A recent article in the journal Science discussed research on immunity based on gut function.
The researchers focused on a gut protein receptor called AhR (aryl hydrocarbon receptor), which when activated, leads to the healthy development of lymphoid tissue in the GI tract. This receptor is turned on my phytochemicals found primarily in fruits and vegetables. The vegetables richest in these phytochemicals are cruciferous vegetables such as broccoli, cabbage and brussels sprouts.
On the other hand, processed foods and foods rich in saturated fats turn off AhR.
When AhR switching leads to lymphoid development it provides a healthy environment in the GI tract. It prevents the gut from being populated by unhealthy bacteria.
Inflammatory bowel diseases such as Crohn’s disease and ulcerative colitis occur when there is gut inflammation and AhR is turned off.
Research is being done to find medicines that turn on AhR, but probably the best medicine is a diet rich in vegetables and fruit.