From boosting brain function to protecting against Alzheimer’s, health experts continue to espouse the benefits of oily fish – but exactly how much should you be eating, and when is an omega-3 supplement necessary? Here’s what you need to know about oily fish...
So, which fish count as oily fish?
Oily fish – namely anchovies, sardines, herring, mackerel, trout, salmon and fresh (not tinned) tuna – are packed full of omega-3 fatty acids. They’re darker and stronger in flavour than white fish such as cod and hake and have a higher healthy fat content.
And why is it good for you?
Omega-3 oils have been credited with a number of health benefits, from easing the stiffness and joint pain of conditions such as osteoarthritis to reducing chances of heart disease. Recent studies have also suggested that such ‘good’ fats can have a positive effect on mental health, helping to lower levels of depression and possibly protect against dementia. Oily fish is also brimming with high levels of protein, vitamin D, iodine, potassium, iron, zinc, selenium, B vitamins and even calcium in the smallest fish (where you can eat the bones, such as anchovies and sardines).
So how do you get enough omega-3 in a vegetarian diet?
Shorter-chain omega-3s can be found in dark green veg, nuts, soya products and rapeseed, but our bodies aren’t very good at converting these shorter chains into longer, beneficial EPA and DHA (the most important forms of omega-3). As a result of this, vegetarians and vegans should consider taking a supplement as well as eating a well-balanced, plant-based diet.
So, how much oily fish should you be eating?
As a polyunsaturated fat (a long-chain fat the body can’t produce itself), it's essential oily fish is present in our diet. As a general rule, it is advised we should be eating around one to two portions of oily fish per week, ideally enjoying more of the smaller varieties (mackerel and sardines) than the larger ones (especially tuna). A portion is in the region of 140g, or one medium-sized fillet. Official NHS advice also says you can eat a further one to two portions of white fish or seafood on top of this per week.
Do you need to take a supplement, too?
Not necessarily. If you tend to eat the weekly recommend amount of oily fish, there’s no need for you to take an additional supplement. And no matter the vitamin or mineral, it’s always better to source it through food rather than supplements, which tend to vary in quality. If you do choose to take a supplement (perhaps you don’t like fish or have been advised by your GP), aim for a daily intake of 500-1000mg of EPA and DHA, and make sure you’re not taking any other form of vitamin A, as excessive amounts can cause health problems.
Is there anyone who should be wary of eating oily fish?
While eating fish in pregnancy is good for both you and your baby, you should be a little more wary of the effects of pollutants and should, therefore, avoid all raw shellfish, such as oysters, as well as fresh tuna. Also, be cautious about taking fish oil supplements during pregnancy – some, such as cod liver oil, can contain high levels of vitamin A, which can be harmful to your unborn baby. The same goes for those who are thinking about getting pregnant as well as those trying to conceive.
Any tips on boosting your oily fish intake?
To reap the benefits, try mixing up your dishes. Make kedgeree, which is brimming with omega-3, and swap the traditional white rice for a brown variety for longer-lasting energy. Also, try using tinned salmon instead of tinned tuna, or stir tinned sardines through linguine with chilli and capers for a fresh, tasty supper.
It’s worth noting most fish and shellfish now contain some levels of pollutants or heavy metals such as mercury – this may be a concern if you eat a lot of fish, or eat mainly the larger types of fish, such as tuna (remember, tinned tuna does not count as an oily fish, but a tuna steak does). Also, farmed fish may contain more pollutants, and fewer omega-3 fats, than wild or marine fish, so be aware of this when in the supermarket.
For more information, check out the official NHS advice.