When we are under acute or chronic episodes of physical or emotional stress, our body protects itself by shifting the relative balance of our nervous system, to  sympathetic dominance (self-control), thereby rapidly releasing specific stress hormones such as cortisol, adrenaline aka epinephrine and noradrenaline aka norepinephrine.   The long-term effects of the continual release of these hormones are not good at all and will eventually lead to significant degenerative changes within the body.

The stress hormone norepinephrine affects parts of the brain where attention and responding actions are controlled.   Along with epinephrine, norepinephrine also underlies the so-called fight-or-flight response.  During this stress response, heart rate increases, glucose is triggered to be released from energy stores, and blood flow is increased to skeletal muscle.  At the same time, blood and energy are drawn away from the gastrointestinal tract and other internal organs.

1.  Norepinephrine is synthesized from dopamine by utilizing the enzyme dopamine β-hydroxylase.

2.  The gene for dopamine β-hydroxylase has shown some association linkages with the gene that controls the ABO blood types.(1)

3.  Norepinephrine and epinephrine possess a synergistic relationship with AI-3, an autoinducer* and may even substitute itself for the AI-3 auto-inducer, resulting in biofilm growth.

4.  The common denominator between type O blood and dopamine appears to be via the null allele (A null allele is a mutant copy of a gene  that completely lacks that gene’s normal function).  In this case, the null allele is the type O blood allele in the human A, B and O blood type system – A, B and AB blood don’t possess it.

A hypothesis  could then be made, based on the above data, those type O blood individuals who are highly stressed (over-activated adrenal glands and sympathetic nervous system dominant) may possess a predisposition to infections or overgrowth of yeasts, bacterias, and biofilm in the GI tract, since both epinephrine and norepinephrine are present throughout the gastrointestinal tract, and are involved in the stress response.  This may be especially relevant for those type O individuals who possess the ‘Hunter’ epigenotype.(2)

*Bacteria communicate via signaling molecules called auto-inducers, a type of bacteria pheromone.  These autoinducers can initiate or interfere with Quorum Sensing.  One of the two series of auto-inducer molecules is the Auto-Inducers AI-1, AI-2, and AI-3.

These autoinducers are one of the very few biologically active family of molecules that contain the element boron.  Some evidence indicates that grapefruit juice and its furocoumarins inhibit autoinducer signaling and biofilm formation in bacteria.  The most abundant source of furocoumarins in our diet would be grapefruit juice.  The average levels of furocoumarins were lower in the juice from red grapefruit than the white variety, with the highest level of  this component found in the meat of the grapefruit.

(1) AF Wilson, RC Elston, R M Siervogel, and LD Tran. Linkage of a gene regulating dopamine-beta-hydroxylase activity and the ABO blood group locus. Am J Hum Genet. 1988 January; 42(1): 160-166.