Cod liver oil is extracted from the liver of cod fish and taken in spoonfuls or capsules as a dietary supplement. Most famously and beneficially, cod liver oil is a source of omega-3 fatty acids, which are linked to many health benefits such as disease prevention and improved cognition.
It’s a rich source of beneficial fats, including monounsaturated, saturated and polyunsaturated fatty acids. Cod liver oil is also one of the few food sources of vitamin D—a common deficiency today .
Besides being a nutritional powerhouse, cod liver oil also reduces anxiety and depression, heals stomach and gut ulcers, promotes bone health and reduces inflammation. It protects your brain, heart and eyes from chronic, age-related diseases. Here’s a roundup of the many health benefits of cod liver oil:
Omega-3 fatty acids are essential nutrients, which means the body can’t produce them on its own and it must be acquired from food. They’re an important part of the membranes surrounding every cell in the body.
There are 3 forms of omega-3 fats: ALA, EPA and DHA. ALA is found in plant foods, while EPA and DHA occur only in fish and other seafood. EPA and DHA are responsible for maintaining the health of sperm in men, as well as protecting your heart and blood vessels, endocrine system, eyes and brain from damage.
While the body can convert a small amount of ALA from plants to EPA and DHA, the best way to get adequate amounts of EPA and DHA is to take fish-derived supplements like cod liver oil to ensure you get these forms of omega-3s directly. 1 teaspoon of cod liver oil provides 890 mg of omega-3 fatty acids. Men need 1600 mg of omega-3 fatty acids per day, while women need 1100 mg .
One teaspoon of cod liver oil delivers 90 percent of your daily vitamin A requirement . Vitamin A protects your eyesight and plays a critical role in activating your immune system. There are two forms of vitamin A: retinol and beta-carotene.
Beta-carotene is the form found in plants, and your liver converts it to retinol, which is the form your body uses. In cod liver oil, vitamin A is already in retinol form, making it a highly bioavailable source of vitamin A.
Vitamin D rarely occurs naturally in foods, but just 1 teaspoon of cod liver oil gives you 133 percent your daily vitamin D requirement. Vitamin D deficiency is common in people who don’t get enough sun exposure, as this vitamin is assimilated through sunlight. The effects of deficiency can include bone loss, mood disorders, gum disease and glucose intolerance.
Symptoms of vitamin D deficiency can include fatigue, weakness, aches and pains, tooth decay and cavities, inflamed or bleeding gums and stress fractures. Vitamin D deficiency has been linked to a higher risk of heart disease, diabetes and cancer, as well as higher rates of asthma in children. In older adults, vitamin D insufficiency causes faster cognitive decline and increases the risk of Alzheimer’s disease.
Vitamin D improves the absorption of calcium, helping you build strong bones and teeth. It also boosts your immune system and helps protect against cancer.
If you don’t get a lot of sun exposure, cod liver oil is a great way to ensure you get enough vitamin D. Vitamin D is fat-soluble, which means the healthy fats in cod liver oil help your body assimilate it .
Omega-3 fatty acids, particularly the EPA and DHA found in cod liver oil and other fish sources, have been shown to improve heart health and protect you from heart conditions.
In a study that looked at smokers and non-smokers in Norway found that cod liver oil reduced the risk of heart disease in both groups. In men and women of various ages, cod liver oil significantly lowered levels of triglycerides. These are stored fats in the body known to increase your risk of heart disease .
Another reason cod liver oil helps your heart is by preventing vitamin D deficiency, which is a risk factor for heart disease. Because of vitamin D’s role in assimilating calcium from your diet, a lack of vitamin D can cause calcium to build up in the bloodstream and calcify your blood vessels. This results in plaque and hardening of the arteries, raising your risk for heart problems.
Studies on the impact of vitamin D supplementation have found it reduces high blood pressure, inflammation and calcified plaque in blood vessels, thereby reducing your risk of atherosclerosis and heart attack.
Gastric ulcers, or stomach ulcers, are holes in the lining of your stomach or intestines, which cause pain, bloating, nausea, vomiting and fatigue. The most common cause of gastric ulcers are bacterial infections.
In animal studies, therapeutic doses of cod liver oil are shown to heal gastric ulcers and prevent their development . One study found that cod liver oil reduced gut inflammation, prevented the formation of ulcers and downregulated genes linked to gut inflammation .
Anxiety and depression have been linked to chronic inflammation, which affects the brain. Considering the role of omega-3 fats in reducing inflammation and supporting brain health, it’s no surprise cod liver oil can help with anxiety and depression.
A study on 68 medical students with no anxiety disorder diagnosis found that omega-3 supplementation lowered inflammation and reduced symptoms of anxiety by 20 percent . This suggests cod liver oil supplementation could help promote better mental states in general.
Clinical evidence also shows that increased omega-3 intake has a positive effect on depression and bipolar disorders . In a study that looked at cod liver oil supplementation in particular, participants who took cod liver oil daily had lower rates of depression compared to individuals who didn’t .
Rheumatoid arthritis is a chronic, age-related disease characterized by pain, inflammation, stiffness and reduced mobility in the joints. Experimental trials on patients with rheumatoid arthritis have found that omega-3 supplements help manage the disease in patients who are also receiving medical treatment.
One study tested the use of cod liver oil versus a placebo on 58 rheumatoid arthritis patients. After 12 weeks of supplementation, participants who took cod liver oil needed a smaller daily dose of nonsteroidal anti-inflammatory drugs (NSAIDs) compared to those who took a placebo .
Supplementing with cod liver oil packs a powerful punch when it comes to your eyesight, as it’s a rich source of both omega-3s and vitamins A and D–all of which are linked to eye health. Omega-3 fatty acids have been shown to reduce your risk of glaucoma by reducing eye pressure and nerve damage.
In a study on 666 individuals over the age of 73, higher intakes of omega-3s were associated with a 17 percent risk reduction in early onset of age-related macular degeneration (AMD) and a 41 percent lower risk of late-onset AMD .
Vitamin A deficiency results in an impaired ability to see in low light, and it can even cause blindness if the deficiency isn’t corrected. Vitamin A is also responsible for keeping your eyes well-lubricated, and deficiency results in dry eyes . Considering cod liver oil is a rich and bioavailable vitamin A source, it can help keep you maintain your vision and improve eye comfort regardless of your age.
The vitamin D in cod liver oil can even help improve vision in people with age-related macular degeneration (AMD)–the leading cause of blindness. In one study, rats given vitamin D for six weeks experienced improved vision.
This effect was accompanied by reduced eye inflammation and levels of amyloid beta accumulation in the eyes, which is a plaque-like buildup that impairs vision. Researchers concluded that vitamin D supplementation could greatly benefit people at risk of AMD .
Other research has suggested vitamin D deficiency is common in the case of AMD. One study found that women with the highest vitamin D intakes had a 59 percent reduced risk of AMD compared to women with the lowest intakes.
By preventing vitamin D deficiency, cod liver oil can help protect against age-related blindness and keep your eyesight strong as you get older.
Getting more omega-3s through fish oil can improve bone health because of its role in bone metabolism. Bone density is known to decline with age, and can put many people–especially postmenopausal women–at risk of osteoporosis.
Studies have determined that omega-3 fish oil supplementation correlates to higher bone density and calcium balance in women .
Additionally, vitamin D is essential for the absorption of calcium. Without it, calcium is excreted instead of being used to build strong bones. Vitamin D is also needed to metabolize phosphorus, which is another mineral required in bones.
According to research, vitamin D can slow the aging of your musculoskeletal structure. Studies have concluded that vitamin D supplementation significantly reduces the instance of fractures and falls in adults over 65, which is a good reason for senior citizens to supplement with cod liver oil.
The vitamin A in cod liver oil also plays a role in bone health, because it helps synthesize osteoblasts–the structural cells that form new bone and are responsible for depositing calcium into bones. Insufficient vitamin A has been shown to reduce your assimilation of calcium, which in turn lowers bone density.
Research has linked vitamin A deficiency to an increased risk of bone fractures and osteoporosis—a condition characterized by bone tissue loss that results in brittle, easily breakable bones. By taking cod liver oil, you can ensure you’re getting a bioavailable source of omega-3, vitamin D and vitamin A, which are nutrients commonly neglected when it comes to bone health.
The omega-3 fats in cod liver oil are known to support healthy serotonin levels. Serotonin, the “happiness hormone,” is a neurotransmitter that plays a key role in regulating your mood and your sleep-wake cycle. When serotonin levels are balanced, you feel “on” and awake during the day, and can enjoy a relaxed sense of focus and concentration on tasks at hand.
At night, serotonin converts to melatonin–the “sleep hormone” that promotes feelings of sleepiness and improves your quality and duration of sleep. By helping you get deeper sleep at night and feel more alert during the day, cod liver oil could help people who need to concentrate on studying, working and other tasks requiring attention and focus.
Omega-3 fats have been shown in studies to help children with ADHD, which goes to show they can probably help anyone improve their focus and attention span, or at least prevent attention deficits caused by omega-3 deficiency.
Besides the omega-3s in cod liver oil, its high vitamin D content also helps promote a better mood. Research has linked vitamin D deficiency to a higher occurrence of mood disorders.
According to a 2014 review of the current research on depression and its connection to vitamin D, vitamin D supplementation significantly improves symptoms of depression. Supplementing with cod liver oil, you get the brain benefits of both omega-3 and vitamin D.
Omega-3 fats can enhance memory function in adults, and higher omega-3 intake is associated with a lower risk for Alzheimer’s disease. Cod liver oil supplementation could even slow the onset of Alzheimer’s disease and dementia, due to the brain-boosting effects of DHA.
Meanwhile, the vitamin D in cod liver oil helps diminish amyloid plaque buildup in the brain, which is found in the case of Alzheimer’s disease. Amyloid plaque in the brain kills nerve cells, resulting in the cognitive decline seen in Alzheimer’s patients.
Research appearing in the Journal of Alzheimer’s Disease found that vitamin D3 supplementation combined with curcumin (a medicinal compound in turmeric root) effectively reduced amyloid plaque in the brains of Alzheimer’s patients .
Insomnia and sleep disturbances happen when there’s an imbalance of chemicals that regulate your sleep-wake cycle. Cod liver oil can improve your quality of sleep and help you fall asleep more easily by balancing these chemicals. Whereas vitamin D deficiency is linked to insomnia, the vitamin D in cod liver oil can shore up any deficiency and prevent sleep problems.
Additionally, omega-3 fats support the release of serotonin, which plays a key role in regulating your sleep-wake cycle. Serotonin helps you feel awake during the day and then converts to melatonin at night, which promotes sleepiness.
The high levels of retinol, or vitamin A, found in cod liver oil regulates several genes involved in your immune response. It’s an essential nutrient that must be obtained from food, and research shoes it helps fight cancer and autoimmune diseases, as well as common infections like colds, flus and stomach viruses.
Vitamin A helps synthesize T helper cells, so sufficient amounts of it are required for you to have the immune cells you need. It also helps develop B cells, which are a type of white blood cell that releases antibodies to kill pathogens.
The vitamin D in cod liver oil also helps your immune system defend against viruses like the common cold and seasonal flus. In fact, cod liver oil has been used in the past to treat tuberculosis and protect against infections before the existence of antibiotics .
Inflammation is normal when you have a wound or sore muscles, but chronic inflammation is an unhealthy state that makes you susceptible to many diseases, such as diabetes, heart disease, cancer, Alzheimer’s and autoimmune diseases.
Many people have chronic low-grade inflammation because of oxidative stress, an imbalanced omega-6 to omega-3 ratio, or a combination of these factors. Cod liver oil does an amazing job bringing inflammation down by tackling both factors that cause chronic inflammation.
It supplies a potent dose of vitamin A, which is an antioxidant shown to protect cells against oxidative damage and have an anti-inflammatory effect. Meanwhile, by increasing your omega-3 fat intake, you can cancel out the inflammatory effect omega-6 fats produce when there’s a lack of omega-3.
The vitamin A and omega-3 fats in cod liver oil play a role in virtually every aspect of your skin’s health. Vitamin A helps with wound healing, new skin cell generation, fighting acne and protecting against skin cancer .
As an antioxidant, vitamin A neutralizes free radicals, which damage skin cells and accelerate aging. By boosting the production of collagen, a protein responsible for your skin’s elasticity and firmness, vitamin A can even fight wrinkles.
Omega-3 fats give your skin cell membranes the strength and moisture they need to stay strong and youthful. They also keep skin inflammation down, preventing inflammatory acne. In fact, research shows that acne patients are more likely to be infrequent consumers of fish and other seafood .
When supplementing with cod liver oil, it’s important to take an appropriate dose. When you consume vitamin A in the form of beta carotene, your liver will only convert as much as your body needs into retinol, and excrete the rest.
Since the vitamin A in cod liver oil is already in the form of retinol, if you take too much, it can be toxic. You would have to take a large amount of cod liver oil to reach toxic levels, but taking the recommended dose on your product label will ensure you stay in the safe range.
There’s concern over heavy metal toxicity in fish, and for good reason. Whereas you can take in heavy metals like mercury when eating whole fish, fish oil supplements like cod liver oil are filtered and purified to remove contaminants. Of course, you want to look into the manufacturing process of any fish oil supplement before you buy it, and make sure the supplements are third-party tested for purity.
The liver organ is designed to filter toxins, but that doesn’t mean it stores them. Instead, it converts toxins into substances that can be excreted when put back into the bloodstream.
It does, however, serve as a storehouse for nutrients, which is why cod liver oil is so high in vitamins A and D. Therefore, you don’t have to worry about heavy metal contamination in cod liver oil more than any other type of fish oil.
Like regular fish oil, cod liver oil is high in omega-3 fatty acids. However, you can get more out of a cod liver oil supplement than regular fish oil, because it’s a great source of vitamins A and D.
Since vitamin D is rarely found naturally in food sources, supplementing with vitamin D can make sure you don’t become deficient, especially in the winter months when sunlight exposure is minimal.
Besides shoring up and preventing deficiencies, and keeping your omega-6 to omega-3 ratio balanced cod liver oil supplementation can also provide a host of health benefits.
It helps your memory function, improves concentration, promotes better sleep and helps fight anxiety and depression. It also supports eye, bone and heart health, helping to lower your risk for diseases and protecting your health as you age.