Respiratory Allergies: How to Fight Them with Omega-3

Omega 3 and allergies: a matter of inflammation

Spring is allergy season for respiratory allergies, but as we well know pollen is not the only source of allergens. Dust mites, dog and cat dander, latex are other common examples of substances that are harmless per se but can trigger an excessive response from the immune system and, consequently, the symptoms of an allergy.

Food can also be a source of allergenic molecules (allergens). Some food allergies can be very dangerous and even lead to anaphylactic shock. The only way to avoid such severe reactions is to adopt appropriate dietary habits consisting of avoiding the food in question and all preparations that may contain it even in traces.

Sometimes there is also a relationship between respiratory allergies and food allergies. This is the case with oral allergy syndrome, a condition in which consumption of raw fruits and vegetables triggers itching and swelling of the throat, mouth, tongue, and lips. A typical feature of this food allergy is precisely being associated with pollen allergies; it affects between 50 and 75% of those allergic to birch, and there is even a correspondence between the pollen and the fruits and vegetables that trigger allergic symptoms. For example, those allergic to the aforementioned birch often cannot eat raw apples, apricots, cherries, peaches, plums, kiwi, and carrots, nor soy and various types of nuts (peanuts, almonds, and hazelnuts).

Given this relationship between food and allergies, it is natural to wonder whether there is a way to avoid excessive immune system reactivity through nutrition. And given their well-known anti-inflammatory properties, polyunsaturated fats Omega-3 are included among the potentially useful nutrients in this sense. We must not forget that allergies are inflammatory phenomena.

Allergies and inflammation

Inflammation can be triggered by contact with one or more specific allergens. Usually, single exposure gives rise to a reaction within a few minutes. This acute reaction can be localized (such as rhinoconjunctivitis, asthma attacks, hives, or gastrointestinal reactions) or extend to the entire body (causing anaphylactic shock).

In many cases, the acute reaction is followed by a delayed reaction, which begins to manifest 2 to 6 hours after exposure and peaks between 6 and 9 hours after contact with the allergen. Possible symptoms include swelling, pain, skin redness, and mucus overproduction in the lungs; usually, all resolves within a couple of days.

If exposure is repeated or constant, however, chronic allergic inflammation can develop, responsible for alterations in the tissues of the body.

The potential anti-inflammatory effect of Omega 3

Unlike other substances present in food, Omega-3s tend to reduce and resolve inflammation. This anti-inflammatory potential is mediated by:

• the ability of Omega-3s to inhibit the function of white blood cells responsible for inflammatory phenomena;
• the inhibition of the production of molecules that participate in and promote inflammation (cytokines, prostaglandins, leukotrienes);
• the promotion of production of anti-inflammatory molecules or molecules with lower inflammatory potential;
• being the precursors of molecules that promote the resolution of inflammation (resolvins, protectins, and maresins).

Another class of well-known essential polyunsaturated fats, Omega-6, has a greater inflammatory potential. For this reason, the risk of inflammation is higher when the ratio between Omega-3 and Omega-6 is lower.

Do Omega 3 help fight allergies?

The hypothesis that the anti-inflammatory potential of Omega-3s might help fight allergies is supported by several studies that 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 red blood cell membranes (a parameter by which Omega 3 levels in the body can be evaluated) 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 (particularly inflammation of the respiratory tract); indeed, asthma is associated with reduced synthesis of those resolvins, protectins, and maresins derived from Omega-3s that are needed to resolve inflammation. Preclinical studies suggest that dietary Omega-3s can reduce inflammation associated with allergic conjunctivitis and its symptoms.

The protective effect is particularly evident in early life. In fact, it seems that the best choice is to prevent allergies by ensuring an adequate intake of Omega-3 already during pregnancy and breastfeeding.

The intake of fish oil supplements (one of the best sources of EPA and DHA) during pregnancy modifies immune response in umbilical cord blood and can counteract sensitization to common food allergens and reduce the appearance and severity of atopic eczema during the first year of life, with benefits persisting up to adolescence.

Moreover, fish oil taken during pregnancy also reduces asthma and persistent wheezing in children aged 3 to 5 years, while when taken in the first six months of life it can reduce allergies to dust mites and milk.

How many Omega-3 against allergies?

Current data do not allow guidelines on the timing and dosages at which Omega-3s should be taken to counter allergies. The minimum that can be done is to ensure an adequate intake according to the different life stages one is in.

Therefore, if 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 amount. Children up to two years of age should be guaranteed an additional 100 mg of DHA every day.

Introducing Omega-3 rich fish (salmon, mackerel, sardines, anchovies, herring, ...) into the diet is the simplest strategy to take high doses of these nutrients. Unfortunately, however, the widespread adoption of dietary habits typical of modern Western societies, in which the consumption of industrial foods or foods prepared outside the home is very frequent, causes Omega-6 fat intake to often be rather high. This increases the tendency to develop inflammatory phenomena, also considering that the transformation of dietary 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 hinders the already limited ability of the human body to produce EPA and DHA.

Thus, meeting the Omega-3 requirement becomes difficult, especially in “critical” population groups such as:

• children, who often refuse fish, the best dietary source of EPA and DHA;
• pregnant or breastfeeding women, whose Omega-3 requirements increase but who cannot eat much Omega-3 rich fish due to the risk of mercury contamination;
• people allergic to fish.

Fortunately, there are supplements based on marine-origin oils (fish, cod liver, krill, algae) that help face these situations. However, the quality of the chosen oil can also make a difference in the ability to prevent allergies. Numerous studies suggest that from this point of view products rich in DHA may be more effective. And to avoid exposing health to risks, it is useful to rely on products with guaranteed purity, such as those certified by the IFOS program (International Fish Oil Standards).

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