What’s the first thing you think of when I say “Cod Liver Oil”? People of a certain age will most likely be turning up their noses at memories of a weekly drenching with a slimy oil that made them gag and left them with fishy burps.
The good news is that 21st Century cod liver oil has had a makeover. It is much more palatable these days. For this we can thank manufacturing advances allowing the removal of components that tended got go rancid quickly and are responsible for the “fishy” taste.
Cod liver oil may well have been one of the first marketed health food supplements. The earliest documented medical use of cod liver was in 1789 for rheumatism1. By the early 19th century it was a well-established remedy in North America and Europe for treatment and prevention of rickets – a disease of brittle bones caused by deficiency of vitamin D 2. This was after observations that children living by the coast with diets high in oily fish had lower occurrence of the disease.
What’s in Cod liver oil?
Cod Liver oil is an excellent source of long chain omega 3 fatty acids, and natural forms of Vitamin A and D. This combination gives it a lot of bang for your supplement buck. It’s one of my core supplements in clinic and I like it as a baseline treatment for conditions that impact the immune system -in particular the prevention or reduction of respiratory tract infections. It’s also beneficial for skin conditions such as eczema, rosacea and psoriasis. If you still want more there is strong evidence that regular consumption can reduce depression by 29%3.
Research has shown that children who regularly consumed cod liver oil reduced visits to their doctor by 30-50% and had 75% less complications such as ear infections, sinusitis and pneumonia4.
Essential Fatty Acids
The long chain omega 3 fatty acids eicosapentaenoic (EPA) and docosahexaenoic (DHA ) are abundant in cod liver oil. These fatty acids are considered essential as they can’t be made in the human body and must be obtained in the diet.
The mechanism for the benefit of essential fatty acids are primarily due to their ability to lower inflammation.
Vitamin A is known as eyesight and anti-infective vitamin.
Because it’s from the liver of a fish the Vitamin A in fish oil is preformed in retinyl esters and requires less conversion in the body than plant sources (carotenoids) that require conversion to the active form**.
Vitamin A protects the health of your mucous membranes, which form the first line of defense of the immune system. It helps produce super-charged, infection-fighting white blood cells. Antibody production is also increased making your immune army bigger and ready to roll out faster.
**A note on safety. More is not better when it comes to Vitamin A. Preformed Vitamin A (retinyl esters) can be toxic when consumed at high levels over long time in amounts greater than 3,000IU per day for 6 year old child or 15,000 IU per day for an adult. Natural cod liver oil contains between 400-900IU per 5mL serve making it a safe source of Vitamin A.
Most known for it’s role in calcium regulation and bone health, Vitamin D is actually very important to keep the immune system in balance. Adequate Vitamin D means your immune system is ready to fight both viral and bacterial pathogens but not too trigger happy to start killing everything in it’s path as happens with autoimmunity. Vitamin D also increases the production of the body’s own antibiotic, cathelocidin 5.
What to look for in a cod liver oil supplement
Purity & Safety
There are very legitimate concerns about heavy metal toxicity when it comes to fish oils so go with a reputable manufacturer who can provide testing data on the quality and safety of their product. In clinic, I use Metagenics and Nordic Naturals. Pricing is often a good guide in this area and good quality supplements will cost you between $40-$50 for 200mL depending on the concentration.
Form of the cod liver oil
The oils from whole fish are in a triglyceride form. Some cheaper cod liver oil supplements will contain them in an ethyl ester form. These have up to 50% less absorption in your body compared to the triglyceride form.
It sounds strange but good quality cod liver oil should not smell overly fishy. If it does this may indicate the oils have gone rancid and will actually be creating inflammation.
Synthetic Vitamin A
Following on from the earlier warning about excessive Vitamin A please also check that your supplement doesn’t have any added synthetic Vitamin A. In cod liver oil with natural Vitamin A the nutritional panel will give a range of the Vitamin A usually around 400-900IU per dose.
Essential Fatty acids
Check the amount of the EFA and DHA. This should be noted individually on the nutritional panel. Aim for around a total of 800-1000mg of these two combined for a standard adult dose. Less means you’ll have to take more which might help you also make a decision on value for money.
These are for health maintenance in adults. Specific conditions may require more but please seek advice from a qualified professional. Cod liver oil is a great supplement for children and dosing is generally based on the child’s weight.
You need to be taking Cod liver oil regularly for between 4-8 weeks to see a benefit. So, if you want to take it just to reduce the risk of colds and flu you could start taking it (in Australia) from April through to September.
This is a supplement that works best with small and regular doses. Kind of like how you’d get nutrients from foods. A standard adult dose is around 5mL or 1 metric teaspoon.
Cod liver oil has the best absorption when taken with a meal containing a small amount of fat (nuts, yoghurt, meats, avocado etc).
No need to take it off the back of a spoon you could also add it to smoothies or mix into a salad dressing. Just make sure you don’t heat it!
Side effects and cautions
Cod liver oil is a pretty safe supplement especially if you avoid the ones with synthetic vitamin A. Some people get fishy burps after having it and this may be a sign that you’re not digesting fats well.
People taking blood-thinning medication should also be cautious with high levels of fish oils.
Storage of Cod Liver Oil
Once opened keep cod liver oil in the fridge and use within 3 months.
Cod liver oil is a supplement that has many benefits for your health. I hope I’ve convinced you to be part of the Cod Liver Oil Comeback!
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Norelle Hentschel is a degree qualified Naturopath and operates a clinic in Crows Nest, North Sydney. She enjoys helping people feel better and can assist with a broad range of health conditions or general health maintenance.
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- Simpson D. Clinical Memoranda. Br Med J. 1935;2:997. doi:10.1192/bjp.19.88.565.
- K R. Vitamin D, cod-liver oil, sunlight, and rickets: a historical perspective. Pediatrics. 2003;112(2):e132 – 5 1p. doi:10.1542/peds.112.2.e132.
- Linday LA, Tapia-Mendoza J, Shindledecker RD, Dolitsky JN. Effect of daily cod liver oil and a multivitamin-mineral supplement with selenium on upper respiratory tract pediatric visits by young, inner-city, Latino children: Randomized pediatric sites. Ann Otol Rhinol Laryngol. 2004;113(11):891–901.
- Linday L a, Umhau JC, Shindledecker RD, Dolitsky JN, Holick MF. Cod liver oil, the ratio of vitamins A and D, frequent respiratory tract infections, and vitamin D deficiency in young children in the United States. Ann Otol Rhinol Laryngol. 2010;119(1):64–70. Available at: http://www.ncbi.nlm.nih.gov/pubmed/20128190.
- Mora JR, Iwata M, von Andrian UH. Vitamin effects on the immune system: vitamins A and D take centre stage. Nat Rev Immunol. 2008;8(SEPTEMBEr):685–698. doi:10.1038/nri2378.