Give seasonal fruits like watermelon, mango, muskmiln, cucumber, sattu, leam water, smoothies etc. It's will help to increase immunity.

Have more of soups, nut and fruits smoothies , buttermilk , curd . It will help you

Rakhi ji, you can give ragi , sattu, curd, buttermilk in the regular meals. They help to boost immunity naturally.

The best is to have home cooked healthy diet. Having seasonal fruits like mangoes, watermelons . Have plenty of liquids. Sattu drink, aam panna, nuts, mint sharbat etc will help deal the heat waves.