DHA - for healthy brain, heart and eyes

Fish oil - polyunsaturated omega-3 fatty acids (PUFA’s) containing EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), is commonly recognised for its use in the prevention and treatment of many health disorders.

EPA and DHA are important components of cell membranes and support the function of their cell receptors; they are precursors to the hormones which regulate blood clotting; are involved in the relaxation and contraction of artery walls; and are anti-inflammatory in action.

EPA and DHA are considered “essential” fatty acids and need to be supplied through the diet (or as a supplement) as only small amounts can be made in the body. They can be found in higher amounts, and well recognised by the body, in fatty fish such as salmon, herring, anchovies and also vegetable oils, nuts (especially walnuts), flax seeds and flaxseed oil, in lesser amounts and not as easily absorbed by the body. Supplements of omega 3, such as fish oil, contain both EPA and DHA, but supplements of DHA alone will offer higher amount of DHA.

Why do we need DHA?

DHA is found throughout the body and is especially high in the brain, eyes and heart where it plays an important role in their healthy function. Examples of benefits include:

• Infant brain development and health
• Adult brain maintenance
• Improve learning ability
• Prevent learning deficits
• Visual acuity and eye health
• Prevent cognitive decline
• Reduce cardiovascular disease

Research studies show supplementing with DHA has many benefits for people of all ages and conditions.

Benefits of supplemental DHA 

Brain Function and DHA

Preventing Cognitive decline. DHA makes up 30% of brain matter. The adult brain acquires DHA from food or DHA produced by the liver. Decreases in DHA in the brain are associated with cognitive decline during aging and with onset of sporadic Alzheimer’s disease. Higher doses of DHA are needed to ensure adequate brain delivery especially for those who carry a gene associated with a higher risk of Alzheimer's disease – the APOE4 gene.

Attention-deficit/hyperactivity disorder (ADHD). ADHD is a common complex and multifactional disorder involving a variety of symptoms such as problems with concentration, impulsivity and excessive motor activity. Studies have shown omega 3 fatty acids, especially DHA, have helped in management of this disorder as a single therapy, or as an adjunct to other therapies.

Cardiovascular disease (CVD) and DHA

Consuming regular amounts of dietary DHA was found to have the potential to reduce endothelial dysfunction and help prevent cardiovascular disease. This is due to the effect it has on inflammation, thrombosis and arrhythmia. Studies concluded that DHA is more effective at modulating specific markers of inflammation and blood lipids than EPA.

Pregnancy and breastfeeding and DHA

Many women of childbearing age fail to meet the recommended dietary DHA intake. The developing foetus receives DHA from the mother during pregnacy and later through breastfeeding (infant formula's are often supplemented with DHA). DHA  is required for brain development and visual health of the baby.

DHA reduces the risk of preterm birth (delivery of baby before 34 weeks of pregnancy). Preterm babies are at increased of risk to their health. Ensuring sufficient amounts of DHA are consumed by the mother, through diet by eating low-mercury fish, or supplement with at least 500mg DHA daily can help prevent preterm birth.

Infants and children can benefit from DHA to support the continued development of eyes and brain. DHA is often added to infant formula or can be supplemented through liquids and drops.

Inflammatory diseases and DHA

Two types of lipid mediators derived from DHA, resolvins and protectins, are able to modulate the inflammatory response, dampening inflammation by actively promoting resolution.

Periodontal disease and inflammatory bowel diseases are just two inflammatory conditions which have been helped through supplementation of DHA. Both these diseases have a common characteristic involving inflammation and bacterial dysbiosis. DHA may be of benefit for sufferers of other diseases which are characterized by bacterial dysbiosis and inflammation, such as metabolic syndrome, obesity and diabetes.

Rheumatoid arthritis RA. Supplementation with microalgae DHA was shown to ameliorates disease activity in patients with RA. Rheumatoid arthritis is an auto-immune disorder characterized by inflammation and joint destruction.

Vision and DNA

The fatty acids within the retina of the eye are composed primarily of DHA which supports the fluid content of membranes and the integrity of the retina and visual function. Supplementing with DHA or including dietary DHA-rich foods helps support the health of the eye, slowing the aging process and the development of degenerative diseases, such as macular degeneration, the most common degenerative disease resulting in blindness.

Diabetic retinopathy (DR). Studies have shown that supplementation with high-dose of DHA combined with xanthophyll carotenoid multivitamin during a 90day period was associated with a progressive and significant improvement of macular function. This was measured by microperimetry. Biochemical changes supported the effect of DHA, which included improved vascular integrity, reduced oxidative stress and better glycaemic control.

Pseudoexfoliation Glaucoma. This is a condition which sees flakes of material accumulating around the edge of the pupil, on the lens, in the drainage and other structures at the front of the eye. The result is an increase in eye pressure, as this material blocks the drainage system, and damage to the optic nerve. Increases in dietary and supplementary DHA may help reduce interocular pressure and inflammation. Whilst taking DHA will not reverse any retinal damage, it may help preserve vision. DHA in the diet has been shown to reduce the incidence of glaucoma.

Dry eye. DHA may help with dry eye and chronic inflammatory eyelids.

The bottom line

Try and include at least 2 fish meals per week in the diet, preferable fatty fish, such as salmon, herring or sardines, grilled, steamed, baked or poached, to benefit from the abundant nutrition they provide – protein, zinc, selenium, vitamin A, D and essential fatty acids - DHA and EPA. Supplements of DHA can provide many benefits for people of all ages and conditions.

References

1. Docosahexaenoic Acid https://www.karger.com/Article/FullText/448262
2. https://www.sahmriresearch.org/user_assets/2b06cb6a6df1d0accafb394907f750e72d88b623/health_professional_summary_cochrane_review_151118.pdf
3. Health benefits of docosahexaenoic acid (DHA) https://pubmed.ncbi.nlm.nih.gov/10479465/#:~:text=Docosahexaenoic%20acid%20(DHA)%20is%20essential,associated%20with%20deficits%20in%20learning
4. https://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/fats-and-cholesterol/types-of-fat/omega-3-fats/
5. https://www.tandfonline.com/doi/full/10.1080/10408398.2018.1425978
6. Docosahexaenoic acid regulates vascular endothelial cell function and prevents cardiovascular disease https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5472966/
7. Endothelial Cell Metabolism https://pubmed.ncbi.nlm.nih.gov/29167330/
8. A randomized, crossover, head-to-head comparison of eicosapentaenoic acid and docosahexaenoic acid supplementation to reduce inflammation markers in men and women: the Comparing EPA to DHA (ComparED) Study https://pubmed.ncbi.nlm.nih.gov/27281302/
9. Docosahexaenoic acid supplementation for children with attention deficit hyperactivity disorder: A comprehensive review of the evidence https://pubmed.ncbi.nlm.nih.gov/29779801/
10. Docosahexaenoic Acid, Inflammation, and Bacterial Dysbiosis in Relation to Periodontal Disease, Inflammatory Bowel Disease, and the Metabolic Syndrome https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3775255/
11. Docosahexaenoic acid in the treatment of rheumatoid arthritis: A double-blind, placebo-controlled, randomized cross-over study with microalgae vs. sunflower oil https://pubmed.ncbi.nlm.nih.gov/28302406/
12. Supplementation with a highly concentrated docosahexaenoic acid plus xanthophyll carotenoid multivitamin in no proliferative diabetic retinopathy: prospective controlled study of macular function by fundus microperimetry https://pubmed.ncbi.nlm.nih.gov/29881256/
13. Retina and Omega-3 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3206354/
14. https://www.health.harvard.edu/heart-health/omega-3-for-your-eyes#:~:text=%22DHA%20is%20the%20primary%20structural,of%20blindness%20in%20older%20people.%22
15. Effects of Oral Supplementation with Docosahexaenoic Acid (DHA) plus Antioxidants in Pseudoexfoliative Glaucoma: A 6-Month Open-Label Randomized Trial https://www.hindawi.com/journals/joph/2018/8259371/
16. https://www.brightfocus.org/glaucoma/article/pseudoexfoliation-pxe-syndrome-and-pseudoexfoliation-glaucoma
17. Oral Omega-3 Supplementation Lowers Intraocular Pressure in Normotensive Adults https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5931260/
18. https://www.betterhealth.vic.gov.au/health/healthyliving/fish