There is a wide range of fish oil capsules available on the market. Of different sizes and colors, they all share one ingredient in common – omega-3, which is a kind of unsaturated fatty acid that is good for the blood vessels.
Omega-3 cannot be synthesized by the body itself so it must be obtained through diet. On top of fish oil capsules, deep-sea fish, nuts and vegetables also contain such unsaturated fatty acids.
Omega-3 is categorized into plant-based alpha-linolenic acid (ALA) and animal-based docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA).
ALA is the precursor of the latter. Once absorbed, ALA can be converted into EPA and DHA. However, such conversion efficiencies range from 5 percent to 25 percent while the rate decreases with age. Although a high dosage of ALA can be converted into a small amount of EPA, the conversion into DHA is much harder.
Research shows that sufficient intake of omega-3 can suppress the enzymes that cause inflammation of cells.
DHA can facilitate the metabolism of omega-6, protect the retina and reduce the accumulation of low-intensity cholesterol in blood vessels, thereby minimizing the risk of arterial stiffness and protecting the heart.
Meanwhile, ALA functions as a strong antioxidant that is anti-inflammatory. It helps with the regeneration of fat and water-soluble vitamins such as vitamin C and E. ALA also improves the metabolism of glucose and fat.
Both fish oil and fish liver oil provide omega-3 but they have different risks and benefits. The fat content in fish liver is not as high as in other parts of the fish. Therefore, the amount of EPA and DHA in fish liver oil is relatively low.
Fish liver oil can also be differentiated from fish oil by its vitamin A and D content. Active vitamin D can be produced by human skin under the sun. Those who do not enjoy sunbathing may be deficient in vitamin D and should consider fish liver oil as the dietary supplement.
Note that a high dosage of fish liver oil can cause excessive vitamin A and D in the body, leading to nausea and loose stool.
Fish oil supplementation also reduces thrombogenicity and is anticoagulatory. Those who take anticoagulants (blood thinners) or soon undergo surgical operations should regulate their fish oil supplementation to allow proper blood clotting and avoid excessive bleeding.
This article appeared in the Hong Kong Economic Journal on April 10
Translation by John Chui
[Chinese version 中文版]
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