Do you know how much fish you should be eating? Well, eating around 250g of seafood twice a week is healthy. But no so much when it’s consumed in excess, and it may also contain methyl mercury, a neurotoxin.
After analysing the data of 10,673 adults who took part in the 2007-2010 NHANES study, researchers found a link between seafood consumption and blood mercury levels. As seafood consumption increased, so did average blood mercury levels, from 0.45 micrograms/L among people who did not eat fish to 1.70 micrograms/L among those who ate fish five or more times per month.
High frequency in crab and shrimp consumption was not associated with increasing blood mercury levels but the increasing frequency of both tuna and salmon consumption was associated with a 14% higher risk and other seafood, 12%.
Mercury levels in fish is a problem. That swordfish you see? It’s practically dripping with mercury – just like king mackerel, and other large predatory fish.
So here’s what you should reel in: according to a Scandinavian study, small, oily fish like sardines, herrings and anchovies contain high levels of heart-healthy omega-3s; and because they’re low on the food chain, they house less mercury than their big brothers.
Try canned versions of the little guys mashed into a mustardy dressing for spinach, or on top of an open-faced sandwich of wholewheat bread, cream cheese, thinly sliced red onion and a squeeze of lemon juice.
But of course, it is always important to check whether the fish you are eating is on the green list and okay to eat. You can find a list on SASSI (The Southern African Sustainable Seafood Initiative).