You have probably heard that we need to consume foods high in omega-3 fatty acids and sometimes even supplements. Let’s start with the basics. What are they? They are essential fatty acids that our organism can NOT produce in the quantities needed, therefore needs to take in through food. They are composed of carbon and hydrogen bonds and are unsaturated fatty acids which means they have more than one double bond. The omega-3 have their first double bond three carbons away from the methyl end of the chain.
The most important omega 3 are eicosapentanoic acid (EPA), docosahexanoic acid (DHA) and alpha linolenic acid (ALA). DHA and EPA can be found mostly in fatty fish and the oils coming from them. Foods high in omega-3 are:
- Sardines
- Salmon
- Trout
- Krill oil (plankton resembling shrimp)
- Foods supplemented with omega 3 such as some eggs. yogurts
ALA can be found in plant food such as flaxseeds and their oil, canola and soybean oils, walnuts and Chia seeds. A small percentage of ALA, less than 15%, can be converted to EPA and DHA, therefore it is recommended all three omega-3 are taken in through a balanced diet.
Why are they essential?
They are components of all cell membranes and are found in especially high concentration in the eye (retina), brain and sperm. They are also used to form compounds called eicosanoids, that are involved in the process of inflammation and platelet aggregation (i.e. blood clot formation). The eicosanoids coming from omega-3 are less potent than the ones derived from omega-6 and compete against each other. A higher omega-3 to omega-6 ratio helps the body to be in a state of…less inflammation, you can think about them a bit like aspirin since they also aid in decreasing platelet aggregation. Keep in mind to consult your doctor before increasing too much your omega-3 intake if you are already taking medication for heart disease.
There is sound evidence from clinical trials and prospective studies that points out their protective effect against heart disease, high triglycerides and rheumatoid arthritis, in adjunct to pharmacotherapy. There are ongoing studies to assess their role in cancer prevention and treatment, Alzheimer and depression as studies up to now have contradictory results.
How much?
The Dietary Guidelines for Americans, 2015-2020 recommend that to promote a “healthy heart” (among other things!) we need 8 oz a week of fatty fish rich in omega-3, thus 2 medium servings per week, that will provide us with 250mg EPA και DHA.
During pregnancy and lactation women need 8-12 oz per week! They are essential for the development of the brain and the nervous system of the fetus and they may play a role in normal cognitive development of the child.
Should salmon be avoided?
No. Salmon is not high in methyl-mercury as is sometimes accused of. It’s consumption, at the recommended portions per week, is safe for the population including pregnant women. On the contrary, swordfish, shark, king mackerel and tile fish should be avoided in pregnancy due to their higher mercury content. As a rule of thumb, the smaller the fish, the fewer heavy metals it will collect, therefore sardines, rich in omega-3 source, have with the lowest mercury content on our list.
The upper level of intake as set by the FDA, for EPA and DHA through food and supplements, has been set to 3 grams per day, with supplements providing up to 2 grams a day. For patients with high triglycerides, usually taking higher omega-3 doses of 2-4 grams, you should do it in close follow-up from your physician.
The acceptable intake levels of omega-3 by age, as set by the Institute of Medicine are presented below. Along with your fish, remember to consume also plant sources of omega-3 mentioned above. Enjoy healthy eating!
| Age | Male | Female | Pregnancy | Lactation |
| Birth to 6 months* | 0.5 g | 0.5 g | ||
| 7–12 months* | 0.5 g | 0.5 g | ||
| 1–3 years** | 0.7 g | 0.7 g | ||
| 4–8 years** | 0.9 g | 0.9 g | ||
| 9–13 years** | 1.2 g | 1.0 g | ||
| 14–18 years** | 1.6 g | 1.1 g | 1.4 g | 1.3 g |
| 19-50 years** | 1.6 g | 1.1 g | 1.4 g | 1.3 g |
| 51+ years** | 1.6 g | 1.1 g |
*As total omega-3s
**As ALA
References
• https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/
• U.S. Department of Health and Human Services, U.S. Department of Agriculture. 2015–2020 dietary guidelines for Americans. 2015.
• U.S. Department of Agriculture, Agricultural Research Service. USDA National Nutrient Database for Standard Reference, Release 28. Nutrient Data Laboratory Home Page, 2015.
• Mozaffarian D, Rimm EB. Fish intake, contaminants, and human health: evaluating the risks and the benefits. JAMA. 2006; 296:1885-99.
• Institute of Medicine, Food and Nutrition Board. Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (macronutrients). Washington, DC: National Academy Press; 2005
