Exploring the Benefits and Risks of Cod Liver Oil

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    There are many benefits to taking cod liver oil, despite the way it may taste.

    What is Cod Liver Oil?

    Cod liver oil is a fatty oil substance that is abstracted from the liver of Atlantic cod. It is often used as a nutritional supplement because it is a rich source of essential fatty acids and vitamins A and D. The exact level of nutrients found in cod liver oil is determined by the breed of the cod, (Gadus).

    The first therapeutic use of cod liver oil dates back to 17th century England. While it continued to be used as a remedy from that point forward, it became more well-known in the early 20th century when it was used to manage vitamin D deficiency. While it was not exactly tasty, children of the 1930s were given cod liver oil in order to help prevent vitamin D deficiency. Since then it has become a daily supplement for many Europeans and Americans.

    Nutritional Profile of Cod Liver Oil

    The Role of Omega-3 Fatty Acids

    The body cannot manufacture essential fatty acids and must get them from food. Cod liver oil is an excellent source because it contains omega-3 fatty acids as well as vitamins A and D. Omega-3s are healthy fats that are vital for the health of every cell in the body. Two of the most important omega-3s are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). DHA is found in large quantities in the eyes and the brains of mammals as it helps to make neurotransmitters. DHA is essential for the growth and functional development of the brain in infants, as well as the maintenance of normal brain function in adults. If you have blood issues or take medication, always check with your physician before taking cod liver oil as it could potentially thin the blood.

    Importance of Vitamins A and D

    Vitamin A is essential for normal vision, a healthy immune system, reproduction, and growth and development. Vitamin D is important for the body’s absorption of calcium, which is critical for healthy bones and teeth. The body normally manufactures vitamin D when exposed to sun rays, but lifestyle and environmental changes have resulted in a serious vitamin D deficiency worldwide. Cod liver oil is one of the most dense sources of both vitamins A and D. A possible alternative to getting your D from cod liver oil is Care/of’s Vitamin D3 The Sunshine Vitamin and Calcium Plus Bone Hugs and Harmony.

    Potential Health Benefits of Cod Liver Oil

    1. Cod Liver Oil Aids with Bone Health

    Vitamin D is essential for bone health and cod liver oil is among the richest food sources of vitamin D with approximately 450 IU per teaspoon. Maintaining adequate levels of vitamin D helps to support bone mineral density. According to this study, cod liver oil has been shown to support bone mineral density in vitamin A-deficient rats.

    2. Boosts Overall Eye Health

    Vitamin A plays a role in maintaining a clear cornea and helps to produce fluids that keep the eyes moisturized and lubricated. This study reports that vitamin A is found in the highest concentration in the eyes. Proponents of cod liver oil believe that both omega-3 fatty acids and vitamin A can play a protective role in overall eye health. Since they’re both plentiful in cod liver oil, it may potentially offer support for eye health, though more research is needed.

    3. Aids in Cardiovascular Health

    There is research that indicates that consuming fish and other types of seafood as part of a balanced diet promotes heart health, especially when the fish is consumed in place of less healthy foods. Cod liver oil and other omega-3 supplements can help manage triglyceride levels already in normal range among people with low dietary omega-3 intakes. There is also some evidence to support the positive impact cod liver oil may have on healthy lipid levels in adults according to this study. More research is required. Eating a heart-healthy diet, getting regular exercise, and making healthy lifestyle choices are proven benefits for cardiovascular health.

    4. May Help with Mood and Cognitive Performance

    Proponents of cod liver oil contend that it aids in both mood and cognitive performance. This long-term animal study found that long-term administration of cod liver oil supported cognitive health negatively impacted by stress. More research, especially with human subjects, is required.

    5. Aids in Stomach Health

    There are initial animal studies that suggest the mucoprotective and anti-secretory properties of cod liver oil, though more research is needed. Other options for stomach and digestive health include probiotics, prebiotics, digestive enzymes, and fiber like Care/of’s premium chia-flax product The Fiber Starters.

    Understanding the Risks and Side Effects of Cod Liver Oil

    Special Precautions and Warnings

    While cod liver oil is generally considered safe when taken as directed, there are people who should exercise caution when taking it. If you are pregnant, it is important to consult your physician before you consume any cod liver oil as it is especially rich in both vitamins A and D. There is an upper limit of vitamin A during pregnancy of 3000 mcg, and for vitamin D the upper limit is 4,000 IU or 100mcg.

    There are also common cod liver oil potential side effects such as mild headaches, an upset stomach, a metallic taste in your mouth, and the dreaded bad breath and fishy burps. These side effects typically do not require medical attention unless they last a long time or become problematic.

    There are rare instances of more serious side effects such as allergic reactions (hives, skin rash, swelling of the lips, face or tongue, and itching), yellowing of the skin or eyes. If these occur, speak to your physician as soon as possible and discontinue use immediately.

    Potential Interactions with Other Medications

    It is always recommended to consult with your physician before you make any changes to your supplement protocol, especially if you are taking any medications. Special precaution should be taken by anyone with blood issues, or anyone taking blood-thinning medication, as cod liver oil can also potentially thin the blood. Any person who supplements vitamins A or D should also check with their physician before taking cod liver oil, especially if pregnant.

    Dosage Recommendations for Cod Liver Oil

    While there are concerns about the number of servings of fresh fish a person eats each week because of the potential toxins and pollutants, there is no such concern when it comes to fish oils. They undergo a distillation process which ensures that all toxins and pollutants have been filtered out of the oil.

    The typical dosage of cod liver oil recommended may vary by product, but most suggest 1-2 tsp daily for a healthy adult. You may want to start on the lower side in order to get used to the taste and to monitor any potential unpleasant side effects. If you want to increase your dose about the recommended maximum, it is best to consult your physician before doing so.

    You also might want to consider mixing your cod liver oil with juice, lemon water, apple sauce, yogurt, almond butter, a smoothie, or anything that might disguise the fishy taste, or make it somewhat less fishy.

    Choosing the Right Cod Liver Oil Supplement

    When choosing your cod liver oil, look for a reputable brand, ideally one that contains antioxidants that can keep the oil from oxidizing. A reputable brand will not add flavor enhancers to remove the odor or mask the taste of the cod liver oil, though some brands may add an extract such as mint or lemon to make it more palatable. Fermented cod liver oil is also an option. The livers are fermented in order to produce more vitamins, which can make the nutrients more bioavailable.

    Helpful hint: Once you have purchased cod liver oil, store it in a cool, dark place, or in the refrigerator to prevent it from spoiling and turning rancid. You’ll be able to tell by the smell if it has turned rancid.

    The Bottom Line

    Cod liver oil has been around since the 17th century and is purported to offer many health benefits, as it is an especially rich source of both vitamins A and D, and is a good source of omega-3 fatty acids. As always, if you’re thinking about changing your supplement protocol, consult your physician or registered dietician before doing so.

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    Dr. Carla Montrond Correia ND, CNS
    Medical Content Manager
    Dr. Montrond-Correia is a licensed naturopathic physician and a certified nutrition specialist (CNS). She holds degrees from University of Bridgeport, Georgetown University, and University of Saint Joseph, and supplemented her education with internships in the health and wellness space. She's focused on research, herbal medicine, nutrigenomics, and integrative and functional medicine. She makes time for exercise, artistic activities, and enjoying delicious food.
    Our Editorial Staff
    Freelance Contributor
    The Care/of Editorial Team is made up of writers, experts, and health enthusiasts, all dedicated to giving you the information you need today. Our team is here to answer your biggest wellness questions, read the studies for you, and introduce you to your new favorite product, staying up to date on the latest research, trends, and science. Each article is written by one of our experts, reviewed both for editorial standards by an editor and medical standards by one of our naturopathic doctors, and updated regularly as new information becomes available.