Cod Liver Oil
What is cod liver oil?
Cod liver oil is produced from the livers of fish which constitute the cod family. White fish such as cod tend to accumulate most of their bodily oil in the liver whereas oily fish such as herring and mackerel accumulate oil in their flesh.
Because the liver also accumulates oil soluble vitamins – particularly vitamins A and D, cod liver oil is a naturally rich source of these vitamins and this fact alongside the traditional belief that cod liver oil is good for general wellbeing has been a major reason for the popularity of cod liver oil as a nutritional supplement for generations.
Does cod liver oil contain omega-3?
Yes, cod liver oil is also a rich source of omega-3 but it tends to have less concentrated amounts than is found with other types of fish oil. Cod liver oil typically contains between 700-900mg EPA/DHA per 5ml teaspoon – the two most important omega-3s. Fish oils typically contain between between 1000mg and 2000mg EPA/DHA per 5ml teaspoon.
Does cod liver oil have benefits apart from omega-3?
Unlike omega-3 fish oils which are produced from the flesh of the fish, cod liver oil is a rich natural source of vitamins A and D, as these are concentrated in fish livers.
However, cod liver oil is also a very rich source of the omega-3 fatty acids EPA and DHA, and so cod liver oil can also claim all of the benefits associated with omega-3s. These are outlined more fully in the ‘Omega-3’ section below, but include benefits in heart health, neural and brain development in babies and infants, and relief from inflammatory conditions, such as arthritis. Indeed, cod liver oil (Seven Seas brand) has a traditional remedy medicinal license for use in improving joint mobility and reducing joint pain. This reflects the existence of a body of evidence which supports this effect for cod liver oil.
What about high strength cod liver oil?
These are cod liver oils which have been blended with concentrated fish oils to produce a higher level of the omega-3s, EPA and DHA. They still contain the same levels of vitamins A and D and are worth considering.
Do all omega-3 and cod liver oils taste fishy?
It is very difficult to completely remove the taste and odour of fish from these oils. However, there are now some cod liver oils and other types of fish oil that have virtually no taste of fish and which are a huge improvement on the type of oil available a generation ago. Also, some flavoured and emulsified oils are now available and these can be very palatable indeed, and do offer a practical means of taking larger amounts of fish oil without taking handfuls of capsules.
Is there any difference in taking fish or cod liver oil as a liquid or in softgel capsules?
Even though the taste quality of cod liver and other fish oils has dramatically improved in recent years, many individuals still find that the mouth feel and aftertaste of fish oils makes them difficult to take. As such, most of these people tend to take cod liver or fish oil capsules. These is no nutritional difference between these two different forms, other than it is a more expensive way of taking the supplement and you will need to take approximately 5 large capsules to deliver one teaspoon of oil.
In the view of our panel and also numerous nutritional organisations such as the British Nutrition Foundation and the World Health Organisation an intake of at least 450mg of the omega 3 fatty acids EPA/DHA is necessary per day for optimum health, and this is difficult to provide in capsules as up to 10 capsules would need to be taken per day to reach this level.
What do I look for in an omega-3 fish or cod liver oil product?
Fish oil supplements are all about delivering sufficient levels of EPA and DHA in a form which is acceptable and/or palatable, and at a realistic price.
Generally, capsule products are acceptable, but often several are required to be taken on a daily basis to deliver sufficient EPA and DHA and it is a more expensive way of delivery.
Liquid oils taken by the spoonful typically provide much higher levels of EPA/DHA and at a lower cost, but many people find taking oils directly unpleasant. Some liquid oils now have virtually no taste or odour of fish and these provide a good option, as often only ¼ or ½ a teaspoon is required to deliver a dose of 500-1000mg EPA/DHA.
Also, liquid fish oil emulsions have been introduced recently, and these appear to be both very palatable and there is also some firm evidence that they are substantially better absorbed than the original oil. These are worth looking at.
Is there any danger of cod liver or fish oils containing pollutants or toxins?
The livers of animals is the organ which is used to detoxify and pollutants so oil from the livers has a likelihood of containing quite high concentrations of these pollutants. However, in cod liver oils and other fish oils the pollutants have been filtered out and as such, these supplements actually contain less contaminants than the original fish.
How have omega-3 fish and cod liver oil products been assessed in Supplements Compared?
Omega-3 supplements have been assessed by Supplements Compared using the following criteria:
1) Does it deliver the intended benefits in the short and long term?
In the case of omega-3, the short term benefits should be achieved if a minimum of 450mg of EPA and DHA collectively are delivered under the advised dosage regime.
If less than 450mg EPA/DHA is delivered then short term benefits are unlikely to be achieved and either augmentation of omega-3 from eating oily fish will be necessary to achieve short term benefits. A longer period of supplementation at lower than 450mg per day may provide some accrued benefit.
With cod liver oil products, an assessment is also made of the ability of the product to deliver the RDA amount of vitamins A and D.
2) Is long term compliance with taking the product likely to be a factor?
Long term compliance with taking a supplement can be the biggest obstacle in achieving benefits in that many people simply stop taking the supplement.
Therefore it is important that a product is easy to take over the long term. For instance, if six capsules have to be taken every day to reach the required dose, compliance will almost invariably be very poor. Similarly, if a liquid omega-3 product tastes horrible, compliance will be poor.
Supplements Compared has assessed value of cod liver and fish oil products on the basis of the price paid to deliver 450mg of the combined level of the omega-3s EPA and DHA.