Oily fish such as salmon and mackerel are rich sources of heart-healthy Omega-3 fatty acids. There is strong scientific evidence showing that people who consume more oily fish are less likely to suffer from heart attacks and other cardiovascular events.
Heart (cardiovascular) disease is the number one cause of death in both men and women worldwide. Large scientific studies have reported that Omega-3s present in oily fish, known as EPA and DHA, are beneficial for the heart because they reduce many risk factors that increase the chances of suffering from cardiovascular disease. Some of the risk factors decreased by EPA and DHA are cholesterol levels and blood pressure. The only bad thing about oily fish is mercury contamination, however, experts state that the benefits far outweigh the risks. Plus you can always avoid fish that are high in mercury like tuna and opt for the low mercury options such as salmon.
Figure 1. Try to choose oily fish with a low mercury content such as salmon, although occasionally eating a bit of tuna isn’t going to hurt you. Either way, whether you choose high or low mercury oily fish, you will still be getting Omega-3s that are beneficial for the heart. Adapted from http://www.healthcastle.com/tuna-food-month
Omega-3s found in fish seem to be of particular benefit at reducing the risk of heart attacks by stabilising atherosclerotic plaques. These are fatty tissue deposits that build up in arteries across the body, a condition called atherosclerosis. Sometimes, plaques can rupture, travelling in the blood until they block a narrower artery. If an artery that supplies the heart with oxygenated blood gets blocked, this will result in a heart attack. If the heart muscle does not receive oxygen and nutrients, it quickly starves and dies.
Research has identified that certain white blood cells knows as macrophages can up-regulate inflammatory processes which makes plaques more likely to break off. Scientists found out that individuals who consumed two or more portions of oily fish on a weekly basis, had fewer numbers of macrophages in atherosclerotic plaques than those who rarely ate oily fish. When EPA and DHA get incorporated into plaques, they cause the production of anti-inflammatory molecules, which reduces infiltration of macrophages into arterial plaques. Additionally, Omega-3s get incorporated into the cell membranes of macrophages, directly lowering their activity. These effects reduces arterial plaque inflammation, decreasing the likelihood that the clot will come off.
Figure 2. Summary of the proposed mechanism that explains how oily fish consumption makes atherosclerotic plaques more stable. Based on Calder and Yaqoob (2010)
Consuming oily fish not only stabilises atherosclerotic plaques, but getting enough EPA and DHA in the diet from an early age can slow down atherosclerosis. Having high levels of bad cholesterol (LDL) increases deposition of fatty deposits in arteries, which may result in heart disease after many years. Luckily, EPA in oily fish reduces the build up of plaques by raising HDL, usually known as good cholesterol. Furthermore, omega-3s in oily fish appear to be effective at lowering blood pressure, a major risk factor in atherosclerosis. Studies in humans showed that the biggest blood pressure lowering effects were observed in older and hypertensive patients, while blood pressure in non-hypertensive individuals was not reduced. Due to the many advantages that omega-3s have in heart health, doctors and nutritionists now advise individuals to eat two portions of oily fish every week.
Calder, P.C. & Yaqoob, P. (2010). Omega-3 (n-3) fatty acids, cardiovascular disease and stability of atherosclerotic plaques. Cellular and Molecular Biology, 56(1), 28-37.
Galli, C. & Rise, P. (2009). Fish consumption, omega 3 fatty acids and cardiovascular disease. The science and the clinical trials. Nutrition and Health, 20(1), 11-20.