Recently, a new study was published by the JAMA Pediatrics, in February 2016, which claims childhood obesity is a result of pregnant mothers eating more fish than recommended. The cohort study found that pregnant mothers eating more than three servings of fish per week increases the likelihood of their child developing obesity. The baby is more prone to becoming obese in the first two years of life, since maternal fish consumption leads to increased risk of rapid growth. The research concluded by advising mothers to take it easy when consuming seafood.

Fish Causes Obesity In Newborn

In America childhood obesity has turned into a critical health problem with the rate doubling in children in the past 30 years, with 1 in 3 American children currently obese. The cohort study was a multi-centered population based study i.e., it used data from different medical institutions and populations. The investigation analysed data from 10 different European countries and one American state i.e., Belgium, France, Greece, Ireland, Italy, Netherlands, Norway, Poland, Portugal, Spain, and Massachusetts (U.S.).

Leda Chatzi, M.D., Ph.D., from the University of Crete in Greece, was the lead author of the study. Chatzi and co-authors analysed long-term data on 26,184 pregnant women and their children, from 1996 till 2011. The objective of the study was to determine if there is a relationship between fish intake and obesity in children. “Fish is generally considered an integral component of a healthy diet. However, it is a complex exposure,” said Leda Chatzi.

Eating More Fish Linked To Obesity in Babies

The analysis showed that pregnant women consuming more fish than recommended tended to give birth to infants with higher BMI rates, compared to women who ate less fish. The BMI percentile curves of the babies were recorded from three  months after birth up until they were six years old. The study used random-effects meta-analysis technique to calculate the cohort estimates on maternal fish intake and childhood obesity.

The research also included a long-term follow up with two-year intervals, with the children being examined at ages of two, four and six years old from their birth. According to the study, higher maternal fish consumption is connected with increasingly rapid growth, especially from birth till the age of two years. Surprisingly, the study also found that the adverse effects of fish intake are magnified in little girls than boys.

The researchers agreed their findings are not different from the fish consumption limits set by the U.S. Food and Drug Administration (FDA) and Environmental Protection Agency (EPA). Since there is not enough data on the extent of how fish consumption affects fetal growth and childhood obesity, the best solution is to limit the fish intake because fish intake in limited amounts has also shown positive effects during pregnancy. The FDA and the EPA recommend not eating more than 2 to 3 servings i.e., 8-12 ounces of fish per week, especially species with lower levels of mercury during pregnancy.

Another unexpected finding of the study was seen in comparing the difference in maternal fish intake from different European countries. Women in Spain were found to eat three times more fish than in Belgium, with mean maternal fish intake in Belgium being 0.5 times per week, while in Spain it was 4.45 times per week.

Fish in diet are credited as being a nourishing source of omega-3 fatty acids i.e., EPA (Eicosapentaenoic acid) and DHA (Docosahexaenoic acid). DHA has been specifically connected with better growth and functional development of neurons of the fetus when consumed during pregnancy. Infants formula-fed with DHA enriched formulas have shown increased visual reflexes. Likewise, DHA deficiencies are also tied with attention deficit hyperactivity disorder, cystic fibrosis, phenylketonuria, unipolar depression and aggressive/ hostile behavior. However, at the same time if the levels of the omega-3 fatty acids are not controlled, excess can lead to adverse effects during pregnancy.

Chatzi also said, “Prior studies and advisories focus on potential neurocognitive harm from exposure to methyl-mercury but not impact on growth. On one hand, fish is a major dietary source of omega-3 fatty acids, which are transferred across the placenta and have been found to reduce fat deposits by reducing production of fat cells. On the other hand, fish is a common source of human exposure to persistent organic pollutants, which may exert endocrine-disrupting properties and contribute to the development of obesity. It is possible that at higher levels of fish consumption, the potential adverse effects of contaminants mask or outweigh the benefits of omega-3 fatty acids.”

The researchers did note that their study lacked enough data to properly distinguish between consumption of different fish types and species. In the same way, the cooking procedures or water source of the fish consumed were unknown so there is always the possibility the fish leading to increase in obesity may be contaminated with heavy metals. The lack of such crucial information begs the need to further analyse the interactions between pollutants or contaminants and valuable nutrients in relation to their effect on growth in infants.  Chatzi said, “Our hypothesis that fish-associated contaminant exposure may play a role in the observed associations remains speculative.”

Obese children tend to have higher cholesterol, glucose or blood pressure levels, along with bone and joint problems and sleep apnea. Such children are also at more risk of having cardiovascular diseases, diabetes, stroke, cancer and osteoarthritis in later life. In children obesity is also related with social and psychological difficulties e.g., poor self-esteem.