alexa
Reach Us +44-1647-403003
The Fish Paradox: Are Maternal Omega-3 (n-3) DHA and Selenium (Se) Intake Protective Against Negative Effects of Methylmercury Exposure on Infant Cognitive Development?
ISSN: 2376-1318
Vitamins & Minerals
Make the best use of Scientific Research and information from our 700+ peer reviewed, Open Access Journals that operates with the help of 50,000+ Editorial Board Members and esteemed reviewers and 1000+ Scientific associations in Medical, Clinical, Pharmaceutical, Engineering, Technology and Management Fields.
Meet Inspiring Speakers and Experts at our 3000+ Global Conferenceseries Events with over 600+ Conferences, 1200+ Symposiums and 1200+ Workshops on
Medical, Pharma, Engineering, Science, Technology and Business

The Fish Paradox: Are Maternal Omega-3 (n-3) DHA and Selenium (Se) Intake Protective Against Negative Effects of Methylmercury Exposure on Infant Cognitive Development?

Mary A Harris*
Department of Food Science and Human Nutrition, Colorado State University, USA
Corresponding Author : Mary A Harris
Department of Food Science and Human Nutrition
Colorado State University, USA
Tel: 970-491-7462
E-mail: [email protected]
Received February 07, 2014; Accepted February 09, 2014; Published February 14, 2014
Citation: Harris MA (2014) The Fish Paradox: Are Maternal Omega-3 (n-3) DHA and Selenium (Se) Intake Protective Against Negative Effects of Methylmercury Exposure on Infant Cognitive Development? Vitam Miner 3:e126. doi:10.4172/2376-1318.1000e126
Copyright: © 2014 Harris MA. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Visit for more related articles at Vitamins & Minerals

Scientific uncertainty surrounds the consumption of fish and seafood by pregnant and breastfeeding women. The developing fetal brain is especially sensitive to the effects of methylmercury. Methylmercury bound to cysteine is the predominant form found in fish tissues and this adduct is able to be transported across placenta [1]. Mercury concentrations in fetal brain have been reported to be about five to seven times those of maternal blood [2]. Methylmercury readily crosses the blood-brain barrier and causes oxidative damage to the developing central nervous system. Neurotoxic effects of severe mercury poisoning resulting from catastrophic accidents in Minamata, Japan and Iraq although unusual are well established [3]. Low level exposure (<10 ppm maternal hair levels) from maternal seafood consumption is more common and the effects are inconsistent. Although a number of epidemiologic studies have shown a subtle negative impact of methylmercury exposure from high seafood intake on certain domains of learning, [4] maternal seafood consumption at lower levels is most often associated with improved cognitive development [5-7] or to have no effect, or inconsistent effects, on scholastic achievement upon long term follow up of children [8]. Seemingly paradoxical is the observation that, at relatively low levels of methylmercury exposure, cognitive ability improves as both fish consumption and maternal methylmercury increase [6,9]. An explanation for this paradox is the confounding effects of other nutrients, selenium which plays in protective role against the neurotoxicity of methylmercury and n-3 DHA which is an essential nutrient for optimal brain development. Although ocean fish are a source of methylmercury, seafood is the richest dietary source of omega-3 DHA and also an excellent source of selenium.
Seleniuim is an essential component of the antioxidant enzymes, glutathione peroxidase and thioredoxin. Methylmercury in excess of dietary selenium intake irreversibly inhibits these selenium-dependent enzymes and compromises the antioxidant defense systems in the brain [1]. The effect is related to reduction in intracellular selenium bioavailability and/or to covalent binding of methylmercury to selenium in the active sites of selenium-dependant enzymes [1]. Neural tissue is especially susceptible to peroxidative damage due the high rate of production of reactive oxygen species and to the neuronal cell morphology with a high ratio of membrane polyunsaturated lipids to cytosolic repair systems. High Se:mercury (Hg) ratios may mitigate the negative effects of methylmercury [1]. The strength of the evidence from animal models is good. In mice, supplementation with selenomethionine was shown to reverse inhibition of seleno-enzymes and prevent the neurotoxic effects of mercury [10]. Mitigation of methylmercury induced cerebral degeneration also been demonstrated in rats receiving selenomethioinine in utero [11]. Evaluation of the Se:Hg ratio may be a better method for examining neurocognitive effects of methylmercury exposure from seafood in humans. A report from the Faroe Island study showed that the negative effects of maternal intake of marine foods disappeared when adjusted for intake of fish, eliminating intake of flesh from marine mammals which is high in Hg low in Se [12]. However, a recent regression analysis of Hg and Se failed to show consistent interactions in two birth cohorts in the Faroe Islands [13].
Similarly, negative effects of higher levels of methylmercury exposure, have been demonstrated in the China only after controlling for n-3 DHA [14], although positive benefits of n-3 DHA were diminished at high maternal levels of mercury in cohorts from the Seychelles and U.S [6,15]. Results from the large British ALSPAC Study showed that mothers who consumed the greatest amount of n-3 DHA from fish throughout pregnancy and breastfeeding gave birth to babies who performed better on a wide variety of neurocognitive tests compared to the least amount of DHA. Effects of fish intake on cognitive development from the longitudinal Seychelles Child Development Nutrition Study have largely been attributable to the maternal n-3 DHA status which parallels dietary seafood intake [9,15,16].
The potential of nutrients to modify mercury toxicity remains an area of great interest. Current evidence suggests that selenium may mitigate the negative effect of methyl mercury and that the benefits of n-3 DHA outweigh the risks of consumption of most seafood during pregnancy and lactation. The greatest cognitive benefits are derived from maternal consumption of seafood which is highest in n-3 DHA and low in methylmercury. The modulating effect of selenium, although clear in animal models, has not been well documented in humans. Further research is needed to address this question.
References
















Select your language of interest to view the total content in your interested language
Post your comment

Share This Article

Article Usage

  • Total views: 12245
  • [From(publication date):
    July-2014 - Dec 15, 2018]
  • Breakdown by view type
  • HTML page views : 8453
  • PDF downloads : 3792
 

Post your comment

captcha   Reload  Can't read the image? click here to refresh

Peer Reviewed Journals
 
Make the best use of Scientific Research and information from our 700 + peer reviewed, Open Access Journals
International Conferences 2018-19
 
Meet Inspiring Speakers and Experts at our 3000+ Global Annual Meetings

Contact Us

Agri and Aquaculture Journals

Dr. Krish

[email protected]

+1-702-714-7001Extn: 9040

Biochemistry Journals

Datta A

[email protected]

1-702-714-7001Extn: 9037

Business & Management Journals

Ronald

[email protected]

1-702-714-7001Extn: 9042

Chemistry Journals

Gabriel Shaw

[email protected]

1-702-714-7001Extn: 9040

Clinical Journals

Datta A

[email protected]

1-702-714-7001Extn: 9037

Engineering Journals

James Franklin

[email protected]

1-702-714-7001Extn: 9042

Food & Nutrition Journals

Katie Wilson

[email protected]

1-702-714-7001Extn: 9042

General Science

Andrea Jason

[email protected]

1-702-714-7001Extn: 9043

Genetics & Molecular Biology Journals

Anna Melissa

[email protected]

1-702-714-7001Extn: 9006

Immunology & Microbiology Journals

David Gorantl

[email protected]

1-702-714-7001Extn: 9014

Materials Science Journals

Rachle Green

[email protected]

1-702-714-7001Extn: 9039

Nursing & Health Care Journals

Stephanie Skinner

[email protected]

1-702-714-7001Extn: 9039

Medical Journals

Nimmi Anna

[email protected]

1-702-714-7001Extn: 9038

Neuroscience & Psychology Journals

Nathan T

[email protected]

1-702-714-7001Extn: 9041

Pharmaceutical Sciences Journals

Ann Jose

[email protected]

1-702-714-7001Extn: 9007

Social & Political Science Journals

Steve Harry

streamtajm

[email protected]

1-702-714-7001Extn: 9042

 
© 2008- 2018 OMICS International - Open Access Publisher. Best viewed in Mozilla Firefox | Google Chrome | Above IE 7.0 version
Leave Your Message 24x7