this whole two portions of oily fish a day in pregnancy

[OstrichRunning]

So, usually I'm a stickler for official pregnancy what-you-can-eat-what-you-can't-eat guidelines except for the occasional extra coffee

But I'm not convinced by the logic behind only two oily fish portions a week and here is why ...

NHS website says:
Women who are planning a pregnancy or who are currently pregnant or breastfeeding should eat no more than two portions of oily fish a week. This is because pollutants found in oily fish may affect the future development of a baby in the womb. www.nhs.uk/Livewell/Goodfood/Pages/fish-shellfish.aspx

Yet, another NHS page says it's basically okay to eat two tuna steaks a week in pregnancy www.nhs.uk/chq/Pages/should-pregnant-and-breastfeeding-women-avoid-some-types-of-fish.aspx?CategoryID=54

Presumably, those two tuna steaks would be your two oily fish ration all used up.

Here's the problem: tuna, a large fish that lives a long time, much longer than the humble sardine e.g., has way higher levels of mercury/pollutants than the smaller oily fish. So if it's okay to eat two tuna steaks a week, surely that means it's okay to eat a lot more than two portions of sardines or mackeral a week, iyswim? Because there's way less pollutants in the small fish.

Or am I missing something?
Thanks : )

I don't eat fish at all so midwife just looked at me and scrapped that bit of advice along with eggs.

I know, there's no point in taking it all too much to heart and have definitely been overthinking this one. I just love tinned mackerel mixed with olive oil and loads of lemon juice with pasta and peas mixed in - quick decent lunch a la Hugh Fearnley ...

NHS advice has to be comprehensible and memorable for everyone though, and half the population is of below average intelligence...

I suspect you are right but am not an expert in marine biology.

Search online for research papers on the subject. You'll get a much more detailed analysis, rather than the advice for the general public.

I think you're right, but I also think 'two portions of oily fish a week' is much simpler advice than 'two of big fish OR four of small' (or whatever). They'd then have to provide a list of which was which (a surprising number of people don't know tuna are large fish) and the more complicated you make a rule the more likely people are to ignore it (this is also the logic behind the rather more controversial 'zero alcohol' rule).

Thanks, that all makes sense.

To be honest I always thought tuna didn't count as oily fish. I mean i know the tinned stuff comes in oil but it's not oily fish as such is it?

So presumably you could have your oily fish and your tuna?

Fresh tuna is an 'oily fish' in terms of being a good source of omega-3 and vitamin D. Tinned tuna doesn't count as an oily fish for these purposes (likewise tinned salmon).

Yeah, I think the oil in tinned tuna gets removed during the tinning process. Tinned I don't think is as bad mercury wise as fresh

Tinned/fresh tuna that is

The reason that mackerel, sardines and tuna should all be limited in pregnancy is that they are all at the end of the food chain, and in each step of the food chain heavy metals like mercury, and other polluants, accumulate more. It's less about how long the fish lives and more about what they've eaten, and what their prey has eaten etc.

I wouldn't personally go above the 2 portions a week for those 3. Farmed salmon should be fine though.

Don'tblameit thanks for that, but are you sure? I'm no expert at all but I was pretty certain that tuna is way higher on the food chain than say sardines. These links seem to confirm that sardines for example are v low in mercury and Atlantic mackerel is low (king/spanish mackerel is different, higher levels there).

www.health.harvard.edu/blog/make-smart-seafood-choices-minimize-mercury-intake-201404307130

nutritionj.biomedcentral.com/articles/10.1186/1475-2891-12-33

lifehacker.com/know-which-fish-are-low-in-mercury-with-this-chart-1639616760

www.bbc.co.uk/guides/zs3882p

I read the title and thought you were mainly subsistence on fish

Oh God yes, it should say week! Two portions of oily fish a week. I'm not that bad

I know this is an old post but posting for anyone that finds it in future - tuna is NOT oily fish. You can have both two portions of tuna (steaks or tins) and two portions of oily fish (mackerel, salmon, herring, trout) per week.