Red bell peppers boost your immune system. They are a rich source of beta carotene, which the body converts into what vitamin? By Mukesh Sharma - April 27, 2021 Amazon Fit India Quiz – Red bell peppers boost your immune system. They are a rich source of beta carotene, which the body converts into what vitamin? Vitamin A Vitamin B Vitamin C Vitamin D The answer is Vitamin A. Red bell peppers boost your immune system. They are a rich source of beta carotene, which the body converts into Vitamin A.