MEDICAL MATTERS:Omega 3 oil can help after heart attacks but they aren't always ideal, writes MUIRIS HOUSTON.
MEDICAL CONSULTATIONS offer a rich tapestry of human interactions. Some have vague beginnings before crystallising into a defined problem with a menu of possible solutions. Others are apparently more direct: the presentation of an apparently simple issue with a request for an immediate resolution.
Last week a man in his early 50s came to see me with just such a request; was there any alternative to a daily dose of omega 3 fatty acids?
The man had a near total blockage of a coronary artery reversed by a means of a stent bypass some years ago.
Since then, he has been an avid student of preventive cardiology, keen to minimise the need to see the inside of a coronary care unit again.
The problem for him was severe tummy upset triggered by his daily dose of omega 3 fatty acid in the form of a prescribed capsule. In fact, he is one of almost 4 per cent of people for whom fish oil preparations cause tummy pain and acid reflux to an extent that they can no longer tolerate omega 3 medications.
Many of us who take fish oil capsules are also on a daily dose of aspirin designed to keep our blood flowing freely. However, it too can cause an upset tummy, with a risk of bleeding from the stomach a rare possibility.
The first evidence of the benefits of omega 3 fatty acids emerged in the early 1970s when Danish doctors noted that the indigenous population in Greenland have a markedly lower incidence of heart disease even though they consumed a high fat diet. Further research established that it was a diet rich in oily fish that was responsible.
We now know that the Inuit eat large amounts of oily fat in the form of the long chain omega 3 fatty acids EPA and DHA and that these substances reduce levels of bad cholesterol and triglycerides in the blood.
The scientific evidence for the cardiac benefits of omega 3 seems robust. One trial of 19,000 patients with high cholesterol found that the risk of a major coronary event in those who received long chain omega 3 was lowered by 18 per cent.
And for people who have already suffered a heart attack, a study of 11,000 patients treated with omega 3 found a 44 per cent reduction in the risk of cardiac death within three months of commencing supplementation with long chain fatty acids.
However, a recent review of the topic in the International Journal of Clinical Practice(IJCP) looked at the evidence in some depth and raised questions.
The argument for supplementation is driven by the Italian GISSI-P study. Some 11,300 patients who had a heart attack in the previous three months were given either omega 3 fatty acids or vitamin E. It showed an 11 per cent reduction in mortality and cardiac events in the group who took fish oils.
A more recent Japanese trial also showed benefits, but in this case only for men who had had a heart attack at least six months prior to starting omega 3 supplementation.
But one question remains unanswered. For patients like mine, with a history of cardiac disease, is there much benefit from starting omega 3 fatty acids when a person is already taking cholesterol-lowering drugs? According to the IJCP, the data is confusing.
What about the practicalities of taking the right dose, especially if the convenient pill popping option causes side effects?
For most of us, two servings of oily fish, such as salmon, mackerel or fresh tuna, should supply the right amount. But for people with existing heart disease, the suggested intake of 1,000mg a day is hard to achieve without taking fish oil supplements.
Although up to three- quarters of adults do not consume oily fish, it is by far the best way to ensure a therapeutic dose of omega 3 fatty acids. However, if you do take supplements, be aware that high doses pose a small risk of bleeding.
If you are taking blood- thinning drugs such as aspirin, warfarin or clopidrogel, then it is best to check with your doctor before taking omega 3 supplements.
For the rest of the population with no heart disease issues, a regular dose of oily fish in the diet is the way to go.
Dr Houston is pleased to hear from readers at mhouston@irishtimes.com but regrets he is unable to reply to individual medical queries