There are numerous omega-3 sources with varying proportions of EPA and DHA, and the balance of EPA and DHA in a supplement influences the actions of these fats in the body. For more information about the different types of omega-3 sources and which are most suited for your individual needs, read our page on the different types of omega-3 supplements
If you find yourself in a position where you are just not eating any of these foods, and you want to get enough omega-3 fatty acids, then I think fish oil is okay, but I would limit not the amount of fish oil but the amount listed on the label of EPA and DHA combined. I would limit that amount to around 250 milligrams per day because I don’t think most people need more than that. Some signs that you might not be getting enough omega-3 fatty acids include chronic low-grade inflammation, poor visual acuity, slower mental processing, trouble learning, and possibly Alzheimer’s disease and psychiatric conditions, like depression, anxiety, and attention deficit and hyperactivity disorder, ADHD.
Bemelmans, W. J., Broer, J., Feskens, E. J., Smit, A. J., Muskiet, F. A., Lefrandt, J. D., Bom, V. J., May, J. F., and Meyboom-de Jong, B. Effect of an increased intake of alpha-linolenic acid and group nutritional education on cardiovascular risk factors: the Mediterranean Alpha-linolenic Enriched Groningen Dietary Intervention (MARGARIN) study. Am J Clin Nutr 2002;75(2):221-227. View abstract.
Cochrane lead author, Dr. Lee Hooper from the University of East Anglia, UK said: “We can be confident in the findings of this review which go against the popular belief that long-chain omega 3 supplements protect the heart. This large systematic review included information from many thousands of people over long periods.  Despite all this information, we don’t see protective effects.

Children require DHA for growth and development, and the brain, CNS and retina rely heavily on the adequate supply of DHA during growth in the womb. Thus women should emphasise DHA in their diets when they become pregnant and continue to take this until they cease breastfeeding. Children continue to need DHA up until the age they start school, so if children under the age of five are taking an omega-3 supplement, it should contain DHA. The exception is for children with developmental problems – where pure EPA or high EPA omega-3 has been shown to be most effective for supporting cognitive function. We would still recommend, where possible, naturally derived sources of omega-3 such as oily fish to support a balanced EPA and DHA intake.
Dyerberg, J., Eskesen, D. C., Andersen, P. W., Astrup, A., Buemann, B., Christensen, J. H., Clausen, P., Rasmussen, B. F., Schmidt, E. B., Tholstrup, T., Toft, E., Toubro, S., and Stender, S. Effects of trans- and n-3 unsaturated fatty acids on cardiovascular risk markers in healthy males. An 8 weeks dietary intervention study. Eur.J.Clin.Nutr. 2004;58(7):1062-1070. View abstract.
Corresponding Author: Yutaka J. Matsuoka, MD, PhD, Division of Health Care Research, Center for Public Health Sciences, National Cancer Center Japan, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan (yumatsuo@ncc.go.jp); Kuan-Pin Su, MD, PhD, China Medical University Hospital, No. 2, Yude Road, North District, Taichung City, Taiwan 404 (cobolsu@gmail.com).
Attention deficit-hyperactivity disorder (ADHD) in children. Early research shows that taking fish oil improves attention, mental function, and behavior in children 8-13 years-old with ADHD. Other research shows that taking a specific supplement containing fish oil and evening primrose oil (Eye Q, Novasel) improves mental function and behavior in children 7-12 years-old with ADHD.
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