Takeaways
- DHA is an omega-3 fatty acid essential for brain and eye health
- Common side effects include digestive issues and fishy aftertaste
- Blood thinning effects may interact with certain medications
- Quality and purity of supplements can impact side effects
- Proper dosage and timing can help minimize adverse reactions
- Natural food sources offer DHA with fewer potential side effects
Understanding DHA
Docosahexaenoic acid, or DHA, is a crucial type of omega-3 fatty acid. Our bodies rely on it for many functions, such as building brain cells and maintaining healthy vision.[1] You’ll primarily find DHA in fish and seafood.[2]
Many individuals choose to take DHA supplements to support their health. These supplements can be derived from either fish oil or algae. While DHA offers various advantages, it can also lead to some side effects. This article explores these potential effects and offers advice on how to minimize them.
DHA is part of the omega-3 fatty acid group, which plays numerous roles in the body. These fats help reduce inflammation and promote a healthy heart. Since our bodies cannot produce enough DHA on their own, we must obtain it through diet or supplements.[3]
Sources of DHA
Natural Sources
Fish and seafood are among the richest sources of DHA. Oily fish like salmon, mackerel, and sardines are particularly good choices.[4] Consuming these types of fish about twice a week can typically provide sufficient DHA for most people.[5]
Some plant-based foods contain omega-3s, but not directly as DHA. Instead, they contain ALA, which the body can convert into DHA.[6] However, this conversion process is not very efficient.[8] Plant sources of ALA include flaxseeds, chia seeds, and walnuts.[7]
- Walnuts
- Flaxseeds
- Chia seeds
- Hemp seeds
- Algae (for vegetarians and vegans)
Incorporating a variety of these foods into your diet can help improve your DHA levels. However, for certain individuals, this may not be adequate to meet their needs.
Supplements
Many people opt for supplements to increase their DHA intake. These supplements are available in several forms, including fish oil, algal oil, and cod liver oil.[9]
- Fish oil capsules
- Algal oil (from algae)
- Krill oil
- Cod liver oil
Each type of DHA supplement has its own set of advantages and disadvantages. Fish oil is a common source, while algal oil provides a plant-based alternative. Cod liver oil also provides vitamins A and D.[10]
Supplement Type | Pros | Cons |
---|---|---|
Fish oil | High in DHA, widely available | May cause fishy burps, potential contaminants |
Algal oil | Vegan-friendly, no fishy taste | More expensive, lower DHA content |
Krill oil | Better absorbed, less fishy taste | More expensive, sustainability concerns |
Cod liver oil | Contains vitamins A and D | Risk of vitamin A toxicity in high doses |
Selecting the appropriate supplement depends on your individual needs and preferences. Consider your dietary habits, budget, and any potential side effects you want to avoid when choosing a supplement.
Benefits of DHA Supplementation
DHA provides a variety of health benefits. Research indicates it can support brain function, eye health, and heart health.[11] These benefits include promoting healthy brain development and reducing risk factors for certain diseases.
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Brain function: DHA makes up a large part of our brain. It helps brain cells communicate.
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Eye health: Our retinas need DHA to work well. It may help prevent age-related eye problems.
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Heart health: DHA can lower triglycerides and increase “good” HDL cholesterol.
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Pregnancy: DHA supports fetal brain and eye development. It may also reduce the risk of preterm birth.
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Inflammation: Omega-3s like DHA have anti-inflammatory effects in the body.
These potential benefits are why many people take DHA supplements. However, it is important to be aware of and consider the possible side effects that can occur when taking them.
Common DHA Side Effects
Digestive Issues
Many people experience stomach issues when they begin taking DHA supplements. These problems can include nausea, diarrhea, and heartburn.[12] Some individuals also report feeling bloated or experiencing gas.
- Nausea
- Diarrhea
- Stomach pain
- Bloating
These issues often happen when someone starts with a high dose of DHA.[13] It takes the body time to adjust to the additional fat intake. Gradually increasing the dose can help prevent these side effects.
Some individuals are more sensitive to these digestive effects. Those with pre-existing digestive conditions may find it more difficult to tolerate the supplements. Taking DHA supplements with food can often help lessen these side effects.
Fishy Aftertaste
A common complaint regarding fish oil supplements is their fishy taste, which can cause unpleasant burps or a lingering aftertaste.[14] While not harmful, this can be bothersome and may affect your willingness to continue taking them.
To minimize any fishy aftertaste, try storing your fish oil capsules in the refrigerator or choose enteric-coated capsules. These measures can help reduce that effect.
- Taking supplements with meals
- Freezing the capsules before taking them
- Choosing enteric-coated supplements
- Switching to a high-quality, purified fish oil
Some individuals find that algal DHA causes less of a fishy taste compared to fish oil. If you are sensitive to fish flavors, algal DHA can be a suitable alternative.
Blood Thinning
DHA can have a mild blood-thinning effect.[15] For most people, this is not a problem, and it contributes to the heart health benefits of omega-3s. However, this effect requires consideration for some individuals.
If you are taking blood-thinning medications, you should use DHA with caution.[16] DHA could potentially enhance the effects of these medications, leading to increased bruising or bleeding. Always discuss with your doctor before starting DHA if you are on blood thinners.
The blood-thinning effect of DHA may also be a concern before surgery. Doctors usually advise patients to stop taking DHA supplements 1 to 2 weeks before any planned procedures to minimize the risk of increased bleeding.[17]
Less Common Side Effects
Allergic Reactions
Although rare, some people may have an allergic reaction to fish oil or algae.[18] Signs of an allergic reaction could include a skin rash, itching, swelling, or difficulty breathing.
- Rash or hives
- Itching
- Swelling, especially of the face or throat
- Difficulty breathing
If you experience any of these allergy symptoms, stop taking the supplement and seek medical attention. People with known allergies to fish or shellfish should be especially careful when using fish oil supplements.
Vitamin A Toxicity
Certain fish liver oils, such as cod liver oil, can have high levels of vitamin A.[19] While vitamin A is important, too much of it can be harmful. Symptoms of excessive vitamin A intake include nausea, headaches, and dizziness.
- Nausea
- Headache
- Blurred vision
- Skin irritation
- Joint pain
To prevent vitamin A toxicity, choose supplements that do not contain excessive amounts of vitamin A.[20] Standard fish oil or algal DHA supplements are usually safe in this regard.
Interactions with Medications
DHA may interact with certain medications.[21] It’s important to talk to your doctor before taking DHA supplements if you are currently taking any medications, such as blood thinners, antiplatelet drugs, or some blood pressure medications.
Medication Type | Potential Interaction |
---|---|
Blood thinners (e.g., warfarin) | May increase bleeding risk |
Blood pressure medications | May enhance blood pressure lowering effects |
Diabetes medications | May lower blood sugar further |
Birth control pills | May reduce effectiveness |
These interactions don’t necessarily mean you cannot take DHA; however, your doctor might need to adjust your dosage or the timing of when you take your medications. It is crucial to work with your doctor to develop a safe plan.
Dosage and Timing
Taking the correct dose of DHA can help you maximize the benefits while minimizing potential side effects. The right dose will vary based on your age, health status, and reason for taking it.
For general health, adults typically take 250 to 500 mg of DHA per day.[22] Pregnant women may require a higher dose, typically between 300 and 900 mg daily.[23] Children’s dosages will be lower and are often based on their weight.
Some tips for dosing and timing include taking your DHA with food to aid absorption and dividing larger doses throughout the day. This could help reduce potential side effects.
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Start low and increase slowly. This gives your body time to adjust.
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Split the dose throughout the day. This can reduce digestive issues.
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Take with meals. Food helps your body absorb DHA better.
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Consider your omega-3 to omega-6 ratio. Too much omega-6 can interfere with DHA benefits.
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Be consistent. DHA builds up in your body over time.
Remember that taking more DHA does not always equal better results. Very high doses (over 3 grams daily) may increase some risks.[24] Always follow the directions on the product label or adhere to your doctor’s advice.
Quality and Purity Concerns
The quality of DHA supplements can vary significantly. This affects how effective they are, as well as the possibility of side effects. Lower quality supplements may contain contaminants like mercury, PCBs, or heavy metals.[25]
- Mercury
- PCBs (polychlorinated biphenyls)
- Dioxins
These contaminants can be harmful to your health over time. To ensure you are using a safe product, look for third-party tested supplements, choose reputable brands, and verify that the supplement has been purified.[26]
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Choose supplements tested by third-party organizations. Look for seals from:
- USP (United States Pharmacopeia)
- NSF International
- ConsumerLab.com
-
Check for molecular distillation or CO2 extraction. These processes remove many contaminants.
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Look for supplements that list the amounts of EPA and DHA, not just “fish oil.”
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Consider the source. Smaller fish like anchovies and sardines often have lower mercury levels.
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Read customer reviews and research the brand’s reputation.
Choosing a high-quality supplement can lower your risk of both side effects and exposure to contaminants. It may be worth spending a bit more to ensure product safety.
Minimizing Side Effects
While DHA side effects can be bothersome, there are ways to reduce them. Consider taking your supplements with food, start with a lower dose, and divide your daily dose into smaller portions.
-
Start with a low dose. Gradually increase over several weeks.
-
Take supplements with food. This improves absorption and reduces stomach upset.
-
Choose a high-quality, purified supplement. This can minimize contaminants and fishy taste.
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Consider enteric-coated capsules. These dissolve in the intestines, not the stomach.
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Try freezing fish oil capsules. This can reduce fishy burps.
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Stay hydrated. Drinking plenty of water can help with digestive issues.
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Consider algal DHA if fish oil causes problems.
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Spread your dose throughout the day instead of taking it all at once.
If side effects continue, it’s a good idea to talk with your doctor. They may suggest adjusting your dose or trying a different form of DHA that might be easier for you to tolerate.
Alternatives to DHA Supplements
If you prefer to avoid supplements, there are several natural ways to increase your DHA intake. Try including more fatty fish like salmon, tuna, and sardines in your diet. Consuming these fish regularly can help boost your DHA levels.
-
Eat fatty fish twice a week. Good choices include:
- Salmon
- Mackerel
- Sardines
- Herring
- Trout
-
Add algae to your diet. Seaweed and microalgae contain DHA.
-
Consume ALA-rich foods. Your body can convert some to DHA:
- Walnuts
- Flaxseeds
- Chia seeds
- Canola oil
-
Choose omega-3 enriched foods. Some eggs, milk, and juices are fortified with DHA.
-
If vegetarian or vegan, consider algae-based DHA supplements.
Remember that whole foods provide not just DHA but many additional nutrients. These whole foods can be a more balanced and safer way to increase your intake.
FAQs
DHA provides several health benefits; however, some individuals may experience side effects. Being aware of these potential side effects and how to minimize them will allow you to use DHA safely and effectively. It is always recommended to consult with a healthcare provider before starting any new supplement. Your doctor can help you weigh the potential benefits against the risks based on your individual health needs.Can DHA supplements cause headaches?
How long does it take to see benefits from DHA supplements?
Is it safe to take DHA during pregnancy?
Can DHA supplements help with depression?
Are there any long-term side effects of taking DHA?
How does DHA compare to EPA in terms of side effects?
DHA is a major structural component of brain tissue and the retina, and plays a key role in their development and function.
Source: “Maternal Supply of Both Arachidonic and Docosahexaenoic Acids Is Required for Optimal Neurodevelopment” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8234848/
Oily fish like salmon, mackerel, and sardines are particularly rich in DHA.
The body can convert ALA to DHA, but this process is inefficient, necessitating intake from dietary sources or supplementation.
These fish are high in omega-3 fatty acids, especially DHA.
The general recommendation is to consume oily fish 1-2 times a week to obtain sufficient DHA, but this amount may differ based on individual factors.
ALA is an omega-3 fatty acid that the body can convert to EPA and then DHA, however, the conversion rate is low.
These foods are among the richest plant-based sources of ALA.
The body converts a relatively small percentage of dietary ALA to EPA and DHA, making it difficult to rely solely on ALA for optimal DHA levels.
Fish oil is extracted from fatty fish, algal oil is a plant based source and cod liver oil is made from cod liver.
Unlike regular fish oil, cod liver oil contains fat soluble vitamins.
DHA plays a role in reducing inflammation, supporting cognitive function and maintaining healthy vision.
Source: “Maternal Supply of Both Arachidonic and Docosahexaenoic Acids Is Required for Optimal Neurodevelopment” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8234848/
Common side effects may include nausea, diarrhea, and heartburn, especially at higher doses.
The body may need time to adjust to the increased fat intake from a high dose of DHA, which can cause digestive discomfort.
The fishy odor and taste of some fish oil supplements can be difficult to tolerate for some individuals.
DHA can reduce blood clotting, which can be beneficial for heart health, but requires caution in certain individuals.
Source: “Marine omega-3 fatty acids and inflammatory processes: Effects, mechanisms and clinical relevance” https://pubmed.ncbi.nlm.nih.gov/25149823/
This can potentially increase the risk of bleeding or bruising.
To avoid the risk of excess bleeding during surgery, it’s often recommended to stop DHA or fish oil supplementation 1 to 2 weeks before a scheduled procedure.
Symptoms of allergy can include skin rashes, itching, swelling, or breathing difficulties.
Cod liver oil contains naturally high levels of vitamin A, which can lead to toxicity with excessive intake.
Standard fish oil and algal oil supplements do not contain high levels of vitamin A like cod liver oil.
It is important to consult a doctor before beginning DHA supplements if you are taking any other medications, including blood thinners and blood pressure medications.
This is a common recommendation for maintaining overall health benefits of DHA. Individual needs may vary.
DHA is important for fetal brain and eye development, often requiring higher supplementation.
Source: “Omega‐3 fatty acid addition during pregnancy” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6516961/
Consuming over 3 grams of DHA daily may increase risks of bleeding or other side effects.
Some low-quality fish oil supplements may contain harmful contaminants such as heavy metals, or PCBs.
These measures help to ensure that supplements are free from contaminants and accurately labeled.
DHA’s anticoagulant effects may contribute to headaches in some individuals.
DHA is crucial for the development of the baby’s brain and eyes during pregnancy.
Source: “Omega‐3 fatty acid addition during pregnancy” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6516961/
While research suggests omega-3s may help some individuals with depression, its use should not replace established treatments. Results are mixed.
Provided the supplements are of high quality and taken at recommended dosages, long term use is generally considered safe.
Consuming extremely high levels of DHA over an extended time may result in an increased bleeding risk or affect immune system function.