Eating one salmon fillet a day is the key to keeping blood pressure at optimal levels, scientists say.
A study has found consuming three grams of omega-3 fatty acids each day is the optimal dose for people of all ages. That is the equivalent of 120g of salmon.
Researchers looked at 70 studies that included 5,000 participants aged 22 to 86.
They found three or more grams of omega 3s per day lowered blood pressure in just 10 weeks by 2mmHg in both systolic pressure and diastolic pressure.
And those with high blood pressure saw more than double the drop.
The team, from Macau University in Guangdong, China, said vegetarians and vegans can also reap the benefits of omega-3s through supplements.
Dr Xinzhi Li, study author and an assistant professor in pharmacy at the university, said adults can see ‘modest’ blood pressure reductions from eating extra portions of the fish.
Current NHS guidelines advise Britons eat 280g of omega 3s per week.
Researchers, who examined 70 studies that included 5,000 participants, found consuming three grams of common omega-3 fatty acids daily can lower blood pressure in just 10 weeks. The portion is equivalent to eating around a 120g salmon fillet each day. Tuna, sardines, trout, herring and oysters are also high in the omega-3s
How much fish should we eat?
A healthy, balanced diet should include at least two portions of fish a week, including one of oily fish.
Most people don’t eat this much. A portion is around 140g.
However, for certain types of fish, there are recommendations about the maximum amount you should eat.
Britons are told to eat at least one portion (around 140g when cooked) of oily fish a week.
However, girls, women planning to have a child and pregnant women should not eat more than two portions of oily fish a week.
This is because pollutants in the fish can affect the future development of babies in the womb.
Britons are also told to avoid eating too much sea bream, sea bass, turbot, halibut, rock salmon and crabs as these also contain pollutants.
More than one in four Britons and nearly half of Americans suffer from high blood pressure, which increases the risk of heart attacks and strokes.
Omega-3s, which people can only get from certain foods and supplements, are involved in making hormones that regulate blood clotting, inflammation and the contraction and relaxation of artery walls.
Studies have suggested that the fats help control blood pressure and prevent heart disease and strokes due to their role in these bodily functions.
Two of the main types of omega-3s are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which mainly come from fish.
But the Macau team said it is unclear how much people need to eat to gain these health benefits.
They analysed the results from 71 clinical trials that examined how DHA and EPA consumption affects blood pressure.
All of the participants consumed different amounts of fatty acids for an average of 10 weeks, either as part of their diet or a supplement.
Blood pressure is measured as two figures in millimetres of mercury (mmHg).
The first is for systolic pressure — the pressure when your heart pushes blood out — and diastolic pressure — the pressure when your heart rests between beats.
The NHS says an ideal blood pressure is between 90/60mmHg and 120/80mmHg, while high blood pressure is considered to be above 140/90mmHg.
The results, published in the Journal of the American Heart Association, show that those who consumed two to three grams per day of DHA and EPA omega-3 fatty acids had lower blood pressure compared to those who had none.
The average reduction was 2mmHg in both systolic and diastolic pressure.
A standard 120g salmon fillet provides three grams of omega 3 fatty acids.
The researchers said a typical fish oil supplement contains around 300mg per pill but doses vary widely.
And those with high blood pressure could benefit even more.
People suffering from hypertension who consumed three grams per day of omega-3s saw their systolic blood pressure drop by 4.5mmHg.
However, upping omega-3 intake further did not seem to trigger any additional benefits. Blood pressure patients saw the reduction fall to 4mmHg if they ate 5g per day, while those without hypertension saw a less than 1mmHg decrease.
The researchers said the findings also applied to those with high blood lipids and older adults.
Dr Li said: ‘Most of the studies reported on fish oil supplements rather than on EPA and DHA omega-3’s consumed in food, which suggests supplements may be an alternative for those who cannot eat fatty fish such as salmon regularly.
‘Algae supplements with EPA and DHA fatty acids are also an option for people who do not consume fish or other animal products.’
The US Food and Drug Administration (FDA) announced in June 2019 that companies could claim food and supplement products with omega-3 fatty acids may reduce blood pressure and heart disease.
However, it noted that the evidence is ‘inconclusive and highly inconsistent’.
Dr Li said: ‘Our study supports the FDA guidance that EPA and DHA omega-3 fatty acids may reduce the risk of coronary heart disease by lowering high blood pressure, especially among people already diagnosed with hypertension.’
WHAT SHOULD A BALANCED DIET LOOK LIKE?
Meals should be based on potatoes, bread, rice, pasta or other starchy carbohydrates, ideally wholegrain, according to the NHS
• Eat at least 5 portions of a variety of fruit and vegetables every day. All fresh, frozen, dried and canned fruit and vegetables count
• Base meals on potatoes, bread, rice, pasta or other starchy carbohydrates, ideally wholegrain
• 30 grams of fibre a day: This is the same as eating all of the following: 5 portions of fruit and vegetables, 2 whole-wheat cereal biscuits, 2 thick slices of wholemeal bread and large baked potato with the skin on
• Have some dairy or dairy alternatives (such as soya drinks) choosing lower fat and lower sugar options
• Eat some beans, pulses, fish, eggs, meat and other proteins (including 2 portions of fish every week, one of which should be oily)
• Choose unsaturated oils and spreads and consuming in small amounts
• Drink 6-8 cups/glasses of water a day
• Adults should have less than 6g of salt and 20g of saturated fat for women or 30g for men a day
Source: NHS Eatwell Guide