Chances are good you’ve heard or read about the way fish oil benefits the brain as well as general physical health. The most beneficial aspect of the fish oil is the omega-3 polyunsaturated fatty acids (PUFAs) that it contains. There are two primary types of omega-3 fatty acids that are delivered from eating oily fish or from fish oil supplementation: DHA and EPA.
Many people don’t really understand the difference between DHA and EPA, know whether they’re getting enough, or how much of each they should be taking. Each fish oil supplement tends to differ in the amount of DHA and EPA per serving. In order to determine which fish oil supplement to purchase, it’s important to know whether you want more DHA, more EPA, or a fairly balanced amount of each.
DHA vs. EPA: Omega-3 Fatty Acids Comparison
This article will discuss the functions of DHA and EPA, the benefits associated with each, as well as compare them. It will then be up to you to decide whether you believe one may be more advantageous than the other in your supplementation regimen. The synergistic effects of combining both DHA and EPA are also noted. For a broader perspective on omega-3 fatty acids, read the article: “Fish Oil Benefits the Brain.”
What is DHA?
DHA (Docosahexaenoic acid) is an omega-3 fatty acid that is considered a “building block” for the structure of your brain, as well as other parts of the body such as the retina, skin, and testicles. Its structure consists of a carboxylic acid with a 22-carbon chain and six double bonds. Most DHA in organisms is obtained from seafood derived from cold-water oceans. The higher an organism is in the food chain, the more concentrated the amount of DHA it tends to contain.
There are several reasons why DHA is considered an essential fatty acid. Approximately 60% of the dry matter of the brain is lipid, with DHA being one of the most prevalent fatty acids within these lipids. In the past, our ancestors consumed significantly more dietary DHA than today, with deficiencies possibly influencing mental health problems. DHA is considered essential for proper brain development and growth.
There are numerous health benefits associated with adequate DHA consumption including: reduced risk of heart disease and prevention of neurodegenerative diseases (e.g. Alzheimer’s). Insufficient DHA consumption may lead to an unwanted conditions such as: fetal alcohol syndrome, cystic fibrosis, depression, and aggression.
- Attention: Deficiencies in DHA are associated with attention-deficit hyperactivity disorder (ADHD). There is evidence suggesting that the way the brains of ADHD children metabolize omega-3 fatty acids is different than normal. That said, it appears as though there is likely some marginal benefit from supplementation of DHA. Some speculate that dietary DHA supplementation may help prevent or mitigate ADHD symptoms.
- Cognition: Age-related cognitive decline has been correlated with low DHA levels. DHA is capable of improving a variety of cognitive functions including: learning ability, memory, and reaction time. It is thought that for optimal cognitive development in children, sufficient levels of DHA are required. Deficiencies in DHA during infancy and childhood may result in lifelong suboptimal cognitive function.
- Learning: Studies have long shown that including significant amounts of DHA improves our ability to learn and that deficiencies in DHA are strongly linked to learning impairments. In a study conducted among children with ADHD, supplementation of DHA was found to improve word-learning ability as well as oppositional behavior. Researchers concluded that literacy scores improved as a result of the DHA. There is evidence that supplementation of DHA improves school performance in children.
- Memory: A study conducted on 176 young adults found that DHA supplementation of 1.16 grams per day significantly improved memory function compared to a placebo. They measured this by administering a computerized test and comparing scores of both episodic and working memory. The memory improvements were sex-based; women experienced a boost in episodic memory, while men experienced a boost in working memory.
- Mood: While many studies correlate low EPA with depressed mood and suicidality, some research has identified a significant correlation between depression and DHA deficiency. It appears as though there may be a small benefit associated with DHA for mood disorders like depression.
- Neurodegeneration: People with neurodegenerative diseases like Alzheimer’s disease tend to demonstrate significant decreases in levels of DHA within the brain. As the disease becomes more severe, levels of DHA continuously decrease. Trials of DHA have been utilized with some success in decreasing cognitive decline associated with dementia.
- Reaction time: In the same study that was already mentioned with 176 young adults, supplementation of 1.16 grams of DHA per day resulted in quicker reaction time in regards to memory recall. There was another study conducted on elite female soccer players that discovered 3.5 grams per day of DHA-based fish oil resulted in quicker complex reaction time compared to a placebo.
- Visual acuity: There is some evidence suggesting that better visual acuity may result from increased intake of DHA. In a study conducted on aging adults (45-77), it was discovered that 90 day’s worth of DHA supplementation resulted in significantly quicker visual acuity than a placebo group.
What is EPA?
EPA (Eicosapentaenoic acid) is an omega-3 fatty acid containing a 20-carbon chain and 5 double-bonds. It functions as a precursor for eicosanoids such as: prostaglandin, thromboxane, and leukotriene. Although many don’t consider it to be as “essential” as DHA, its primary benefit is that of inflammation reduction.
EPA is primarily known for its anti-inflammatory properties as well as its ability to improve mood. EPA itself doesn’t seem to play a direct role in the reduction of inflammation, but does reduce the amount of arachidonic acid (an omega-6). Arachidonic acid synthesizes prostaglandins that lead to inflammation.
Since EPA contains the same number of carbon atoms as arachidonic acid, it competes with it for metabolizing enzymes. The prostaglandins produced from the EPA are considered significantly less inflammatory than those made by arachidonic acid. EPA isn’t considered an “essential fatty acid” but can reduce inflammation, and has been associated with mood improvement.
- Depression: Many studies have found that taking fish oil for depression significantly reduces symptoms. Most of these studies found that EPA rather than DHA produces improvement in mood. For targeting depression, researchers have recommended taking formulations with at least 60% of the omega-3 fatty acids consisting of EPA.
- Inflammation: EPA is well-known to help reduce inflammation throughout the nervous system and brain. The reduction in cellular inflammation within the brain may lead to neuroprotection as well as improvements in mood. Some believe that the anti-inflammatory properties of EPA may be responsible for its mental health benefits.
- Neuroprotection: It is thought that EPA may help act as a neuroprotective agent within the brain. Its anti-inflammatory effects may help reduce tissue damage as well as enhance existing neural activity. Some researchers speculate it accomplishes this by clearing apoptotic cells and debris from the brain, thus helping restore tissue homeostasis. EPA is also thought to improve synaptic plasticity.
- Neurodegeneration: EPA is thought to play a role in reducing oxidative stress within the brain. The reduction in oxidative stress is thought to help prevent onset of neurodegenerative diseases like Alzheimer’s. While there is more evidence suggesting DHA plays an important role in preventing neurodegenerative diseases, EPA may offer synergistic benefits.
- Schizophrenia: A study published in 2011 revealed that supplementation of EPA at 2 grams per day improved cognitive symptoms of schizophrenia. Researchers noted that positive symptoms also experienced marked improvement following supplementation over 24 weeks. Other research suggests that supplementation of omega-3 fatty acids (with DHA and EPA) could help prevent schizophrenia.
DHA vs. EPA: Comparison
DHA: DHA has 6 double-bonds and an increased carbon length, meaning it accounts for greater space in the membrane when compared to EPA. EPA has only 5 double-bonds and 20 carbons compared to 22 possessed by DHA. DHA tends to improve membrane fluidity much more than EPA, allowing for synapses to transmit signals quicker and with greater effectiveness.
DHA tends to be very active and is capable of breaking up “lipid rafts” within membranes, leading to decreased likelihood that cancer cells will survive. It also decreases the ability of cytokines to send out inflammatory signals, leading to less likelihood of inflammation. The DHA also helps to inhibit large LDL particles into muscle cells surrounding the artery, meaning you’re less likely to develop atherosclerosis.
EPA: EPA is primarily responsible for reducing cellular inflammation by minimizing arachidonic acid (AA) derived eicosanoids. EPA does this by inhibiting the D5D (delta-5-desaturase) enzyme that is responsible for producing arachidonic acid. The greater the quantity of EPA you consume, the less arachidonic acid your body can produce.
This inhibits all eicosanoid-induced inflammation as a result of prostaglandins, leukotrienes, thromboxanes, etc. DHA is incapable of inhibiting this particular enzyme because it is larger than EPA, and simply cannot fit into the particular enzymatic site that yields inhibition. Another function of EPA is that it reduces the amount of phospholipase A2 obtained by arachidonic acid, leading to diminished corticosteroid function.
Which is more important? DHA vs. EPA
It totally depends upon your target goal of omega-3 supplementation. If you are primarily focused on enhancing your cognition, some sources suggest that a DHA-based fish oil may be your best option. If your goal is treating a mood disorder like depression, there is significant evidence that an EPA-based fish oil is likely to provide more benefit.
From an evolutionary perspective, DHA is the most important of the omega-3 fatty acids and is regarded as “essential.” To ensure optimal brain function and prevent disease, it is recommended that infants and elderly consume adequate DHA. Dietary changes in the United States over the past 100 years have lead to inadequate consumption of both DHA and EPA.
The deficiencies incurred may be responsible for numerous health problems such as: cardiovascular disease, mood disorders, and poor brain development. When deciding whether DHA or EPA is more important, it is important to take an individualized approach. Some people may respond better to a DHA-weighted supplement, while others may benefit more from an EPA-weighted one depending on the treatment goal.
There are companies that go as far as to sell 100% EPA or 100% DHA for those who are interested in one omega-3 over the other. Assuming you’re taking fish oil or plan on it, it is best to start with a supplement that contains both so that you can reap the benefits of both omega-3’s.
Why you probably want both DHA and EPA…
Although each is associated with certain benefits, there is significant overlap in some of the benefits to be obtained. For example, some research shows that both DHA and EPA are capable of improving depressive symptoms and mood disorders. There is even some evidence suggesting that DHA and EPA may elicit synergistic effects in improving cognition and inflammation.
Unless you are absolutely sure (via experimentation) that one provides more benefit than the other, it is recommended to consume both. Most people will want the balanced mood and reduced inflammation associated with EPA, and nearly everyone will want the potential cognitive enhancement associated with DHA.
What is the best source of DHA and EPA? Fish oil.
Many people assume that they can get sufficient omega-3 fatty acids from plant sources such as ALA (alpha-linolenic-acid). This is found in green leafy vegetables (e.g. Brussels sprouts, kale, spinach, etc.), flaxseed, vegetable oils, as well as walnuts. Despite the fact that the body converts ALA to DHA and EPA, the conversion is very inefficient.
It is estimated that less 0.5% of ALA is converted into DHA and less than 5% of all ALA gets converted into EPA. Therefore if you’re eating foods with ALA and thinking that you’re getting sufficient DHA and EPA, you’ve been duped. Even ALA supplements (e.g. flax oil) don’t provide a significant increase in levels of DHA.
Instead of shoveling down flaxseed oil thinking that it’s helping boost levels of DHA and EPA, it’s recommended to invest in some fish (or fish oil supplements). The best source of DHA and EPA is clearly fish oil due to the fact that the omega-3 fatty acids are “preformed.” Our bodies don’t need to go through an inefficient conversion process as they would with ALA.
To make sure that you’re getting enough DHA and EPA, take the time to research and invest in some high quality fish oil supplements, or start eating more wild-caught fish. If you want to ensure optimal mental health and functioning, consumption of these omega-3 fatty acids is not something to neglect.