Osteoarthritis and rheumatoid arthritis
There are a number of different forms of arthritis, but two of the most common ones are osteoarthritis and rheumatoid arthritis. In the UK alone around 8 million people have been diagnosed with osteoarthritis, with 400,000 having rheumatoid arthritis.1 The ways these impact the joints are similar, but their causes are very different.
Osteoarthritis is a degenerative disease that begins by affecting the smooth cartilage lining in the joint, which results in making movement more difficult. Over time, this can lead to bone rubbing against bone, altering the shape of the joint and exacerbating pain. Osteoarthritis generally occurs in older adults, but it can also occur in younger people if a joint has been significantly injured.2
Rheumatoid arthritis is an autoimmune disease, in which the immune system attacks the synovial membrane lining joints, causing pain and swelling. Over time, this can lead to changes in the joint shape and a breakdown of cartilage. What’s more, rheumatoid arthritis can also cause inflammation in other parts of the body, such as the heart, kidney and eyes.3
What are the symptoms, and how can these impact daily life?
Depending on the type of arthritis, there can be a number of different symptoms. These commonly include joint pain, inflammation of the joint, restricted movement, and weakness and wasting of the surrounding muscles.4
For some, these symptoms can be only a minor concern; but for many, they can have a big impact on daily life. A recent study showed people with arthritis tend to avoid everyday activities such as exercise, gardening, climbing stairs and cleaning as a result of the discomfort and pain caused.5
Leaving arthritis untreated
If you don’t manage your arthritis properly, further issues can occur down the road. If you have osteoarthritis, for example, then leaving it untreated can lead to more pain and greater damage to the joint later on, due to it being a degenerative disease. You can also be at risk of muscle imbalances and osteoarthritis forming in other joints, as a result of changing the way you move your body to compensate for pain.6
It’s even more dangerous to leave rheumatoid arthritis untreated, as this form of arthritis can lead to serious health concerns. While joint damage is a concern, leaving it untreated can also result in higher risks for anaemia, cardiovascular disease, osteoporosis and depression.7
If you have any significant risk factors, you should take action early to prevent osteoarthritis from developing. Some common risk factors include smoking, previous injury to a joint, infection, physically demanding work and obesity — so trying to reduce these by altering your diet and making general lifestyle changes can help.8, 9
What is cod liver oil?
An increasingly popular way of treating arthritis symptoms is through supplementation with cod liver oil. This oil is sourced from the liver of cod fish, and is high in beneficial nutrients including vitamin A, vitamin D and omega-3 fatty acids.
Depending on where it’s sourced and how it’s processed, there are many variations of cod liver oil.10 If it’s unrefined or fermented, for example, then it can taste and smell foul, as well as have potential contaminants such as heavy metals. Whereas if refined, the contaminants and the unpleasant scent and taste are removed.
How cod liver oil can support joint health
Cod liver oil has been shown to provide joint benefits as a result of its omega-3 fatty acid content. Omega-3 fatty acids are well-known for their anti-inflammatory properties, and because inflammation is closely linked to autoimmune conditions like rheumatoid arthritis, reducing it can relieve many of the symptoms.11 Inflammation and oxidative stress can also damage cartilage, so this could be another contributing factor to osteoarthritis.12
Although cod liver oil does contain omega-3 fatty acids, what sets it apart is the vitamin A content. It’s believed that sufficient vitamin A can protect the bones and joints, likely due to its antioxidant properties, in addition to reducing the oxidative stress that can lead to bone resorption — the breaking down of bones.13
Cod liver oil is also a natural source of vitamin D. Vitamin D is essential for maintaining bone and joint health, in addition to preventing bone resorption, as it plays a role in increasing calcium absorption.14 The vitamin can also encourage bone mineralisation — depositing minerals such as calcium into the bone.15 When consumed with sufficient calcium, supplementing vitamin D can also help to reduce bone loss in adults.16
Cod liver oil and joint health: the research
What does the research have to say about cod liver oil and joint health? Although it’s not as commonly used in trials as fish oil, the findings are promising.
One study in rheumatoid arthritis found that taking 1g of cod liver oil daily led to significant reduction in symptoms. Morning stiffness was reduced by 52%, pain intensity by 67.5% and swelling in the joints by 40%.17 Another study showed that taking cod liver oil for 9 months led to 39% of patients being able to reduce their anti-inflammatory medications by at least 30%.18 It’s also been suggested that cod liver could have a beneficial effect for osteoarthritis, given that omega-3s have been found to reduce cartilage degeneration and pain in joint conditions.19, 20
What’s more, some studies support the use of cod liver in combination with medications such as disease-modifying anti-rheumatic drugs. When cod liver was used in combination with 3 common rheumatoid arthritis medications, 29% of patients were in remission by 3 months — with 54% being in remission by 3 years. This suggests that cod liver oil could be used in conjunction with medical interventions to provide enhanced treatment. It’s important to check with your doctor before taking alongside other medicine.21
How to consume cod liver oil
Typically, cod liver oil is consumed either through a supplement, whether in the form of a liquid or a capsule, or through cod liver directly.
If you’re more inclined to adopt a wholefood approach, but cod livers aren’t to your taste, then you can obtain similar nutrients through consuming a variety of fatty fish and foods high in vitamin A, such as liver, pâté and eggs. The body can also produce vitamin A if you consume carotenoids, which are found in foods such as sweet potato, carrot and spinach.22
1NHS (2016). Arthritis
2NHS (2016). Arthritis
3Manole Cojocaru, R. (2010). Extra-articular Manifestations in Rheumatoid Arthritis, PubMed Central (PMC)
4NHS (2016). Arthritis
5Hunter, D. J., and Riordan, E. A. (2014). The impact of arthritis on pain and quality of life: an Australian survey, International Journal of Rheumatic Diseases
Hernborg, J. S., and Nilsson, B. E. (1977). The natural course of untreated osteoarthritis of the knee, Clinical Orthopaedics and Related Research, (123), 130-7
77. Johns Hopkins Arthritis Center (2017). Rheumatoid Arthritis : Symptoms, Diagnosis and Treatment
8NHS (2016). Arthritis
9Arthritis Research UK (2018). What causes arthritis?
10Standal, I. B., Praël, A., McEvoy, L., et al. (2008). Discrimination of cod liver oil according to wild/farmed and geographical origins by GC and 13C NMR, Journal of the American Oil Chemists' Society, 85(02)
11Akbar, U., Yang, M., Kurian, D., and Mohan, C. (2017). Omega-3 fatty acids in rheumatic diseases: a critical review, JCR: Journal of Clinical Rheumatology, 23(06)
12Rosenbaum, C. C., O'Mathána, D. P., Chavez, M., and Shields, K. (2010). Antioxidants and anti-inflammatory dietary supplements for osteoarthritis and rheumatoid arthritis, Alternative Therapies in Health & Medicine, 16(02)
13Tanumihardjo, S. A. (2013). Vitamin A and bone health: the balancing act, Journal of Clinical Densitometry, 16(04)
14Suda, T., Takahashi, N., and Abe, E. (1992). Role of vitamin D in bone resorption, Journal of Cellular Biochemistry, 49(01)
15Eisman, J. A, and Bouillon, R. (2014). Vitamin D: direct effects of vitamin D metabolites on bone: lessons from genetically modified mice, Bonekey Reports, 3
16Ebeling, P. R. (2014). Vitamin D and bone health: epidemiologic studies, Bonekey Reports, 03(511)
17Gruenwald, J., Graubaum, H. J., and Harde, A. (2002). Effect of cod liver oil on symptoms of rheumatoid arthritis, Advances in Therapy, 19(02)
1818. Galarraga, B., Ho, M., Youssef, H.M., et al. (2008). Cod liver oil (n-3 fatty acids) as an non-steroidal anti-inflammatory drug sparing agent in rheumatoid arthritis, Rheumatology
19Curtis, C. L., Hughes, C. E., Flannery, C. R., et al. (2000). n-3 fatty acids specifically modulate catabolic factors involved in articular cartilage degradation, Journal of Biological Chemistry, 275(02)
20Goldberg, R. J., and Katz, J. (2007). A meta-analysis of the analgesic effects of omega-3 polyunsaturated fatty acid supplementation for inflammatory joint pain, Pain
21Proudman, S. M., Keen, H. I., Stamp, L. K., et al. (2007). Response-driven combination therapy with conventional disease-modifying antirheumatic drugs can achieve high response rates in early rheumatoid arthritis with minimal glucocorticoid and nonsteroidal anti-inflammatory drug use, Seminars in Arthritis and Rheumatism, 37(02)
22Tanumihardjo, S. A. (2013). Vitamin A and bone health: the balancing act, Journal of Clinical Densitometry, 16(04)
23Tanumihardjo, S. A. (2013) Vitamin A and bone health: the balancing act, Journal of Clinical Densitometry, 16(04)