Supplements are a useful way to add nutrients and specific vitamins to your diet if you struggle to get through eating foods rich in these nutrients. However, it can get quite overwhelming when you’re trying to balance taking several different supplements every day at different times. Cod live oil contains the omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid, as well as several different vitamins. This is hugely beneficial for a range of people, but not everyone needs to take a cod liver oil supplement. Express.co.uk chatted to Dr Deborah Lee from Dr Fox Online Pharmacy to find out who should be taking cod liver oil supplements and why.
Cod liver oil is the oil removed from the liver of Atlantic cod.
The supplement is rich in two specific omega-3 fatty acids – eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), and also contains large quantities of vitamins A and D.
Just one teaspoon of cod liver oil (4.5 g) contains the following:
- Energy: 41 calories
- Vitamin A: 4,500 international units (IU)
- Vitamin D: 450 IU
- Saturated fatty acids: 1.017 g
- Monounsaturated fatty acids: 2.102 g
- Polyunsaturated fatty acids: 1.014 g
- Cholesterol: 26 milligrams (mg)
Dr Lee pointed out: “Cod liver oil differs from other types of fish oil in that it contains fewer omega-3 fatty acids, but more vitamin A and D.”
Cod liver oil benefits
The health benefits of cod liver oil were first recognised in 1789 when it was used as a treatment for rheumatism.
Dr Lee said: “Then in 1824, cod liver oil was first given to children suffering from malnutrition to help prevent bone disease, rickets.
“After that in the 1930s, children were regularly given a spoonful of cod liver oil a day, to help prevent medical conditions linked to vitamin D deficiency.
“On top of that, the omega-3 fatty acids found in cod liver oil, are long-chain, polyunsaturated fatty acids, which are ‘good’ fats for health. Every cell of the body needs fat for survival.”
Cod liver has been reported to have preventative health benefits as listed below:
- Age-related macular degeneration
- Wound healing
- Bone health
- Brain function
- Anxiety and depression
- Artherosclerosis (and other inflammatory conditions)
- Non-alcoholic fatty liver disease (NAFLD)
There aren’t specific signs that you should take cod liver oil, but specific groups of people should think about taking it.
We don’t all need to take a cod liver oil supplement because we can normally get these nutrients through our diets.
Dr Lee said: “The NHS recommends UK adults eat two portions of fish per week, one of which should be oily fish such as salmon, trout, mackerel, sardines, pilchards or herring.”
However, if you can’t or don’t eat fish, an omega-3 supplement like cod liver oil is a possible alternative.
Dr Lee warned: “Don’t overdo eating fish – some fish such as shark, swordfish or merlin – contains high levels of mercury.
“Fish is also high in vitamin A, and excess vitamin A can be harmful.”
The British Dietetic Association (BDA) doesn’t make any specific recommendations about who should take omega-3 supplements and instead recommends that omega- 3 should be obtained from the diet wherever possible.
They recommend a specific omega-3 supplement, rather than a fish oil supplement like cod liver oil.
The main difference between the two is that cod liver oil also contains vitamins A and D.
If you choose to take an omega-3 supplement, the BDA suggest a dose of 450mg EPA and DHA per daily dose – the equivalent of eating one to two portions of oily fish
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While cod liver oil has proven useful in a number of studies as a preventative health benefit, it actually isn’t recommended by the NHS for many things.
For example, the NHS does not currently recommend cod liver oil or fish oil supplements to reduce the risk of Alzheimer’s Disease.
Dr Lee said: “However, they do advocate following a healthy diet, such as the Mediterranean and the MIND diet, which both include regular portions of oily fish, and have been shown to lower the risk of dementia.”
The same is true for arthritis, with a 2017 review in the Journal of Clinical Rheumatology concluding that omega- 3 supplements will work better at lowering inflammation, especially if you have rheumatoid arthritis rather than osteoarthritis.
If you’ve got cardiovascular disease, the British Heart Foundation (BHF) recommends taking omega- 3 supplements for those with raised triglyceride levels rather than cod liver oil supplements.
Who should not be taking it?
Cod liver oil should not be taken by those with the following medical conditions:
- High calcium levels in the blood
- High phosphate levels in the blood
- Excessively high vitamin D levels
- Kidney stones
- Kidney failure
The NHS also advises against taking CLO in pregnancy, as high levels of vitamin A may cause harm to the developing foetus.
Dr Lee added: “There are no general recommendations for omega -3 supplements for those with cardiovascular disease.
“A large 2019 clinical trial failed to show any benefit from taking fish oil supplements – there was no reduction in cardiovascular disease, or cancer, in those who took fish oil compared to those who took a placebo.”
There are some negative side effects or adverse effects that can happen when you take cod liver oil. The most common are:
- Bleeding problems – Most commonly bleeding gums or noses. This may be because they have an antiplatelet effect to inhibit the formation of blood clots.
- Raised blood sugar levels – Fish oils can increase levels of adiponectin which affects insulin sensitivity.
- Gastrointestinal symptoms – Such as nausea, indigestion, acid reflux.
- Low blood pressure – CLO may slightly lower blood pressure, perhaps because it lowers triglycerides.
- Diarrhoea – Fish oil can make faces slippery due to the lubricant effect of the oil.
- Weight gain – CLO is an oil, and oils are high in calories.
- Insomnia – Most studies show that fish oil tends to improve sleep. But omega-3 is also linked to serotonin production and perhaps this may explain why in some people it is linked to insomnia. This does tend to improve over time.
Always check with your GP if you suffer from any chronic medical conditions before starting to take CLO supplements.