Hay fever and vitamin D: lessons from a recent

What is hay fever?

Hay fever, or allergic rhinitis, is an inappropriate and excessive reaction by the immune system to environmental allergens such as pollen, dust mites or certain animal hairs (1). On contact with these normally harmless substances, the body triggers an inflammatory response in the nasal mucosa, typically resulting in:

• a runny nose
• repeated sneezing
• nasal discomfort or obstruction
• fatigue and/or sleep disturbance

Although hay fever is essentially a benign condition, medical advice is still recommended in the event of severe or persistent symptoms.

Vitamin D and allergic rhinitis: the results of a recent meta-analysis

Study overview

Researchers recently published a systematic review and meta-analysis of randomised clinical trials of vitamin D supplementation in people with allergic rhinitis (2). In particular, they monitored changes in allergic symptom scores compared to a placebo and examined specific subgroups according to average age, proportion of women, associated background treatments, duration of supplementation and initial vitamin D status.

Observed but variable benefits

Their observations suggest a possible improvement in hay fever symptoms in subjects supplemented with vitamin D, but point to a high degree of variability in the results depending on the context. In particular, the effects seem to vary according to sex and the concomitant use of corticosteroids (which may lead to reduced effectiveness). It should be noted, however, that the scope of the conclusions is limited by the great heterogeneity of the protocols.

This publication therefore does not establish a universal benefit of vitamin D in hay fever. It does, however, sketch out some interesting avenues of research that should be supported by other, more homogeneous and better stratified clinical trials.

Does vitamin D mediate the allergic response?

What about the physiological mechanisms at work? It has been established that vitamin D plays a part in the proper functioning of the immune system, particularly the adaptive system, which we acquire and develop throughout our lives through contact with the pathogens or antigens we encounter (3).

In particular, it is thought to help maintain a balanced inflammatory response, by supporting the differentiation of regulatory T lymphocytes (Treg), inhibiting the production of pro-inflammatory cytokines (IL-6, IL-7, TNF-α, etc.) and stimulating the secretion of anti-inflammatory cytokines (IL-10) (4-5). It may therefore have some relevance to allergic reactions, which are underpinned by inappropriate immune activation.

Where to find vitamin D, and how to incorporate it into your diet in the event of hay fever

Vitamin D is mainly synthesised by the skin through exposure to the sun, which is why it is known as the 'sunshine vitamin' (6). It is also provided, in more modest quantities, by oily fish, egg yolks, offal such as liver, or certain fortified foods (milk, cottage cheese, etc.) (7).

In the event of suspected or proven deficiency, vitamin D supplementation can be discussed with a health professional. This should, of course, remain under supervision, especially in the case of known pathologies. It should also be remembered that food supplements are never a substitute for medical treatment for allergic rhinitis. They are part of an overall support approach that includes reducing exposure to allergens, good nasal hygiene, quality sleep and, of course, applying all the measures prescribed by the doctor or allergist.

Thinking of taking a supplement? Vitamin D supplements come in different forms and dosages.

Vitamin D3 1000 IU, packaged in oily capsules, is suitable for everyone.

With its practical spray format, Vitamin D3 Spray 2,000 IU is particularly well tolerated by the stomach.

Vitamin D3 5000 IU uses a powerful dosage to quickly restore adequate levels.

Its 100% plant-based version, Vegan D3 5000 IU, is derived from non-GMO, pesticide-free algae.

For broader support, you can also rely on certain plants or substances studied for their potential antihistaminic and/or immunomodulating properties to help you feel more comfortable during allergy season. Like astragalus, which contributes to general well-being and regulates the immune system, or maritime pine, which promotes good respiratory health (8-9).

Aller Fight synergy combines the best allergy-tested ingredients in a single formula: astragalus, maritime pine, spirulina, bromelain, etc.

Finally, it's a good idea to supplement the action of vitamin D with other vitamins and minerals that help maintain normal immune function, such as vitamins A, B6, B12 and C, and zinc (10-12).

You'll find it in Daily 3®, the most complete multivitamin supplement on the market.