Abstracts: ISEE 20th Annual Conference, Pasadena, California, October 12–16, 2008: Contributed Abstracts
Selenium is an essential element that acts in antioxidant reactions, thyroid metabolism, and immune function. To promote health, selenium levels need to be maintained within a narrow range; either deficiency or excess can result in adverse health effects. The US population is generally selenium-replete. Among US adults higher selenium levels have been associated with higher lipid levels. No information is available on the relationship of selenium levels with lipid levels in the fetus and child.
Our objective was to examine the relationship of umbilical cord serum selenium and lipid levels.
The Baltimore THREE Study is a cross-sectional study which collected umbilical cord blood, maternal and infant medical record data, and census tract data for births occurring within a 6-month period in 2004–5 at the Johns Hopkins Hospital in Baltimore, Maryland. We used multivariable regression analyses to evaluate the association of quartiles of umbilical cord serum selenium levels with umbilical cord serum triglyceride, total cholesterol, and total lipid levels among 285 births. Multivariable models were adjusted for maternal age, maternal race, infant gestational age, maternal smoking, maternal prepregnancy body mass index, maternal parity, chronic or pregnancy-related maternal hypertension, maternal chronic or pregnancy-related diabetes, and median household income at the neighborhood-level. For sensitivity analysis and to assess potential confounding by gestational age, we also conducted our analyses excluding preterm births.
Mean umbilical cord selenium levels were 70.1 μg/L (95% confidence interval: 68.6, 71.5). The mean umbilical cord levels of total cholesterol and total lipids were 67.3 mg/dL (64.9, 69.7) and 253.5 mg/dL (247.0, 260.1), respectively. Triglyceride levels were right-skewed and log-transformed for analyses. The geometric mean of triglyceride levels were 34.9 mg/dL (33.2, 36.7). Participants with the highest quartile of selenium exposure had elevated triglyceride, cholesterol and total lipid levels compared to participants in the lowest quartile. There was a 33% increase (95% confidence interval: 17%, 52%) in triglyceride levels among those in the fourth quartile of selenium compared to those in the first quartile. Comparing those in the fourth to the first quartile of serum selenium levels, total cholesterol and total lipid levels were increased 5.48 (−1.34, 12.30) mg/dL and 25.2 mg/dL (6.5, 43.9), respectively. Results were similar when limited to full-term infants.
Our cord serum selenium levels are consistent with prior reports: they are higher than cord selenium values reported outside the US. Our cholesterol values are also similar to prior reports among newborns; for triglycerides, our levels are within the lower end of a wide range of reported averages. We found a positive relationship of umbilical cord serum selenium levels with umbilical cord serum triglycerides, total cholesterol, and total lipid levels. The health implications of this variation in newborn lipid levels are unclear. To better understand the long-term consequences of this relationship, prospective studies evaluating the temporality of the association and the impact on maternal and infant health are needed.