Dr Joseph Hibbeln, chief of the Outpatient Clinic at the National Institute on Alcohol Abuse and Alcoholism in Maryland, USA, detailed the work he has done on the Avon Longtitudial Study of Parents and Children (ALSPAC) survey findings in relation to the consumption of seafood by pregnant mothers.
From 1991, the ALSPAC team, under Jean Golding, has followed some 8,000 children, recording, amongst much other data, omega 3 fatty acid consumption, particularly DHA from fish.
Methyl mercury in fish
The early 1990s saw the outbreak of bovine spongiform encephalitis (BSE) and foot and mouth disease followed by ominous warnings about the degree of pollution in fish.
Fish, we were led to believe, were dangerously laden with methyl mercury, PCBs and other horrors. Warnings were flashed across the media: pregnant mums could not eat more than two portions of fish a week without risking foetal damage. The then Ministry of Agriculture, Fisheries and Food repeated the advice which had come, initially from the US Federal Drugs Administration.
It is likely that those women who heeded the advice may have suspected, as a result, that there was something bad about fish, so they may well not have eaten any at all.
In February this year Dr Hibbeln published his analysis of maternal
diet compared with the children’s learning and behavioural characteristics at the age of eight. (1) The results were extraordinary.
The study makes it clear that those mothers who followed government advice and consumed two portions of fish a week or less had children whose test scores were low and who suffered from problems with verbal IQ, fine motor skills and social development. Mothers who ignored the advice and ate ‘normal’ amounts of fish had children who scored highly and had a significantly lower incidence of developmental problems.
The advice had been based on the assumption that increased intakes of fish would lead to increased intakes of methyl mercury. Yet there was no attempt to balance the increase in methyl mercury with benefit. Moreover, the evidence of harm had come from the use of mercury as a fungicide for seeds - not from its consumption in fish.
There is some evidence of mild harm from people in the Faroes eating pilot whale. This animal has high levels of methyl mercury but little selenium. Selenium protects against mercury toxicity because it binds with mercury, thus making it unavailable.
A similar study in the Seychelles where people eat a lot of fish (not including pilot whales) did not confirm such damage; nor does the long-term experience of the Japanese who eat fish and seafood almost every day and often more than once a day.
According to the World Health Organisation the Japanese and Icelanders are the two nations with best birth weights and longevities.
Moreover, forgotten in the equation was the marine fixation of carbon dioxide through phytoplankton and algae. The oceans cover more than two- thirds of the earth’s surface and remain the richest source of food on the planet.
Fish eating advice
The real answer is for regional governments and the UN to arrest the pollution of the oceans by cleaning the coast, rivers and estuaries where the marine chain should take off in earnest. Sadly it no longer does because of the pollution.
For those who remain concerned about possible mercury pollution the solution is simple: eat the small fish (whitebait, sild, sardine, herring, mackerel, shrimp, prawn - even seaweeds) at the lower end of the food chain. They not only contain the highly prized EPA and DHA, but also a wide spectrum of minerals and trace elements necessary for the enzymatic reactions that convert the parent EFAs to their long chain derivatives.
The point about the bigger fish is that they eat smaller fish that have eaten smaller fish etc. The big fish therefore collect with compound interest the pollution of all the smaller ones.
So don’t eat big fish too often, and try to avoid too much pilot whale.
Forget the ‘names’ given to the various behavioural difficulties of young children; these are only labels for overlapping or differently expressed developmental disorders. Such erroneous development, she suggests, comes largely (but not always) from nutritional insult. The architect’s blueprint is there in full, but the builder’s materials have been in short supply.
DHA and DNA
Professor Michael Crawford, Director, Institute of Brain Chemistry and Human Nutrition, explained his recent work on the essential fatty acid docosahexaenoic (DHA) and its relationship with DNA.
While DHA (which builds, brains, eyes, nervous and vascular tissue etc) has remained unchanged for between 500 and 600 million years, ‘the conditions of existence’, to quote Charles Darwin, have changed constantly. For as life forms have evolved they have done so within an environment which is itself evolving.
Professor Crawford argued that DHA and, more generally, membrane lipids (fats), can be seen as the masters of DNA. For we now know that DHA, which has always been rigidly entrenched in vision, neural transmission and cellular organisation, is also a regulator of gene expression.
Despite many changes in DNA and in other aspects of cephalopods, fish, amphibia, reptiles, birds, mammals, primates and humans, the rigid, unchanging 600 million year track record of DHA suggests that it is the ‘selfish DHA’, not the ‘selfish gene’, that has been most powerful.
This, he explained, is the meaning of the term epigenetic - the power of environmental pressures to change the behaviour (or expression) of DNA. Thus, although its structure remains unchanged, environmental pressures on the genome will cause it to produce more or less of specific proteins, thus causing generational change in different tissues and organs.
Omega 3 / omega 6 imbalance
All four speakers were in agreement as to the main reason for these discrepancies: an imbalance in the ratio of omega 6 to omega 3 fatty acids. Ideally this should be a ratio of 2:1 or even 1:1.
In North America and Europe, as a result of changing eating patterns (decline in the consumption of omega-3-rich fish and increase in that of omega-6-rich seeds and meats) this ratio is commonly wildly distorted at 10:1 even 20:1. It is often also accompanied by
deficiencies in minerals, trace minerals and vitamins.
Why is this important? Because every one of the 30
trillion cells in our bodies have walls comprising a bilipid layer - a sort of three dimensional super sophisticated mesh.
The outer cell membrane and the membranes surrounding inner cell organelles are bilipid layers. Each cell wall is so intricately constructed that they allow specific chemicals into and out of the different minuscule ‘factory departments’ of each cell. These super biological meshes are central to our health. If they cannot access the nutrients they need they lose their integrity, and thus their efficiency, and ill health ensues.
Ratios of 10:1 or even 20:1 omega 6 to omega 3 fatty acids instead of 2:1 or 1:1 do not provide them with those nutrients.
All the speakers saw this as a primary cause of the rise in heart disease, cancer and other physical ailments and, maybe far more importantly, the dramatic increase in mental health disorders over the last 25 years.
(1) Maternal seafood consumption in pregnancy and neurodevelopment outcomes in childhood (ALSPAC STUDY): an observational cohort study. Lancet 2007;369;578-585
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First Published in October 2007
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