Fish is good source of omega-3 fatty acids and other nutrients that are important for normal development of the fetus. Still, there has been a lot of discussion about whether or not pregnant women should eat fish, as this is also a source of mercury and other environmental toxins. A whole new study shows that pregnant women who eat moderate amounts of fish tend to give birth to children with a lower risk of diabetes and overweight later in life compared with women that eat very little fish or none at all. Beware that fish often contains mercury but it also contains selenium, which has a protective effect.
Fish contains a number of essential nutrients that are of vital importance to fertility, fetal development, and the development of the child later in life. Some of the really important nutrients are the omega-3 fatty acids EPA and DHA, selenium, and zinc.
According to the leader of the new study, Associate Professor Leda Chatzi, Keck School of Medicine at the University of Southern California, fish is a source of many nutrients, but she says that pregnant women should stick with the official guidelines and limit their intake to 1-3 servings of fish per week because fish contains mercury and other environmental toxins. It is also important to focus on tuna, mackerel, and other predatory fish in the upper part of the food chain because they contain higher levels of mercury that may cause permanent neurological damage to the fetus. Amalgam fillings are also a source of mercury, just like we are exposed to mercury from incineration plants, crematoriums, and other sources that pollute the soil, the air, the water, and plants.
Moderate fish intake is best for the pregnant woman
In the new study, Dr. Leda Chatzi and her team of scientists studied 805 mother-and-child couples from five European countries. The mothers and their children were already part of a larger study (HELIX) that followed them from pregnancy and onward. During pregnancy, all women were asked about their fish consumption and they were tested for mercury poisoning. When their children had reached an age of 6-12 years, various clinical assessments were made and blood samples were taken to get information about such things as waist circumference, blood pressure, LDL cholesterol, triglycerides, and insulin levels. Various tests were combined to help the researchers calculate if the children had metabolic syndrome, which is a widespread forerunner of type 2 diabetes.
It turned out that those children whose mothers had eaten fish 1-3 times per week had a lower score with regard to metabolic syndrome, compared with children whose mothers never ate fish or ate less than one serving of fish per week. However, no additional health benefits were observed among those children whose mothers consumed fish more than three times per week.
According to another scientist involved in the study, Dr. Nikos Stratakis, PhD, it is plausible that pregnant women that eat fish more than three times per week get too many environmental toxins, which outweighs the health benefits of the nutrients in the fish. The study therefore showed that higher levels of mercury in the expecting mother’s blood are linked to an increased risk of metabolic syndrome in the child.
Fish, inflammation, metabolic syndrome, and type 2 diabetes
The scientists also looked at how maternal fish intake affected the child’s levels of cytokines and adipokines. These two biomarkers are related to inflammation, which is a common thread in metabolic syndrome, type 2 diabetes, and many other chronic diseases. It turned out that children of the mothers with moderate fish intake during their pregnancy had fewer pro-inflammatory cytokines and adipokines later in life.
According to the researchers, this is the first human study to show how a reduction of these pro-inflammatory biomarkers may be an underlying mechanism that can help explain why a mother’s intake of fish intake during pregnancy can affect the health of her offspring later in life – including such things as sugar metabolism and other metabolic processes.
The new study is published in JAMA Network Open.
The next step for the scientists is to investigate how consumption of different types of fish during pregnancy – with different nutrient content and mercury concentrations – can affect the children until the age of 14-15 years.
Eat fish from the lower part of the food chain
According to the Danish Health Authority, pregnant women should follow the official dietary guidelines and eat at least 350 grams of fish every week with 200 grams coming from oily fish. Pregnant women, however, should avoid predatory fish like tuna, pike, perch, swordfish, shark, halibut, and mackerel, all of which contain more mercury. It is safe to get your essential omega-3 fatty acids from other types of fish like herring, anchovies, and salmon that are from the lower part of the food chain. Salmon from the Baltic Sea may contain too many heavy metals and other sources of pollution, so it is safer to opt for salmon from purer waters or even organic salmon.
Omega-3 fatty acids, selenium, zinc, and supplements
If you dislike the taste of fish or simply don’t eat enough, a fish oil supplement is a useful solution. Fish oil in the form of free fatty acids have the best bioavailability. It is also important to choose a fish oil preparation that complies with the official threshold values regarding peroxide count and environmental toxins. It is also important to get extra selenium and zinc, as these two nutrients are important for ensuring a normal pregnancy.
Nikos Stratakis et al. Association of Fish Consumption and Mercury Exposure During Pregnancy With Metabolic health and Inflammatory Biomarkers in Children. JAMA Network Open, 2020
Keck School of Medicine USC. Benefits of fish in moderation while pregnant outweigh risk for child. ScienceDaily. 2020
Nicholas V.C. Ralston, Laura J. Raymond. Mercury´s neurotoxicity is characterized by its disruption of selenium biochemistry. 2018
Ralston,N., BBA- Gewneral Subjects (2018), https://doi.org/10.1016/j.bbagen.2018.05.009
DR-dokumentar: De ufødte børn 03-11-2014
Njord, V Svendsen: Næringsstoffer i fisk neutraliserer miljøgifte. Videnskab.dk 2012
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