INMA: “Association between Mediterranean diet and metal(loid) exposure in 4-5-year-old children living in Spain”

30/07/2024

A recent study using data from the INMA cohort has revealed that differences in adherence to a typical Mediterranean diet can affect children’s exposure to metals found in food. While some metals, such as calcium, copper and zinc, are essential elements of human physiology, others, such as arsenic, cadmium and lead, can be harmful. Interestingly, ingesting too much of even the essential metals can lead to harm. This is especially important in children, who have a lower tolerance to over-exposure to harmful substances than adults do.

Diet is one of the two main sources of metals (the other being drinking water), and so it is important to understand how the type and composition of diet affects our exposure to them. The Mediterranean diet is one such dietary type that is commonly associated with being good for health, and it is composed of individual elements such as vegetables, pulses, seafood and meat. It is not clear though, how this dietary pattern might influence exposure to metals.

Thus, in this study the authors sought to investigate whether adherence to a Mediterranean diet affected children’s exposure to metals, and subsequently whether the individual components of this diet that may account for any observed differences.

This study included 2,139 children participating in the INfancia y Medio Ambiente (INMA) study. The INMA study recruited pregnant women from Asturias, Gipuzkoa, Sabadell and Valencia in Spain between 2003 and 2008, and their children were assessed at follow-up when they were between 4 and 5 years old. At this time, the children completed questionnaires about their dietary habits (the “food frequency questionnaire”) and provided urine samples, which were tested for the presence and quantity of metals. The authors also made sure to check for other potential influences on metal exposure, such as age, sex, body mass index, socio-economic status and total energy intake.

The study found that adherence to the Mediterranean diet was associated with higher levels of arsenobetaine, a non-toxic, organically occurring derivative of arsenic, but lower levels of copper, an essential mineral. Overall, the levels of metals reported in this study were lower than those from an Italian study of 5-11-year-old children, although the observed levels of cobalt, zinc and selenium were similar to those of a previous study of 8-14-year-old Mexican children.

Interestingly, further examination by individual components of the diet showed that fish and seafood consumption specifically was associated with higher levels of arsenobetaine, which is consistent with previous reports. On the other hand, there was no clear reason for reduced levels of copper, although consumption of meat in the study group was almost 30% less than that reported in similar aged children across the whole of Spain, which may have played a role. In addition, while urine samples are an acceptable measure of copper concentration, they may not be the most accurate means of assessment, so results must be interpreted with caution.

An additional consideration is that this study was cross-sectional in design, which means that dietary adherence and metals were measured at the same point in time. A stronger design is a longitudinal study, which means measuring diet and metals in the same people at several points in time. Such a design provides stronger evidence but takes more time and resources. The study reported here provides evidence to support the conduct of a longitudinal study in this field of research at future points in follow-up.

Ultimately, the authors concluded that this study shows that adherence to the Mediterranean diet increases exposure to some metals but reduces exposure to others, and that it highlights the importance of considering individual components of the diet when assessing its impact.

Reference: Notario-Barandiaran L, Irizar A, Begoña-Zubero M, Soler-Blasco R, Riutort-Mayol G, Fernández-Somoano A, Tardón A, Casas M, Vrijheid M, Meharg A, Carey M, Meharg C, Ralphs K, McCreanor C, Grimalt JO, Vioque J, Signes-Pastor AJ. Association between mediterranean diet and metal(loid) exposure in 4-5-year-old children living in Spain. Environ Res. 2023 Sep 15;233:116508.

Link to scientific article: https://pubmed.ncbi.nlm.nih.gov/37392824/