From the symbolic use of the fish by early Christians, to present day perceptions of healthy eating, fish is commonly regarded as wholesome. We were told as children that fish is brain food, and that eating it will make us clever.

The benefits

Child development and ADHD

A study of ADHD in adults suggested that high dose fish oil may be preferable to high     dose flax oil in increasing EPA, DHA, and total omega-3 levels, however this study     does not report on behavioural outcomes (Young, 2005).

Mood, mental health, and Alzheimer’s

The risks

Allergy
True allergic reactions may occur from fish proteins, but these reactions are not usually as severe as these proteins occur singly in fish, in contrast to foods with multiple proteins such as milk, eggs, and peanuts. All bony fish share the same protein, parvalbumin which is a known allergen. It is uncertain whether cartilaginous fish, such as shark, ray, skate, and dogfish contain parvalbumin, and so fish allergic individuals may tolerate these.

Mercury
Both a naturally occurring metal and a pollutant, being heavy it falls from the air, accumulates in water and converts into methylmercury which is neurotoxic to babies and young children. Methyl mercury is high in predatory fish like swordfish and shark. Current Food Standards Agency (FSA), and Food and Drug Administration (FDA) advice for women and children, from preconception through the early years of their child’s life, are to limit mercury consumption. They should avoid swordfish, shark, king mackerel, and tilefish, limit albacore tuna, and check local advisories about locally caught fish (FDA, 2004).

PCB’s
Polychlorinated biphenyls (PCB’s) and Polychlorinated dibenzo-p-dioxins and debenzoflurans (PCDD/Fs) affect human health, increasing risk of cancers, thyroid problems, weakened immunity, and foetal development problems. Prenatal exposure compromises neurological functioning, psychomotor skills, and cognition. PCB’s accumulate in the body over a lifetime, so the intake a mother has had in the years prior to her pregnancy may still effect her child. Oily fish contain the highest level of environmental pollutants, as they concentrate in the very oil we value. Farmed salmon has on average 10 times more contamination with PCB’s, dioxin, and pesticides than wild salmon, with the most contaminated samples being found in Scotland and the Faroes (Edwards, 2004). In 2004 the independent expert Committee on the Medical Aspects of Food Policy advised people to eat an average of one portion of oily fish per week.

Pesticides
Those routinely used in farmed fish include Dichlolovos, and the newer much more toxic organophosphate Azamethiphos. Also used are Cypermethrin, a neurotoxin, Teflubenzuron, and Emamectin. Some experts consider all these last four to be both carcinogenic and hormone disrupting.

While fish in it’s natural state provides excellent brain nutrition, the environment may render it a source of neurotoxins and other health risks.

So what should we do?

Buy wild or organically farmed fish from ethical suppliers.
Waitrose and Marks and Spencer, have adopted sustainable fishing policies for their products. Their fish farms have been set up with integrity, limiting damage to the environment.

Avoid cod liver oil as contaminants concentrate more in the liver than the flesh.

Supplement our omega-3 intake with vegetable sources such as flax oil – this may be drizzled onto steamed vegetables or salad, or added to smoothies. Pumpkin seeds, walnuts, hemp, dark leafy green vegetables, and soya beans are also good sources.

Buy supplements from reputable manufacturers We recommend and can supply:

We believe that essential fatty acid supplementation should be by individual prescription, taking account of existing disease, medical and family history, medications and other supplements. Blood tests for Essential Fatty Acid Profile are recommended in some cases.

References
Barberger-Gateau , P., Letenneur, L., Deschamps, V., Peres, K.., Dartigues, J-F., Renaud, S., 2002, Fish, meat, and risk of dementia: cohort study, BMJ, 325:932-933

Edwards, R., 2004, Farmed salmon more contaminated than wild, www.newscientist.com

FDA, 2004, What you need to know about Mercury in Fish and Shellfish,
www.cfsan.fda.gov

Hirayama, S., Hamazaki, T., Terasawa, K., 2001, Effect of docosahexaenoic acid containing food administration on symptoms of attention deficit hyperactivity disorder – a placebo controlled double-blind study, Eur. J. Clin. Nutr. Mar;58(3):467-73

Isosaari, P. Hallikainen, A. Kiviranta, H. Vuorinen, P.J. Parmann, R. Koistinen, J. Vartianen, T., 2005, Polychlorinated dibenzo-p-dioxins, dibenzofurans, biphenyls, naphthalenes and polybrominated diphenyl ethers in the edible fish caught from the Baltic Sea and lakes in Finland, Environ. Pollut. Oct 11;(epub ahead of print)

Lauritzen, L., Jorgensen, M.H., Olsen, S.F., Straarup, E.M. Michaelsen, K.F., 2005, Maternal fish oil supplementation in lactation: effect on developmental outcome in breast-fed infants, Reprod. Nut. Dev., Sep-Oct;45(5):535-47

Richardson, A.J., Montgomery, P., 2005, The Oxford-Durham Study: a randomised, controlled trial of dietary supplementation with fatty acids in children with developmental coordination disorder, Paediatrics, May;115(5):1360-6

Ross, B.M., McKenzie, I., Glen, I., Bennett, C.P., 2003, Increased levels of ethane, a non-invasive marker of n-3 fatty acid oxidation, in breath of children with attention deficit hyperactivity disorder, Nutr. Neurosci., Oct;6(5):277-81

Salam, M.T., Li, Y.F., Langhoz, B., Gilliland, F.D., 2005, Maternal fish consumption during pregnancy and risk of early childhood asthma, J. Asthma, Jul-Aug,;42(6):513-8

Young, G., Conquer, J., 2005, Omega-3 fatty acids and neuropsychiatric disorders, Reprod. Nutr. Dev., Jan-Feb;45(1):1-28

Young, G., Conquer, J., Thomas, R., 2005, Effect of randomised supplementation with high dose olive, flax, or fish oil on serum phospholipid fatty acid levels in adults with attention deficit hyperactivity disorder, Reprod. Nutr. Dev., Sep-Oct;45(5):549-58