Respiratory allergies: how to fight them with Omega-3s
Omega 3 and allergies: a matter of inflammation
Spring is time for respiratory allergies, but as we all know pollens are not the only source of allergens. Dust mites, cat and dog dander, and latex are other common examples of inherently harmless substances that can trigger an over-response by the immune system and, consequently, allergy symptoms.
Food can also be a source of allergenic molecules (the allergens). Some food allergies can be very dangerous and even lead to anaphylactic shock. The only way to avoid such severe reactions lies in adopting appropriate eating habits consisting of avoiding the food in question and all preparations that may contain it even in trace amounts.
Sometimes there is also a relationship between respiratory allergies and food allergies. This is the case with oral allergy syndrome, a condition in which the consumption of raw fruits and vegetables triggers itching and swelling of the throat, mouth, tongue, and lips. A typicality of this food allergy is precisely being associated with pollen allergies; 50 to 75 percent of those who are allergic to birch suffer from it, and there is even a correspondence between pollen and the fruits and vegetables that trigger allergic symptoms. For example, people who are allergic to the aforementioned birch often cannot eat apples, apricots, cherries, peaches, plums, kiwis, and raw carrots, nor can they eat soy and different types of nuts (peanuts, almonds, and hazelnuts).
Given this relationship between food and allergies, the question arises as to whether there is a way to avoid excessive immune system reactivity through diet. And given their known anti-inflammatory properties, potentially useful nutrients in this regard include Omega-3 polyunsaturated fats. Indeed, it should not be forgotten that allergies are inflammatory phenomena.
Allergies and inflammation
Inflammation can be triggered by contact with one or more specific allergens. Usually the single exposure gives rise to a reaction within a few minutes. This acute reaction may be localized (such as a rhinoconjunctivitis, asthma attacks, hives, or gastrointestinal reactions) or spread throughout the body (causing anaphylactic shock).
In many cases the acute reaction is followed by a later reaction, which begins to occur 2 to 6 hours after exposure and peaks between 6 and 9 hours after contact with the allergen. Possible symptoms include swelling, pain and redness of the skin and overproduction of mucus in the lungs; this usually resolves within a couple of days.
If exposure is repeated or constant, however,chronic allergic inflammation can develop, which is responsible for tissue changes in the body.
The anti-inflammatory potentialmatory potential of Omega 3
In contrast to other substances found in food, Omega-3s tend to reduce and resolve inflammation. This anti-inflammatory potential of theirs is mediated:
- by the ability of Omega-3s to inhibit the function of white blood cells responsible for inflammatory phenomena;
- byinhibiting the production of molecules that participate in and promote inflammation(cytokines, prostaglandins, leukotrienes);
- from promoting the production of anti-inflammatory molecules or molecules with less inflammatory potential;
- from being the precursors of molecules that promote the resolution of inflammation(resolvins, protectins, and maresins).
In contrast, another well-known class of essential polyunsaturated fats, Omega-6, has greater inflammatory potential. Therefore, the risk of inflammation is higher when the ratio of Omega-3 to Omega-6 is lower.
Do Omega 3s help fight allergies?
The hypothesis that the anti-inflammatory potential of Omega-3s could help fight allergies is supported by several studies that have found an association between the intake of these fats and a reduction in the incidence of symptoms of these disorders.
For example, both a high percentage of EPA (eicosapentaenoic acid, one of the biologically active Omega-3s) in the red blood cell membrane (a parameter by which levels of Omega-3s in the body can be assessed) and a diet rich in ALA (alpha-linolenic acid, the precursor of EPA and the other biologically active Omega-3, docosahexaenoic acid or DHA) are associated with a lower risk of sensitization to potential allergens and allergic rhinitis.
Omega-3s have also been associated with a reduced risk of asthma and its symptoms (in particular, of airway inflammation); indeed, asthma is associated with a reduction in the synthesis of those Omega-3-derived resolvins, protectins and maresins that serve to resolve inflammation. And preclinical studies suggest that food-derived Omega-3s may reduce the inflammation associated with allergic conjunctivitis and its symptoms.
The protective effect is particularly evident in early life. Even, it seems that the best choice is to prevent allergies by ensuring adequate Omega-3 intake already during pregnancy and breastfeeding.
Taking fish oil supplements (one of the best sources of EPA and DHA) during pregnancy modifies the immune response in the cord blood and can counteract sensitization to common foodborne allergens and reduce the occurrence and severity ofatopic eczema during the first year of life, with benefits persisting well into adolescence.
Not only that, fish oil taken during pregnancy also reduces asthma and persistent wheezing in children aged 3-5 years, while when taken during the first six months of life it can reduce mite and milk allergies.
How many Omega-3s against allergies?
The data currently available do not allow us to give guidelines on the timing and dosages at which Omega-3s should be taken to counteract allergies. The least one can do is to ensure adequate intake according to the different stages of life one is in.
While, therefore, everyone should take at least 250 mg of EPA+DHA daily, pregnant or breastfeeding women should add another 100-200 mg of DHA to this quota. Children up to two years of age, on the other hand, should be guaranteed an additional 100 mg of DHA each day.
Introducing fish rich in Omega-3 (salmon, mackerel, sardines, anchovies, herring, ...) into the diet is the easiest strategy to take high doses of these nutrients. Unfortunately, however, the widespread dietary habits typical of modern Western societies, in which the consumption of industrial or prepared foods outside the home is very common, means that the intake of Omega-6 fats is often quite high. This increases the tendency for the development of inflammatory phenomena, also in light of the fact that the transformation of food-derived Omega-6 and Omega-3 into the biologically active molecules derived from them (EPA and DHA) requires the same enzymes and that, therefore, a diet rich in Omega-6 hampers the human body's already poor ability to produce EPA and DHA.
Meeting Omega-3 requirements becomes, thus, difficult, especially in "critical" population groups such as:
- children, who often reject fish, the best dietary source of EPA and DHA;
- Pregnant or breastfeeding women whose Omega-3 requirements have increased but who cannot eat much Omega-3-rich fish because of the risk of mercury contamination;
- le people who are allergic to fish.
Fortunately, there are supplements based on oils of marine origin (fish, cod liver, krill, seaweed) that help to cope with these situations. Be careful, however: the quality of the oil chosen can also make a difference in the ability to prevent allergies. Numerous studies suggest that products rich in DHA may be more effective in this respect. And to avoid exposing your health to risks, it is useful to rely on products with guaranteed purity, such as those certified by theInternational Fish Oil Standards (IFOS) program.
Bibliographical references
D'Vaz N et al. Fish oil supplementation in early infancy modulates developing infant immune responses. Clin Exp Allergy. 2012 Aug;42(8):1206-16. doi: 10.1111/j.1365-2222.2012.04031.x
Furuhjelm C et al. Fish oil supplementation in pregnancy and lactation may decrease the risk of infant allergy. Acta Paediatr. 2009 Sep;98(9):1461-7. doi: 10.1111/j.1651-2227.2009.01355.x
Galli SJ et al. The development of allergic inflammation. Nature. 2008 Jul 24; 454(7203): 445-454.
doi: 10.1038/nature07204
Hirakata T et al. The roles of omega-3 fatty acids and resolvins in allergic conjunctivitis. Curr Opin Allergy Clin Immunol. 2019 Oct;19(5):517-525. doi: 10.1097/ACI.0000000000000561
Hoff S et al. Allergic sensitization and allergic rhinitis are associated with n-3 polyunsaturated fatty acids in the diet and in red blood cell membranes. Eur J Clin Nutr. 2005 Sep;59(9):1071-80. doi: 10.1038/sj.ejcn.1602213
Miles EA and Calder PC. Can Early Omega-3 Fatty Acid Exposure Reduce Risk of Childhood Allergic Disease? Nutrients. 2017 Jul 21;9(7):784. doi: 10.3390/nu9070784
Miyata J and Arita M. Role of omega-3 fatty acids and their metabolites in asthma and allergic diseases. Allergol Int. 2015 Jan;64(1):27-34. doi: 10.1016/j.alit.2014.08.003
Miyake Y et al. Fish and fat intake and prevalence of allergic rhinitis in Japanese females: the Osaka Maternal and Child Health Study. J Am Coll Nutr. 2007 Jun;26(3):279-87. doi: 10.1080/07315724.2007.10719612
Sartorio MUA et al. Potential Role of Omega-3 Polyunsaturated Fatty Acids in Pediatric Food Allergy. Nutrients. 2021 Dec 29;14(1):152. doi: 10.3390/nu14010152
Sawane K et al. Dietary Omega-3 Fatty Acid Dampens Allergic Rhinitis via Eosinophilic Production of the Anti-Allergic Lipid Mediator 15-Hydroxyeicosapentaenoic Acid in Mice. Nutrients. 2019 Nov 22;11(12):2868. doi: 10.3390/nu11122868
Willemsen LEM. Dietary n-3 long chain polyunsaturated fatty acids in allergy prevention and asthma treatment. Eur J Pharmacol. 2016 Aug 15;785:174-186. doi: 10.1016/j.ejphar.2016.03.062
