Lactic acid bacteria have long been considered to be probiotics that help with gastrointestinal motility, but recently a research team from the University of Toronto published a literature on tryptophan and tumors in the cell sub-journal, which was interpreted as: Lactic acid bacteria are harmful to health, destroy immunosuppression, and promote tumor progression! This news surprised the editor, let's find out.
Review of study details
Lactic acid bacteria metabolize tryptophan in food to activate AhR
After ingesting food, tryptophan is obtained in the human body, a necessary amino acid, and lactic acid bacteria can further metabolize tryptophan, and the metabolites produced can activate aromatic hydrocarbon receptors (AhR).
AhR has tumor-associated immunomodulatory effects
AhR is able to inhibit the maturation of immune T cells, thereby destroying the immunosuppression of pancreatic cancer cells. In addition, AhR can affect interferon responses, promoting inflammatory responses.
Effects of dietary changes on pancreatic cancer
In addition to the molecular mechanism level, the researchers also made corresponding experiments and statistics from the actual situation of animals and pancreatic cancer patients.
Mouse experiments
The researchers divided pancreatic cancer mice into three groups, namely the normal diet control group, the tryptophan deficiency group, and the tryptophan deficiency but added AhR products IAA and ILA group.
The results showed that the tumors in the tryptophan deficiency group were significantly reduced compared with the control group, while the mice with the addition of The AhR products IAA and ILA significantly increased the tumor weight.
Observations of pancreatic cancer patients
By single-cell sequencing of pancreatic cancer patients, it was found that patients with high AhR expression had poor survival, and AhR was inversely correlated with CD8+ T cell-related gene expression.
What are the foods rich in lactic acid bacteria?
Lactic acid bacteria is a general term for a class of bacteria that produce lactic acid mainly based on sugar, and the lactic acid bacteria that are more used in the food field mainly include lactobacillus, bifidobacteria, lactococci and so on. Foods rich in lactic acid bacteria are:
Fermented dairy products with lactic acid bacteria, including lactic acid bacteria drinks, sour cream, dry cheese, etc. made of milk or milk powder;
Lactic acid bacteria fermented plant protein products, including capers milk, peanut fermented yogurt, etc.;
Lactic acid bacteria fermented fruit and vegetable products, including kimchi, sauerkraut, lactic acid bacteria fermented fruit and vegetable drinks, enzymes, etc.
Can cancer patients still eat yogurt?
Through careful study of the above research, Xiaobian shares several views with you here.
1.
The mouse experimental part did not directly feed the mice with lactic acid bacteria, but demonstrated the role of AhR in promoting pancreatic cancer by controlling the presence or absence of tryptophan and AhR products.
2.
The research data in pancreatic cancer patients is not directly related to lactic acid bacteria intake, but the role of AhR is illustrated by observing the relationship between the expression of AhR in patients and survival.
3.
Although the presence of lactic acid bacteria is related to the exertion of AhR function, it has not been quantified.
Therefore, through this study alone, it does not mean that tumor patients cannot eat yogurt.
Instead, the value of this study is more about providing pancreatic cancer treatment with improving the effect of immunotherapy by inhibiting AhR and prolonging patient survival.
Also, as mentioned above, many foods in life contain lactic acid bacteria, which we cannot avoid completely. Secondly, yogurt, cheese, caperilla milk and other foods not only contain lactic acid bacteria, but also rich in a large number of proteins and other elements, which can provide the nutrition and energy needed for tumor patients.
Although yogurt is good, it needs to be selected and eaten correctly
Select products with product names such as "yogurt", "fermented milk", "sour cow's milk", "yogurt", etc.;
Select the product whose first place in the ingredient list is "cow's milk" or "sheep's milk";
Select products with a protein content greater than or equal to 2.3% in the ingredient list;
Products whose product category is "Beverages" or "Beverages" are not selected;
"Yogurt itself is a fermentation product, and you can eat it when it expires" Is wrong and untrustworthy!
bibliography
Hezaveh K, et al. Tryptophan-derived microbial metabolites activate the aryl hydrocarbon receptor in tumor-associated macrophages to suppress anti-tumor immunity. Immunity. 2022 Feb 8;55(2):324-340.e8.