Omega-3 fatty acids from cold-water fish
Omega-3 fatty acids are increasingly recommended for healthy eyes. This type of essential fatty acids is thought to maintain good blood flow, which is critical for enough oxygen and nutrients supplement to the eyes. Omega-3 fatty acids are polyunsaturated fats so that they can reduce unhealthy cholesterol in the body.
Among various foods, cold-water fish is the best source of omega-3 fatty acids. The American Heart Association says that people should consume weekly at least two servings of cold-water fish such as salmon, mackerel, herring, sardine and tuna. High intake of fish is thought to reduce the risk of cardiovascular disease. In addition, choosing “unpolluted” fish is also necessary. Some farmed fish may contain environmental toxins such as mercury, polychlorinated biphenyls and organochlorine pesticides.
Fish oil supplements offer same benefits as whole fish. These supplements can be preferred alternatives for people who don’t like fish. What’s more, fish oil is free of toxins. Flaxseeds, flaxseed oil, walnuts and dark green leafy vegetables can also be good sources of omega-3 fatty acids, but they are harder for the body’s absorption.
Another type of essential fatty acids is omega-6 fatty acids, including linoleic acid, gamma-linolenic acid, and arachidonic acid. Sources of these acids include sunflower oil, corn oil, canola oil, safflower oil, certain seeds, meat and animal products. Since excessive omega-6 fatty acids are harmful, you should replace cooking oils plentiful in omega-6 with olive oil, in order to lower omega-6 level.
Hydrogenated oils in processed foods and deep-dried foods contain much trans-fatty acids, which affect the body’s normal absorption of omega-3 fatty acids. These trans-fatty acids have altered structures and may bring potential diseases including cancer, heart disease, high blood pressure, diabetes, obesity and so on. Experts suggest that a healthy diet should avoid hydrogenated oils, margarine, fried foods and other foods containing trans-fats.
Two types of essential fatty acids
Excessive fat is always associated with obesity, but normal level of fat is essential to our health. Proper kinds and mount of fats help maintain our body’s function and overall health including eyes. Fatty acids are indispensable in forming fats. These nutrients help in the normal production and functioning of cells, muscles, nerves and organs as well as the regulation of blood pressure, heart rate and blood clotting. Omega-3 fatty acids and omega-6 fatty acids are two types of essential fatty acids, which can only acquired from external foods. The human body can not produce these essential fatty acids.
Plenty of studies focus on the role of omega-3 fatty acids in affecting eye health. Deficiencies of omega-3 have been linked to some eye problems such as impaired vision, retina damage and high intraocular pressure. In contrast, high consumption of foods plentiful in omega-3 is suggested to reduce the risk of several vision problems. For instance, eating two servings of fish or more every week can significantly reduce the risk of developing age-related macular degeneration.
Foods rich in omega-3 also play a key role in dry eye syndrome (DES) prevention among women. Women taking the highest amount of omega-3 fatty acids have a much lower rate of DES than those containing the lowest level of omega-3 fatty acids. Tuna is particularly effective in protecting against DES in women.
The balance between omega-3 and omega-6 fatty acids is especially important, since improper ratios may lead to harmful effects. A 15:1 ratio of omega-6 to omega-3 can bring 2.5 times increased risk of DES in women. Other healthy problems associated with imbalance of omega-6 fatty acids to omega-3 fatty acids include heart disease, cancer, asthma, arthritis and depression.