Friday, February 10, 2012

Omega 3 and Reduced Risk of Myocardial Infarction

Myocardial infarction is a technical term used to describe an irreversible injury to heart muscle. It is normally used as a synonym for a heart attack and will be so used in this essay. Myocardial infarction is normally related to progressive atherosclerosis (blockage of the arteries.) Essentially the heart is slowly starved of oxygen and stops functioning properly causing irreparable damage and even death.
It is no surprise that much of the developed world suffers from heart disease because of diet and other lifestyle habits. In the United States heart disease remains the number one killer among adults and demonstrates similar statistics in many other modern countries. The surprise comes in knowing that the majority of heart disease is avoidable yet educated people continue to ignore the dangers and promote lifestyles conducive to cardiac damage. Though many factors contribute to heart disease the current essay will focus on one, in two parts. First we will consider the relation of fish consumption and myocardial infarction. Secondly we will consider the effects of dietary supplementation with omega-3 and vitamin E for those who had previously survived a heart attack.
Fish consumption and heart disease has been a topic of innumerable studies. One research project combined data taken from several such studies including the Chicago Western Electric Study, the Zutphen, Rotterdam and Swedish studies and the Study of U.S. Physicians among others. The goal of this research was to examine the relationship between fish consumption and the 30-year risk of death from coronary disease.
The participants of the study included 1,822 men between the ages of forty and fifty-five who were free of cardiovascular disease. For the first ten years annual examinations were given and mailed questionnaires and/or telephone interviews were used for the next fifteen years. Death certificates were used to classify cause of death for each patient.
During the 30-years follow up there were a total of 430 deaths from cardiovascular disease with 293 due to myocardial infarctions. Of the latter 196 were sudden, 94 were non-sudden and the remaining three could not be classified as either. Almost all of the sudden deaths were caused by myocardial infarction.
Detailed dietary history was kept on each participant with daily fish consumption as the primary focus. Each participant was categorized into one of four groups. The first group reportedly consumed no fish. The second group consumed between one and seventeen grams of fish per day. The third and fourth groups measured consumption as eighteen to thirty-four grams per day and greater than thirty-four grams per day respectively.
Predictably the results demonstrated an inverse relationship between fish consumption and the occurrence of myocardial infarction. In particular the participants who ate at least 35 grams of fish per day had a 42% lower death rate from heart attack compared to those who ate no fish at all.
The findings of these combined studies were consistent with other data concluding that diets high in fish demonstrate a reduced occurrence of death from coronary heart disease. This is especially true in relation to deaths that are of a non-sudden nature. That is not to conclude, however, that fish consumption does not inversely affect the risk of sudden cardiac death. Other studies have verified that such a relationship exists. Those studies are, however, beyond the scope of this essay.
But why does fish consumption improve heart health? It could just be the fact that people who eat fish eat less of other harmful foods. To focus a little more closely on the beneficial causes of fish consumption it is important to consider at least one study that isolated omega-3 intake via dietary supplements regardless of diet. The interesting thing about this study is that it was concerned with the effects of omega-3 and vitamin E supplementation on patients who had already experienced a heart attack.
The GISSI-Prevenzione trial, as it is known, hoped to establish any relationship that might exist between omega-3 and vitamin E as combined agents in the fight against heart disease. It was a randomized trial involving 11,234 patients who had survived a heart attack within the previous three months at the time the study began. The participants were divided into four groups. Group one received one gram of omega-3 supplements daily. Group two received 300mg of vitamin E every day. Group three received both while the control group received neither. Each participant received clinical examinations with blood samples taken and were asked to fill out diet questionnaires at the outset of the experiment and at six, twelve, eighteen, thirty and forty-two months.
The data were analyzed using two methods. A two-way analysis was made comparing omega-3 supplementing and no omega-3, as well as vitamin E intake compared to no vitamin E. A four-way analysis was also conducted comparing the combination of omega-3 and vitamin E with omega-3 alone and vitamin E alone. The effects of the combined supplements were also compared with the group that took no supplements.
The results of the test demonstrated a 14% decrease in death from any cause for the two-way analysis and a 20% drop in death rate for the four-way analysis. Concerning only death due to cardiovascular disease, the two-way analysis showed a 17% reduction of risk while the four-way analysis revealed a 30% decrease. Though vitamin E is known to be a powerful antioxidant, the group that supplemented with the combination of omega-3 and vitamin E showed no life-expectancy advantage over the group that supplemented with only the omega-3.
The overall conclusion of the GISSI-Prevenzione trial was that supplementing with omega-3 provided long term benefits in lowering risk of death for patients who had experienced a myocardial infarction.