Monday, January 18, 2016

Brain food

Jordi Julvez, Michelle Méndez, Silvia Fernandez-Barres, Dora Romaguera, Jesus Vioque, Sabrina Llop, Jesus Ibarluzea, Monica Guxens, Claudia Avella-Garcia, Adonina Tardón, Isolina Riaño, Ainara Andiarena, Oliver Robinson, Victoria Arija, Mikel Esnaola, Ferran Ballester, Jordi Sunyer.   Maternal Consumption of Seafood in Pregnancy and Child Neuropsychological Development: A Longitudinal Study Based on a Population With High Consumption Levels.  Am. J. Epidemiol. (2016) doi: 10.1093/aje/kwv195 First published online: January 5, 2016.

Seafood consumption during pregnancy is thought to be beneficial for child neuropsychological development, but to our knowledge no large cohort studies with high fatty fish consumption have analyzed the association by seafood subtype. We evaluated 1,892 and 1,589 mother-child pairs at the ages of 14 months and 5 years, respectively, in a population-based Spanish birth cohort established during 2004–2008. Bayley and McCarthy scales and the Childhood Asperger Syndrome Test were used to assess neuropsychological development. Results from multivariate linear regression models were adjusted for sociodemographic characteristics and further adjusted for umbilical cord blood mercury or long-chain polyunsaturated fatty acid concentrations. Overall, consumption of seafood above the recommended limit of 340 g/week was associated with 10-g/week increments in neuropsychological scores. By subtype, in addition to lean fish, consumption of large fatty fish showed a positive association; offspring of persons within the highest quantile (>238 g/week) had an adjusted increase of 2.29 points in McCarthy general cognitive score (95% confidence interval: 0.42, 4.16). Similar findings were observed for the Childhood Asperger Syndrome Test. Beta coefficients diminished 15%–30% after adjustment for mercury or long-chain polyunsaturated fatty acid concentrations. Consumption of large fatty fish during pregnancy presents moderate child neuropsychological benefits, including improvements in cognitive functioning and some protection from autism-spectrum traits.
When mothers eat three sizeable servings of fish each week during pregnancy it may benefit children’s brains for years to come, according to a large study in Spain.

Researchers followed nearly 2,000 mother-child pairs from the first trimester of pregnancy through the child’s fifth birthday and found improved brain function in the kids whose mothers ate the most fish while pregnant, compared to children of mothers who ate the least.

Even when women averaged 600 grams, or 21 ounces, of fish weekly during pregnancy, there was no sign that mercury or other pollutants associated with fish were having a negative effect that offset the apparent benefits.

“Seafood is known to be an important source of essential nutrients for brain development, but at the same time accumulates mercury from the environment, which is known to be neurotoxic,” lead author Jordi Julvez, of the Center for Research in Environmental Epidemiology in Barcelona, said in an email.

In an attempt to balance the potential harms of such pollutants with the general health benefits of fish, the U.S. Food and Drug Administration’s 2014 guidelines encourage pregnant women to eat fish, but no more than 12 ounces per week.

The European Food Safety Authority recently issued a scientific opinion endorsing 150 g to 600 g of fish weekly during pregnancy, Julvez and colleagues note in the American Journal of Epidemiology. But, the study team writes, the effects of maternal fish consumption during development are still not well understood and more research could help give pregnant women clearer guidance...

Women were tested for blood levels of vitamin D and iodine, and cord blood was tested after delivery to measure fetal exposure to mercury and PCB pollutants. At ages 14 months and five years, the children underwent tests of their cognitive abilities and Asperger Syndrome traits to assess their neuropsychological development.

On average, the women had consumed about 500 g, or three servings, of seafood per week while pregnant. But with every additional 10 g per week above that amount, children’s test scores improved, up to about 600 g. The link between higher maternal consumption and better brain development in children was especially apparent when kids were five.

The researchers also saw a consistent reduction in autism-spectrum traits with increased maternal fish consumption.

Mothers’ consumption of lean fish and large fatty fish appeared most strongly tied to children’s scores, and fish intake during the first trimester, compared to later in pregnancy, also had the strongest associations.

“I think that in general people should follow the current recommendations,” Julvez said.

“Nevertheless this study pointed out that maybe some of them, particularly the American ones, should be less stringent.”

Julvez noted that there didn’t appear to be any additional benefit when women ate more than 21 oz (about 595 g) of fish per week.

“I think it's really interesting, and it shed a lot more light on the benefits of eating fish during pregnancy,” said Dr. Ashley Roman, director of Maternal Fetal Medicine at NYU Langone Medical Center in New York.

“I think what's interesting about this study compared to some data previously is that they better quantify the relationship between how much fish is consumed in a diet and then the benefits for the fetus and ultimately the child,” said Roman, who was not involved in the study.

“They're able to correlate the fish consumption with protection from autism and I think that is potentially a very important finding,” she added.

Roman said that fish is really important for the fetus's brain development.

“We still recommend that women avoid the fish that are highest in mercury like catfish, shark, swordfish and giant mackerel, typically the larger fish that have longer lifespans and they tend to concentrate more mercury in their tissue,” she said.


  1. M. Gispert-Llaurado, Miguel Perez-Garcia, J. Escribano, R. Closa-Monasterolo, V. Luque, V. Grote, M. Weber, F.J. Torres-Espínola, J. Czech-Kowalska, E. Verduci, F. Martin, M.J. Piqueras, B. Koletzko, T. Decsi, Cristina Campoy, P.M., The EU Childhood Obesity Trial (CHOP) Study Group, NUHEAL Study Group. Fish consumption in mid-childhood and its relationship to neuropsychological outcomes measured in 7–9 year old children using a NUTRIMENTHE neuropsychological battery. Clinical Nutrition in press.


    Long-chain polyunsaturated fatty acids (LCPUFA), particularly n-3 LCPUFA, play a central role in neuronal growth and the development of the human brain. Fish is the main dietary source of n-3 LCPUFA. To assess the relation between fish consumption, estimated dietary n-3 LCPUFA intake and cognition and behaviour in childhood in a multi-centre European sample.

    Children from 2 European studies, CHOP and NUHEAL, were assessed at 8 and 7.5 years of age, respectively. Different outcomes of neuropsychological development (assessed with the standardized NUTRIMENTHE Neuropsychological Battery (NNB) consisting of 15 subtests) were related with outcomes from a food-frequency questionnaire (FFQ) focussing on the consumption of fish.

    A total of 584 children completed the FFQ and the neuropsychological tests. We found no associations with calculated DHA or EPA intakes for any of the neuropsychological domains. Children who consumed 2 fish meals per week including one of fatty fish, showed no substantive differences in the cognitive domains from the children who did not. However negative associations with fatty fish consumption were found for social problems (p = 0.019), attention problems (p = 0.012), rule-breaking problems (p = 0.019) and aggressive behaviour problems (p = 0.032). No association was observed with internalizing problems. Higher levels of externalizing problems (p = 0.018) and total problems (p = 0.018) were associated with eating less fatty fish.

    Children who consumed 2 fish meals per week including one of fatty fish were less likely to show emotional and behavioural problems than those who did not.

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  2. Eating at least one seafood meal a week can help protect the brains of persons at heightened risk for Alzheimer's disease, and there seems to be no downside from the levels of mercury found in fish, according to an analysis of autopsied brain tissue from 286 elderly persons who had filled out food diaries as part of a longitudinal study on aging and memory.The Rush University study found that the benefits of eating seafood applied only to people who carried the apolipoprotein E4 (APOE e4) gene, which is linked to an elevated risk of Alzheimer's disease. For persons who did not have the genetic variant, seafood consumption did not afford protection against the amyloid deposits and neurofibrillary tangles indicative of Alzheimer's.“We found that seafood consumption was associated with higher brain levels of mercury, but that mercury was not correlated with brain neuropathologies of any type associated with dementia,” said Martha Clare Morris, ScD, lead author of the study, published in the February 2 edition of the Journal of the American Medical Association (JAMA).Other studies have likewise suggested that seafood may help fend off Alzheimer's-related dementia, but there has been a worry that the mercury found in fish could harm the brain. Mercury is known to be neurotoxic at high levels. [There have also been concerns about fish levels of a toxin, alpha-amino-beta-methylaminopropionic acid (BMAA), produced by blue-green algae blooms, but the current study did not screen for that.]Dr. Morris, a professor of epidemiology at Rush University, told Neurology Today that her team's findings suggest that “patients don't have to be all that concerned that the mercury they are getting from fish may be having a bad effect on the brain.”From an everyday practical standpoint, it was noteworthy that the study found a benefit from eating even a modest amount of seafood — as little as one serving a week. Seafood is high in long-chain omega-3, or n-3 fatty acids, which are important to normal neuronal function...

    Levels of mercury and selenium, another metal found in fish, were also measured in the brain tissue. Autopsy results were compared with information from the dietary questionnaires, which asked about the frequency of eating four seafood items — a tuna sandwich, fish sticks, cakes or sandwich; fresh fish as a main dish; and shrimp, lobster or crab. The questionnaire also asked about use of fish oil supplements. On average 2.4 years passed from the time the last questionnaires was completed until death...

    “To our knowledge, this is the first study to report on the relationship between brain concentrations of mercury and brain neuropathologies or diet,” the researchers reported.Why seafood consumption did not appear to benefit persons who were not APOE e4 carriers is not clear, Dr. Morris said. It is possible the study was not large enough to detect more subtle differences in brain pathology among person not at high risk for Alzheimer's.The study also could not prove a cause and effect between seafood consumption and risk of Alzheimer's disease, though the findings were consistent with previous observational studies that found an association between eating seafood and lower risk of dementia.While it is not reported in the study, Dr. Morris said her team did not find that one category of seafood was better than another. Other studies have suggested that dark oily fish, such as tuna or salmon, are most beneficial.