Allergic rhinitis or hay fever is an allergic inflammation of the nasal airways. When an allergen, such as pollen, dust or animal dander (particles of shed skin and hair) is inhaled by an individual with a sensitized immune system, they may get allergic rhinitis. In such individuals, the allergen triggers the production of the antibody immunoglobulin E. When grass pollens cause allergic rhinitis, it is known as hay fever.
Symptoms include sneezing, itchy and watery eyes, swelling and inflammation of the nasal passages, and an increase in mucus production. In Western countries, up to 25% of the population are affected by allergic rhinitis.
There are conflicting data on vitamin D and allergic rhinitis. A 2007 NHANES III study showed that the higher your vitamin D level, the more likely you would have allergic rhinitis.
On the other hand, in a randomized controlled trial, vitamin D supplementation boosted corticosteroids in the treatment of allergic rhinitis and helped decrease sneezing, nasal congestion, and postnasal drip.
Baroody F, et al. The Addition of Vitamin D (VitD) to an Intranasal Steroid (INS) Improves Control of Symptoms in Seasonal Allergic Rhinitis (SAR). The Journal of Allergy and Clinical Immunology. Feb 2012.
Now researchers in Korea studied vitamin D levels in more than 8,000 people in a cross sectional study of a normal population.
They found that the mean 25(OH)D level of the hay fever group was slightly lower than that of the non-allergic rhinitis group (16.71 vs. 17.75 ng/mL, P < .001).
They then separated the 8,000 people into 3 groups according to 25(OH)D level. Group I (<15 ng/mL, 2,644 patients), group II (between 15 and 25 ng/ml, 3,543 patients, and group III (>25 ng/mL, 1,099 patients). The researchers found that those in the lowest vitamin D group were more likely to have hay fever. The prevalence of hay fever was 13.0% in group I, 11.5% in group II, and 7.2% in group III. That is, allergic rhinitis was almost twice as likely if you had low 25(OH)D levels.
I don’t know what to make of the conflicting studies to date. The data in the Korean study was a little strange. For example, hypertension was significantly more prevalent in those with higher 25(OH)D levels, something we know is not the usual case (and does not corroborate with randomized controlled trials).
My allergic rhinitis continues even with my 25(OH)D level of 75 ng/ml. What have readers noticed?