Omega-3 fatty acids are essential nutrients found only in animal products such as fish oil, eggs, milk and butter. They are essential because they cannot be synthesized from other sources. They must come directly from food or dietary supplements (see table). The body converts them into their active forms called eicosanoids. These eicosanoid substances have many important functions in the human body including protection against inflammation, cell growth and repair, neurotransmission and immune function.
The most common form of omega-3 fatty acid is known as alpha-linolenic acid (ALA) which comes from fish oils. ALA is present in all types of foods and may be converted to EPA and DHA via the enzyme called linoleic acid desaturase 1 (LAD1). However, some fats contain very high levels of omega-6 fatty acids such as corn oil, soybean oil, sunflower seed oil and palm kernel oil. These oils are commonly used in processed foods and beverages.
They contain much higher amounts of omega-6 than do plant oils such as olive oil, peanut oil, flaxseed oil or rapeseed oil. Because these oils are so rich in omega-6 fatty acids, they increase the risk of heart disease and cancer. This is the reason why plant oils are better for consumption than animal oils.
However, there is an enzyme called delta-5-desaturase that reduces the amount of omega-3 fatty acids in the body. It converts them into arachidonic acid (AA). Arachidonic acid creates inflammatory substances that can increase the risk of coronary heart disease and cancer. This is the reason why it’s much better to consume foods containing ALA instead of AA.
The best source of ALA comes from oily, cold water fish such as tuna, halibut, mackerel and herring. Plant sources include nuts (especially flax seeds), legumes (including soybeans) as well as green leaves such as watercress, purslane and certain types of lettuce.
Flax and chia seeds are the richest sources of ALA, but they contain very little amounts of essential fatty acids.
Sources & references used in this article:
Health effects of omega-3,6,9 fatty acids: Perilla frutescens is a good example of plant oils by M Asif – Oriental Pharmacy & Experimental Medicine, 2011 – Springer
Essential fatty acids for dry eye: a review by M Roncone, H Bartlett, F Eperjesi – Contact Lens and Anterior Eye, 2010 – Elsevier
The effects of addition of omega-3, 6, 9 fatty acids on the quality of bovine chilled and frozen-thawed sperm by R Robertson – Pridobljeno, 2017
Long chain omega-3 dietary supplements: a review of the National Library of Medicine Herbal Supplement Database by MAS Kandelousi, J Arshami, AA Naserian… – Open veterinary …, 2013 – ajol.info
Omega-3 fatty acids–A review of existing and innovative delivery methods by A Zargar, MK Ito – Metabolic syndrome and related disorders, 2011 – liebertpub.com
Open trial of supplements of omega 3 and 6 fatty acids, vitamins and minerals in atopic dermatitis by KE Lane, EJ Derbyshire – Critical reviews in food science and …, 2018 – Taylor & Francis
The oxidative stability of omega-3 oil-in-water nanoemulsion systems suitable for functional food enrichment: A systematic review of the literature by BB Eriksen, DL Kåre – Journal of dermatological treatment, 2006 – Taylor & Francis
Polyunsaturated fatty acids in male ruminant reproduction—a review by L Bush, L Stevenson, KE Lane – Critical reviews in food science …, 2019 – Taylor & Francis
Omega-3 fatty acids for breast cancer prevention and survivorship by L Van Tran, BA Malla, S Kumar… – Asian-Australasian journal …, 2017 – ncbi.nlm.nih.gov