Friday, 1 April 2011

Why the government is right to recommend restricting the intake of oily fish.

Toxicity is a huge subject because it is so omnipresent in our lives. And it is injurious to good health. But here the subject is fish oil, oily fish and just why they can be so toxic. Oily fish is sort of good for you and certainly is a very good source of omega 3. However since toxins are stored in fat, some oily fish are best avoided. These are tuna, swordfish and shark. They very big fish and are highly contaminated. The smaller the oily fish, the lower the levels of contamination, so essentially any oily fish salmon sized or smaller is OK. If salmon is to be eaten for the omega 3 content, however, source wild salmon since farmed salmon is not eating its natural food and so is not a good source.

To get enough omega 3 from the diet would entail eating an awful lot of fish, so it is easier to take a fish oil supplement. The problem is that it is very expensive to clean it properly and most companies take short cuts. Currently there are some big companies being sued for having PCBs in their fish oil (more on PCBs soon). To be sure your fish oil has been fully cleaned with non-toxic cleaners, check that the country of origin is either Norway or California. In these places, the oil has to be good by law. If there is no country of origin on the label, it is very advisable not to buy it until that is found out.

A common measure for baseline toxicity in studies is to analyse the umbilical cord blood of newborn babies and this shows that a newly born baby is born with 200 industrial chemicals and pollutants in place. Studies of the Eskimo/Inuit people show high levels of toxicity (particularly heavy metals, eg mercury) – yet they live in the most pristine environment. Their toxicity is coming from the diet they live on which has a large amount of whale and seal blubber in it.

So here is a brief tour of some of the pollutants found in the seas. The list is far from entire as that would entail talking about 200 pollutants.

Heavy metals, eg lead, cadmium, arsenic and mercury – which is the most poisonous of the heavy metals. There are at least 643 scientific papers linking mercury toxicity to cardiovascular disease (heart attacks, strokes, angina et al). There are at least 1,445 linking mercury to neurodegenerative diseases (eg alzheimers, parkinsons, dementia). The brain has no defence against any toxin that is fat-soluble – it crosses the blood/brain barrier.

Research has found that all cancer cells have mercury in them. And mercury leads to cancer by depleting the immune system – anything doing this increases the chances of cancer. It also increases oxidative stress (oxidisation – the simplest and best explanation is oxidisation makes things rust) while damaging DNA, which results in mutations that promote cancer. It disrupts apoptosis which is programmed cell death leading to the safe removal of sick or unhealthy (e.g. cancerous) cells. Mercury also binds with haemoglobin (the oxygen transport system in the tissues) so there is less oxygen reaching the tissues.

Another group of toxins found in the seas are the PCBs and Dioxins. There are 209 different PCBs (polychlorinated biphenyls) also known as congeners. They have no smell or taste and there are no natural sources. They were first used in the 1920s and production stopped in 1977 because they are so toxic. They were used in old fluorescent lighting, as coolants, in hydraulic fluids, as lubricants and flame-retardants. They were not well disposed of and get concentrated in the food chain, principally in fish. Studies in the 1970s showed they harm the neurological development of children; they are also harmful to the reproductive system and the thyroid; they harm the immune system (and are therefore carcinogenic).

Dioxins are also chlorinated chemicals with a high affinity for fats. There are 75. They are mainly man made, but are also the product of forest fires and volcanic activity (i.e. they are found in smoke). They are formed as a by-product of incomplete combustion e.g. waste incineration, cigarette smoke, car exhausts and also in the chlorine bleaching of pulp and paper and in the production of chlorinated pesticides. They are released into the wastewater where they are non soluble, so settle on plants and plankton, so working their way up the food chain.

A dioxin binds strongly to the intra cellular receptors in the nuclei of the cells throughout the body – so it easily gets to the DNA and damages it. Causing the similar disruption as the mercury does. Dioxins are known carcinogens. They are particularly bad for children and the developing foetus, causing problems in the reproductive, nervous and immune system.

To get a dioxin out of your body completely is impossible – it has a half-life of 7 years. So in 7 years, half of it has gone. 7 years later half of that half has gone. And so on. So I suppose if you stop ingesting dioxins as a child, you would clear most them from the body – but you have to be sure you are not ingesting any more!

The final group of toxins to think about is the plastics. Plastic bottles, bags, food packaging, floor coverings, furniture, car seats. These have clearly been shown to be oestrogenic in wildlife. Oestrogenic = acting on the body like female hormones do, feminising men and leading to health problems in females- eg PMS, menopausal problems, weight gain. Signs of oestrogen toxicity are fat bottoms and/or thighs. The proper term is xenoestrogens (foreign oestrogens). Their effects upon humans are only being fully studied now – and industry is busy down playing their effects, insisting that they do not pose a problem to our health.

Plastics are slow to break down and found in swirling masses in the oceans. One mass the size of Texas is found in the North Pacific gyre. Another place a large mass of floating plastic has been found is in the Amundsen Sea. This is in the Pacific sector of Antarctica thousands of miles away from the nearest urban centre. In these masses, the plastics slowly break down into smaller and smaller pieces and the birds and fishes eat them in mistake for their normal food. And so by this way plastics find their way into fish oils.

There are many other pollutants in the seas. Solvents, APEs (main source is detergents), herbicides, pesticides. The list goes on. All of them cause disease and dysfunction. So fish oils have to be cleaned of these things. What is really worrying is that some companies use Hexane to clean the oil because it is cheap. Now hexane is itself a solvent that can have neuropsychiatric effects by slowing down the impulses from the spinal chord to the arms and legs and it causes headaches.

So it is best to make sure that the country of origin is either Norway or California!


1. Oily fish are tuna, swordfish, salmon, herrings, sardines, anchovies etc. Cod, plaice or whiting, for example are white fish so are not such good sources of omega 3 – and are less toxic than some of the oily fish.
2. Most toxins are fat-soluble. Ideally the liver converts them to water-soluble form so they can be excreted. But the liver gets very overloaded by the sheer quantity of toxins in the environment alone. Never mind the other daily insults of pharmaceuticals, poor food choices, excessive alchohol etc. Another factor lies in the genes. The various toxins are rendered harmless by the liver through different pathways and genetically this capability varies from person to person. So some people have a much harder time neutralising heavy metals, for example, than others. Genetic testing is a growing market. Once the problem gene(s) are known, wise supplementation and good nutrition is vital for good detoxification.

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