Interest in the Mediterranean diet with its high content of Omega-3 fatty acids from fish has skyrocketed in recent years, after it has been observed that people living in regions bordering the Mediterranean Sea appeared to live longer and suffer less from cardiovascular disease. In particular, a Mediterranean diet that includes fish has long been associated with a low rate of heart disease in countries such as Spain, Greece, and Italy.
But whether or not this diet can benefit patients who have already suffered a heart attack has not been tested in depth before the GISSI study. Thus, the purpose of GISSI was to investigate the effects of omega-3 fatty acids and vitamin E on cardiovascular events after people have had a heart attack.
Who forms the GISSI study group?
GISSI, an Italian group for the study of the survival of Heart Attacks (Myocardial Infarction) is an influential cardiology research group founded as a collaboration between two Italian organisations the Mario Negri Institute and the Associazione Nazionale dei Medici Cardiologi Ospedalieri. The trials carried out by GISSI have obtained wide recognition in the international world of cardiology and are considered a methodological landmark. Four large-scale clinical trials over the past 20 years (GISSI 1, GISSI 2, GISSI 3, GISSI Prevention) have involved more than 60,000 patients with acute myocardial infarction.
The GISSI study
Between October 1993 to September 1995, 11,324 patients participated in the GISSI trial. To qualify as a participant for the study, the patients must have survived a recent heart attack (less than three months prior to being enrolled in the study). Patients were randomly assigned to four treatment groups:
Group 1- Patients received 1 gram of fish oil containing 85% of Eicosapentaenoic acid, EPA, and Docosahexaenoic acid, DHA.
Group 2- Patients received 300 mg of vitamin E, a synthetic a-tocopherol supplement.
Group 3- Patients received a combination of omega-3 and vitamin E
Group 4- Control group, patients did not receive treatment
The results were very significant for dietary supplementation with omega-3s from fish oil. Treatment with omega-3s resulted in a 45% reduction in the risk of having a sudden fatal heart attack, a 30% decrease from cardiovascular mortality and a 20% reduction in overall mortality. According to the researchers, Vitamin E supplements were found to have no benefits on heart attacks.
Marchioli, senior author of the study, reported that the people who followed a Mediterranean style diet that included more vegetables, fruit, fish, but little butter, were less likely to die than people who reported eating higher amounts of butter, cheese, and vegetable oils other than olive oil.
Similar benefits of a Mediterranean-style diet were seen in earlier, smaller randomized trials. In the Lyon Diet Heart Study, benefits were seen in patients who after a heart attack were assigned to a diet rich in [alpha]-linoleic acid, ALA, from plant sources along with plenty of legumes, cereals, fresh fruits, and vegetables. Compared with those assigned to a “prudent” diet similar to the American Heart Association step 1 diet, those on the Mediterranean style diet had a 70% reduction in deaths, repeat heart attacks, unstable angina, stroke, congestive heart failure, or embolic events.
Where do you find EPA and DHA?
Long-chain omega-3s, EPA and DHA, are most abundant in fish and shellfish, particularly fatty fish such as salmon, rainbow trout, tuna, mackerel, herring, and sardines. All seafood has some EPA and DHA. Fish oil capsules are a rich source of EPA and DHA, too.
How much Omega-3s do you need to take?
100 grams (3.5 ounces) of salmon provide 5,000 mg of EPA and DHA, followed by tuna with about 2,300 mg and trout with 1,470 mg. Other fish with high content of Omega-3s are sardines, mackerel, and anchovies.
A daily ingest should contribute between 1.1 and 1.4 grams. A fatty fish portion will cover this need.
For people who already have a heart condition, eating seafood more often, or consuming marine omega-3s from supplements, is just as important. If you have already suffered a heart attack, you could supplement your fish intake with a good quality fish oil supplement.
Are Plant and Fish Omega-3s born equal?
No. The omega -3s found in terrestrial plants, such as some nuts or the ones found in enriched foods, are ALA. Terrestrial plants have only ALA . This omega-3 has some, but not all, of the health benefits associated with fish oil omega-3s. It can also be converted in the body to EPA and very small amounts of DHA but humans perform this conversion very poorly, less than 5%, so relying only on ALA for all omega-3s risks having a deficiency in EPA and especially in DHA
And remember that
Our body either cannot produce Omega-3s or does not produce enough quantities to support good health. Therefore, they have to be ingested from our diet.