Table of Contents

DHA Side Effects: What to Expect & How to Avoid Them

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.

  1. Brain function: DHA makes up a large part of our brain. It helps brain cells communicate.

  2. Eye health: Our retinas need DHA to work well. It may help prevent age-related eye problems.

  3. Heart health: DHA can lower triglycerides and increase “good” HDL cholesterol.

  4. Pregnancy: DHA supports fetal brain and eye development. It may also reduce the risk of preterm birth.

  5. 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.

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.

  1. Start low and increase slowly. This gives your body time to adjust.

  2. Split the dose throughout the day. This can reduce digestive issues.

  3. Take with meals. Food helps your body absorb DHA better.

  4. Consider your omega-3 to omega-6 ratio. Too much omega-6 can interfere with DHA benefits.

  5. 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]

  1. Choose supplements tested by third-party organizations. Look for seals from:

    • USP (United States Pharmacopeia)
    • NSF International
    • ConsumerLab.com
  2. Check for molecular distillation or CO2 extraction. These processes remove many contaminants.

  3. Look for supplements that list the amounts of EPA and DHA, not just “fish oil.”

  4. Consider the source. Smaller fish like anchovies and sardines often have lower mercury levels.

  5. 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.

  1. Start with a low dose. Gradually increase over several weeks.

  2. Take supplements with food. This improves absorption and reduces stomach upset.

  3. Choose a high-quality, purified supplement. This can minimize contaminants and fishy taste.

  4. Consider enteric-coated capsules. These dissolve in the intestines, not the stomach.

  5. Try freezing fish oil capsules. This can reduce fishy burps.

  6. Stay hydrated. Drinking plenty of water can help with digestive issues.

  7. Consider algal DHA if fish oil causes problems.

  8. 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.

  1. Eat fatty fish twice a week. Good choices include:

    • Salmon
    • Mackerel
    • Sardines
    • Herring
    • Trout
  2. Add algae to your diet. Seaweed and microalgae contain DHA.

  3. Consume ALA-rich foods. Your body can convert some to DHA:

    • Walnuts
    • Flaxseeds
    • Chia seeds
    • Canola oil
  4. Choose omega-3 enriched foods. Some eggs, milk, and juices are fortified with DHA.

  5. 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

Can DHA supplements cause headaches?
Some people report headaches when taking DHA supplements. This is often due to the blood-thinning effect.[27] Starting with a lower dose and increasing slowly can help. If headaches persist, consult your doctor.

How long does it take to see benefits from DHA supplements?
The timeline varies depending on why you’re taking DHA. Some people notice improved mood or reduced joint pain within a few weeks. For heart health benefits, it may take several months of consistent use.

Is it safe to take DHA during pregnancy?
DHA is generally considered safe and beneficial during pregnancy. It supports fetal brain and eye development.[28] However, pregnant women should consult their doctor about the right dose and source of DHA.

Can DHA supplements help with depression?
Some studies suggest omega-3s, including DHA, may help with depression symptoms.[29] However, results are mixed. DHA shouldn’t replace prescribed treatments. Talk to your doctor before using it for mental health.

Are there any long-term side effects of taking DHA?
Long-term use of high-quality DHA supplements is generally considered safe.[30] However, very high doses may increase the risk of bleeding or affect immune function.[31] Regular check-ups with your doctor can help monitor for any issues.

How does DHA compare to EPA in terms of side effects?
DHA and EPA are both omega-3 fatty acids often found together in supplements. They have similar side effect profiles. However, some people find DHA causes more digestive upset. EPA may have a stronger effect on mood.

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.

Fact Check
Claim: 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.
Fact check: True. DHA is an important omega-3 fatty acid essential for brain and vision health.

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/

Claim: You’ll primarily find DHA in fish and seafood.
Fact check: True. Fish and seafood are primary dietary sources of DHA.

Oily fish like salmon, mackerel, and sardines are particularly rich in DHA.

Claim: Since our bodies cannot produce enough DHA on their own, we must obtain it through diet or supplements.
Fact check: True. Humans can synthesize small amounts of DHA but not enough to meet needs.

The body can convert ALA to DHA, but this process is inefficient, necessitating intake from dietary sources or supplementation.

Claim: Oily fish like salmon, mackerel, and sardines are particularly good choices.
Fact check: True. These are excellent sources of DHA.

These fish are high in omega-3 fatty acids, especially DHA.

Claim: Consuming these types of fish about twice a week can typically provide sufficient DHA for most people.
Fact check: Likely True, but individual needs may vary.

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.

Claim: Some plant-based foods contain omega-3s, but not directly as DHA. Instead, they contain ALA, which the body can convert into DHA.
Fact check: True. Plant sources contain ALA, a precursor to DHA.

ALA is an omega-3 fatty acid that the body can convert to EPA and then DHA, however, the conversion rate is low.

Claim: Plant sources of ALA include flaxseeds, chia seeds, and walnuts.
Fact check: True. Flaxseeds, chia seeds, and walnuts are good sources of ALA.

These foods are among the richest plant-based sources of ALA.

Claim: However, this conversion process is not very efficient.
Fact check: True. The conversion of ALA to DHA is limited in humans.

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.

Claim: These supplements are available in several forms, including fish oil, algal oil, and cod liver oil.
Fact check: True. DHA supplements are commonly found in fish oil, algal oil and cod liver oil

Fish oil is extracted from fatty fish, algal oil is a plant based source and cod liver oil is made from cod liver.

Claim: Cod liver oil also provides vitamins A and D.
Fact check: True. Cod liver oil is a source of vitamins A and D.

Unlike regular fish oil, cod liver oil contains fat soluble vitamins.

Claim: Research indicates it can support brain function, eye health, and heart health.
Fact check: True. Studies suggest DHA has benefits for brain, eye, and heart health.

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/

Claim: Many people experience stomach issues when they begin taking DHA supplements. These problems can include nausea, diarrhea, and heartburn.
Fact check: True. Some individuals experience gastrointestinal distress when starting DHA supplements.

Common side effects may include nausea, diarrhea, and heartburn, especially at higher doses.

Claim: These issues often happen when someone starts with a high dose of DHA.
Fact check: True. Starting with high doses of DHA increases the likelihood of digestive side effects.

The body may need time to adjust to the increased fat intake from a high dose of DHA, which can cause digestive discomfort.

Claim: A common complaint regarding fish oil supplements is their fishy taste, which can cause unpleasant burps or a lingering aftertaste.
Fact check: True. Fishy burps and aftertaste are common side effects of fish oil supplements.

The fishy odor and taste of some fish oil supplements can be difficult to tolerate for some individuals.

Claim: DHA can have a mild blood-thinning effect.
Fact check: True. DHA has a mild anticoagulant effect.

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/

Claim: If you are taking blood-thinning medications, you should use DHA with caution.
Fact check: True. DHA can enhance the effects of blood thinning medications.

This can potentially increase the risk of bleeding or bruising.

Claim: Doctors usually advise patients to stop taking DHA supplements 1 to 2 weeks before any planned procedures to minimize the risk of increased bleeding.
Fact check: True. It’s common medical advice to discontinue DHA before surgery.

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.

Claim: Although rare, some people may have an allergic reaction to fish oil or algae.
Fact check: True. Allergic reactions to fish oil and algae are possible, though infrequent.

Symptoms of allergy can include skin rashes, itching, swelling, or breathing difficulties.

Claim: Certain fish liver oils, such as cod liver oil, can have high levels of vitamin A.
Fact check: True. Cod liver oil is high in vitamin A.

Cod liver oil contains naturally high levels of vitamin A, which can lead to toxicity with excessive intake.

Claim: To prevent vitamin A toxicity, choose supplements that do not contain excessive amounts of vitamin A.
Fact check: True. Choosing supplements with controlled vitamin A content can prevent toxicity.

Standard fish oil and algal oil supplements do not contain high levels of vitamin A like cod liver oil.

Claim: DHA may interact with certain medications.
Fact check: True. DHA may interact with medications such as blood thinners.

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.

Claim: For general health, adults typically take 250 to 500 mg of DHA per day.
Fact check: True. A daily intake of 250-500 mg of DHA is often recommended for general health.

This is a common recommendation for maintaining overall health benefits of DHA. Individual needs may vary.

Claim: Pregnant women may require a higher dose, typically between 300 and 900 mg daily.
Fact check: True. Higher DHA intake is often recommended during pregnancy.

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/

Claim: Very high doses (over 3 grams daily) may increase some risks.
Fact check: True. High doses of DHA can increase health risks.

Consuming over 3 grams of DHA daily may increase risks of bleeding or other side effects.

Claim: Lower quality supplements may contain contaminants like mercury, PCBs, or heavy metals.
Fact check: True. Lower quality supplements can be contaminated.

Some low-quality fish oil supplements may contain harmful contaminants such as heavy metals, or PCBs.

Claim: 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.
Fact check: True. Look for third-party testing and reputable brands.

These measures help to ensure that supplements are free from contaminants and accurately labeled.

Claim: Some people report headaches when taking DHA supplements. This is often due to the blood-thinning effect.
Fact check: True. Headaches can occur as a result of the mild blood thinning effect.

DHA’s anticoagulant effects may contribute to headaches in some individuals.

Claim: DHA is generally considered safe and beneficial during pregnancy. It supports fetal brain and eye development.
Fact check: True. DHA is considered safe and important for fetal development during pregnancy.

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/

Claim: Some studies suggest omega-3s, including DHA, may help with depression symptoms.
Fact check: Possibly True, further research is needed. Some studies suggest a potential link, but results are inconsistent.

While research suggests omega-3s may help some individuals with depression, its use should not replace established treatments. Results are mixed.

Claim: Long-term use of high-quality DHA supplements is generally considered safe.
Fact check: True. High-quality DHA supplements are generally safe for long term use.

Provided the supplements are of high quality and taken at recommended dosages, long term use is generally considered safe.

Claim: However, very high doses may increase the risk of bleeding or affect immune function.
Fact check: True. Excessively high doses of DHA may pose some risks.

Consuming extremely high levels of DHA over an extended time may result in an increased bleeding risk or affect immune system function.


Medically reviewed and fact checked

Colors Nutrition does not provide medical advice, diagnosis, or treatment.