DHA stands for DocosaHexaenoic Acid, the most important omega-3 nutrient. DHA is a fatty acid that is naturally built into our biochemistry. Two-time Nobel prizewinner Linus Pauling dubbed these “ortho” molecules, “right” nutrients for the body. Ortho nutrients typically are extremely effective and extremely safe, and DHA fits this pattern.
Judging from its great diversity of positive actions in the brain, DHA is currently the most important natural brain enhancer. It is in fact important for all our organs. DHA is so important that it is concentrated in the breast milk to support the baby’s fast-developing vision, learning, and all other life functions.
DHA is a critically important nutrient for us all, whatever our age or state of health. Technically, the body can make it from the simpler omega-3 EPA (EicosaPentaenoic Acid) or possibly the even simpler ALA (Alpha Linolenic Acid). However this capacity is extremely limited, even in healthy people, so that DHA is practically a “dietarily essential” nutrient — we have to get virtually all of it from our diet.
DHA In Overview
DHA’s fundamental importance for health comes from being a building block for the cell membrane systems that make up all our cells. The body’s trillions of cells all are organized around cell membranes, which are thin molecular sheets that make up the outer boundary of the cell but also extend inside the cell, to create compartments — each having specialized functions. The cell membrane networks are packed with proteins, which are the molecular catalysts that drive metabolism and the other processes that make up life. Each membrane has a matrix, a continuous double layer of lipid molecules into which the proteins insert. These lipid building blocks include DHA.
DHA is present in the membranes of all our cells, being an indispensable membrane building block. DHA has a powerful fluidizing effect that makes the membranes semi-fluid, which then allows the membrane proteins to move about within the membrane. The proteins must be mobile in order to carry out their necessary functions. DHA also makes other types of chemical associations with certain of the membrane proteins, which further adds to its nutritional importance.
Cell membranes manage most of our life processes and, as a general rule, the more DHA in a membrane the more dynamic is that membrane and the more it will contribute to the cell’s functional efficiency. This is most evident in cells of the brain’s gray matter and the retina of the eye, whose membranes carry more DHA than any others in the body.
The DHA in cell membranes also can be transformed into a variety of smaller “messenger” molecules that diffuse out of the membrane to help coordinate important life processes. These “docosanoids” (protectins, resolvins, maresins, and others) have numerous regulatory effects. They are generally protective, and help in the positive management of inflammation and other necessary responses to infection, injury, or other forms of damage. DHA and its docosanoids are involved in regulating a broad array of important life processes.
Most DHA dietary supplements come from fish oils. The numerous fish oil supplements that are commercially available have widely differing amounts of DHA, EPA and other omega-3 fatty acids. The research indicates that DHA is the important omega-3 fatty acid. Further, there is a potential problem: supplements that provide more EPA than DHA are unlikely to provide DHA benefits since EPA may negatively interfere with DHA. I will return to this topic after I review the proven health benefits of DHA.
Important From The Very Beginning
DHA’s crucial importance begins at conception: its presence in the sperm’s cell membrane allows this cell to swim vigorously and fertilize the egg. And DHA remains important all through life. Our nutritional DHA status can be figured by measuring its level in the blood or (better still) in the membranes of the red cells that circulate with the blood. Human studies have made it clear that high red cell DHA indicates good health, and low red cell DHA indicates increased risk for health problems.
DHA becomes ever more important as the fetal heart and brain become organized. By the third semester of pregnancy, DHA is becoming progressively more concentrated in the brain and in the retina. This intensive DHA buildup continues until birth. Babies born with poor DHA status (usually from mothers low in DHA) are more likely to have poor sleep patterns, slower processing speed, and visual and cognitive limitations, compared to those from mothers with good DHA status.
Relative lack of DHA especially hurts infants born prematurely. Preemies average lower brain DHA compared to full-term infants. They will get DHA by breastfeeding, but breast milk DHA content depends on the mother’s DHA intake, which in the U.S. averages quite low (below 100 mg per day). Whether her baby was born premature or full term, if the lactating mother lacks adequate DHA her baby has long-term risk for poor vision and for potentially big problems with learning, self-control, mood, and other mental functions. What’s more, low DHA intake is also bad for the mother.
DHA Deficiency Threatens Both Mother and Child
All the way through pregnancy, the mother must transfer DHA to the developing baby. After birth she continues transferring DHA to the baby via her breast milk. This long period of passing DHA on to the child can deplete her DHA stores unless she is supplementing them. In the days following delivery a mother can have very low blood DHA, which then places her at very high risk for postpartum depression and other potentially severe mood problems.
DHA deficiency also can be caused by poor lifestyle. Habitual drinking can deplete the mother’s DHA and so can smoking (by anyone in the household). Low DHA in the mother increases her long-term risk for problems with mood, behavior, attention, learning, and other mental performance. The evidence is very clear: adequate DHA intakes before and during pregnancy and lactation are crucial for both mother and child.
The risks of brain problems from DHA deficiency apply to everyone. There is substantial evidence that poor DHA intakes increase the risks for learning disorders, AD(H)D (attention deficit-hyperactivity disorder), anxiety, depression, bipolar disorder (“manic depression”), suicidal tendencies, domestic abuse and other violent behavior, and stress-related mental trauma states. DHA positively affects hundreds of genes involved with managing these mental states.
Lifelong Importance for Memory and Other Cognition
DHA status is closely linked with memory and the other higher brain functions across our entire lifespan. The clinical evidence suggests that giving a “difficult child” DHA will likely improve their behavior and academic performance in school. For middle-aged people, findings from population studies suggest that the higher their blood DHA the lower their risk for severe memory loss, as compared to their peers with low DHA levels. For the middle aged and the elderly, good DHA status is linked to better reaction time, sharper attention, and better performance on tests of memory, reasoning and vocabulary. DHA even seems to help protect against Alzheimer’s.
The large Framingham population study tracked 899 men and women beginning at ages 55–88 years, for an average 9.1 more years. Those with the highest DHA levels were found least likely to progress to Alzheimer’s during that period.
In 2010 a double-blind trial was conducted on 500 subjects aged over 55 who had age-related cognitive decline, a condition that features troublesome memory loss. Those subjects who got DHA (at 900 milligrams per day for 6 months) improved significantly over those on placebo. Their learning and memory errors were reduced by half, which the researchers judged was likely equivalent to more than 3 years’ worth of cognitive improvement.
Numerous Actions That Support Brain Health
Our brain is highly enriched in DHA but makes very little of it—the liver has to produce most of the body’s DHA but may not be meeting all the brain’s needs. A study on Alzheimer’s disease patients found their liver DHA production impaired. The more severe their DHA depletion, the more severe was their memory impairment.
When researchers can identify the action mechanisms of a nutrient—how it works, including its safety for long-term use—this gives everyone greater confidence in using it and in recommending it to others. DHA is known to have a great many positive brain actions:
- Natural regulator of genes that manage brain development, maturation, and maintenance.
- Regulates genes involved with mood management, behavior, and violence control.
- Promotes the maturation of nerve cells and their capacity to make connections (synapses).
- Improves membrane fluidity at the synapses. Much of the DHA at the synapses is molecularly linked in with PS (PhosphatidylSerine), another very important brain nutrient.
- Potentiates NGF (nerve growth factor), BDNF (brain-derived neurotrophic factor) and other growth factors that stimulate repair and renewal in the brain.
- Elevates the activity of antioxidant protective enzymes such as glutathione peroxidase.
- Improves glucose delivery and energy efficiency in the aged brain (established in monkeys).
- Lowers brain beta-amyloid production, which can contribute to dementia.
- Limits enzymes that can promote formation of tau tangles, which like beta-amyloid are implicated in Alzheimer’s and other dementias.
Lifesaving Benefits For The Heart and Circulation
Brain health relies on heart and circulatory health. The brain is so active that at times it demands half or more of all the blood in circulation. No wonder that just about all the risk factors for cardiovascular disease are also risk factors for Alzheimer’s! DHA’s premier brain benefits likely rest on its multiple cardiovascular benefits, including improved heart rate control, positive blood pressure effects, better blood vessel tone, and benefits to cholesterol management.
The healthy heart is able to sensitively vary its strength and rate of beat in response to varying demands for blood around the body. Poor control of heartbeat is strongly linked to cardiovascular problems. In three double-blind trials conducted with men in Australia, DHA not only improved heart rate control but also blood pressure and blood vessel tone. Tested in parallel, omega-3 EPA did not.
Two of these double-blind trials also examined the blood cholesterol profile. DHA raised the levels of HDL (high-density cholesterol) and increased the HDL particle size, both of which are linked to lowered risk for heart attack. DHA also increased the LDL particle size, another effect linked to lowered cardiovascular risk. Here also, EPA had none of these benefits.
DHA Is The Important Omega-3, Not EPA or ALA
Whatever type of human cell is analyzed, its membranes contain 5–10 times more DHA than EPA, and traces of ALA (if any). Abnormally low DHA levels in membranes correlate with disease or dysfunction, but EPA and ALA levels show no correlation. And there is a real possibility that consuming more EPA or other omega-3s than DHA could actually block DHA’s benefits.
Currently the majority of DHA supplements are fish oil preparations that also contain EPA in varying amounts. Careful examination of the research reveals that consuming supplements with more EPA than DHA tends to lower the DHA in the red cell membranes (which match up well with DHA in the body’s other cells). In contrast, taking DHA alone increases both DHA and EPA in the red cell membranes.
Let me be explicit: Avoid taking fish oil supplements that provide more EPA than DHA. We really need DHA and we don’t need anything to interfere with getting it. There is no compelling evidence that humans need any EPA or ALA if they are getting DHA in sufficient amount. DHA benefits the heart and circulation in many ways, EPA and ALA hardly at all. DHA by itself improves memory problems, and an extensive animal study demonstrated that DHA alone regulates hundreds of genes that normally manage mood, behavior and healthy judgment skills in humans.
How to Get DHA
Food sources of DHA are few, especially since food plants don’t make it. Most human populations get their DHA from the fish they consume, but these days the fish stocks worldwide are contaminated with mercury, PCBs, and other toxins. Therefore taking DHA as a dietary supplement is the safest and most convenient means to ensure you are receiving enough of it.
To drive sufficient DHA into our cell membranes we need supplements that are much higher in DHA than in EPA—the higher the better, but go for at least a 3 to 1 ratio of DHA to EPA. For the person who is basically healthy, I join other experts in suggesting 500 mg of DHA per day. Pregnant or lactating women should take at least 1000 mg per day. Individuals with memory, mood or behavior problems, or recovering from a brain injury of whatever kind, and those with cardiovascular problems can take 1000 –3000 milligrams per day. Babies likely need at least 315 mg per day for the first 6 months. Children will benefit from intakes up to 1000 mg per day, or from even higher intakes, preferably under physician supervision.
DHA is generally recognized as safe for long-term supplementation in amounts up to 3 grams (3000 milligrams) per day. Intakes above 2000 mg per day really should be monitored by a qualified healthcare professional. This nutrient is so important, I strongly recommend everyone have their red cell DHA levels tested once every 5–7 months. The optimal DHA level in the red cell membrane is likely 7 and above (measured as percentage by weight of all the red cell fatty acids). At this level DHA is likely to help manage CRP (C-Reactive Protein), a major risk factor for cardiovascular disease.
The planet is running short of fish to make fish oil and DHA. But squid fisheries are abundant and sustainable, and the parts not consumed for calamari are a great source of DHA. For strict vegetarians, DHA is also available from cultured algae.
DHA’s positive actions and clinical benefits apply all around the body. Its awesome benefits for the brain, heart and circulation are not matched by any other nutrient, and send the message that this is an exceptionally important nutrient. Since it is practically a vitamin, we all should be taking DHA every day, along with our multivitamin-mineral supplement.