Eating two portions of oily fish a week could help ward off a stroke, research suggests.

Scientists have found that eating two helpings of oily fish - such as salmon, trout or mackerel - every week could moderately reduce risk of a stroke.

However, fish oil supplements do not have the same beneficial effect as oily fish such as kippers, sardines, fresh tuna or whitebait, the study found.

An international team of researchers, including Cambridge-based academic Dr Rajiv Chowdhury, examined the association between oily fish, which are a good source of Omega 3 fatty acids, and the risk of strokes or mini-strokes.

They looked at 38 studies involving almost 800,000 people across 15 countries, and examined participants' fish and long chain omega 3 fatty acid consumption. During the studies, a total of 34,817 strokes and mini strokes were recorded.

After adjusting for several risk factors, participants eating two to four servings a week had a 6% lower risk of stroke compared with those who consumed one portion or less every week, the study found.

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  • Severe Headaches

    Sudden severe headaches could be a sign of a stroke, according to the <a href="http://www.stroke.org/site/PageServer?pagename=SYMP" target="_hplink">National Stroke Association</a>.

  • Difficulty Walking

    Having "trouble walking, dizziness, loss of balance or coordination" are all signs of a stroke, according to the <a href="http://www.stroke.org/site/PageServer?pagename=SYMP" target="_hplink">National Stroke Association</a>.

  • Trouble Seeing

    Is the person having difficulty seeing in one or both eyes? This is one of the symptoms of a stroke, according to the <a href="http://www.stroke.org/site/PageServer?pagename=SYMP" target="_hplink">National Stroke Association</a>.

  • Confusion

    "Sudden confusion, trouble speaking or understanding," are all signs of a stroke, according to the <a href="http://www.stroke.org/site/PageServer?pagename=SYMP" target="_hplink">National Stroke Association</a>.

  • Numbness

    One-sided numbness of the face, arms or could be a sign of a stroke, according to the <a href="http://www.stroke.org/site/PageServer?pagename=SYMP" target="_hplink">National Stroke Association</a>.

  • Remember FAST

    The National Stroke Association also recommends you get familiar with the acronym FAST. <strong>F is for face.</strong> When you ask the person to smile, does their face droop? This is one of the a warning signs of a stroke, according to the <a href="http://www.stroke.org/site/PageServer?pagename=SYMP" target="_hplink">National Stroke Association</a>.

  • Remember FAST

    <strong>A is for arms.</strong> When you ask the person to raise up both arms, does one droop? This is a warning sign of a stroke, according to the <a href="http://www.stroke.org/site/PageServer?pagename=SYMP" target="_hplink">National Stroke Association</a>.

  • Remember FAST

    <strong>S is for speech.</strong> "Ask the person to repeat a simple phrase," advises the <a href="http://www.stroke.org/site/PageServer?pagename=SYMP" target="_hplink">National Stroke Association</a>. "Is their speech slurred or strange?"

  • Remember FAST

    <strong>T is for time.</strong> Time is of the essence if you observe any of these warning signs, according to the <a href="http://www.stroke.org/site/PageServer?pagename=SYMP" target="_hplink">National Stroke Association</a>. Call 911 immediately.

Fish oil supplements were not significantly associated with a similar reduced risk, according to the paper published on bmj.com.

Eating oily fish has already been linked to other health benefits such as reducing the risk of heart disease.

The Food Standards Agency recommends that everyone should eat at least two 140g portions of fish a week, including one portion of oily fish.

"From past research we know that eating plenty of fish is good for our general health," said Dr Peter Coleman, deputy director of research at the Stroke Association.

"This research shows that it could also help to protect us against stroke. However, it's interesting to see that taking fish oil supplements doesn't have the same beneficial effect.

"People who eat lots of fish may have healthier diets in general which could go some way to explain the results. However, a lot more research is needed in this area before we decide to eat fish every day of the week.

"Everyone can reduce their risk of stroke by exercising regularly, consuming a healthy, balanced diet and getting your blood pressure checked."