Researchers from Linköping University in Linköping found that exposure to heavy metals through fish consumption in utero or during the first year of life was associated with a five-fold increased risk of subsequent development of juvenile idiopathic arthritis (JIA).
According to the study, the odds ratio for JIA among children whose mothers ate fish more than once a week during pregnancy was 4.5. The children who themselves consumed fish more than once a week during the first year of life, reported odds ratio of 5.1.
The researchers highlight the importance of knowledge of the role of early nutrition and its association with autoimmunity, as dietary recommendations may help to prevent these chronic diseases.
The study analyzed data of children from the All Babies in Southeast Sweden project for the years 1997 to 1999 and the Swedish paediatric JIA registry. Biologic samples were obtained at birth and throughout childhood, and analysed for factors such as antinuclear antibody (ANA) positivity. Prenatal heavy metal exposure was assessed in cord blood samples.
Almost half of the cases had the oligoarticular subtype of JIA.A total of 87% of children with JIA had been exposed to fish through maternal consumption during pregnancy or during their first year of life. Early fish exposure also was associated with an increased risk of ANA positivity, and all children who were ANA positive had consumed fish more than once weekly during their first year.
Among children with JIA, mean cord blood concentrations of several heavy metals were significantly higher than among controls: aluminum: 11.2 vs 6.1 µg/L, cadmium: 0.19 vs 0.07 µg/L, mercury: 0.33 vs 0.24 µg/L, lithium: 2.79 vs 1.01 µg/L.
More than half of the JIA children had concentrations of these metals two standard deviations above the mean.
Concentrations of aluminum, cadmium, and lithium in cord blood also were significantly higher among patients who were ANA positive, and almost two-thirds had concentrations more than two standard deviations above the mean.
The frequency of maternal fish consumption during pregnancy correlated with concentrations of cadmium, lithium, and mercury.
Based on their findings the authors noted that fish consumption could help reduce the likelihood of inflammatory and autoimmune diseases because of the presence of long-chain polyunsaturated fatty acids and other micronutrients. However, contamination of fish with polychlorinated compounds, dioxin, and heavy metals could outweigh the benefits.
“Thus, it is reasonable to believe that the increased concentrations of cadmium, aluminum, mercury, and lithium may play a role in changes in the immune balance, which could contribute to the development of autoimmune rheumatic diseases,”stated the researchers in the study.
Consideration should be given to including cautions in future nutrition guidelines against heavy metal exposure during pregnancy and early life, they suggested.