Cod liver oil provides omega-3s and vitamins A and D, which may support heart, joint, bone, eye, and immune health. Common side effects include fishy burps and digestive discomfort, while excess vitamins A and D can be harmful. When choosing a supplement, check its nutrient content, dosage, and third-party purity testing.
Key Insights
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If you could take just one daily supplement to support your heart, joints, skin, eyes, and immunity, without buying five different bottles, would you?”
Well, definitely, yes!
Cod liver oil is a natural supplement extracted directly from the liver of cod fish, usually atlantic cod. It offers a unique combination of three key nutrients: omega-3 fatty acids (EPA and DHA) that support heart and joint health, vitamin A for healthy vision and skin, and vitamin D for bone strength and immune function.
With this nutrient-rich profile, it’s worth understanding how cod liver oil works and what to keep in mind before adding it to your routine.
In this guide, we'll explore the health benefits of cod liver oil, its potential side effects and precautions, and what you should know before choosing a supplement.
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Did You Know? Long before it reached drugstore shelves, fish liver oil was part of northern European food and folk-medicine traditions. Historical accounts describe its use during winter and its application to sore joints and muscles. |
What Are the Health Benefits of Cod Liver Oil?
The following are the health-based benefits of cod liver oil.
Cod liver oil has strong clinical evidence for lowering triglycerides and treating Vitamin D deficiency, moderate evidence for reducing joint pain and stiffness, and emerging evidence for supporting eye health and immune function.
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Rich in Vitamin A and D
Cod liver oil brings more than just healthy fats to the table. Alongside essential omega-3s, it naturally provides two important micronutrients: vitamins A and D.
Here’s what these two vitamins do for your body:
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Vitamin A: Helps maintain healthy vision and supports your immune defenses.1
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Vitamin D: Helps your body absorb calcium to build and maintain strong bones.
One teaspoon (about 4.5 g) of Omega 3 provides approximately 1,350 mcg RAE of vitamin A and 11.25 mcg (450 IU) of vitamin D, based on the USDA reference profile
Pro Tip Before You Buy: Flip the bottle over and check the supplement label! Vitamin A and D amounts can vary by brand.
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Did you know? In 1922, researchers testing the oil made a shocking discovery: even after destroying all the Vitamin A inside it, the oil still cured rickets. That medical mystery revealed another bone-supporting nutrient hiding in the oil, which they named Vitamin D. |
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May Reduce Heart Disease Risk
The Omega-3s in cod liver oil help reduce blood triglycerides, a type of fat in your blood that, when elevated, can contribute to overall cardiovascular risk. 2
High-dose Omega-3 studies usually use elevated clinical doses to treat high triglycerides. A standard daily spoon of cod liver oil provides a great baseline boost, but it might not match those prescription doses on its own.
So, give fish a spot on your plate, too! Aim for two servings a week, especially oily fishlike salmon or sardines, as part of a heart-healthy diet.
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May Reduce Inflammation and Support Joint Health
Omega-3s work at a cellular level to help lower inflammatory proteins like TNF-α and IL-6, potentially easing joint tenderness and morning stiffness in people managing rheumatoid arthritis. 3
In a nine-month trial, 39% of participants taking 10 grams of cod liver oil daily successfully reduced their daily anti-inflammatory painkiller use by over 30% (compared to just 10% in the placebo group).
While this is promising for reducing reliance on painkillers, researchers also noted that overall disease activity did not significantly differ between groups, meaning it works best as a supportive daily tool rather than a standalone cure.
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May Support Bone Health
Cod liver oil supplies natural Vitamin D3, which acts like a key to help your body absorb calcium and support normal bone mineralization, especially if your dietary intake or sunlight exposure is running low.
Pro tip: Include calcium-rich foods such as milk, yogurt, cheese, calcium-set tofu, or calcium-fortified soy or almond milk in your daily diet.
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May Support Eye Health
Cod liver oil contains vitamin A, which supports a healthy cornea and vision in dim light, while DHA helps maintain your retina structure.4 They play a supporting role in eye health, but cod liver oil isn’t a treatment for dry eyes or night blindness.
Cod Liver Oil vs. Regular Fish Oil
Confused about which one to pick? You’re definitely not alone!
Both provide omega-3s, but the main difference is the extra vitamins: cod liver oil typically supplies vitamins A and D, while regular fish oil usually contains little or none unless added.
Here’s a simple rule of thumb:
Choose cod liver oil if you also need these vitamins, or regular fish oil if omega-3s are your main goal. Remember, neither replaces eating fish. The NHS recommends two portions of fish a week, including one oily fish portion.
What Are the Side Effects of Cod Liver Oil?
Cod liver oil is well-tolerated by most people, but it can cause mild digestive discomfort. The bigger concern is taking too much vitamin A or D, especially if you already use other supplements.
Common side effects include:
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Fishy burps or bad breath
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Heartburn or nausea
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Loose stools
Sometimes, allergic reactions can also occur. Stop taking it and seek urgent medical help if you have facial or throat swelling or trouble breathing.
Potential Medication Interactions
Cod liver oil can sometimes interact with other medications such as:
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Blood thinners, like warfarin, as omega-3s can increase the risk of bleeding when taken with warfarin, so check with your doctor before combining them.
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Retinoid medicines, such as acitretin, can cause vitamin A overdose.
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Orlistat, cholestyramine, or colestipol can interfere with vitamin absorption.
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Calcitriol or thiazide diuretics C may raise calcium levels too much when taken with vitamin D.
Who Should Avoid Cod Liver Oil?
Cod liver oil isn’t suitable for everyone. It’s best to avoid it or check with your doctor first if you:
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Are pregnant or trying for a baby. Avoid it unless your doctor specifically advises otherwise, as excess preformed vitamin A can harm a developing baby.
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Have a fish allergy.
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Have kidney or liver disease, or high calcium levels:
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Take blood thinners or other medicines that may interact as discussed above.
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Already take vitamin A or D supplements.
If you’re breastfeeding or considering cod liver oil for your child, check with a healthcare professional first to find out what’s safe for you or your little one.
How Much Cod Liver Oil Should You Take Daily?
There’s no single recommended dose of cod liver oil. Follow your product’s directions and check its vitamin A and D content, especially if you already take a multivitamin.
For adults aged 19 and older, the daily upper limits from food and supplements combined are:
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Preformed vitamin A, such as retinol: 3,000 mcg RAE
Remember, these are limits, not amounts to aim for!
Caution: If you take a multivitamin, be careful not to double up on vitamin A. The amount it contains adds to what you get from cod liver oil and food. Take a moment to check your labels; the infographic below shows how these amounts can add up over a day.
| How Vitamin A adds up in a day |
The infographic shows how vitamin A from cod liver oil, multivitamins, and food can add up to 2,600 mcg RAE in a day, approaching the adult upper limit of 3,000 mcg RAE for preformed vitamin A.
How to Choose the Best Cod Liver Oil Supplement
Not every bottle offers the same quality or amount of product. Before adding one to your cart, here’s what to look for:
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Check the label for independent third-party testing to verify that the omega-3 content matches the stated amount and that contaminants, such as heavy metals and PCBs, are within acceptable safety limits.
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Read the nutrient amounts: Compare EPA, DHA, and vitamins A and D per serving. Prioritize natural vitamins over synthetic additives.
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Look for the extraction process. Labels like “cold-pressed” or “molecularly distilled” alone don’t guarantee freshness.5
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Choose your preferred format: liquid oil or softgel capsule. Check the nutrients and cost per serving and follow your bottle’s refrigeration and use-after-opening instructions.
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Choose soft gel if you want to avoid the liquid taste and texture, though fishy burps can still happen.
Conclusion
Cod liver oil is rich in nutrients that are beneficial for your heart, bones, and immune system, but it's important to choose the right product. Ensure the bottle has third-party purity certifications, keep track of your total daily intake of vitamins A and D if you are also consuming a multivitamin, and maintain a balanced diet.
Remember, omega-3 fatty acids can interact with specific medications. Therefore, it is advisable to consult your healthcare provider before using cod liver oil, particularly if you are on blood thinners or are pregnant.
FAQs
Q1. What Are the Benefits of Cod Liver Oil for Women?
Cod liver oil provides omega-3s and vitamins A and D, which may support heart, bone, eye, joint, and immune health. However, women who are pregnant or trying to conceive should avoid it due to its vitamin A content.
Q2. Does Cod Liver Oil Help with Hair Growth?
Possibly, but research is still limited. Some studies suggest omega-3 fatty acids may help reduce hair loss and improve hair density, but cod liver oil itself hasn't been proven to promote hair growth. Excess vitamin A may even contribute to hair loss.
Q3. Is cod liver oil safe for kidneys?
Yes, cod liver oil is generally safe for healthy kidneys when taken in appropriate amounts. However, excessive vitamin D intake can raise blood calcium levels, potentially leading to kidney stones or kidney damage. If you have kidney disease, consult your doctor before taking cod liver oil.
Q4. How Do You Use Cod Liver Oil for Glowing Skin?
Cod liver oil is usually taken orally, with food, rather than applied to the skin. Its omega-3s may support skin hydration and barrier function, while vitamins A and D contribute to skin health. However, evidence that cod liver oil directly makes skin glow is limited. Always follow the recommended dosage.
Q5. Can Cod Liver Oil Help with Weight Loss?
Not directly. Cod liver oil contains omega-3 fatty acids, which have been studied for their potential effects on metabolism and body fat. However, there’s limited evidence that cod liver oil itself promotes weight loss.
Reference
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Office of Dietary Supplements, National Institutes of Health. Dietary supplements for immune function and infectious diseases: fact sheet for health professionals. Accessed November 2, 2026. https://ods.od.nih.gov/factsheets/ImmuneFunction-HealthProfessional/
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National Institutes of Health, Office of Dietary Supplements. Omega-3 fatty acids: fact sheet for consumers. Updated July 18, 2022. Accessed November 2, 2026. https://ods.od.nih.gov/factsheets/Omega3FattyAcids-Consumer/
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Calder PC. Omega-3 fatty acids and inflammatory processes: from molecules to man. Biochem Soc Trans. 2017;45(5):1105-1115. doi:10.1042/BST20160474
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National Institutes of Health, Office of Dietary Supplements. Vitamin A and carotenoids: fact sheet for health professionals. Accessed November 2, 2026. https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/
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Yi M, You Y, Zhang Y, et al. Highly valuable fish oil: formation process, enrichment, subsequent utilization, and storage of eicosapentaenoic acid ethyl esters. Molecules. 2023;28(2):672. doi:10.3390/molecules28020672
Disclaimer: This article is for informational purposes only and is not intended to replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider regarding any medical concerns or conditions.
