Mixed hyperplastic/adenomatous polyp with moderate dysplasia

Hello,

I am a 31 years old woman. I did a colonoscopy last week and I received the results of the biopsy today. They removed a 5mm polyp from my colon the diagnosis is Mixed hyperplastic/adenomatous polyp with moderate dysplasia. What exactly does this mean?  I was told that I need to do a colonoscopy every year for the rest of my life to ensure that no other polyps or colon cancer develops. Is there any dietary recommendations that could decrease my chance of getting another polyp in my colon or anything else that I should think of. I eat very health food, exercise between 3-5 times a week and drink very little alcohol. I believe that this occurs mostly for people over 50 years old, what could be the reasons why I got a polyp in my colon? Do I run a greater risk to get colon cancer?

In addition the Gastric biopsies showed a "Mild chronic non-specific gastritis with reactive epithelial hyperplasia" what does that mean?

I am looking forward to your answer as my doctor was busy so I have not been able to receive a proper answer to my questions.

Thank you!