Orange-fleshed sweet potatoes are one of the richest natural sources of beta-carotene, a plant-based compound that is converted to vitamin A in your body.
Vitamin A is critical to a healthy immune system, and low blood levels have been linked to reduced immunity.
It’s also key for maintaining healthy mucous membranes, especially in the lining of your gut.
The gut is where your body is exposed to many potential disease-causing pathogens. Therefore, a healthy gut is an important part of a healthy immune system.
Source: https://www.healthline.com/nutrition/sweet-potato-benefits#section6