Recently, I visited the Emergency Room because my boyfriend had a severe allergic reaction to the point where he could no longer breathe.

He accidentally had pecans (a class of tree nuts) to which his body responded immediately with a heightened immune response. The medical team used epinephrine in an effort to open up the airways that were swelling and increase the blood flow throughout the body so that he could breathe again. Epinephrine has these effects because they have receptors on smooth muscles – involuntary muscles – that block the airway, subsiding the tightening. Seeing him go through the significant swelling and discomfort, I began to wonder if allergies are truly useful for us to survive or if they are simply a neutral byproduct of genetic and environmental influences that falsely attack foreign substances that are nontoxic.

Interestingly, a new study this month in 2018 revealed that perhaps this same process by which an allergic reaction is triggered can save lives – though in many cases we often refer to these same processes as life-threatening. When an allergic reaction takes place in your body, mast cells release histamines, which are the contributors of smooth muscle contraction and most of the symptoms we associate with allergies. The study found that during a fasting period, mast cells release histamine, which elicits the release of oleoylethanolamide (OEA) by activating H1 receptors on the liver. OEA was previously established to inhibit hunger, but the researchers revealed that OEA biosynthesis in the liver induces the production and release of ketone bodies. This is important because ketone bodies are what keeps the brain active when there is insufficient glucose, as when fasting.

The brain is an organ that "consumes about 120g [of glucose] daily, which corresponds to an energy input of about 420 kcal (1760 kJ), accounting for some 60% of the utilization of glucose by the whole body during resting state." Consequently, the same components which are active during an allergic reaction are thus helping us survive and function in periods of fasting. It would then behoove you to thank your body during an allergic reaction for keeping you alive and functional in timers of energy deficiency.