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Study calls for change in guidance about eating fish during pregnancy

by University of Bristol

salmon

The guidance for pregnancy should highlight 'Eat at least two portions of fish a week, one of which should be oily'—and omit all warnings that certain fish should not be eaten.

FAB RESEARCH COMMENT:

Once again, researchers are calling for public health authorities to do more to encourage women to eat more fish and seafood during pregnancy, as all the evidence shows the benefits of this far outweigh any possible risks.

They also provide evidence that these benefits apply to all type of fish and seafood - and that health suthorities and professionals should stop telling women to avoid fish that may contain higher mercury levels.

This new review shows - yet again - that there really is no evidence to support fears that fish consumption might cause harm to their unborn children, irrespective of possible mercury contamination - quite the opposite. 

Instead, detailed analyses have repeatedly shown no adverse effects on child development from maternal levels of methyl mercury (of which fish accounts for less than 10% in any case, as most exposure comes from industrial pollution and/or dental amalgam fillings) - provided that mothers eat fish and seafood. 

Both in the UK, and the Seychelles (where both fish consumption and mercury levels in pregnancy are many times higher), the data clearly show that the more fish and seafood pregnant women eat, the better are the outcomes for their children's brain development

Both European and US guidelines recommend that mothers-to-be consume at least 2 portions a week of fish and seafood during their pregnancy (and that up to 4 portions leads to significantly better outcomes for their children's cognition, behaviour outcomes than none.

But average intakes for most women remain seriously sub-optimal - and as the researchers highlight, continued mention of (unwarranted) fears about mercury only contribute to this shortfall.

For details of this new study, see:


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06/09/2022 - Medical Xpress

A woman's mercury level during pregnancy is unlikely to have an adverse effect on the development of the child provided that the mother eats fish, according to a new University of Bristol-led study.

The findings, which drew together analyses on more than 4,131 pregnant mothers from the Children of the 90s study in the U.K., with similar detailed studies in the Seychelles, are published in 
NeuroToxicology.

Importantly, the researchers also found that it does not appear to matter which types of fish are eaten because the essential nutrients in the fish could be protective against the mercury content of the fish. The more important factor was whether the woman ate fish or not. This contrasts with current advice warning pregnant women not to eat certain types of fish that have relatively high levels of mercury.

Although there are several studies that have considered this question, this research has looked at two contrasting studies of populations with mercury levels measured during pregnancy where the children were followed up at frequent intervals during their childhood.

The first is a study focused on a population in the Seychelles, where almost all pregnant women are fish eaters. The second study considered analyses of data from the University of Bristol's Children of the 90s study (also known as the Avon Longitudinal Study of Parents and Children (ALSPAC)), based in a relatively industrialized area in south-west England where fish are consumed far less frequently. No summary of the findings from this study has been published before.

Although it has been known for some time that the children of women who eat fish in pregnancy are likely to benefit in various ways in regard to their eyesight and intellectual abilities, official advice has included the warning not to eat certain types of fish that have relatively high levels of mercury. As a result, there is the possibility that some women will stop eating any fish "to be on the safe side."

Dr. Caroline Taylor, Senior Research Fellow and co-author of the study, said, "We found that the mother's mercury level during pregnancy is likely to have no adverse effect on the development of the child provided that the mother eats fish.

"If she did not eat fish, then there was some evidence that her mercury level could have a harmful effect on the child. This could be because of the benefits from the mix of essential nutrients that fish provides, including long-chain fatty acids, iodine, vitamin D and selenium."

Professor Jean Golding, co-author and Emeritus Professor of Pediatric and Perinatal Epidemiology at the University of Bristol, said,

"It is important that advisories from health professionals revise their advice warning against eating certain species of fish. There is no evidence of harm from these fish, but there is evidence from different countries that such advice can cause confusion in pregnant women.

"The guidance for pregnancy should highlight 'Eat at least two portions of fish a week, one of which should be oily'—and omit all warnings that certain fish should not be eaten."