Human reliance on DHA begins soon after conception and continues for life. DHA levels in the blood or in the membranes of the circulating red blood cells generally reflect its levels in the other tissues.12 By these measures, higher DHA status correlates with good health.
Essential for Early Brain and Eye Development
DHA helps regulate genes that control the emergence of the fetal brain in the first trimester of pregnancy.13 By the third semester DHA is being rapidly concentrated in the retinal and brain cells (EPA is virtually absent).2,10 These cells especially need DHA since their membrane systems are the most fluid and the proteins typically operate at ultrafast speeds.4,5,6 Higher maternal DHA status during pregnancy is linked to more mature sleep patterns in newborns, along with better vision, better attention, faster processing speed, and higher cognitive function.10
The brain’s intensive DHA buildup continues until birth and for many years after birth.10,14 This helps explain why infants born preterm have low brain DHA compared to full term infants. For full term as well as preterm infants, clinical studies have linked adequate DHA intake after birth to healthy vision, cognitive functions, mood, and behavior control.10,14,15 The DHA content of breast milk varies directly with the mother’s DHA intake, which is significantly below optimal in the U.S.14 Adequate dietary intake of DHA supports the health of the mother as well as the child.16 Many international agencies support the inclusion of DHA in infant feeding formulas.
DHA Sufficiency Supports Both Mother and Child
After enduring ongoing transfer of DHA from her tissues to that of the child during the pregnancy, following delivery the mother can have very low blood DHA, and this relative deficiency can adversely affect her mood.16 Negative lifestyle factors prior to birth, such as habitual alcohol consumption or smoking in the household, can deplete the mother’s DHA stores.17 Adequate DHA intake before and during pregnancy and all through lactation supports healthy mood, behavior, and cognition, and is therefore crucial, not only for the child but the mother as well.
Lifelong Importance for Memory and Other Cognitive Functions
Numerous studies indicate DHA status is closely linked with memory and other brain functions across the lifespan. Supplementation in childhood can improve mental performance.18 At middle age, individuals with relatively high blood DHA have significantly better chance of having healthy memory retention, compared to individuals with relatively low levels.19 For middle aged and older individuals, higher blood DHA is also linked to better reaction time, sharpened attention, and achievement on tests of memory, reasoning and vocabulary.20 EPA and other omega-3s show no such links to mental performance at any life stage.
DHA remains essential for higher brain functions well into old age. In the classic Framingham study, subjects with the highest DHA levels were most likely to exhibit better memory over a subsequent 10-year period.21 In a landmark 2010 double blind trial conducted on more than 500 over-55 subjects, those taking DHA (900 mg/day for 6 months) had significantly superior memory over those on placebo. Their learning and memory errors were reduced by 50 percent.22 The DHA used in this trial was sourced from algae (Schizochytrium sp.), the same material available by taking Best Vegetarian DHA from Algae.
Numerous Actions That Support Brain Health
The brain is highly enriched in DHA and contains only trace amounts of other omega-3 nutrients.2 Yet the brain apparently makes very little new DHA—the liver produces most of the body’s DHA albeit at a very slow pace. A study on aging subjects found a link between more efficient DHA production by the liver and better memory performance.23 As with other clinical studies, this study found no link between EPA status and memory performance.
DHA supports the brain via a plethora of beneficial actions:7,13,24
• Helps regulate genes that manage brain development, maturation, and maintenance.
• Competes against (“crowds out”) less advantageous fatty acids from nerve cell membranes.
• Promotes nerve cell maturation and new nerve cell extensions.
• Source for docosanoids that promote healthy tissue maintenance.
• Improves synaptic membrane fluidity, often in combination with PS (phosphatidylserine).
• Potentiates the beneficial activities of various brain growth factors.
• Increases brain production of the protective BDNF (brain-derived neurotrophic factor).
• Upregulates glutathione peroxidase and other protective antioxidant enzymes.
• Promotes glucose delivery and energy efficiency in aged brain (monkey).
• Improves cell activation mechanisms, as best proven for the retina.
Range of Benefits for the Heart and Circulation
As with the brain, DHA’s benefits predominate over EPA in the heart and circulation. While fish oils are complex mixtures of DHA with EPA and other fatty acids, the availability of virtually pure preparations of DHA and EPA has allowed direct comparisons between them in clinical studies. DHA’s superior benefits over EPA include support for maintenance of a normal, healthy heart rate and blood pressure, arterial microcirculatory tone, and healthy maintenance of cholesterol already within the normal range.25-31
The healthy heart is able to vary its beat rate on demand.25 In a double-blind trial conducted with overweight men, DHA and not EPA helped promote 24-hour ambulatory heart rate control.26 In another study with these subjects, DHA enhanced blood vessel tone while EPA did not.27
In the double blind trial mentioned above,26 DHA enhanced maintenance of healthy blood pressure while EPA showed no benefit. Another double blind trial found that just 700 mg/day of DHA for 3 months gave significant healthy blood pressure support.28 Yet another double blind trial found that DHA promoted cardiovascular health as measured by several parameters, including maintenance of a healthy heart rate, already healthy blood pressure, and already healthy cholesterol.29 In all these beneficial actions DHA consistently outperformed EPA.30,31
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