A daily dose of beneficial bacteria from yogurt, acidophilus milk, or capsules like Culturelle does reduce the amount of sinus infections. In one study of kids in daycare, half the kids had regular milk and the other half got 8 oz a day of acidophilus milk. The kids and the daycare workers never knew which was which. The kids who got 8 oz a day of acidophilus milk had fewer sinus infections, colds and sick days.