Can too much fish be bad for you?

I was wondering if you could get too much vitamin A and D if you eat a lot of oily fish? How much would you have to eat to be at risk?

Just how much fish are you knocking back there Griffin?

Well I would say I’m eating a two or 3 mackeral fillets and maybe trout once a week.

Too much of anything can be bad for you; that’s precisely what ‘too much’ means.

Doesn’t sound like the intake you’re describing is even close to excessive though; mackerel is very good for you.

Darnit, you beat me to it!

On a serious note: You can die of vitamin A overdose, but I doubt that’s enough to do it. Other cultures (I’m thinking mediterranean fishing ones, for example) probably ate a lot more fish than that.

You can also die of e.g. mercury poisoning, so it pays to know where your fish are from and how toxic that water is.

Eskimos have been known to die of a vitamin A overdose after eating polar bear liver.

Around here, this is a trivial amount of fish.

This here site states:

So, unless you’re pregnant, in order to get your toxic dose of 20 mg per day, you would need to eat 5,000 grams of mackerel. Every day. So let’s say your fillet weighs in at 100 grams, you will need to eat 50 of them to get sick.

I hope I got that right.

According to this it is not recommended to eat more than one portion of oily fish a week. This isn’t because oily fish itself isn’t good for you, but because it picks up pollutants from the enviroment.

What kind of fish?

We get this type of thing at work alot. Small fish swim in mercury ladden seas, bigger fish eat those, then bigger fish eat those fish. You keep going until you get to the big fish like Tuna, chock full of mercury or whatever is in the sea the fish swam. Around here they dump all the treated sewage into the bay. Often you see people selling, say, ‘Fresh Monterey Bay Caught Fish’. Yeah, right.

This site states that you should

“Choose smaller fish instead of the large predatory marine fish. These safe and healthy fish include sardines, herring, smelt, mackerel, trout, salmon, pollock, tilapia, catfish, sole, and scrod.”

So it looks like you’re in the clear, as long as you take their word for it.

Thanks for the info guys. I might cut down my oily fish intake slightly due to the dioxins. I did know about tuna being high in mercury, and I try not to eat that very often. The worst thing for mercury though is shark fin soup.

Well, there is also farmed fish.

Are farmed fish better then?

It’s not clear. I’ve found it very hard to find unbiased info.

These guys say yes, farmed salmon has less dioxins than some wild fishes.

This guy, however, disagrees and says levels are about the same.

This site says the problem is complicated but there is no doubt that there is some PCB in farmed fish.

The problem is that the food that the fish are fed has to come from somewhere. Ideally, fish farmers can choose fish feed that comes from parts of the world where dioxin levels are the lowest. That doesn’t mean, however, that this is what all fish farmers do.

When I lived on the river, I ate fish damned near everyday. Freshwater fish of course, lower iodine IIRC. Never had a problem with it.

I imagine it’s what your used to as well. Lots of people around the world eat fish everyday. As I understand it, shellfish and mollusks are quite another kettle…

They absorb excessive amounts of Iodine as well as other toxins.

Well, realistically when you get as far down the chain of supply as the fish farmer, none of them can choose this - unless they have incredible wealth (which would make one wonder why they’d throw it away on fish farming).

First there’s the guys who say where/when these fish can be caught, then the fishermen who go catch them, then the guys who buy them, then the guys who sell them in big quantites, then the feed companies who by it by the thousands of tones and decide how to mix it with what, then finally the lowley fish farmer who tries his best to strike a deal with one of those huge (usually as local as possible) feed companies to get a few bucks off per ton for whatever they can afford; the cheaper the better (provided it’s of high enough quality). Every step along the way it gets harder to trace exactly where that fish meal came from and what kind of contamination levels it had - if they’re even measured… which AFAIK they aren’t except when someone wants to do a study, and there have only been a handfull of those.

For the most part fish farming right now just doesn’t have a high enough profit margin to allow the farmers to be picky about such things.

Which would kind of lend credence to the folks saying there’s not much difference between wild and farmed when it comes to dioxins.

Mercury presence in fish occurs naturally. Evil humans creating Native-American-played by an Italian guy-induced-crying-over-pollution-a la-some-70’s-style commercial is not why there is mercury is some fish.