Can Stomach Acid Kill Coronavirus?
Stomach acid helps protect us against food-borne pathogens, but what about Covid-19? Here’s the science behind the popular rumor that stomach acid kills coronavirus.
It started as a viral tip a few months ago: Drink water every 15 minutes to wash the coronavirus into your stomach — where the acid will kill it.
There’s a seductive logic to this idea which helped it spread like wildfire. And although numerous articles and the WHO were quick to label it a baseless rumor, the visual memory of a virus-melting acid bath in our stomachs is pretty hard to forget. So now that we’re being assured we have a low risk of catching Covid-19 from food, the rumor is gaining traction again in a new form: You can’t catch the coronavirus from food because your stomach acid will kill it.
Although (hopefully) you probably won’t catch Covid-19 from food, believing that food is always “safe” because your stomach acid will protect you is dangerous. A person who truly believes they can’t catch it from food won’t see much reason not to share food or drinks — or to even wash their hands before eating.
If you currently think your stomach will protect you from the coronavirus, this article might change your mind. And if you know you shouldn’t eat contaminated food but you’re not sure why, you’ll find your answer here. Let’s give the stomach acid question the attention it deserves — so we can finally put it to rest.
First off, can acid kill the coronavirus?
Acidity, or low pH, can kill many bacteria and viruses. It’s not quite like throwing a bucket of water on the Wicked Witch of the West, but… you get the picture. That’s why white vinegar, with a low pH of 2.4, is a popular natural disinfectant.
Unfortunately, not all bacteria and viruses are easily destroyed by acid. And SARS-CoV-2, the virus that causes Covid-19, doesn’t seem to hate acid as much as other viruses. When tested, researchers found that the coronavirus stayed about as dangerous at a pH of 3.0 as compared to a neutral pH.
Despite that finding, the study did not test the virus at a pH below 3.0. And there’s a very high chance that something more acidic could still kill the coronavirus.
Technically speaking, viruses are “inactivated” — not “killed.” But for the sake of simplicity, the popular term “kill” is used in this article.
Can stomach acid kill the coronavirus?
The stomach pH of a fasting person is pretty acidic — around 2.0. So whether or not gastric juice can destroy the virus is a solid maybe.
However, 2.0 is the stomach pH of a fasting person, not a fed person. When eating a standard Western meal, research finds that the pH of the stomach immediately jumps to a very neutral pH of 6.0, and doesn’t return to a pH of 2.0 for about 3 hours — at which point half the food in the stomach will have already passed to the small intestine.
This tendency of the stomach pH to rise with food is part of the reason why food-borne pathogens can be so dangerous: Research often shows that a much lower dose of pathogen (like Salmonella) is required to cause disease if it’s consumed with food. Experiments find that people need to drink 100,000 or more Salmonella to get sick — but can fall ill by eating less than 1,000.
This means that — if you’re going to swallow the coronavirus — swallowing it with food might be the very worst time to do so. Whatever protection your stomach acid can offer will be buffered by a meal.
Can the coronavirus infect you before it reaches your stomach?
Another small catch to the stomach acid theory is the fact that food is placed in your mouth — not your stomach. It spends time in your mouth and travels through the esophagus before reaching the stomach.
The coronavirus infects cells that contain the ACE2 receptor on their surfaces. This receptor is like a lock, and the key is located on the spikes covering the virus. The ACE2 receptor is found on many different types of cells: Along with your lungs, research finds it on your stomach, small intestine, colon and esophagus cells… among other places.
Although time spent in the esophagus is short and the density of receptors might be low, the coronavirus could theoretically infect you before even reaching the stomach.
If Covid-19 is a lung disease, why does this matter?
Since Covid-19 is mostly described as a respiratory disease, people sometimes assume that you can only catch it by inhaling it.
Although the main reason people die from Covid-19 stems from the infection and inflammation it causes in the lungs, it can spread to many different locations throughout the body. Covid-19 doesn’t necessarily have to start in the lungs to be deadly… it just has to get there.
Research finds that the digestive tract could contain a higher density of ACE2 receptors than the lungs. And when researchers test for signs of a digestive tract infection (coronavirus in poop), they find it in around half of patients. How it spreads between different regions of the body is still unknown — but the evidence suggests that it does spread.
Can you catch Covid-19 from food?
Despite everything above, there is still a lot of wisdom to the popular reassurance that food is relatively safe… just don’t give the credit to your stomach acid.
Since viruses are not alive, they do not replicate in food (unlike Salmonella) — which means there can never be more viruses in your food than what lands there in the first place. And research finds that the coronavirus could be killed by cooking — since the virus becomes undetectable within a few minutes at 160°F. Also, restaurants and food manufacturers are generally pretty vigilant about not spreading diseases to their customers.
So, you can probably follow the popular advice to not stress about groceries or takeout food as long as you’re staying safe and washing your hands.
But at the same time, don’t take that as a free pass to ignore the risk of food entirely. If you think the person who prepared your food is sick… maybe don’t eat it. If you’re in a group setting, don’t share food or taste each other’s drinks. And for goodness’ sake, always wash your hands before putting them in your mouth.
(For more on eating out, check out my guide to COVID dining)
