German nutritional expert Uwe Knop said the smell of fermentation from the mouth indicates lactose intolerance (milk sugar).
Knop explained that the lack of the lactase enzyme leads to the non-digestion of the lactose, and the lactose is exposed to fermentation due to intestinal bacteria. During this process, gases arise that lead to the emission of fermentation odor from the mouth, in addition to the foul smell of feces.
Other symptoms of lactose intolerance are:
3- Severe abdominal cramps.
4- Diarrhea, especially after eating dairy products.
Note that lactose is hidden in other foods such as baked goods and ice cream.
In any case, the doctor should be consulted to verify lactose intolerance through a breath test. In the event of verification of the injury, the patient should resort to lactose-free foods, which are now widely available in the market.