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The protein myth: The significance of fish and sea foods is not protein

Article by Professor Michael A Crawford

Several speakers referred to the importance of fish and sea food for protein. This is a common misconception. The value of fish and or sea foods does not lie in protein. Protein is readily obtainable. A cow, horse and rhinoceros eat all the protein they need from the simplest food namely grass. Human milk has the least amount of protein compared to any other large mammal. Protein is good for body growth. Human developmental biology is about brain growth. The brain is largely made of fat (60%).

Human milk contains long chain essential fats that are critically important for brain growth and function. The Omega 3 DHA for example, is present at over 10 times that found in cow’s milk whilst cow’s milk has some 4 times the amount of protein. 

We are not a fast-growing animal like a cow or horse. Homo sapiens is characterized by extraordinary brain growth. The brain requires essential fats of which fish and sea food are the richest source.

It is an interesting and relevant fact that the brain evolved in the sea some 500-600 million years ago. Despite genomic changes from dinoflagellates to cephalopods, to fish, to amphibians, to reptiles, to birds, mammals and ourselves, the use of omega 3 DHA (an essential fatty acid) has been strictly conserved for the construction and function of the photo-receptor, the synapse and neurons, as well as for the instruction of gene expression on how to serve the brain, throughout that whole period of animal evolution. 

There is abundant evidence in animals and humans on the need for DHA for the brain. The international expert consultation on the role of dietary fatty acids, jointly of FAO and WHO, accorded the highest level of confidence to the evidence for the requirement of DHA for the infant retina and brain development (FAO nutrition report no 91, 2010). Of all the essential fatty acids needed by the brain DHA is the most limiting in availability

Land foods are relatively poor in DHA which comes largely from eggs and small mammals and poultry. Unfortunately, intensive poultry has substantially depressed their value as a source[i].  As all land mammals evolved faster body growth based on protein so their brain shrank relative to their body size. It was different for the marine mammals. For example, a Dolphin has a 1.8 Kg brain compared to about 350g for a land mammal with a similar body weight such as a zebra. It is most likely that human evolution was coastal to ensure a rich DHA supply for the mothers and so secure the epigenetic cerebral enhancement from embryogenesis to fetal and infant development. There is now good fossil and biological evidence for cerebral expansion at the coast.[ii],[iii]. There is also human evidence of substantial cognitive and behavioral advantages for children at 8 years of age when women eat fish and/or sea food during pregnancy from the ALSPAC study[iv] in the Avon District of West England. This study followed up the children born to over 14,000 pregnancies with a straight-line incrementing performance assessed in the 8-year old with the fish and sea food omega 3 eaten in the pregnancy.

The importance of detaching fish and sea foods from protein also includes the value of sea foods as a source of iodine and other trace elements. There are today some 2 billion people at risk to iodine deficiency which induces mental impairment.

The question was also raised from the floor of the impact of pollution and Guy Grieve talked about destruction of the seabed. It is astonishing just how this reckless behavior has been allowed. The spawning ground destruction from the Humber to the Thames was described. But it is much deeper than that. The estuaries and coastlines are where the sea food chain takes off in earnest. Yet almost EU wide fi not worldwide, the estuaries and coast lines have been destroyed and the UK is one of the worst. As a child my father used to take us to Crammond Inn to enjoy the wonderful sea food gathered from the shore. On return from Africa in July 1965 my wife and I took my brother and his wife and my mother to Crammond Inn for a trip down memory lane. There stood a brand new yellow Dept of Environment Notice *DANGER MUSSELS UNFT FOR HUMAN CONSUMPTION”. My photograph appears in a book I wrote on conservation[v]. Today the Vets advise people to keep their dogs on a lead for fear they might pick up a dead toxic fish.

Around 1900 the barmen in the East end of London would go down to the Thames and fill their buckets with oysters to put on the bar free for people who bought beer[vi].

There are two consequences of pollution and coastal seabed destruction. 

  • First it is likely to be responsible for a significant but undeclared decline in oceanic stocks of fish and sea foods. 
  • Secondly, it has destroyed a carbon sink worldwide the size of several rainforests.

Take the oyster harvest in Maryland as an example:

  • 1889:  616.000 tons
  • 2002:  12,000 tons

Apart from the loss of health-giving food:

  • 1889: 270,000 tons of solid CO2 was removed
  • 2002: Only 7,000 tons CO2 removed.
  • Difference: 263,000 tons not removed.

Oysters are only a small part of the carbon fixing systems of the estuaries and coast lines.

In 2008 the Declaration of <Muscat. Oman called for a realignment of the approach to human nutrition focusing on maternal health, nutrition, aaand brain development as well as the development of novel methods for marine agriculture. 

In 2009 11 representatives of Ministries from the Far Eastern Countries agreed on a Declaration of Manila in which addressing marine and freshwater pollution was given high priority.  We have not even begun to think about it in Europe toying mostly with ideas on controlling fish catches and burning boats.

There needs to be a radical re-thing of the funding into the fisheries and oceans in the EU. Apart from the logic voiced at the meeting, there is a vital subject not so far discussed: mental ill health.

The EU commissioned an audit on the health costs for the 25 member states. The result was that at 2004 prices mental ill health had overtaken all other burdens of ill health at €386 billion[vii]. Questions were asked in the House of Lords. In 2007 Dr Jo Nurse of the Dept of Health did the sums. The answer was a cost of £77 billion, greater than cancer and heart disease combined. She re-assessed the numbers in 2010 which came out at £105 billion.

At several scientific conferences over the last 12 months, at NOAA, Beijing, the International Sea Food and Health Conference, Melbourne. Salt Lake City (GOED) and the Omega 3 Summit in Bruges, this subject has been aired and questions asked as to whether there is enough fish to meet the requirements recommended by FAO and WHO. 

Now there is a disproportion fish and sea food use with the Far East consuming the most. Interestingly they have the least mental ill health, least heart disease and least Western cancers with Japan having the best longevity of any industrialized nation. The mental health issue as predicted in the 1970s is a Western problem but tragically, like much else it is being globalised.

This scenario raises important issues if we are to arrest the climb in mental ill health. It requires a multi-factorial attack ranging from education, water quality to agriculture and the food system.  However, one key issue that stands above all is that the wild catch has been stagnant for several decades.  Although aquaculture has expanded rapidly, it cannot continue to do so for the carnivorous fish which require offal etc from the wild catch. 

Astonishing as it may seem, the use of the oceans today is Neanderthal. We are still hunting and gathering.  Some 10,000 years ago, people recognized the unsustainability of hunting and gathering on land and invented agriculture and animal husbandry.  They did not need expert committees. The rivers, lakes and seas had an abundant harvest at that time and indeed until very recently

The only real solution to providing adequate fish and sea food is to do the same in the oceans. We need to develop marine agriculture and husbandry. This is now happening in Japan and the Far East. Take a simple example: we all know about cows on green pastures.  Starting in 1991, Dr Takehiro Tanaka who is Director of Fisheries Division, Department of Agriculture, Forest and Fisheries, Okayama Prefectural Government has been developing the same in the sea. They are using Zostera marina to make ocean bed pastures for fishThey have developed an extensive area of seabed with a variety of ecological techniques to encourage the primary productivity using sunlight as the main energy source, and with it, the productivity of fish and sea foods has grown.


I hope I have made the case that fish, and sea foods are not of value for protein but are for their essential fats and trace elements needed for the brain.  They also happen to be needed for the heart, vascular and immune systems but that is another story. The rise in mental ill health is the greatest health threat facing us today. Its continued escalation is predictable which is also unthinkable. The brain evolved in the sea 500-600 million years ago using marine fats and trace elements.  It still uses the same today.  Addressing this issue is the greatest challenge we face as humans. The need cannot be met from existing wild fish stocks.  Marine agriculture and husbandry are a solution.

Professor Michael A Crawford, PhD, FSB, FRCPath

Imperial College, London.

Department of Cancer and Surgery,

Division of Reproductive Physiology, Obstetrics and Gynaecology,

Room 3,34

Chelsea and Westminster Hospital Campus,

369 Fulham Road
London SW10 9NH

Tel:  +44 (0) 208 8467892  mobile 07725250541

[i]  Wang Y, Lehane C, Ghebremeskel K, Crawford MA (2010) Modern organic and broiler chickens sold for human consumption provide more energy from fat than protein. Public Health Nutr;13(3):400-8

[ii] Marean CW, Bar-Matthews M, Bernatchez J, Fisher E, Goldberg P, Herries AI, Jacobs Z, Jerardino A, Karkanas P, Minichillo T, Nilssen PJ, Thompson E, Watts I, Williams HM (2007) E arly human use of marine resources and pigment in South Africa during the Middle  Peistocene.Nature.18;449(7164):905-8

[iii] Leigh Broadhurst C, Wang Y, Crawford MA,  Cunnane SC, Parkington JE, Schmidt WE. (2002) Brain-specific lipids from marine, lacustrine, or terrestrial food resources: potential impact on early African Homo sapiens. Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology; 131 (4), 653-673. 

[iv] Hibbeln JR, Davis JM, Steer C, Emmett P, Rogers I, Williams C, Golding J (2007) Maternal seafood consumption in pregnancy and neurodevelopmental outcomes in childhood (ALSPAC study): an observational cohort study. Lancet;369(9561):578-85.

[v] Conservation by M.A. Crawford. Aldus Books Ltd., London, 1976. Forward by Sir David Attenborough.

[vi] The history is displayed in the Museum of London.

[vii] Andlin-Sobocki P, Jonsson B, Wittchen HU, and Olesen J. 2005. Cost of disorders of the brain in Europe. Eur J Neurol 12 Suppl 1:1-27.

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