A new study suggests that good intakes of fish oil can reduce the risk of developing hypertension.
Researchers analysed data from 8 trials, involving over 56,000 people, who were followed for between 3 to 20 years. They found that having a good circulating blood level of long chain omega-3 fatty acids, especially one called DHA, was associated with a 33% lower relative risk of developing hypertension, suggesting a protective effect.
Eating more fish can lower your blood pressure
Interestingly, no significant associations were found for dietary intakes of fish in this analysis – it all came down to blood levels of circulating omega-3s.
In many ways this is not surprising, as few people eat enough fish to maintain protective levels of omega-3. The National Diet and Nutrition Surveys in the UK, for example, found that only 23% of people aged 19-64 ate any oily fish at all, and that the average consumption in all age groups was well below the recommended one portion per week (140g).
Among adults, average consumption was just 54 to 87 grams per week – around a third to one half of a portion – too little to have any beneficial effect on blood pressure or arterial stiffness.
Official recommendations are to eat two portions of fish per week, of which one is oily (eg salmon, herring, mackerel, sardines, pilchards, fresh tuna). This is very much a minimum and is limited by the fact that deep-sea fish contain harmful pollutants such as PCBs, dioxins and mercury. As a result, girls and women of fertile age are advised to eat no more than two portions of oily fish per week (to protect future offspring), while boys and men can eat up to four portions of oily fish per week.
To achieve protective circulating levels of omega-3 that are high enough to prevent hypertension, most people will need to take a fish oil supplement.
Take a fish oil supplement
If you have high blood pressure, I recommend that you take a pharmaceutical grade fish oil supplement as these are screened and distilled to remove pollutants.
If you already have a raised blood pressure, doses of between 0.7g and 1.8g of the long-chain omega-3s (EPA and DHA) are needed to have a significant antihypertensive effect.
If your blood pressure is raised, self-monitoring is key to maintaining good control.
Click here for advice on choosing a blood pressure monitor to use at home.
See my recommended upper arm blood pressure monitors.
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