinc Levels in Hair Linked to Neural Tube Defects
Despite a recent article suggesting that hair analysis is not a valid diagnostic method, it appears that these authors found otherwise. As a society, we have become fixated on folic acid to prevent NTDs, at the expense of a well rounded program. I recently had a patient bring in a “prenatal” vitamin from her primary care physician. This was one of the more popular brands produced by one of the pharmaceuticals. To put it frankly, it was awful. Artificial food colorings (does anyone really care what color their multi is????), tableting agents. And, worst of all, it only contained a few nutrients (folic acid, B12 and B6). How can we sometimes wear such blinders when it comes to health?
Indian J Pediatr 2001;68:519-522 A study conducted in Delhi, India, has documented an association between neural tube defects and low zinc levels in mothers’ and neonates’ hair. Although folic acid supplements are given in pregnancy, trace element supplements are not recommended, Dr. M. Srinivas, of the All India Institute of Medical Sciences, and colleagues note in the June issue of the Indian Journal of Pediatrics. This and the fact that zinc deficiency has been known to produce congenital abnormalities in animal studies prompted them to study the link between zinc and neural tube defects. Using atomic absorption spectrophotometry, Dr. Srinivas and his team evaluated the serum and hair zinc levels in 80 neonates born with neural tube defects and their mothers. An equal number of normal mother-infant pairs served as controls. Assuming a hair growth of 0.4 mm per day, maternal hair samples were taken 10 cm from the scalp so as to estimate what the status was in the first trimester of pregnancy. The mean zinc level in serum and hair of the healthy neonates was 77.8 and 188.8 µg/L, respectively, and in their mothers it was 74.1 and 142.3 µg/L. In the neonates with neural tube defects, the corresponding figures were 80.1 and 174.2 µg/L, and in their mothers 75.7 and 129.9 µg/L. “The hair zinc levels of the affected babies and their mothers were significantly lower (P < 0.001) than the controls,” the researchers report. They postulate that the role of zinc as a co-factor of various enzymes involved in nucleic acid metabolism could possibly explain the link with birth defects. While recommending larger controlled studies, the researchers suggest a possible role for zinc supplementation in pregnancy to prevent neural tube defects.