"My 4-year-old child is very often sick. I wonder if probiotics could help boost his immune system?"

Probiotics may help support the immune system in some individuals, but there is no guarantee. It is important to focus on non-pharmacological measures such as eating plenty of fruits and vegetables, getting enough sleep, managing stress, and maintaining good sinus hygiene using saline solutions to prevent mucus build-up. These measures can help support your child's overall health and potentially strengthen their immune system.