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The Effects of Cod Liver Oil on Allergies and Asthma 

By: Angela Moore

October 10, 2008           


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For ages, parents have been forcing a spoonful of cod liver oil down the throats of little children. The nasty aftertaste that it leaves makes you wonder why go through the trouble. What does cod liver oil do anyway? In present day, the use of cod liver oil has decreased but there are still those faithful few that hold on to the notion that cod liver oil is a cure all especially in regards to allergies and asthma.









What is it?

Cod fish are found on both sides of North Atlantic’s deep waters. They are valued for their flesh and the oil it produces in its liver (   

Cod Liver Oil is “light yellow oil… that is one of the most important natural sources of vitamins A and D.” ( It also is a great source for omega 3 fatty acids.



Why is this important?

          Vitamin A, vitamin D and omega 3 fatty acids are three important nutrients for the upkeep of the body. Vitamin A, a fat- soluble vitamin, plays an integral role in cell growth, vision, and the immune system as well as “helps maintain the mucous membranes that trap microbes and fight infection” (

Vitamin D is mostly known for keeping bones strong and healthy. The component of cod liver oil is a partial cause of its popularity. In the late 19th and early 20th century, cod liver oil was used to treat rickets because of its strong source of Vitamin D (

Omega 3 fatty acids, also known as polyunsaturated fatty acids, are also essential to health, and most are obtained by certain foods, namely fish. Its uses range from lowering LDL cholesterol and lowering risk for heart disease to acting as an anti- inflammatory.

By reviewing cod liver oil’s components it seems as though it could be a perfect cure all for different ailments including allergies and asthma.




What are allergies?                         

Medline Plus describes allergies as having “an oversensitive immune system, which leads to a misdirected immune response. The immune system normally protects the body against harmful substances, such as bacteria and viruses. It reacts to substances (allergens) that are generally harmless… But in a person with allergies, the immune response is oversensitive. When it recognizes an allergen, it releases chemicals, such as histamines. This causes itching, swelling, mucus production, muscle spasms, hives, rashes, and other symptoms, which vary from person to person” (


What is asthma?

According to Medline Plus, “asthma is caused by inflammation in the airways. When an asthma attack occurs, the muscles surrounding the airways become tight and the lining of the air passages swell. This reduces the amount of air that can pass by, and can lead to wheezing sounds. In sensitive individuals, asthma symptoms can be triggered by breathing in allergy-causing substances (called allergens or triggers). Triggers include pet dander, dust mites, cockroach allergens, molds, or pollens” (


What are the Web Claim(s)???

Breathe Easy with Omega 3 Fatty Acids

          On the site states that “fish oil and Cod Liver Oil may reduce inflammation and allergic response…cod liver oil… improves immune system and repairs mucous membranes” ( It also states it has “a positive calming effect on an immune system that has gone haywire” (

If you review the site, you will find advertisements for “organic” omega- 3 supplements and articles that claim that fish oils help with breathing. However, where is the proof?



What the Experts Say

In Bergen, Norway, Birger Laerum and a team of researchers investigated the relationship between childhood and adult intake of cod liver oil and fish with risk for asthma. They used a Respiratory Health in Northern Europe (RHINE) study in which they sent out a postal questionnaire regarding fish intake in childhood and adulthood. The respondents’ ages ranged from 23-54 years. Results found that “fish intake in childhood was weakly correlated with intake of cod oil in adulthood… fish intake in adulthood was correlated at the same level with cod oil intake in adulthood” (Laernum et al, 2007, 1617). Reports also showed that in adults the higher amount of fish consumed the lower the susceptibility of allergies. It also showed that children who ate fish had lower susceptibility, but this did not translate with age: “further analyses showed no interaction of childhood and adult fish intake” (Laernum, 2007, 1619).


In a relatively smaller study, Linda Linday and other pediatric researchers designed a study to determine whether multivitamins with cod liver oil have an effect on sinusitis. “Chronic sinusitis is characterized by inflammation of the nasal and sinus mucosa” (Linday et al, 2004, 786). The participants ranged from 2 years old to 18 years old or various gender and race. They used an open- label, dose titration in which they increased dosages of supplements and cod liver oil during a four month study. Through three of the four case studies, they found that the dosages of multivitamins and cod liver oil were positive in lowering sinus effects. They noted that this treatment does not work on severe symptomatic sinusitis patients. Nevertheless, I am not certain how reliable this study is due to the few case studies produced. Also it mentioned that “the marketed nutritional supplements used in this study were donated by J.R. Carlson Laboratories, Inc” (Linday et al, 2004, 787). This makes me question the motives of the study: was this a marketing tool?


        Another study tested the effects of early intake of fruits and vegetables versus multi vitamins and COD liver oil. The researchers used a cross- sectional survey of children aged 6- 16 years old. The researchers showed that the intake of cod liver oil during the first year of life showed increased allergy sensitivity.



In adults, cod liver oil may have its benefits of decreasing asthma and allergy symptoms. However it may increase allergic sensitization in children so caution should be taken. Even so, it may be better to increase children’s diet of fruits and vegetables to lower the risk of asthma and allergies. Also, one must remember that with taking cod liver oil, as any supplement, there are some risks. Over- consumption of cod liver oil means over- consumption of vitamin A which can cause toxicity in the body. Therefore, further research should be done on the matter as well as consulting a physician before adding a supplement to your diet.





Laerum, B. N., Wentzel- Larsen, T., Gulsvik, A., Omenaas, E., Gislason, T., Janson, C., and Svanes, C. (2007). Relationship of fish and cod oil intake with adult asthma. Clinical and Experimental Allergy, 37, 1616-1623.


Linday, Linda; Dolitsky, Jay; Shindledecker, Richard. (2004). Nutritional supplements as adjunctive therapy for children with chronic/ recurrent sinusitis: pilot research. International Journal of Pediatric Otorhinolaryngology, 68, 785-793.


Nja, Frode; Nystad, Wenche; Lodrup Carlsen, Karin; Hetlevik, Oystein; and Carlsen, Kai-Hakon. (2005). Effect of early intake of fruit or vegetables in relation to later asthma and allergic sensitization in school- age children. Acta Paediatrica, 94:147-154.




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