Children whose mothers ate fish between one and three times a week during pregnancy are more likely to have a better metabolic profile — despite the risk of exposure to mercury — than those whose mothers rarely ate fish (less than once a week), according to a new study by the University of Southern California (USC).
Whether pregnant women should eat fish or not has been a long-debated topic. While fish is a major source of omega-3 long-chain polyunsaturated fatty acids (vital for fetal development), it is well-known that some types of fish, including swordfish, shark and mackerel, have high levels of mercury, a potent toxin that can cause permanent neurological damage.
The findings, published in JAMA Network Open, show that the children of women who ate fish from one to three times a week during pregnancy had lower metabolic syndrome scores than the children of women who ate fish less than once a week. But the benefit declined if women ate fish more than three times a week.
Metabolic syndrome is a cluster of conditions that increase the risk of heart disease, stroke, and diabetes.
“Fish is an important source of nutrients, and its consumption should not be avoided,” said Dr. Leda Chatzi, associate professor of preventive medicine at the Keck School of Medicine of USC and the senior investigator on the study.
“But pregnant women should stick to one to three servings of fish a week as recommended, and not eat more, because of the potential contamination of fish by mercury and other persistent organic pollutants.”
For the study, the researchers evaluated 805 mother-child pairs from five European countries participating in a collaborative research project known as the HELIX study, which follows women and their children from pregnancy onwards.
During their pregnancy, the women were asked about their weekly fish consumption and tested for mercury exposure. When the children were between 6 and 12 years old, they were given a clinical examination with various measurements including waist circumference, blood pressure, high-density lipoprotein cholesterol, triglyceride levels and insulin levels. These measures were combined to calculate a metabolic syndrome score.
Overall, children whose moms ate fish from one to three times a week during pregnancy had lower metabolic syndrome scores than children whose moms ate fish less than once a week. But if pregnant women ate fish more than three times a week, the benefit was reduced.
“Fish can be a common route of exposure to certain chemical pollutants which can exert adverse effects,” said Nikos Stratakis, Ph.D., a USC postdoctoral scholar who was one of the study authors.
“It is possible that when women eat fish more than three times a week, that pollutant exposure may counterbalance the beneficial effects of fish consumption seen at lower intake levels.”
The researchers found that higher mercury concentration in a woman’s blood was linked to a higher metabolic syndrome score in her child.
The team also looked at how fish consumption by the mother affected the levels of cytokines and adipokines in her child. These biomarkers are related to inflammation, a contributor to metabolic syndrome. Compared with low fish intake, moderate and high fish consumption during pregnancy were associated with reduced levels of proinflammatory cytokines and adipokines in the children.
This is the first human study to reveal that the reduction in these inflammation biomarkers could be the underlying mechanism explaining why maternal fish consumption is associated with improved child metabolic health.
Next, the team plans to examine the effects of consuming different types of fish with different nutrients and mercury levels and to follow up on these children until the age of 14-15 years.
Source: Keck School of Medicine of USC