Excellent info in this thread Winston.
I just wanted to add that not all animal proteins are created equal. Fish three times (or more) per week is fine IF the fish involved is a bottom of the food chain, short lived variety. So small whiting, herring, bream, trout, even farmed salmon etc. Tuna however qualifies as closer to the top of the food chain so eat moderately although I'm not so sure of the farmed stuff as their diet is controlled for them. Shark is definitely toward the top although most commercial shark species are taken relatively young.
This is all due to potential concentration of heavy metals. Top of the food chain fish have a long time to ingest and concentrate heavy metals from all the fish they eat in their (longer) life while heavy metal levels in bottom of the food chain varieties are much less. In any case, you have to eat an awful lot of fish for any of this to be a problem anyway, so don't let it put you off!
Other than the (IMO slightly over hyped) heavy metal issue, fish is a fantastic source of protein / omega 3s etc for so many reasons and great for weight loss. It also helps that the bottom of the food chain fish species are relatively cheap and abundant...
I just wanted to add that not all animal proteins are created equal. Fish three times (or more) per week is fine IF the fish involved is a bottom of the food chain, short lived variety. So small whiting, herring, bream, trout, even farmed salmon etc. Tuna however qualifies as closer to the top of the food chain so eat moderately although I'm not so sure of the farmed stuff as their diet is controlled for them. Shark is definitely toward the top although most commercial shark species are taken relatively young.
This is all due to potential concentration of heavy metals. Top of the food chain fish have a long time to ingest and concentrate heavy metals from all the fish they eat in their (longer) life while heavy metal levels in bottom of the food chain varieties are much less. In any case, you have to eat an awful lot of fish for any of this to be a problem anyway, so don't let it put you off!
Other than the (IMO slightly over hyped) heavy metal issue, fish is a fantastic source of protein / omega 3s etc for so many reasons and great for weight loss. It also helps that the bottom of the food chain fish species are relatively cheap and abundant...