Health benefits of seafood
Research carried out on seafood consumption has shown compelling evidence of associated health benefits. In fact, has been proved that eating seafood can help prevent some diseases and improve the symptoms of others.
1 Brain power
The human brain is almost 60% fat and much of this is the Omega-3 fat DHA (docosahexaenoic acid). Studies have shown that people who eat plenty of fish during their lives tend to experience less dementia and memory problems as they get older.
Other research has also suggested that adding more DHA to the diets of children with attention-deficit hyperactivity disorder (ADHD) can reduce their behavioural problems and improve their reading skills, while there have also been links suggested between DHA and better general concentration.
2 Heart health
The strongest evidence for the nutritional value of seafood is for its role in maintaining a healthy heart. Interest in this was sparked when scientists noticed that traditional fish-eating communities, such as Inuits and the Japanese, experience less heart disease and fewer strokes. This led to a number of studies comparing fish eaters and non-fish eaters around the globe. One long-term study of American nurses found that deaths from heart disease were 50% lower in nurses who ate seafood five times a week. This increased to a 60% lower risk if the nurses had diabetes. A review of the independent studies showed that eating seafood even one to three times a month reduced the risk of heart attack or stroke, although eating seafood more than once a week gave the best results.
Other studies have looked at the impact of fish or fish oils on risk factors that can lead to a heart attack, e.g. LDL cholesterol or triglycerides. Some blood fats clog up arteries if they get too high; diets high in saturated animal fat are known to push up levels of LDL cholesterol and triglycerides. In contrast, many studies have shown that habitual fish-eaters have a better balance of blood fats, meaning that their risk of a heart attack is lower. Fish also seems to have beneficial effects on risk factors for coronary heart disease, e.g. reducing the risk of blood clots.
3 Immune function support
The immune system exists in a fine balance. EPA (eicosapentaenoic acid) and DHA – the natural Omega-3 fatty acids in oil-rich fish – are thought to have specific properties that calm and normalise the immune system. While eating seafood can’t prevent inflammatory or allergic conditions from developing in the first place, it can help with symptoms such as swelling and pain.
4 Pregnancy
The good news is that eating seafood and shellfish while you’re pregnant or breastfeeding is beneficial for your health and the development of your baby – in fact, they should play an important role in every mother’s diet. However, there are just a few types you need to limit or avoid.
Types of fish to avoid or limit while pregnant
During pregnancy, there is an increased need for essential fatty acids – for the mother, the placenta and the baby it supports, particularly in the third trimester. Omega-3, found in a wide range of seafood, is an important source of these essential fatty acids.
The British medical journal, The Lancet, has showed that fish is an extremely important substance to have during pregnancy. Children whose mothers ate fish during their pregnancy had a ‘higher intelligence quotient’ (IQ) than those who didn’t eat fish. This is largely due to the Omega-3 fatty acids. Which makes seafood a pretty bright choice.
Eat seafood twice a week, both before and during your pregnancy, for the benefit of your unborn baby. Vary the types of seafood that you eat, so that you maximise the benefits of the nutrients contained in seafood.
How much fish to eat while pregnant
There’s absolutely no need to limit the amount of white fish or shellfish you eat when you’re trying for a baby, or while pregnant, apart from shark, swordfish and marlin. Why? Because these species contain more mercury than other types of fish. The amount of mercury in food isn’t harmful for most people, but if you take in high levels when pregnant, this could affect your baby’s developing nervous system. When you’re breastfeeding, you don’t need to avoid eating these fish. The UK Food Standards Authority recommends that you eat at least two portions of fish each week, one of which should be oil-rich fish (to help you obtain healthy Omega-3 fatty acids).
Types of fish to avoid or limit while pregnant
Avoid shark, swordfish and marlin, as they contain mercury and other pollutants that can harm your baby’s developing nervous system. You should also limit the amount of tuna you eat to no more than two medium-sized tuna steaks (weighing about 140g when cooked, or 170g raw) or four medium-size cans of tuna per week (with a drained weight of about 140g per can). You should also generally avoid having more than two portions of oily fish per week, e.g. salmon, trout, mackerel and herring, because they can contain pollutants such as dioxins and PCBs (polychlorinated biphenyls).
Fresh tuna is an oil-rich fish, so if you eat two fresh tuna steaks in one week, you shouldn’t eat any other oil-rich fish that week. During the canning process, the oil-rich content is lost and therefore, tinned tuna doesn’t count as oily fish, so you can eat this as well as your two portions of oil-rich fish. But remember not to eat more than four medium-sized cans of tinned tuna per week when you’re pregnant or trying to get pregnant.
Eating shellfish while pregnant
According to the UK Food Standards Agency, shellfish is safe to eat while pregnant as long as it’s well cooked. In fact, it’s an important and healthy protein, high in Omega-3 fatty acids, which, together with other nutrients, are vital for the development of your baby’s brain, eyes and nervous system. Shellfish is also low in saturated fat. If you’re expecting, there’s no need for you to miss out on shellfish, as long as you ensure that it’s thoroughly cooked, as raw shellfish carries a risk of food poisoning. Good ideas for healthy recipes include crab cakes or a quick prawn stir-fry.
Eating smoked fish while pregnant
Smoked fish is cured and not ‘raw’, so it’s safe to eat while pregnant, according to the Food Standards Agency. Some countries advise pregnant women not to eat smoked fish because of the risk of listeria, but here in the UK the risk is very low. Oil-rich fish, such as mackerel, sardines, herring, pilchards and salmon, are great during pregnancy, and rich in essential fats such as Omega-3 – but not more than two portions a week.
Try flaking heated smoked mackerel into rice and adding hard-boiled egg and chives for a quick kedgeree, or adding it to a baked potato for lunch with some crème fraîche.
Eating fish at a restaurant while pregnant
Seafood is safe to eat while pregnant as long as it’s well cooked or cured, according to the Government’s Food Standards Agency. UK restaurants must comply with strict hygiene and cooking standards, but if you want extra reassurance then you could always inform the restaurant staff that you would like special care to be taken that the seafood is cooked through.
Eating sushi while pregnant
It’s fine to eat sushi when you’re pregnant, and other dishes made with raw fish, as long as the fish used to make it has been frozen first. This is because, occasionally, fish contains small parasitic worms that could make you ill. Freezing kills the worms and makes raw fish safe to eat.
Sushi sold in shops or restaurants, whether it’s ready-made or prepared in the shop, should be fine to eat. This is because the raw fish that the shop uses to make sushi must have been frozen at minus 20°C for at least 24 hours.
If you make your own sushi at home, freeze the fish for at least 24 hours before using it. Some raw fish used to make sushi, such as smoked salmon, doesn’t need to be frozen before it’s used. This is because smoking the fish kills any worms that might be in it. Other methods, such as salting or pickling, are also used to make raw foods safe to eat.
Eating fish when trying for a baby
Oil-rich fish, in particular, should be eaten as part of a healthy varied diet when you’re trying for a baby. Fish pie, for example, is classic comfort food and is rich in nutrients, especially as it contains salmon, which provides the Omega-3 fats you need to store up in preparation for your pregnancy.
For more information on fish and pregnancy, visit www.nutrition4baby.co.uk
5 Infants
It’s important for infants to obtain Omega-3 via their diet – and seafood is a natural source. DHA is vital for normal brain and eye development. It’s good for the brain, because it makes brain cells more responsive to messages; and it helps eyesight by boosting and developing the retina. Breast-fed babies have better eyesight and higher IQs than bottle-fed babies because breast milk is rich in DHA and arachidonic acid (an essential polyunsaturated Omega-6 fat). Babies supplemented with DHA and arachidonic acid seem to benefit, particularly if they were born pre-term. Other supplementation studies have found that women taking fish oil during pregnancy give birth to babies who have sharper eyesight and grow up having a higher IQ than children from unsupplemented women.
Babies can safely start eating fish at 6 months.So, when weaning little ones, be aware of the following:
- Prawns (small ones used for a prawn cocktail) are great for children. Wash the prawns to remove any excess salt and then just let them pick them up themselves.
- Smoked mackerel should not be given to a child under the age of 18 months, due to the salt content.
- When preparing fish for infants, always take great care to ensure that all bones have been removed.
6 Post-natal depression
Pregnancy is known to deplete mothers’ DHA reserves due to it being used to assist with brain development in the foetus, particularly in the third trimester. By the time the baby is born, blood DHA levels in the mother can be very low, which impacts on breast milk DHA content. Scientists are already seeing a steady decline in the Omega-3 content of breast milk over the last few decades combined with a rise in Omega-6. As expected, low intakes of seafood and high intakes of vegetable oils and margarine are blamed. These changes in breast milk are likely to have an impact on DHA intake in babies, but no one knows what might arise from this. A low-DHA status after pregnancy could also increase the risk of post-natal depression. Low levels of DHA have been found in the blood of new mums who didn’t develop the condition. Pregnant women should be encouraged to eat more seafood, especially oil-rich fish, but should be aware of the species to avoid during pregnancy.
Other kinds of depression may have a link with a poor DHA status. Studies have found that people diagnosed with clinical depression have low levels of DHA in their blood.
7 Depression and hyperactivity
A study of 3,200 Finnish people discovered a link between low fish intake and symptoms of depression. It‘s likely that regular fish intake boosts DHA status and protects against depression.
Much has been reported in the media about the impact of fish oils on behaviour. While the evidence is not yet complete, it’s clear that fish oils help certain conditions. Hyperactivity in children (or ADHD) is a learning disorder that often responds to supplementation with fish oils. Around 2-4% of children in the UK have ADHD and studies have found sufferers to have imbalances in their blood Omega-3 levels. Supplementation studies don’t always give the same result, which suggests that some children respond better than others. Eating more seafood is perhaps a more natural way to ensure that children get enough DHA and EPA.
8 Dementia and Alzheimer’s disease
Dementia is a common disorder among elderly people and can affect as many as 30% of those aged over 85 years. Two Dutch studies, involving several thousand subjects, have reported that regular consumption of fish seems to protect against age-related brain impairment and dementia.
A USA study found a link between low fish consumption and Alzheimer’s disease. No supplementation studies have been carried out, as yet, in the elderly. However, the idea that fish is helpful for maintaining brainpower throughout life is certainly gaining approval among scientists.
9 Obesity
With obesity on the rise, more and more consumers are interested in foods that support weight loss. Many studies have now shown that a high-protein, low fat diet is best for aiding weight loss. Protein seems to control appetite, helping people to feel full. So, seafood, as a low fat, high-protein food is ideal for this type of diet, particularly if the fish is grilled, baked or poached.
Research, presented at a Seafood and Health conference in London in 2009, indicates that seafood satisfies the appetite more than other forms of protein, thereby encouraging weight loss.
In the 1990s, researchers at the University of Sydney, Australia, compared the ‘filling’ effects of different foods on appetite. Their study came up with the ‘satiety index’: participants in the study rated their satiety (their ‘feelings of fullness’) over two hours following eating a 240-calorie portion of different foodstuffs.
Scientists then developed a list of the best foods for keeping people feeling fuller for longer, meaning that you are less likely to overeat. It’s clear that certain foods satisfy hunger much better than others, with seafood ranking highly. For the best results, steam or grill a fillet of white fish, such as bass or halibut.
In other studies, participants consuming the rich fish or Omega-3 diets felt significantly more full and less hungry compared with those on the diets low in Omega-3. They also showed that eating seafood regularly might improve several metabolic and clinical alterations observed in obesity.
10 Eye health
Eating oil-rich fish regularly can also help keep eyes bright and healthy. According to a recent study, marine Omega-3 fatty acids can help protect the eyesight of people suffering with age-related macular degeneration (AMD), a condition caused by the deterioration of the retina, causing blurred, fuzzy or distorted vision. Scientists recommend that people suffering with AMD should eat oil-rich fish at least twice a week, while some experts have also suggested that a diet rich in Omega-3 can cut a person’s risk of getting AMD by a third. Fish and shellfish are also known to be rich in retinol – a form of vitamin A that is easily absorbed into the body and helps to boost night vision.
11 Cancer
Some studies are now linking a high intake of fish with a lower risk of cancer, particularly bowel cancer. No one knows, as yet, why this is the case or what sort of impact eating fish might have on cancer development.
12 Diabetes
New research suggests that a regular intake of fish and seafood protects people from developing Type 2 (maturity onset) diabetes. This condition, usually controlled by drugs or diet, is now affecting more people in the UK because of our growing waistlines. It’s not yet known for certain why fish consumption helps combat the condition.
13 Circulation
Eating seafood regularly can improve your circulation and reduce the risk of thrombosis – painful blood clots in the arteries that can be fatal. This is because fish oils are rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). If a diet is high in EPA and DHA, the body is less likely to use other fats that produce powerful versions of hormone-like substances called eicosanoids. These powerful signalling chemicals make the body more likely to suffer inflammation and form blood clots. So, more EPA and DHA means less risk for your circulation. Fish oils are also thought to increase the levels of nitric oxide released by the body into the blood, which helps to relax the blood vessels and so improve blood flow.
14 Joint benefits
Including seafood as a regular part of a balanced diet has been shown to help the symptoms of rheumatoid arthritis – a painful condition that causes joints to swell up, reducing strength and mobility. Studies also show that sufferers feel less stiff and sore in the morning if they keep their fish oil intake topped up. Recent research has also found a link between Omega-3 fats and a slowing down in the wearing down of joint cartilage that leads to osteoarthritis, opening the door for more research into whether eating more seafood could help prevent the condition.
15 Breathing and asthma
A number of studies have suggested that fish may help protect the lungs. One found that children suffering from asthma were more likely to show an improvement when fish oils were introduced into their diet, while another suggested that children who eat lots of fish might be less likely to become asthmatic. Fish may also help to increase your ‘puffing’ power – with research showing that people who eat a lot of fish tend to have more powerful lungs in old age than those who eat none.
16 Healthy skin
Not only do Omega-3 fats help the skin protect itself against harmful effects of the environment, such as UV damage from the sun’s rays, but eating lots of fish oils can also help with the symptoms of skin conditions such as eczema and psoriasis, making skin feel less itchy. And as fish is also a rich source of protein – an essential ingredient of collagen, which keeps skin firm – a seafood-rich diet could help to hold back the years by making skin more resistant to the effects of ageing.
17 Digestion
There is some evidence to suggest that a diet rich in fish oils can help to protect against serious IBDs (inflammatory bowel diseases), such as Crohn’s disease and ulcerative colitis. Studies of the Inuit populations in the Arctic have shown very low levels of IBD, and some scientists believe this may be thanks to Omega-3 fats in these people’s fish-based diet. There is also some evidence that taking in more Omega-3 fats may help slow the progression of disease in some IBD sufferers. More research is being conducted.
18 Cholesterol
It’s an old fishwives’ tale that certain foods containing dietary cholesterol, such as shellfish, should be avoided. It’s now known that saturated fat is more influential in raising blood cholesterol than dietary cholesterol itself.
There’s cholesterol and then there’s cholesterol: first, there’s dietary cholesterol that’s present in food, such as eggs and prawns; and then there’s blood cholesterol, which is the level present in the bloodstream. It’s blood cholesterol that people need to control in order to remain healthy. Generally, cholesterol from food has very little effect on the blood cholesterol level; the amount of saturated fat you eat is far more crucial.
The healthy option is to enjoy a balanced diet while cutting down on saturated fat, rather than exclude foods containing cholesterol. Shellfish is a prime ‘healthy’ candidate. The many species available in the UK are both delicious and extremely nutritious. Thankfully, not only very low in saturated fat, shellfish also counts towards the recommended two portions of seafood that we’re all advised to eat each week.
Good news for all mollusc lovers: cockles, mussels, oysters, scallops and clams all are very low in cholesterol – about half as much as chicken – and contain much less cholesterol than red meats. They’re also very low in saturated fat, low in calories and contain Omega-3 fats – so you can eat as much as you like.
Around one in a 100 people suffers from high blood cholesterol caused by a genetic condition called Familial Hypercholesterolemia (FH) or Familial Combined Hyperlipidaemia (FCH). Those with this condition often need to be more cautious in their consumption of high-cholesterol foods. Their dietary cholesterol may also need to be carefully managed in line with advice from a doctor or registered dietician.
