When we eat garlic And onion some volatile molecules, in particular theallyl methyl sulfidepass from the intestine to the bloodstream, reach the lungs and are expelled through breathing (in the case of garlic also from glands sweat found on the skin). So bad onion or garlic breath doesn’t come from pieces left in the mouth, but directly from our lungs. And not only that: these volatile molecules actually they do not exist in fresh garlic and onionbut they are formed when we cut them and eat them. In any case, don’t worry: some foods like parsleymint, apples and milk they can help reduce by up to 50% this annoying smell.
The molecules in garlic and onion responsible for bad breath
We know them as garlic and onion but they are called respectively Allium sativum And Allium cepa and are part, together with shallots, chives and leeks, of the leek family Alliaceae. As close relatives they share many moleculesresponsible for the typical smell of these vegetables. As with peach pits and many other cases, these molecules are a defense mechanism of the plant world: the unpleasant taste discourages animals from eating that fruit or vegetable again.
The molecules responsible for “oniony” and “garlic” breath, actually they do not exist in fresh, whole vegetablesbut they arrive from a series of reactions that start from a particular molecule contained within them: thealliina. When we cut garlic and onion, we bring the alliin into contact with the enzyme allinase. Usually, they are contained in different areas of the cell: alliin in the cytoplasm and allinase in the vacuole. When we break the cell by cutting or crushing garlic and onion, they come into contact and the enzyme allinase transforms alliin into allicinwith a typical pungent odor.
Allicin though it’s not very stable and degrades quickly four volatile compounds sulphur-containing (i.e. containing sulphur), responsible for garlic breath: allyl methyl sulphide, diallyl sulphide, allyl methyl disulphide and allyl mercaptan.
Bad breath from garlic or onion comes from the lungs
Obviously, as soon as we eat garlic and onion, these molecules can travel up the esophagus and “embellish” our breath through belching. But the mechanism by which we have unpleasant breath is also long after eating them it’s another.
These compounds are rather stable, and remain in our body for a long time. The most persistent of all is theallyl methyl sulfide (AMS) which, together with the others, travels from our digestive system to the intestine and liver (following the common path of all foods). In the liver, however, only a part is metabolised, while the majority enters the bloodstream and travels to the liver lungs and from there, being volatile, is expelled with breathing, spreading its unpleasant odor while we speak or breathe!
The power of AMS is such that it makes our breath smell like garlic and onion even 24 hours after eating them! And it can also be eliminated through the sweat glands, giving not only to the breath, but also to the skin a questionable and not very pleasant smell.
How to reduce garlic or onion breath
Even if it is not a symptom of any pathology, breath that smells of garlic and onion can still cause discomfort and embarrassment. But there is a solution!
According to several in vitro and in vivo studies, some foods such as parsley, mintthe lettuce or the apples they can help reduce the presence of volatile sulfur compounds up to 50%. This effect is probably linked to the action of polyphenols and specific enzymes present in these foods which react with volatile sulfur compounds such as AMS, reducing its concentration and therefore the stink.
Also milk and yogurt seem to have the same effect, but in this case they are thought to improve breath thanks to the presence of water and fats, which in a certain sense capture AMS and co, reducing its volatility and the possibility that, by speaking, they reach the noses of our neighbors.
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