science has a different opinion

For a person with celiac diseasesocial life can be a real minefield. Cross contamination is a dangerous enemy that is present in the way food is prepared, but also in the kisses we have with other people. In this way, the question is obligatory: if my partner has eaten bread, pizza or pasta… Is it dangerous for us to kiss if I am celiac? To answer, luckily we have science on our side.

Until now, people who have to stay away from gluten for serious medical reasons could be afraid to kiss if their partner had not rinsed their mouth or brushed their teeth before. But science is pretty transparent. in the preliminary study presented at Digestive Disease Week 2025.

Their conclusion is quite clear: some gluten can be passed through a kiss between two people, but the amount is so small that it is very unlikely to have relevant clinical consequences.

The study. To reach this conclusion, 20 non-celiac people who ate a food with a large amount of gluten were recruited. Immediately afterwards, they had to kiss their celiac partners, allowing the researchers to measure the concentration of gluten in the saliva that had passed from one boba to another.

The results were quite clear: in 18 of the 20 couples, the levels in the recipient’s saliva were below the international “safe” threshold, which is 20 mg, and furthermore, none reported symptoms related to intolerance. Although if you drink a little water before kissing, this risk decreases even more.

Why 20 mg. This threshold value is not something random, but rather it turns out to be defined by science itself. Here one of the reference studies comes into play, Catassi’s essay and collaborators published in American Journal of Clinical Nutritionwhich administered 10 or 50 mg of gluten daily to adults with treated celiac disease for 90 days. What was seen is that the daily exposure was clearly below that 10 mg range for the majority of patients.

A later review in Alimentary Pharmacology & Therapeutics reached similar conclusions: the doses that are beginning to be worrying move in the order of tens of milligrams per day, especially if they are maintained over time, not in single isolated traces. In this way, an isolated kiss has the same concentration of gluten as foods that are categorized as safe.

How is it possible that a kiss after eating a large amount of gluten-containing foods is not dangerous? This is the question we ask ourselves after reading these conclusions, and it has an answer, but in studies done on peanutsanother allergen.

In this case it was seen that just after eating, the concentration of allergen in the mouth is really high. But after simple measures such as waiting a few minutes, drinking water or brushing your teeth, levels drop drastically.

In this way, a kiss does not transfer food, but rather a fraction of a milliliter of saliva. And that saliva, minutes after eating, has already “cleaned” most of the protein that was inside. And this is valid for all allergies that are mediated by immunoglobulin E (which is responsible for generating the allergic response).

There is a margin of safety. On a daily basis, people who are intolerable to gluten and who follow a very strict diet to avoid contamination, the truth is that they consume this allergen. Although in a very small quantity. This shows it a study who developed techniques to measure gluten immunogenic peptides (GIP) in urine and feces.

The work showed that many people with celiac disease who follow a strict diet have small accidental exposures on a regular basis, the result of cross-contamination in modern life. However, the majority do not show clinical worsening or intestinal damage if these exposures are spontaneous and at very low doses.

A kiss, in the worst case scenario, is exactly that: an isolated microdose exposure.

The final verdict. What this new study provides is not a revolution, but a reassuring quantification of something that the consensus of experts already sensed. Even the main patient associations, such as the Celiac Disease Foundation or Coeliac UK, have been with a practical message for some time: the risk of kissing is low.

The only common sense recommendation, which is still valid, is to avoid kissing right at the moment when the other person is eating gluten or has obvious remains of food in their mouth. You always have to wait a little for the saliva to take effect, but it doesn’t have to be a problem beyond this.

Images | Cassie Lopez Wesual Click

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