About one fifth of unsupplemented breast fed infants develop evidence of iron deficiency by 9 months of age. Iron fortified cereal starting around 4 to 6 months greatly reduces the risk of iron deficiency. Before mandated use of vitamin K in the newborn, the devastating hemorrhagic disease of the newborn stuck about 1 in 100 babies. This condition has been almost eliminated by vitamin K use at birth. While adequate dietary fluoride helps prevent tooth decay, an unsightly mottling and structural weakening of the permanent teeth known as fluorosis has become more prevalent in the United States in recent years due to the widespread adoption of fluoride supplementation in public water supplies and fluoride toothpastes.
Younger children get a significant amount of dietary fluoride simply by swallowing their toothpaste.
For this reason, the current recommendation is to not supplement infants under 6 months, and to supplement only those children from 1 to 3 years old whose water supply contains less than 0.3 ppm of fluoride. Your health department or municipal water supply office can confirm the level of fluoride in your municipal water.