Emetophobia: Why vomiting is a good thing!
So if you have emetophobia you may be reading this thinking “how could vomiting be a good thing?”. And it makes sense you think that. You have spent your life trying to avoid vomiting because of how awful you feel it is. But have you ever stop to ask yourself a very simple question. Why do we even vomit in the first place?
Nearly every vertebrate has the ability to vomit. The only vertebrates without this ability are some rodents (Horn et al., 2013) and horses. So there must be a reason right? Consider your answer for a moment.
So lets explore the reasons why we need to vomit:
Emptying noxious chemicals from the gut:
Food intake is a risky behaviour which can expose the body to a range of possible viral and bacterial infections, allergies or poisons (Bischoff and Renzer, 2006). Animals have a wide range of ways to detect and avoid these types of foods (bad smells, tastes or visual cues leading to a disgust response). However, these are not full proof, so the body needs a way to remove toxins when ingested. This is achieved with vomiting or diarrhoea.
The ability to vomit plays a large role in the modern world due to our interconnected food supply and the mass production of food. According to the Centre for Disease Control (CDC), over 76 million Americans get sick, more than 300,000 are hospitalised, and 5,000 people die from food-borne illnesses each year. Without the ability to vomit, these numbers would be dramatically higher. One example of this in action is looking at rats. As rats cannot vomit, rat poison is highly effective at killing them (as they can not remove it from their system). This would be the same for us if we could not vomit, but not just for poison but any contaminated food.
Defence against illness:
So, why does norovirus make you vomit?
Viruses trigger an inflammatory response from the immune system, leading to symptoms like nausea and vomiting. This inflammatory response is the bodies natural reaction to infection, and is designed to expel harmful substances through vomiting.
This serves a purpose. Throwing up is the bodies may of attempting to eliminate pathogens before they can cause further harm.
Nausea:
“So what about nausea. It feels awful… That cant be helpful either right?….Right…?…."
Well…..
Although nausea often accompanies vomiting, an episode of nausea doesn't necessarily lead to an episode of vomiting. Nausea plays a protective role, warning the animal experiencing it to avoid potentially toxic substances which have been ingested previously (Singh, Yoon and Kuo, 2016). The sensation of nausea can easily be paired with certain foods, situations or triggers, especially if they previously led to an episode of food poisoning or vomiting. If you have ever vomited soon after eating a certain food, you may have noticed that you have “gone off” that food for months or even years. Your body have learnt it is toxic (even if it’s not true). When looking at that food your body causes you to feel nauseous to stop you eating it again.
It is also common to be nauseous when vomit is seen. This is adaptive as it signals that the food ingested nearby may be toxic and is designed to stop you from ingesting that same food as someone else who has vomited.
This system is also activated by the “perception” of toxicity. Therefore, when someone with Emetophobia is having thoughts about vomiting or potential food poisoning, they can be activating this system and producing feelings of nausea unnecessarily.
Morning sickness:
During pregnancy morning sickness mostly occurs during the time the central nervous system of the foetus is developing, which is a time when it is more at risk of toxins (Flaxman and Sherman, 2000). Morning sickness aims to protect the foetus, alongside pregnancy-related behavioural changes in eating habits which aims to reduce foodborne illness.
In conclusion:
If we could not vomit, we would be at a high risk of death from food poisoning, illness or ingesting toxins.
So next time you vomit or feel nauseous, just remember that your body has been designed to do this in order to keep you safe. Vomiting is a good thing! Even through it doesn’t feel nice.
References:
Bischoff, S.C. and Renzer, C. (2006) ‘Nausea and nutrition’, Autonomic Neuroscience, 129(1-2), pp. 22–27. Available at: https://doi.org/10.1016/j.autneu.2006.07.011
Flaxman, S.M. and Sherman, P.W. (2000) ‘Morning Sickness: A Mechanism for Protecting Mother and Embryo’, The Quarterly Review of Biology, 75(2), pp. 113–148. Available at: https://doi.org/10.1086/393377.
Singh, P., Yoon, S.S. and Kuo, B. (2016) ‘Nausea: a review of pathophysiology and therapeutics’, Therapeutic Advances in Gastroenterology, 9(1), pp. 98–112. Available at: https://doi.org/10.1177/1756283x15618131.