Not only good for the taste: Lemon and ginger substances stimulate the body's defenses
Lemons and ginger are two particularly healthy foods. After all, both contain large amounts of vitamin C and therefore help to strengthen the immune system. But they contain even more important substances: citric acid and 6-gingerol. These stimulate the molecular defenses in human saliva, as researchers have now found out.
Do something good for your health with lemons and ginger
If you want to do something good for your health, you should drink a glass of lemon water regularly in the morning. Important vitamins and nutrients from the lemon are added to the body. In addition, digestion is stimulated and liquid is added. It is also recommended to start the day with ginger water. The hot tuber is not only rich in vitamin C, but can also protect against diseases and help you lose weight. But lemons and ginger can do even more: As researchers have now found out, flavoring substances from the two foods stimulate the immune system.
Citric acid and sharp-tasting 6-gingerol from ginger
As the Technical University of Munich (TUM) reports in a recent report, citric acid and hot-tasting 6-gingerol from ginger not only give food and drinks a special flavor.
Both substances also stimulate the molecular defenses in human saliva. A team of researchers from TUM and the Leibniz Institute for Food Systems Biology found this out.
The results of the study were recently published in the journal "Journal of Agricultural and Food Chemistry".
Saliva fulfills a wide variety of biological tasks
Human saliva is a complex, watery mixture of different components. In addition to mucous membrane and immune cells, it contains a large number of molecules that perform a wide variety of biological tasks.
Because saliva not only plays an essential role in food intake, but is also crucial for keeping the teeth, gums and oral mucosa healthy. At the same time, it represents the first bastion against pathogens entering from outside.
Therefore, various antimicrobial molecules are contained in the saliva, including the antibacterial lysozyme. They are part of the innate, molecular immune system.
Certain factors affect the composition of saliva
It has now been proven that factors such as age, state of health, but also what someone eats and drinks influence the composition of saliva. However, little is known about the effects of individual food ingredients.
In order to learn more about these, the research team led by study leader Professor Thomas Hofmann, head of the Leibniz Institute for Food Systems Biology at TUM, examined the influence of different flavors on the saliva composition of humans:
Citric acid (acidic), the sweetener aspartame (sweet), iso-alpha acids (bitter), the flavor enhancer sodium glutamate (umami), table salt (salty), 6-gingerol (spicy) and the substances hydroxy-alpha-sanshool contained in the Szechuan pepper (tingling) and Hydroxy-beta-Sanshool (anesthetic).
Flavoring substances already have biological effects in the mouth
As the scientists demonstrated for the first time through the combination of saliva flow measurements, proteome analyzes and bioinformatics evaluations, all investigated substances modulate the protein composition of saliva to a greater or lesser extent.
Biological function analyzes of the saliva proteins affected by the modulation also showed that the changes triggered by citric acid and 6-gingerol activate the molecular defense system in the saliva.
For example, 6-gingerol increased the activity of an enzyme that converts the thiocyanate dissolved in saliva into hypothiocyanate, which roughly triples the amount of hypothiocyanate with antimicrobial and fungicidal activity in saliva.
In contrast, the changes caused by citric acid caused the lysozyme levels in the saliva to increase up to ten times.
As studies on bacterial cultures show for the first time, this increase is sufficient to almost completely prevent the growth of Gram-positive bacteria. Lysozyme works against this type of bacteria by destroying their cell wall.
"Our new findings show that flavoring substances already have biological effects in the mouth that go far beyond their known sensory properties," says Hofmann from the Chair of Food Chemistry and Molecular Sensor Technology at TUM.
The food chemist explains that researching these further using the latest analysis methods is one of the goals that food systems biology has set itself.
This is the only way to find new approaches for the production of food in the long term, the ingredients and functional profiles of which are geared to the health and sensory needs of consumers. (ad)