Docosahexaenoic acid (DHA) is an omega-3 long-chain polyunsaturated fatty acid that plays an essential role in the growth and development of the human brain in utero and throughout infancy, as well as in the ongoing health of the skin, eyes, and, in particular, the brain throughout one’s life.­¹ DHA is primarily used for cell membrane structure and function and is involved in several biological processes in the human body, such as angiogenesis (the development of new blood vessels); immune modulation; inflammatory response; cell signaling, death, and proliferation; and many other critical biological functions that affect health.¹ 

Low maternal DHA status impairs the in-utero development and growth of the fetal brain, which increases the infant’s risk of developing neurodevelopmental disorders (e.g., autistic spectrum disorder [ASD], attention deficit/hyperactivity disorder [ADHD]).¹ As we age, a deficiency in DHA and eicosapentaenoic acid (EPA) increases risk of developing cognitive disorders (e.g., dementia, Alzheimer’s disease, behavioral changes, mood disorders) and certain chronic diseases (e.g., inflammatory disease, cardiovascular disease) later in life.² Research has shown that dietary consumption of omega-3 fatty acids—DHA in particular—is associated with improvements in cognitive function and/or reductions in cognitive decline among healthy older individuals. In a prospective study, investigators found that declines in cognitive function measured at baseline and five years later among 70- to 89-year-olds were associated with reduced EPA and DHA consumption,³ whereas in another study, 65- to 80-year-old healthy adults who consumed more than 2.1 grams of omega-3 fatty acids per day had better memory and executive function compared to those who consumed less.⁴ Numerous other studies over the years have shown a positive correlation between omega-3 fatty acid consumption and slower cognitive decline among older individuals, a strong positive association between fish consumption and reduction in sudden death from myocardial infarction, and evidence that DHA exerts antitumoral activity, among other benefits.­^5–7

The human body cannot produce enough DHA on its own, so it must get it through diet or supplements. While currently there is no official recommended daily allowance for EPA or DHA, most experts agree that 250 to 500mg of combined EPA and DHA is sufficient for adults to maintain their overall health.¹ According to a 2022 study based on data from the National Health and Nutrition Examination Survey (NHANES) 2017–2018, American adults consume far below the expert-recommended 250 to 500 milligrams of combined EPA and DHA a day.²

Good Sources of DHA

• Herring fish—5 ounces contains 3.1 grams

• Fish oil—1 tablespoon contains 2.9 grams

• Mackerel—4 ounces contains 2.6 grams

• Salmon—3 ounces contains 1.5 grams

• Rainbow trout—5 ounces contains 1.4 grams

• Halibut—3 ounces contains 1.0 gram

• Tuna (canned)—3 ounces contains 0.7 grams

• Rockfish—5 ounces contains 0.6 grams

• Shrimp—½ cup contains 0.4 grams

• Catfish—5 ounces contains 0.3 grams

For individuals who find it hard to consume fatty fish once or twice a week or for those who only consume a plant-based diet, incorporating a DHA + EPA supplement may be the way to go. However, consult with a qualified healthcare professional first to determine the best dosage for you, particularly if you have cardiovascular disease. 

Important to note: Taking a DHA or DHA+EPA supplement can increase risk for bleeding among those taking blood thinners, such as warfarin. Additionally, too much EPA and/or DHA can cause an upset stomach or diarrhea.⁶ And finally, omega-6 fatty acids can interfere with your body’s ability to convert omega-3 fatty acids, and vice versa. Omega-6 fatty acids come mainly from refined vegetable oils that are added to processed food. Consider reducing your intake of omega-6 fatty acids while increasing your intake of omega-3 fatty acids for optimal benefits.⁹

Sources

1. Basak S, Mallick R, Duttaroy A. Maternal docosahexaenoic acid status during pregnancy and its impact on infant neurodevelopment. Nutrients. 2020;12(12):3615.

2. Froyen E, Maarafi Z. The consumption of omega-3 fatty acids in American adults. Curr Develop Nutrition. 2022;6(Suppl 1):902.

3. Van Gelder BM, Tijhuis M, Kalmijn S, Kromhout D. Fish consumption, n-3 fatty acids, and subsequent 5-y cognitive decline in elderly men: The Zutphen elderly study. Am J Clin Nutr. 2007;85:1142–1147.

4. Eskelinen MH, Ngandu T, Helkala EL, et al. Fat intake at midlife and cognitive impairment later in life: a population-based CAIDE study. Int J Geriatr Psychiatry. 2008;23:741–747. 

5. Weiser MJ, Butt CM, Mohajeri MH. Docosahexaenoic acid and cognition throughout the lifespan. Nutrients. 2016;8(2):99. 

6. Horrocks LA, Yeo YK. Health benefits of docosahexaenoic acid (DHA). Pharmacol Res. 1999;40(3):211–25.

7. Petermann AB, Reyna-Jeldes M, Ortega L, et al. Roles of the unsaturated fatty acid docosahexaenoic acid in the central nervous system: molecular and cellular insights. Int J Mol Sci. 2022;23(10):5390.

8. Texas Health website. Americans aren’t getting enough of this key nutrient for brain health. 29 Sep 2022. https://www.texashealth.org/areyouawellbeing/Eating-Right/Americans-Arent-Getting-Enough-of-This-Key-Nutrient-for-Brain-Health. Accessed 14 Nov 2022. 

9. Hjalmarsdottir F. How much omega-3 should you take per day? Updated 13 Oct 2022. Healthline website. https://www.healthline.com/nutrition/how-much-omega-3. Accessed 14 Nov 2022.