Women with Higher EPA Levels Have Fewer Nonfatal Coronary Events
For reasons we do not understand, fish and fish oil consumption, which protects against heart disease mortality and sudden cardiac death, has little effect on the occurrence of nonfatal heart events in western populations. This is not the case among the Japanese, who consume nearly 10 times as much fish as westerners. The Japanese also have half the chance of dying from heart disease. In trying to understand these striking differences, researchers have turned their attention to the long-chain omega-3 fatty acids found in fish. These fatty acids are also more abundant in the blood of Japanese fish-eaters than in most westerners. Although there is good reason to think long-chain omega-3s are at least part of the answer, a relationship between the two has not been observed in westerners.
Now the potential relationship between blood long-chain omega-3 fatty acid concentrations and the occurrence of nonfatal heart events, such as a heart attack, has been examined in a large sample of US women who were monitored for 6 years. This was a case-control study in which the investigators identified participants who incurred a nonfatal heart attack and then matched them with women having the same age and smoking status, but who did not have such an event. Blood samples were obtained from both groups of women. This study included 146 women with a nonfatal heart attack and 288 control women without a heart attack. On average, the women were 60 years old.
When the two groups of women were compared, those who had had a heart attack weighed more, consumed less alcohol and were more likely to have diabetes, hypertension and high blood cholesterol levels, as well as a parental history of heart attack. Women who had higher levels of EPA (eicosapentaenoic acid), a long-chain omega-3 fatty acid, in their blood plasma had a 77% lower chance of having a nonfatal heart attack compared with women having lower levels. The reduced chance of heart attack was not related to their blood levels of DHA (docosahexaenoic acid), another long-chain omega-3 found predominantly in fatty fish.
The researchers also noted that women with higher long-chain omega-3s in their plasma had higher HDL levels (“good” cholesterol) and lower triglycerides (blood fats). Overall, this study provides some support in western women for fewer nonfatal heart attacks with higher levels of long-chain omega-3s in blood. The study had some other perplexing observations that are not easy to explain. For example, why was the relationship observed only for plasma omega-3s and not red blood cell omega-3s? Plasma values reflect more recent dietary intakes. It is also not clear why plasma DHA was not related to nonfatal heart attacks, as it too is associated with fish and fish oil consumption. What is encouraging about these findings is that they suggest that westerners may improve their heart health from a preventive point of view, just as happens in the fish-loving Japanese.