Takeaways
- DHA is an omega-3 fatty acid essential for brain and eye health
- It supports cognitive function, heart health, and fetal development
- Fish, algae, and supplements are common sources of DHA
- Proper dosage varies by age and life stage
- DHA works alongside other omega-3s for optimal health benefits
What is DHA?
DHA, or docosahexaenoic acid, is an omega-3 fatty acid that is crucial for human health.[1] It performs many functions in the body, with brain and eye health being two of its most important roles.
DHA is a long-chain fatty acid composed of 22 carbon atoms and 6 double bonds.[2] This unique structure gives DHA its special properties, which are essential for its functions within the body.
You can find DHA naturally in fish and algae.[3] Some foods, such as eggs, milk, and juice, are also fortified with DHA. Supplements provide another option to increase your intake.
The Science Behind DHA
Chemical Structure
The chemical structure of DHA, with its long chain and multiple double bonds, makes it very flexible.[4] This flexibility allows DHA to interact easily with other molecules in the body.
DHA’s shape influences its activity in cell membranes.[5] It can alter how fluid and functional these membranes are, affecting how cells communicate and work together.
Metabolism
When you consume DHA, whether from food or supplements, your body absorbs it.[6] It then enters the bloodstream, where it travels to various tissues throughout your body to be used.
Your body can convert some omega-3s, like alpha-linolenic acid (ALA), into DHA. However, this process is not very efficient, making direct DHA intake a more effective method.[7]
| Age Group | DHA Metabolism Efficiency |
|---|---|
| Infants | High |
| Children | Moderate |
| Adults | Low |
| Elderly | Very Low |
The body’s ability to convert other omega-3s into DHA changes with age. Infants are quite good at this conversion, but the ability decreases as we get older.[8]
Health Benefits of DHA
Brain Function
DHA is a major component of the brain, helping brain cells communicate with each other.[9] This impacts important functions like learning, memory, and overall thinking skills.
Studies suggest that DHA might be beneficial for brain health, with some research linking it to improved memory and thinking abilities.[10] It may also help in preventing cognitive decline.
- Attention and focus
- Memory formation
- Mood regulation
- Learning ability
Adequate levels of DHA may support healthy cognitive function. However, further research is needed to fully understand and confirm these positive effects.
Eye Health
The retina of the eye contains high levels of DHA. This fatty acid is essential for maintaining the eye’s structure and function, as well as playing a role in visual development.[11]
Research into DHA and eye health indicates that it could lower the risk of certain eye conditions. This includes age-related macular degeneration and dry eye syndrome.[12]
Heart Health
DHA has several potential benefits for heart health. It may help to lower triglycerides, which are a type of fat found in the blood.[13] DHA might also improve heart rhythm and reduce blood pressure.[14]
Studies on DHA and heart health are promising, with many showing positive effects. However, results can vary, and more research is necessary to fully understand its impact.
| Study Type | Findings |
|---|---|
| Meta-analysis | DHA may lower risk of heart disease |
| Clinical trial | DHA reduced triglycerides by 15-30% |
| Observational | Higher DHA levels linked to lower stroke risk |
While research on DHA and heart health is encouraging, further investigation is still needed. This will help solidify our understanding of the benefits.
DHA Throughout the Lifespan
Pregnancy and Infancy
DHA is very important during pregnancy, as it supports the development of the baby’s brain and eyes.[15] The demand for DHA increases significantly during the last trimester when brain growth is rapid.
Breast milk naturally contains DHA, and many infant formulas now include it as well. This ensures that babies receive sufficient DHA for their healthy growth and development.[16]
- Neural tube formation
- Brain cell growth
- Eye development
- Cognitive skill foundation
- Motor skill development
DHA plays a key role in development during infancy and early childhood. Getting enough DHA during this period is critical for optimal growth and development.[17]
Childhood and Adolescence
As children grow, their brains continue to develop and change. DHA remains important during this time, and may support learning and academic success.[18]
The recommended intake of DHA differs depending on age. Children and teenagers generally need more DHA than adults.[19] Both food and supplements can help meet these needs.
Adulthood and Aging
DHA continues to support brain health throughout adulthood. Research suggests that it may help to maintain cognitive functions as people get older.[20]
Some studies have investigated DHA’s role in age-related cognitive decline, with some indicating potential benefits. However, more research is needed for a complete understanding of its impact.[21]
Dietary Sources of DHA
Fish and Seafood
Fish, particularly cold-water, fatty fish, are among the best natural sources of DHA. Examples include salmon, mackerel, and sardines, which contain high amounts.[22]
Health experts often advise eating fish twice a week to maintain adequate DHA levels. However, it’s important to consider mercury levels, and to consume fish in moderation.[23]
- Salmon
- Mackerel
- Sardines
- Herring
- Tuna (in moderation)
These fish not only provide a good source of DHA, but they also contain other beneficial nutrients, such as protein and vitamin D.
Plant-Based Sources
Algae is the primary plant-based source of DHA, and it is where fish get their DHA.[24] Algae-based supplements offer a good option for vegetarians and vegans.[25]
You can now find some foods fortified with algal DHA, such as certain brands of milk, juice, and bread. This gives more options for people who don’t eat fish.
Supplements
DHA supplements are available in various forms. Fish oil is a common source, but algal supplements are becoming more popular, as they provide a vegetarian option.[26]
When choosing a DHA supplement, look at factors such as DHA content, purity, and form.[27] It’s also beneficial to consider supplements that have undergone third-party testing for quality.
DHA Dosage and Supplementation
Recommended Intake
The amount of DHA you need varies throughout your life. Factors like your age, health status, and diet can influence how much you need.[28]
While general guidelines exist for DHA intake, individual needs can vary. It’s best to consult with a healthcare professional for personalized recommendations.[29]
| Life Stage | Recommended DHA Intake (mg/day) |
|---|---|
| Infants | 100-200 |
| Children | 200-500 |
| Adults | 250-500 |
| Pregnancy | 300-900 |
While this table provides a general guide, it’s important to note that individual needs can vary. Factors such as diet and health conditions may affect your specific requirements.
Supplement Forms
DHA supplements come in a few different forms, such as fish oil, krill oil, and algal oil.[30] Each form has its own set of advantages and disadvantages.
The form of the supplement can affect how well your body absorbs DHA. Triglyceride forms are often absorbed more easily than ethyl esters, although other factors are involved.[31]
Safety and Side Effects
DHA supplements are considered safe for most people, but some may experience side effects. Common side effects include fishy burps and digestive upset.[32]
High doses of DHA may potentially increase the risk of bleeding, especially for individuals who take blood thinners.[33] Always inform your doctor of any supplements you are taking.
- Fishy aftertaste
- Digestive upset
- Headache
- Increased bleeding risk (at high doses)
These side effects are generally mild, and choosing good quality supplements while following dosage instructions can help reduce potential risks.
DHA Deficiency
Signs and Symptoms
Low levels of DHA can impact various body systems. However, symptoms are often subtle and may not be very specific.[34]
Possible signs of a DHA deficiency may include:
- Dry, itchy skin
- Brittle nails and hair
- Poor concentration
- Joint pain
- Mood changes
It’s important to know that these symptoms can be caused by many things. A healthcare professional can help determine if a low DHA level is a contributing factor.
Certain groups are at higher risk of DHA deficiency. These include:
- Vegans and vegetarians
- People with limited fish intake
- Those with certain digestive disorders
- Premature infants
Regular checkups and a healthy diet can help prevent a deficiency in these at-risk groups.
Testing for DHA Levels
Blood tests can be used to measure your DHA levels. One common test is the omega-3 index, which measures the levels of DHA and EPA in red blood cells.[35]
Testing isn’t always routine for everyone, but doctors may recommend it for those with certain health conditions or if there is a high risk of a deficiency.
DHA vs Other Omega-3s
DHA and EPA
DHA and EPA often work together in the body. They are both long-chain omega-3 fatty acids that share some functions but also have different roles.[36]
EPA has stronger anti-inflammatory effects, while DHA is more critical for brain and eye health. Many supplements combine both to provide balanced benefits.
| Feature | DHA | EPA |
|---|---|---|
| Carbon atoms | 22 | 20 |
| Double bonds | 6 | 5 |
| Main benefits | Brain, eye health | Heart, inflammation |
| Food sources | Similar (fatty fish, algae) | Similar (fatty fish, algae) |
This table highlights some of the key differences between DHA and EPA. Both are important for good overall health.
DHA and ALA
ALA is a short-chain omega-3 fatty acid found in plant foods like flax seeds and walnuts. While our bodies can convert ALA to DHA, this process is not very efficient.[37]
The conversion rate of ALA to DHA is low, especially in adults. This means that relying solely on ALA might not provide enough DHA, making direct sources often more effective.[38]
FAQs
These are common questions about DHA. Remember that everyone’s needs may vary, and it’s always best to seek professional advice for your individual concerns.What is DHA good for?
How much DHA should I take daily?
What foods are high in DHA?
Is DHA the same as fish oil?
Can vegans get enough DHA?
Is it safe to take DHA during pregnancy?
Conclusion
DHA plays a significant role in human health, with benefits extending from brain function to heart health. Understanding DHA can help you make well-informed decisions about your diet and supplementation.
Getting enough DHA involves a balanced approach. Food sources such as fatty fish are good for natural DHA. Supplements can help fill in the gaps when necessary. The right choice depends on your own individual needs and lifestyle.
Remember that nutrition is complex, and DHA is only one part of the bigger picture. For personalized guidance, talk to a healthcare professional or registered dietitian. They can help develop a plan that suits your particular situation.
DHA is a long-chain polyunsaturated fatty acid and a crucial component of cell membranes, particularly in the brain and retina. It is considered essential because the human body can’t produce it efficiently and it must be obtained from diet or supplementation.
Source: “Maternal Supply of Both Arachidonic and Docosahexaenoic Acids Is Required for Optimal Neurodevelopment” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8234848/
The molecular structure of DHA is characterized by its long carbon chain and the presence of multiple double bonds, which contribute to its unique properties and flexibility.
Source: “Maternal Supply of Both Arachidonic and Docosahexaenoic Acids Is Required for Optimal Neurodevelopment” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8234848/
Fatty fish like salmon, mackerel, and sardines accumulate DHA from their diets which include algae. Algae are the primary producers of DHA, making them the original source in the food chain.
Source: “Maternal Supply of Both Arachidonic and Docosahexaenoic Acids Is Required for Optimal Neurodevelopment” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8234848/
The multiple double bonds within the DHA molecule introduce kinks and bends, reducing the rigidity of the fatty acid chain, which allows it to conform and interact more readily with cell membranes and other molecules.
Source: “Emerging Role of Phospholipids and Lysophospholipids for Improving Brain Docosahexaenoic Acid as Potential Preventive and Therapeutic Strategies for Neurological Diseases” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9000073/
The unique shape and flexibility of the DHA molecule directly impact how it integrates into cell membranes. This influences membrane fluidity and the function of proteins embedded within them.
Source: “Maternal Docosahexaenoic Acid Status during Pregnancy and Its Impact on Infant Neurodevelopment” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7759779/
DHA, like other dietary fats, is absorbed primarily in the small intestine. The absorbed DHA is then transported through the lymphatic system to the bloodstream and various tissues.
Source: “Lipopolysaccharides transport during fat absorption in rodent small intestine” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7311662/
ALA, a plant-based omega-3 fatty acid, can be converted into DHA through a series of enzymatic reactions. However, the conversion rate is very low, especially in adults, making dietary sources or supplements of DHA generally a better option.
Source: “α-Linolenic Acid Suppresses Proliferation and Invasion in Osteosarcoma Cells via Inhibiting Fatty Acid Synthase” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9105512/
Infants have a higher capacity to convert ALA to DHA due to the high demand for DHA for brain and eye development. As we age the efficiency of this process slows.
Source: “Omega-3 Polyunsaturated Fatty Acids in Depression” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11354246/
DHA is highly concentrated in brain cell membranes. It contributes to membrane fluidity which is crucial for effective communication between neurons via neurotransmitter release and receptor function.
Source: “Omega-3 Polyunsaturated Fatty Acids in Depression” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11354246/
Several studies suggest that DHA supplementation might improve cognitive functions such as memory and attention, but the results are not always consistent, and further research with more rigorous designs is needed.
Source: “Omega-3 Polyunsaturated Fatty Acids in Depression” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11354246/
The retina has the highest concentration of DHA in the body, and DHA is crucial for maintaining the structural integrity and function of the photoreceptor cells, which enable vision. It is also vital for development of visual system during fetal and infant stages.
Source: “Retinal Docosahexaenoic Acid Is Significantly Reduced in Diabetic Humans and Mice: Possible Relationship to Diabetic Retinopathy” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11684127/
Several studies have investigated the potential of DHA supplementation to reduce the risk or severity of age-related macular degeneration and dry eye syndrome, and some have shown promising results. However, further research, including large-scale clinical trials, are needed to confirm these findings and establish specific guidelines for DHA intake.
Source: “Role of omega-3 fatty acids in the prevention and treatment of cardiovascular Diseases: A consensus statement from the Experts’ Committee Of National Society Of Cardiometabolic Medicine” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9791266/
Studies have shown that DHA can lower blood triglyceride levels, which is associated with a reduced risk of cardiovascular disease.
Source: “Functional Lipids and Cardiovascular Disease Reduction: A Concise Review” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11314407/
Some studies suggest that DHA may help to improve heart rhythm and reduce blood pressure in some populations. However, the findings are not always consistent and further research is needed to determine the overall impact and specific recommendations.
Source: “Omega-3 Polyunsaturated Fatty Acids in Depression” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11354246/
DHA is a critical component of the rapidly growing brain and eyes of the fetus and infant. It is transferred from the mother to the fetus during pregnancy and continues to be needed throughout infancy and early childhood.
Source: “Omega‐3 fatty acid addition during pregnancy” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6516961/
Breast milk naturally contains DHA, which is essential for optimal development. Due to the importance of DHA, many infant formula companies now add DHA to their products.
Source: “The imperative of arachidonic acid in early human development.” https://pubmed.ncbi.nlm.nih.gov/36746351/
DHA is a crucial building block for the brain and eyes during the early stages of life, and deficiencies during this time can have lasting impacts on cognitive and visual function.
Source: “Multiple Micronutrients and Docosahexaenoic Acid Supplementation during Pregnancy: A Randomized Controlled Study” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7468952/
While the rate of brain development slows down after infancy, it continues to evolve and change throughout childhood and adolescence. DHA contributes to healthy brain structure and function during this period and there is evidence to suggest it may support cognitive functions that are essential for learning.
Source: “Polyunsaturated Fatty Acids: What is Their Role in Treatment of Psychiatric Disorders?” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6862261/
DHA requirements are generally higher during periods of rapid growth and development, especially in the brain. Children and teens tend to need a higher relative amount compared to their body size, as this is a critical period for brain development.
Source: “Omega-3 Polyunsaturated Fatty Acids in Depression” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11354246/
DHA is involved in ongoing cellular function and communication in the brain throughout adulthood, and there is evidence to suggest it can help maintain cognitive function as people age.
Source: “The Relationship of Omega-3 Fatty Acids with Dementia and Cognitive Decline: Evidence from Prospective Cohort Studies of Supplementation, Dietary Intake, and Blood Markers” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10447496/
While some studies have indicated that DHA might play a role in preventing cognitive decline in older adults, the findings are mixed and more robust and long-term clinical trials are needed to establish the effectiveness and make concrete recommendations.
Source: “The Relationship of Omega-3 Fatty Acids with Dementia and Cognitive Decline: Evidence from Prospective Cohort Studies of Supplementation, Dietary Intake, and Blood Markers” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10447496/
Cold-water, fatty fish such as salmon, mackerel, and sardines are among the richest natural sources of DHA due to their consumption of algae.
Source: “Role of omega-3 fatty acids in the prevention and treatment of cardiovascular Diseases: A consensus statement from the Experts’ Committee Of National Society Of Cardiometabolic Medicine” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9791266/
Many health organizations recommend consuming fish twice a week as part of a healthy diet to achieve adequate DHA intake. However, it is also important to be aware of the potential presence of mercury in some types of fish, and choose options that are low in mercury to minimize exposure.
Source: “Biotechnological production of omega-3 fatty acids: current status and future perspectives” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10662050/
Algae are the primary producers of DHA. Fish accumulate DHA through their diets, and when fish are eaten humans then obtain DHA from the fish.
Source: “Omega-3 fatty acids for nutrition and medicine: considering microalgae oil as a vegetarian source of EPA and DHA.” https://pubmed.ncbi.nlm.nih.gov/18220672/
Algal oil supplements are a plant-based source of DHA and therefore are an excellent option for vegetarians and vegans who do not consume fish.
Source: “A Comprehensive Review of Chemistry, Sources and Bioavailability of Omega-3 Fatty Acids” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6267444/
DHA supplements are available from different sources. Fish oil is a traditional source and algal oil is a plant-based alternative that is becoming increasingly popular.
Source: “Biotechnological production of omega-3 fatty acids: current status and future perspectives” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10662050/
When choosing a DHA supplement, it is important to consider the actual amount of DHA it contains, to ensure that it is free of contaminants and of good quality. Also, different forms of DHA can differ in absorption and other characteristics.
Source: “Biotechnological production of omega-3 fatty acids: current status and future perspectives” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10662050/
Individual DHA requirements can vary depending on factors such as age, stage of development, overall health, and other dietary sources of omega-3 fatty acids.
Source: “Total Fat and Fatty Acid Intake among 1–7-Year-Old Children from 33 Countries: Comparison with International Recommendations” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8537778/
There are general recommendations for DHA intake but individual needs will vary due to numerous factors. Consulting a healthcare provider or registered dietitian can help determine personalized recommendations for specific needs.
Source: “A historical, evidence-based, and narrative review on commonly used dietary supplements in lipid-lowering” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10844731/
DHA supplements are derived from different sources with fish oil, krill oil, and algal oil being common options.
Source: “Biotechnological production of omega-3 fatty acids: current status and future perspectives” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10662050/
DHA supplements may come in different chemical forms and the triglyceride form has been shown to be better absorbed than the ethyl ester form. Other factors also influence absorption including individual factors.
Source: “Biotechnological production of omega-3 fatty acids: current status and future perspectives” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10662050/
DHA supplements are generally safe for most people, but some individuals may experience mild side effects like fishy burps, indigestion, or nausea, especially with higher doses. Taking them with meals can help mitigate these effects.
Source: “Biotechnological production of omega-3 fatty acids: current status and future perspectives” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10662050/
High doses of DHA may have a blood-thinning effect which could increase the risk of bleeding, particularly in people who are already taking blood-thinning medications. It is important to consult a healthcare professional when combining blood thinners with DHA.
Source: “Role of omega-3 fatty acids in the prevention and treatment of cardiovascular Diseases: A consensus statement from the Experts’ Committee Of National Society Of Cardiometabolic Medicine” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9791266/
Low levels of DHA can impact the brain, eyes, and heart, as well as general cellular function. However, the symptoms are usually non-specific and may not be easily recognizable, making it challenging to diagnose a deficiency based solely on symptoms.
Source: “Role of Omega-3 Fatty Acids as Non-Photic Zeitgebers and Circadian Clock Synchronizers” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9603208/
There are a number of ways that DHA levels can be assessed including blood testing. The Omega-3 Index test measures the levels of EPA and DHA in red blood cells which may help assess someone’s overall omega-3 status.
Source: “Omega-3 Polyunsaturated Fatty Acids in Depression” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11354246/
Both EPA and DHA are important omega-3 fatty acids that often work together in the body. They have some overlapping functions but also differ in their primary roles. DHA is more important for brain and eye health, while EPA has stronger anti-inflammatory effects.
Source: “Omega-3 Polyunsaturated Fatty Acids in Depression” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11354246/
Alpha-linolenic acid (ALA) is a short-chain omega-3 fatty acid found in plant-based sources such as flaxseeds and walnuts. However, human conversion of ALA to DHA is limited, particularly in adults, making ALA alone an unreliable source of DHA.
Source: “α-Linolenic Acid Suppresses Proliferation and Invasion in Osteosarcoma Cells via Inhibiting Fatty Acid Synthase” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9105512/
The conversion of ALA to DHA is limited by several factors, and the conversion rate is usually very low especially in adults and particularly when there is a lack of other key nutrients. This often means that direct sources of DHA are preferable to relying on dietary ALA alone.
Source: “α-Linolenic Acid Suppresses Proliferation and Invasion in Osteosarcoma Cells via Inhibiting Fatty Acid Synthase” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9105512/
While general recommendations exist for daily DHA intake, individual needs can vary. These cited ranges are reasonable guidelines, but healthcare providers may advise differently based on individual health factors. Pregnant women typically need higher levels.
Source: “A historical, evidence-based, and narrative review on commonly used dietary supplements in lipid-lowering” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10844731/
DHA is a specific fatty acid found in fish oil, which also contains other fatty acids, notably EPA. Pure DHA supplements are available and are often derived from algae making them suitable for those who avoid fish.
Source: “Biotechnological production of omega-3 fatty acids: current status and future perspectives” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10662050/
