Debating the nutritional benefits, toxin and sustainability issues of fish eating

Open any newspaper and you’re likely to read about the benefits of eating fish; but should we eat more fish? There are issues with fish eating: sustainability debates and the toxins fish may contain versus the nutritional benefits.  There is also the smoked fish debate – is it beneficial for us? Click here to read more on the subject.

This blog was initially inspired by my great Aunty Doris. She passed away recently and amongst many memories is a bizarre one of her telling me I should eat salmon skin, as that’s the best bit of the fish. I’ve begun to wonder whether she was right. Back when Aunty Doris would have first started eating fish, eating the skin would probably have been a good thing:

But back then, industrialisation and chemical pollutants weren’t such an issue. These days our waters, both sea and river, are contaminated with varying levels of pollutants including dioxins, mercury and PCBs, (known as gender-bender chemicals for their hormone-disrupting properties). These chemicals are associated with cancer and hormone problems, from PMS to prostate complications. Farmed fish isn’t a solution either – they also accumulate toxins, although much less so if they’re certified organic.

Paradoxically, the fattier areas of fish contain the most beneficial fats but it’s also where more toxins accumulate. So what’s the answer – especially when you throw sustainability into the equation?

Fish benefits

salmonlemon2We know oily fish is good for us a couple of times a week due to the omega-3 content, so we should keep eating it. Studies repeatedly show fish oils are protective against many diseases. For instance recent research revealed that a lifelong diet rich in omega-3 fats can inhibit growth of breast cancer tumours by 30 percent. Fish is also a great source of vitamin D (especially fish with bones), selenium, zinc and vitamin B12, vital nutrients many of us are low in.

How much omega-3 do we need?

This really depends on the person, but generally you’re looking at the equivalent of 7,000mg a week of EPA and DHA combined (the two most beneficial ones). A 100g portion of salmon can give around 1,000mg, the same amount of mackerel 2,000mg. So, eating oily fish a couple of times a week can get you up to around 3,500mg. To make up the rest, I’d suggest a daily supplement containing 500mg of combined EPA and DHA. In our clinic we don’t second-guess how much you need – we often use Essential Fatty Acid testing to see what your personalised requirement really is.


It’s probably not a great idea to eat salmon skin. Larger fish such as salmon and tuna accumulate more toxins than smaller fish. Organic farmed or wild salmon is better, and smaller fish such as sardines, mackerel, herring, trout and anchovies are likely to have less contamination. Arctic cod and halibut are among the least polluted fish.

Children and pregnant or nursing mothers should limit consumption of oily fish to just a couple of times a week due to the toxins. The omega-3 content is extremely beneficial for children’s developing brains, but babies and kids are also more vulnerable to toxins. To reduce concerns about the toxins in fish, make sure to eat lots of antioxidant-rich fruits and vegetables, which can help protect against cancer-forming chemicals. It’s also important to remember that fish also are a good source of selenium though – in itself a powerful antioxidant.


The situation changes all the time – a while ago mackerel was officially overfished but now it’s back on the ‘ok’ list; the Marine Conservation Society recommends line-caught mackerel but to avoid trawler-caught. Rainbow trout, sardines, pilchards, herring, anchovies and certain types of salmon (including Alaskan – normally found in tins) get good sustainable fish ratings.

The overfishing situation is important – if we’re not careful our children won’t be able to benefit from eating fish. Check out for more information.



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