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A Little History
The first link between omega-3 fatty acids and good health was discovered back in the 1970s. Researchers studying the Inuit people of Greenland noted that these individuals had a lower incidence of heart disease than their European neighbors.
What was their secret?
The researchers hypothesized that the Inuit had much better blood circulation to their heart and brain than Western people groups, a physiological phenomenon likely enhanced by a high consumption of healthy fats in their diet of whale blubber, seal, and salmon.1 All of these foods are rich in omega-3s.
Omega-3s are also abundant in our brains. Literally thousands of research studies have been conducted to determine if omega-3 fatty acids can effectively treat depression and anxiety disorders. These studies show that omega-3s can reduce symptoms of depression2 and anxiety.3
So, in addition to other lines of treatment, getting plenty of omega-3s is important for good brain health.
The Omega-3 to Omega-6 Ratio
In addition to omega-3, the human diet also contains omega-6 fatty acids.
Both omega-3s and omega-6s are important because they help the body build itself and make enough energy for its needs. Both are also necessary for the heart, lungs, immune system, and hormone systems.4
But we do need to watch the relative amount of each in the diet. Since omega-6 and omega-3 fatty acids compete for some of the same enzymes, the ratio of ingested omega-6 to omega-3 fatty acids can change the course of certain biological pathways in the brain and body.
WHO Dietary Guidelines
The World Health Organization says that for every four omega-6s, we should eat at least one omega-3:5
|Dietary Fat||Goal (% of needed energy or calories each day)|
|Trans fat||little to none|
In the Western diet, getting enough omega-6 is not really a problem. Omega-6 fatty acids are found in the seeds of most plants and the oils made from them (like corn, sunflower, and cottonseed oils).
The Omega-6 to Omega-3 Ratio and Body health
Unfortunately, with the rise of more processed and fried fast food and snacks, the Western diet has lurched way beyond the recommended ratio of 4 to 1. The American diet can be as high as 20 to 1.6
This is a problem because too much omega-6 can tip the body toward obesity 6 and inflammation7 as well as greater risk of life-threatening illness including heart disease,autoimmune problems, and possibly even cancer.8
MyFoodData.com lists the following as high omega-6 foods:
|Food item||Omega-6 to Omega-3 Ratio|
|Safflower oil, per tbsp||14 g Omega-6:No omega-3s|
|Peanut Butter, per 2 tbsp||332:1|
|Corn Chips, per cup||28:1|
|Cured meats (pepperoni), per 3 oz||21:1|
|Cake with frosting, per slice||9:1|
Other foods are healthier because they have a reasonable omega-6 to omega-3 ratio and other nutrients:
|Food item||Omega-6 to Omega-3 Ratio|
|Firm tofu, per cup||7:1|
|Walnuts, per oz||4:1|
|Berries (blueberries, strawberries, raspberries, cranberries), per cup||1:1|
|Lettuce, per cup||1:2|
|Kidney beans, per cup||1:2|
|Mango, per cup||1:3|
|Flax seeds, per oz||1:4|
|Spinach, per cup, cooked||1:5|
|Broccoli Rabe, per cup, cooked||1:7|
|Tuna, per 6 oz fillet||1:25|
Nearly 70% of avocado oil is oleic acid, a mono-unsaturated omega-9 fatty acid. Aside from the significant monounsaturated content, avocado oil is about 16% saturated fatty acids and 14% polyunsaturated. The omega-6 to omega-3 ratio is about 13:1.
The Omega-6 to Omega-3 Ratio and Brain health
While Omega-3s tend to reduce risk of depression,2 omega-6s tend to increase the risk.9
A lifelong imbalance in the omega-6 to omega-3 ratio in laboratory mice resulted in chemical changes in the prefrontal cortex, a brain area involved in decision-making and emotional regulation. When these mice were exposed to stress, the chemical imbalance induced symptoms of depression.10
Here’s the take-home message I get from these studies: most of us are getting surplus omega-6s, but not enough omega-3s. For optimum physical and mental health, we need a healthier balance between the two.
To Restore Balance
Restoring balance between omega-6s and omega-3s is a two-step process.
First, we can cut back on omega-6 intake. Top offenders are fried foods, cured meats, commercially baked cakes and pastries, and convenience foods like chips.
Second, we can increase our intake of omega-3s.
3 Types of Omega-3
Three types of omega-3 fats are important for humans:
- ALA (short for alpha-linolenic acid);
- EPA (eicosapentaenoic acid); and
- DHA (docosahexaenoic acid).
ALA is the precursor to all three – it can be used to make the longer EPA form. In turn, EPA can be converted to the longest form: DHA.
Medical researchers believe it’s more important to raise EPA and DHA blood levels than to lower omega-6 levels.11
There are two ways to get all three fatty acids in the body: 1) eat them in our food or 2) take them as supplements.
Omega-3s in Our Food
Food sources of ALA are walnuts, seeds, and plant oils (flaxseed, soybean, and canola oils).
Food sources of EPA and DHA are oily fish that live in cold water (e.g. Atlantic Ocean). But the fish do not produce these fatty acids themselves. EPA and DHA are manufactured in the fish’s food: seaweed and marine algae. This is good news for vegetarians and vegans, who can go straight to the same source for their omega-3s – more on this in a bit.
This table gives the ALA, EPA, and DHA amounts in omega-3 rich foods:11
|Food||milligrams per serving|
|Flaxseed oil, 1 tbsp||7260|
|Chia seeds, 1 oz||5060|
|English walnuts, 1 oz||2570|
|Flaxseed, whole, 1 tbsp||2350|
|Canola oil, 1 tbsp||1280|
|Soybean oil, 1 tbsp||920|
|Black walnuts, 1 oz||760|
|Soybeans (edamame), cooked, ½ cup||280|
|Avocado, 1 whole||221|
|Refried beans (vegetarian), canned, ½ cup||210|
|Kidney beans, canned, ½ cup||100|
|Atlantic salmon (wild), cooked, 3 oz||1220||350|
|Atlantic Herring, cooked, 3 oz||940||770|
|Sardines, canned, 3 oz||740||450|
|Atlantic Mackerel, cooked, 3 oz||590||430|
|Salmon, canned, 3 oz||40||630||260|
|Rainbow Trout (wild), cooked, 3 oz||440||400|
|Sea Bass, cooked, 3 oz||470||180|
|Tuna, canned in water, 3 oz||170||20|
|Tilapia, cooked, 3 oz||40||110|
|Pacific Cod, cooked, 3 oz||100||40|
The omega-3 content of farm-raised fish will depend on what they eat. This is why it’s recommended to eat wild fish for the most reliable source of omega-3s.
Omega-3s and the Vegetarian Diet
The human body is not very good at converting ALA into the longer forms, EPA and DHA. But if you’re a vegetarian, your body may be a little better at doing this. Some research says that the digestive system of a long-term vegetarian seems adapted to making more DHA from ALA than a non-vegetarian’s.13
We all can help the process along by eating certain other nutrients, like Vitamin B9 (folate).14 In populations where many people are vegetarian for cultural or economic reasons, eating folate-rich foods (i.e. dark leafy greens) increases DHA levels.15
Curcumin, an ingredient in the spice turmeric, also improves ALA to DHA conversion.16
Fish oil supplements: A good omega-3 supplement made from fish oil has about 800 mg EPA and 600 mg DHA, with a total daily dose of 1500 mg.Fish oil capsules have an added benefit: environmental contaminants like mercury and pesticides are removed during the purification process.11
Plant-based supplements are also available, made from the same marine plants and algae that fish eat. Clinical studies show that these plant-based supplements increase both EPA and DHA levels in humans,17 in some cases reaching the same levels as cooked salmon.18
The Health Benefits of Omega-3s
The health benefits of omega-3s include:11
- reduced risk of heart disease, certain cancers (e.g. breast and colorectal), and age-related macular degeneration;
- reduced dependence on anti-inflammatory drugs for rheumatoid arthritis;
- improved neurodevelopment outcomes of babies whose mothers breastfeed and get adequate amounts;
- reduced risk of dementia and Alzheimer’s Disease;
- reduced (some) ADHD symptoms; and
- reduced symptoms of depression and anxiety.
There are hundreds of studies that link higher fish consumption to improved health outcomes. However, it should be noted that these studies do not always determine if the health income was due to the omega-3 content of the food, other nutrients in the fish or meals in general, the substitution of fish for less healthy foods, other healthy behaviors the study participants used, or a combination of these factors.11
Clinical trials using specific omega-3 supplements are used to shed more light on these issues. Clinical trials have shown that omega-3s are useful for treating:
- Bipolar disorder;
- Post-traumatic Stress Disorder;
- Major Depression; and
In these types of targeted clinical trials, EPA was the type that most reliably decreased depressive symptoms.2
Current Dietary Guidelines:
The 2015-2020 Dietary Guidelines for Americans suggest eating 8 oz (a little more than two servings) of fish per week, which would result in about 250 mg each of EPA and DHA per day.19
Women who are pregnant or breastfeeding should choose fish varieties high in EPA and DHA (e.g. salmon, herring, sardines, trout) and avoid those high in mercury (e.g. mackerel, shark, swordfish, tilefish). They should limit the amount of white (albacore) tuna to 6 oz a week.20
Strict vegetarians can choose from several ALA-rich foods and improve their conversion rates with folate-rich foods and spices like turmeric. They can also use plant-based supplements.
The FDA recommends a maximum of 2000 mg omega-3s per day from supplemental sources (fish oil or plant-based), not to exceed 3000 mg/day of EPA and DHA combined.21
To get the FREE pdf version of this blog post, download below:Download
Make some simple changes to re-balance your intake of omega-6 and omega-3 fats:
- Try eliminating or at least reducing the amount of fried and processed foods you eat every week. This would include fast food meals and in-between snacks like cookies and chips.
- Increase omega-3 in your diet by adding one or more servings of fish to your weekly menu. If you are vegetarian/vegan, eat some walnuts, flax seeds, or chia seeds every day.
- Look into getting some quality omega-3 supplements, either fish oil or plant-based. The following can be found at Amazon.com:
1 Nettleton, J. A. (1995). Omega-3 fatty acids and health. In Omega-3 Fatty Acids and Health (pp. 64-76). Springer, Boston, MA.
2 Mocking, R. J. T., Harmsen, I., Assies, J., Koeter, M. W. J., Ruhé, H., & Schene, A. H. (2017). Meta-analysis and meta-regression of omega-3 polyunsaturated fatty acid supplementation for major depressive disorder. Translational psychiatry, 6(3), e756.
Hallahan, B., Ryan, T., Hibbeln, J. R., Murray, I. T., Glynn, S., Ramsden, C. E., … & Davis, J. M. (2016). Efficacy of omega-3 highly unsaturated fatty acids in the treatment of depression. The British Journal of Psychiatry, 209(3), 192-201.
Li, F., Liu, X., & Zhang, D. (2016). Fish consumption and risk of depression: a meta-analysis. J Epidemiol Community Health, 70(3), 299-304.
3 Su, K. P., Tseng, P. T., Lin, P. Y., Okubo, R., Chen, T. Y., Chen, Y. W., & Matsuoka, Y. J. (2018). Association of use of omega-3 polyunsaturated fatty acids with changes in severity of anxiety symptoms: A systematic review and meta-analysis. JAMA Network Open, 1(5), e182327-e182327.
4 Jones, P.J.H, & Rideout, T. (2014). Lipids, sterols, and their metabolites. In: Ross AC, Caballero B, Cousins RJ, Tucker KL, Ziegler TR, eds. Modern Nutrition in Health and Disease. 11th ed. Baltimore, MD: Lippincott Williams & Wilkins.
5 World Health Organization: Population nutrient intake goals for preventing diet-related chronic diseases.https://www.who.int/nutrition/topics/5_population_nutrient/en/
6 Simopoulos, A. P. (2016). An increase in the omega-6/omega-3 fatty acid ratio increases the risk for obesity. Nutrients, 8(3), 128.
7 Simopoulos, A. P. (2016). Evolutionary aspects of the dietary omega-6/omega-3 fatty acid Ratio: Medical implications. In Evolutionary thinking in medicine (pp. 119-134). Springer, Cham.
8 Simopoulos, A. P. (2002). The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomedicine & pharmacotherapy, 56(8), 365-379.
9 Fernandes, M. F., Mutch, D. M., & Leri, F. (2017). The relationship between fatty acids and different depression-related brain regions, and their potential role as biomarkers of response to antidepressants. Nutrients, 9(3), 298.
10 Lafourcade, M., Larrieu, T., Mato, S., Duffaud, A., Sepers, M., Matias, I., … & Rodríguez-Puertas, R. (2011). Nutritional omega-3 deficiency abolishes endocannabinoid-mediated neuronal functions. Nature neuroscience, 14(3), 345.
11 National Institutes of Health. Omega-3 Fatty Acids: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/#en176
12 Balanza-Martinez, V., Fries, G. R., Colpo, G. D., Silveira, P. P., Portella, A. K., Tabares-Seisdedos, R., … & Kapczinski. (2011). Therapeutic use of omega-3 fatty acids in bipolar disorder. Expert review of neurotherapeutics, 11(7), 1029-1047.
Matsuoka, Y., Nishi, D., Yonemoto, N., Hamazaki, K., Hashimoto, K., & Hamazaki, T. (2010). Omega-3 fatty acids for secondary prevention of posttraumatic stress disorder after accidental injury: an open-label pilot study. Journal of clinical psychopharmacology, 30(2), 217-219.
Su, K. P., Wang, S. M., & Pae, C. U. (2013). Omega-3 polyunsaturated fatty acids for major depressive disorder. Expert opinion on investigational drugs, 22(12), 1519-1534.
Amminger, G. P., Schäfer, M. R., Papageorgiou, K., Klier, C. M., Cotton, S. M., Harrigan, S. M., … & Berger, G. E. (2010). Long-chain ω-3 fatty acids for indicated prevention of psychotic disorders: a randomized, placebo-controlled trial. Archives of general psychiatry, 67(2), 146-154.
12 U.S. Department of Agriculture, Agricultural Research Service. (2015). USDA National Nutrient Database for Standard Reference, Release 28.. https://ndb.nal.usda.gov/ndb/
13 Brenna, J. T., Salem Jr, N., Sinclair, A. J., & Cunnane, S. C. (2009). α-Linolenic acid supplementation and conversion to n-3 long-chain polyunsaturated fatty acids in humans. Prostaglandins, leukotrienes and essential fatty acids, 80(2-3), 85-91.
14 Kulkarni, A., Dangat, K., Kale, A., Sable, P., Chavan-Gautam, P., & Joshi, S. (2011). Effects of altered maternal folic acid, vitamin B12 and docosahexaenoic acid on placental global DNA methylation patterns in Wistar rats. PLoS One, 6(3), e17706.
15 Chopra, H. V., Kehoe, S. H., Sahariah, S. A., Sane, H. N., Cox, V. A., Tarwade, D. V., … & Joshi, S. R. (2018). Effect of a daily snack containing green leafy vegetables on women’s fatty acid status: A randomized controlled trial in Mumbai, India. Asia Pacific journal of clinical nutrition, 27(4), 804.
16 Wu, A., Noble, E. E., Tyagi, E., Ying, Z., Zhuang, Y., & Gomez-Pinilla, F. (2015). Curcumin boosts DHA in the brain: Implications for the prevention of anxiety disorders. Biochimica et Biophysica Acta (BBA)-Molecular Basis of Disease, 1852(5), 951-961.
17 Craddock, J. C., Neale, E. P., Probst, Y. C., & Peoples, G. E. (2017). Algal supplementation of vegetarian eating patterns improves plasma and serum docosahexaenoic acid concentrations and omega‐3 indices: a systematic literature review. Journal of Human Nutrition and Dietetics, 30(6), 693-699.
18 Arterburn, L. M., Oken, H. A., Hall, E. B., Hamersley, J., Kuratko, C. N., & Hoffman, J. P. (2008). Algal-oil capsules and cooked salmon: nutritionally equivalent sources of docosahexaenoic acid. Journal of the American Dietetic Association, 108(7), 1204-1209.
19 U.S. Department of Health and Human Services, U.S. Department of Agriculture. (2015). 2015–2020 dietary guidelines for Americans.
20 U.S. Food and Drug Administration. (2014). Fish: what pregnant women and parents should know.
21 U.S. Food and Drug Administration. (2004). FDA annoz qualified health claims for omega-3 fatty acids.
Dr. Pamela Coburn-Litvak has published research articles on exercise and stress in Neuroscience and Neurobiology of Learning and Behavior. After receiving a Ph.D. in Neurobiology and Behavior from the State University of New York at Stony Brook, she served as both Assistant Professor of Physiology & Pharmacology and Special Assistant to the Vice President for Research Affairs at Loma Linda University in Loma Linda, California. She then joined the Biology department at Andrews University and developed courses in human physiology as well as the neurobiology of mental illness. She also founded Rock @ Science LLC, a company that specializes in health and science education and web development. She co-developed the brain and body physiology segment of the Stress: Beyond Coping seminar with its creator, Dr. William “Skip” MacCarty, DMin.
Dr. Coburn-Litvak currently lives in California with her husband. Their two daughters are mostly grown and attending school elsewhere.
When she’s not studying or teaching about stress, she enjoys stress-relieving activities like puttering around the garden, taking nature walks with her family, knitting, cooking, and reading.