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Supplements

DHA

What Is It?
Health Benefits
Forms
Dosage Information
Guidelines for Use
General Interaction
Possible Side Effects
Cautions
References

Evidence Based Rating Scale

What Is It?  

Docosahexaenoic acid, or DHA is an essential omega-3 polyunsaturated fatty acid (PUFA) that is not produced by the human body and must be present in the diet to maintain health. DHA is found in oily fish such as herring, mackerel, salmon, and tuna as well as microalgae. Fish oils are also a good source of DHA, but most commercially-available fish oils contain less DHA and more of the omega-3 fatty acid eicosapentaenoic acid (EPA). When DHA is not consumed in the diet, it is synthesized through conversion of EPA. High-purity vegetarian DHA is produced from a controlled fermentation process of two microalgae and is the only type of DHA currently accepted for use in infant formulas in the United States. (1)  

DHA makes up 60 percent of the PUFA's in the retina and is necessary for optimal visual acuity. Additionally, DHA comprises 40 percent of the PUFA's in the brain and is necessary for neural development as well as cell membrane function. (2)    

Health Benefits

DHA is essential to fetal brain and vision development and is currently recognized as an important dietary fatty acid during pregnancy. Infants who are breast-fed receive at least 60mg/day of DHA from breast milk and accumulate 10mg/day in the whole body during the first six months of life with 48 percent of that amount appearing in the brain. This increases the infant's whole-brain concentration of DHA by 39 percent while their whole-body DHA concentration approximates 3,800 mg. In contrast, infants who consume non-supplemented formula lose whole-body DHA stores at a rate of 5.1 mg/day for a total loss of 1,000 mg of DHA in the first six months of life. (3) A 2010 review of human studies indicates DHA supplementation during pregnancy, lactation and childhood plays a significant role in childhood neurodevelopment. There is a positive association between blood levels of DHA and improved cognitive and visual function in healthy children. (4) However, more recent findings from a large study published in the Journal of the American Medical Association suggest DHA supplements taken by women during pregnancy have no clear cognitive benefit for their infants. The study mainly assessed full-term infants and found no cognitive differences at eighteen months of age between infants whose mothers consumed DHA supplements and infants whose mothers consumed a vegetable oil placebo. This study suggests that full-term infants receive sufficient DHA in the womb and that supplements provide no added benefit; however it may be that cognitive differences were not detectable in the tests used for this age group. Additionally, the study does not address potential benefits in pre-term infants. More studies are warranted. (4, 5)

Supplementation with DHA and EPA may also help to manage childhood psychiatric disorders. Cognitive disorders, such as dyslexia and autism, and neurological disorders, such as dyspraxia, are often associated with a lack of omega-3 fatty acids. (6) Dyslexia, a reading disability, results from the inability to process graphic symbols. In one small study, twenty children diagnosed with dyslexia were given a supplement containing high-DHA fish oil and evening primrose oil. After four months, thirteen of seventeen children showed a 60 percent improvement in reading speed and a 23 percent improvement in letter decoding. (7) Studies have also shown that a combination of DHA and EPA may benefit autism and dyspraxia—a disorder that affects movements and coordination. (8) Additionally, a 2010 review of studies suggests 3-4 months of supplementation with a combination of DHA and EPA along with omega-6 gamma-linolenic acid (GLA) could lead to a reduction of attention deficit/hyperactivity disorder (ADHD) symptoms. (9)

DHA also has anti-inflammatory properties. DHA and other PUFA's are precursors of lipid mediators known as eicosanoids, which play a role in regulating inflammation. Omega-3 eicosanoids have anti-inflammatory properties due to their ability to inhibit the formation of pro-inflammatory omega-6 eicosanoids. The typical Western diet has more omega-6 than omega-3 fatty acids. Research has shown that increasing the ratio of omega-3's to omega-6's in the diet (either through foods or supplementation) may reduce the prevalence of chronic diseases that involve inflammation including certain cancers, cardiovascular diseases, inflammatory bowel disease, and rheumatoid arthritis. (10) In one study, injections of an emulsion of 4.2 grams each of EPA and DHA reduced overall severity and scaling of psoriasis, an inflammatory skin disorder. (11)

Specifically, DHA may help:

Prevent age-related macular degeneration. In age-related macular degeneration, the macula, which is located in the center of the retina and is the area important for sharp detailed vision, gradually deteriorates. DHA deficiency is associated with this disease. Since DHA comprises 60 percent of the fatty acids in the retina, supplementation with DHA could potentially prevent occurrences of macular degeneration. However, studies are needed before DHA supplementation can be recommended as preventive therapy. (12) 

Slow the symptoms of Alzheimer's Disease. Fish oils may help slow the cognitive decline of Alzheimer's. In animal models the docosahexaenoic acid (DHA) found in fish oil specifically helps to protect the brain from the accumulation of the beta amyloid plaques that accompany mental decline in Alzheimer’s Disease. (13) In human studies, using omega-3s as a part of an integrative treatment program slowed cognitive decline for 24 months. (14) 

Reduce the risk of breast cancer. High consumption of oily fish has been associated with a reduced risk of breast cancer, most likely due to DHA in the fish. In one study, 358 patients with breast cancer and 360 patients with no history of malignancies were given a food-intake frequency questionnaire to determine their dietary consumption of fatty and lean fish and omega-3 fatty acids derived from fish. Reductions in breast cancer risk were seen in both premenopausal and post-menopausal women who had consumed at least 0.213 grams of DHA daily from fish. (15)  

Inhibit cell growth in colorectal and pancreatic cancer. Laboratory and animal studies indicate DHA inhibits the growth of malignant colorectal cancer cells. In one animal study, human colon carcinomas were grown subcutaneously in mice.  When the mice were fed a high-fat diet containing a mixture of omega-3 fatty acids made from menhaden fish, cell growth of the carcinomas was inhibited by 80 percent compared to mice fed a corn oil diet rich in omega-6 fatty acids. In mice fed a diet of golden algae oil containing only DHA, cell growth of the carcinomas was inhibited by 93 percent. These findings suggest DHA is the major tumor-suppressive fatty acid. (16) In addition, laboratory studies of the effect of DHA on two human pancreatic cell lines found DHA inhibited growth of pancreatic cells. (17) 

Relieve symptoms of major depression. In an eight-week study, 432 individuals with major depressive episodes (MDE) or with MDE plus anxiety disorders were randomly assigned to receive a daily combination of 1.05 grams EPA and 0.150 grams DHA or a placebo of sunflower oil. The results indicated that compared to placebo, although there was only a slight benefit of omega-3 supplementation for reducing depressive symptoms in individuals with both MDE and anxiety disorders; for those with the single diagnosis of MDE, omega-3 supplementation significantly reduced depressive symptoms. (18) Another eight-week study involved 46 women aged 66-95 with depression. Twenty-two of the women received a daily supplement of a combination of 1.67 grams of EPA and 0.83 grams of DHA while 26 women received a placebo. At the end of the study, the omega-3 group experienced greater improvements in depressive symptoms and quality of life than the placebo group. (19)  

Benefit heart disease. Three large trials with a total of 32,000 participants who randomly received supplements of EPA and DHA or placebo provide the most compelling evidence for the benefit of omega-3's on heart disease. Cardiovascular events were reduced between 19 and 45 percent through a combination of dietary sources of omega-3 and fish oil supplements. Optimal consumption levels of DHA and EPA were at least 1 gram per day for individuals with coronary artery disease and 0.5 grams per day for those without the disease. Individuals with elevated triglyceride levels, (hypertriglyceridemia) were able to lower their levels by 20 to 50 percent with minimum daily consumption of 3 to 4 grams EPA and DHA. (20) In a small study, 59 overweight men with mildly elevated lipid levels (hyperlipidemia) consumed 4 grams per day of EPA, DHA, or an olive oil placebo. The men who consumed DHA exhibited lowered heart rates and lower ambulatory blood pressure (blood pressure taken at regular intervals over a twenty-four hour—a more accurate reflection of a patient's blood pressure). (21) The findings from this study suggest DHA is the principal omega-3 fatty acid responsible for lowering blood pressure and heart rate. (22)

Forms

  • powder
  • liquid
  • intravenous

Dosage Information

  • For infant development: 300 mg per day for pregnant and lactating women (1)

  • For dyslexia: 480 mg DHA per day (23)

  • For breast cancer: 0.213 g per day (15)

  • For depression: 0.150 g DHA combined with 1.05 g EPA per day for individuals with major depressive episodes; 0.83 g DHA combined with 1.67 g EPA per day for elderly women with depression (18,19)

  • For coronary artery disease: 1 g per day of EPA and DPA (20)

  • For hyperlipidemia: 4 g per day of DHA (22)

Guidelines for Use

For vegetarians, DHA from microalgae is a good source that is equivalent to DHA derived from fish.

General Interaction

  • Theoretically, high doses (greater than 3 grams) of DHA in combination with EPA as fish oils may increase bleeding when taken with other anticoagulant/antiplatelet drugs and herbs including garlic, ginger, ginkgo, turmeric, and others. This reaction has not been seen in DHA used as a single agent.

  • DHA taken with other anti-hypertensive medications and herbs including cat's claw, L-arginine, lycium, stinging nettle, and others could lower blood pressure excessively causing hypotension.

Possible Side Effects

Oral DHA may cause nausea, flatulence, prolonged bleeding, and bruising. Other side effects include fishy taste, belching, nosebleeds, nausea, and loose stools.

Cautions 

High doses of fish oils may decrease blood coagulation and increase bleeding. 

References 

1. Docosahexaenoic acid (DHA). Monograph. Altern Med Rev. 2009 Dec;14(4):391-9.
2. Spector AA. Essentiality of fatty acids. Lipids. 1999;34 Suppl:S1-3.
3. Cunnane SC, Francescutti V, Brenna JT, Crawford MA. Breast-fed infants achieve a higher rate of brain and whole body docosahexaenoate accumulation than formula-fed infants not consuming dietary docosahexaenoate. Lipids. 2000 Jan;35(1):105-11.
4. Ryan AS, Astwood JD, Gautier S, Kuratko CN, Nelson EB, Salem N Jr. Effects of long-chain polyunsaturated fatty acid supplementation on neurodevelopment in childhood: a review of human studies. Prostaglandins Leukot Essent Fatty Acids. 2010 Apr-Jun;82(4-6):305-14.
5. The New York Times. Available at http://www.nytimes.com/2010/10/20/health/research/20fishoil.html?_r=2&hp. Accessed October 24, 2010.
6. Schuchardt JP, Huss M, Stauss-Grabo M, Hahn A. Significance of long-chain polyunsaturated fatty acids (PUFAs) for the development and behaviour of children. Eur J Pediatr. 2010 Feb;169(2):149-64.
7. Lindmark L, Clough P. A 5-month open study with long-chain polyunsaturated fatty acids in dyslexia. J Med Food. 2007 Dec;10(4):662-6.
8. Kidd PM. Omega-3 DHA and EPA for cognition, behavior, and mood: clinical findings and structural-functional synergies with cell membrane phospholipids. Altern Med Rev. 2007 Sep;12(3):207-27.
9. Transler C, Eilander A, Mitchell S, van de Meer N. The Impact of Polyunsaturated Fatty Acids in Reducing Child Attention Deficit and Hyperactivity Disorders. J Atten Disord. 2010 Apr 27.
10. Wall R, Ross RP, Fitzgerald GF, Stanton C. Fatty acids from fish: the anti-inflammatory potential of long-chain omega-3 fatty acids. Nutr Rev. 2010 May;68(5):280-9.
11. Mayser P, Mrowietz U, Arenberger P, Bartak P, Buchvald J, Christophers E, Jablonska S, Salmhofer W, Schill WB, Krämer HJ, Schlotzer E, Mayer K, Seeger W, Grimminger F. Omega-3 fatty acid-based lipid infusion in patients with chronic plaque psoriasis: results of a double-blind, randomized, placebo-controlled, multicenter trial. J Am Acad Dermatol. 1998 Apr;38(4):539-47.
12. Desmettre T, Lecerf JM, Souied EH. Nutrition and age-related macular degeneration. J Fr Ophtalmol. 2004 Nov;27(9 Pt 2):3S38-56.
13. Lim GP, Calon F, Morihara T, Yang F, Teter B, Ubeda O, Salem N Jr, Frautschy SA, Cole GM. A diet enriched with the omega-3 fatty acid docosahexaenoic acid reduces amyloid burden in an aged Alzheimer mouse model. J Neurosci. 2005 Mar 23;25(12):3032-40.
14. Bragin V, Chemodanova M, Dzhafarova N, Bragin I, Czerniawski JL, Aliev G. Integrated treatment approach improves cognitive function in demented and clinically depressed patients. Am J Alzheimers Dis Other Demen. 2005 Jan-Feb;20(1):21-6.
15. Kim J, Lim SY, Shin A, Sung MK, Ro J, Kang HS, Lee KS, Kim SW, Lee ES. Fatty fish and fish omega-3 fatty acid intakes decrease the breast cancer risk: a case-control study. BMC Cancer. 2009 Jun 30;9:216.
16. Kato T, Kolenic N, Pardini RS. Docosahexaenoic acid (DHA), a primary tumor suppressive omega-3 fatty acid, inhibits growth of colorectal cancer independent of p53 mutational status. Nutr Cancer. 2007;58(2):178-87.
17. Strouch MJ, Ding Y, Salabat MR, Melstrom LG, Adrian K, Quinn C, Pelham C, Rao S, Adrian TE, Bentrem DJ, Grippo PJ. A High Omega-3 Fatty Acid Diet Mitigates Murine Pancreatic Precancer Development. J Surg Res. 2009 May 15.
18. Lespérance F, Frasure-Smith N, St-André E, Turecki G, Lespérance P, Wisniewski SR. The efficacy of omega-3 supplementation for major depression: a randomized controlled trial. J Clin Psychiatry. 2010 Jun 15.
19. Rondanelli M, Giacosa A, Opizzi A, Pelucchi C, La Vecchia C, Montorfano G, Negroni M, Berra B, Politi P, Rizzo AM. Effect of omega-3 fatty acids supplementation on depressive symptoms and on health-related quality of life in the treatment of elderly women with depression: a double-blind, placebo-controlled, randomized clinical trial. J Am Coll Nutr. 2010 Feb;29(1):55-64.
20. Lee JH, O'Keefe JH, Lavie CJ, Marchioli R, Harris WS. Omega-3 fatty acids for cardioprotection. Mayo Clin Proc. 2008 Mar;83(3):324-32.
21. Marchiando RJ and Elston MP.  Automated Ambulatory Blood Pressure Monitoring: Clinical Utility in the Family Practice Setting. Am Fam Physician. 2003 Jun 1;67(11):2343-2351.
22. Mori TA, Bao DQ, Burke V, Puddey IB, Beilin LJ. Docosahexaenoic acid but not eicosapentaenoic acid lowers ambulatory blood pressure and heart rate in humans. Hypertension. 1999 Aug;34(2):253-60.
23. Stordy BJ. Dark adaptation, motor skills, docosahexaenoic acid, and dyslexia. Am J Clin Nutr 2000;71:323S-6S.

Evidence Based Rating Scale

The Evidence Based Rating Scale is a tool that helps consumers translate the findings of medical research studies and what our clinical advisors have found to be efficacious in their personal practice into a visual and easy to interpret format. This tool is meant to simplify the information on supplements and therapies that demonstrate promise in the treatment of certain conditions.

 

Condition

Rating

Explanation

 

ADHD

   

Several studies indicate DHA along with EPA and omega-6 gamma-linolenic acid decreases symptoms of ADHD. (9)

 

Alzheimer's Disease  

Animal studies show DHA reduces formation of beta-amyloid plaques that accompany mental decline in Alzheimer’s; human studies are needed. (13)

 

Cancer  
Small study shows reduced risk of breast cancer in women who consume DHA daily; more large-scale studies are needed. (15) Laboratory and animal studies show DHA inhibits cell growth in colorectal and pancreatic cancer; human studies are needed. (16, 17)
 
Depression  
In small studies, DHA combined with EPA slightly reduced symptoms of major depressive episodes and depression; more studies are needed. (18, 19)
Heart Disease
Date Published: 10/24/2010
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