Spring is in full force here, and with it has come the need to dust off the lawnmower.  As the smell of fresh cut grass fills the air, many people also know the feelings of watery eyes, runny noses, and itching everything.

Speaking of smelling the grass… Did you know that some people can’t smell the odor of fresh cut grass?  There is actually a genetic variant (not covered by 23andMe data) that prevents some people from knowing that wonderful summertime smell.

There are several different gene variants that are tied to an increased risk of grass pollen allergies.

A study found that in people with grass pollen allergies there was an upregulation of MC1R in their noses.  If that gene sounds familiar, it is the same gene that codes for the melanin receptor which causes red hair.

HLA-DRB4 gene:

Human leukocyte antigens (HLA) are part of our immune system and help the body recognize foreign invaders. People have many different variants of these genes, giving rise to protection against different pathogens. Different HLA types lead to an increased ability to fight off diseases and also lead to increased susceptibility to autoimmune diseases and allergies.

rs7775228  (v4, v5)

  • CC: more likely to be allergic to grass pollen[ref]
  • CT: more likely to be allergic to grass pollen
  • TT: normal (most common genotype)

FLG gene:

Filaggrin, a protein encoded by the FLG gene, increases the epithelial integrity. Variants that decrease filaggrin have been tied to different types of allergies.

rs61816761 R501X (v4, v5):

  • AA: (rare) more likely to be allergic to grass pollen [ref]
  • AG: more likely to be allergic to grass pollen
  • GG: normal (most common genotype)

IL2 gene:

Interleukin 2 (IL2) is involved in the body’s immune system response to foreign invaders. It is a cytokine produced by Th1 cells when they are stimulated by, in this case, an allergen.

rs2069762 -330T/G (v4, v5):

  • AA: normal (most common genotype)
  • AG: normal risk of grass allergy
  • GG: 2.6x increased risk of grass allergy, [ref]

IL33 gene:

Interleukin 33 is involved in the body’s immune system response, also.  IL-33 drives the production of Th2 cytokines, acting on mast cells (among others).  It is thought to be responsible for itching sensations from allergies.[ref]

rs928413 (v4, v5)

  • AA: normal
  • AG: increased risk of hay fever, allergy
  • GG: increased risk of hay fever [ref]


A study on children with seasonal pollen allergies compared the effects of 1,000 IU of Vitamin D daily vs. placebo. The study found that the vitamin D group had reduced allergy symptoms compared to the placebo group. Another study looked at vitamin D combined with Lactobacillus rhamnosus GG (probiotic) on children’s allergies and found that the combo was also effective.

Nasal rinsing has been shown to be effective for grass pollen allergies.[ref]  The easiest way to nasal rinse is using a sinus rinse kit or with a neti pot.

Spirulina, a new favorite of mine, has been found in studies to reduce the symptoms of allergic rhinitis.[ref][ref]  You should be able to find spirulina in any health food store, or you can get it online.  Look for an organic version.

Bifidobacterium lactis reduced grass pollen reactions (taken for 8 weeks). [ref]

If you normally take antihistamines for pollen allergies, this study suggests that taking the antihistamines for three days before the exposure prevented the histamine 1 (H1) receptors from increasing expression in the nose. In an allergic response, your body releases histamine as a signaling molecule and then the receptors for histamine cause the reaction to occur.  H1 receptors are the ones involved in your typical seasonal allergy reaction with a runny nose and itchy, watery eyes. So the study showed that without the increase in histamine receptors, there were few allergy type symptoms. The antihistamine prevented the body from upregulating the H1 receptors.

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