Secretor status (norovirus resistance & B12)

The FUT2 gene decides whether you release your blood-group sugars onto your gut lining and other body surfaces (this is called your secretor status). People who don't release them (non-secretors) resist many common stomach-flu noroviruses and tend to have higher vitamin B12.

Possible results

Secretor type. You're a secretor: you release blood-group sugars onto the lining of your gut and other surfaces. One practical effect is that you're susceptible to the common noroviruses behind most stomach flu, and you tend to have somewhat lower vitamin B12 levels.

Secretor type. You carry one working copy of FUT2, which is enough to make you a secretor. You release blood-group sugars onto body surfaces, so you have typical norovirus susceptibility and B12 levels for a secretor.

Non-secretor type. You're a non-secretor: you don't put blood-group sugars on your gut lining. A neat side effect is that you resist many of the common noroviruses that cause stomach flu, and you tend to have higher vitamin B12 levels. Protection isn't total, since some norovirus strains get around it.

Evidence & sources

Across global populations, about 22% of people carry two copies of this variant, and about 31% carry none.

This variant appears in 1 published genetic study: PubMed 39024449.

Related

Adult lactose digestion · Alcohol response (flushing & dependence risk) · Folate metabolism (MTHFR gene) · LDL cholesterol · Sweet tooth / carbohydrate preference (FGF21) · Triglycerides · Vitamin D status (low-D genetic burden)