Let's talk about Vitamin D and why it's necessary for strong bones. Without Vitamin D, our bodies cannot effectively absorb calcium, which (as we know) is essential to good bone health. Technically Vitamin D is a hormone as our bodies can make it in our skin when it is exposed to good sunlight.
Depending on where you live in the world and with the known risks of not wearing sunscreen it can be very difficult to absorb enough Vitamin D through the skin from the sun. Unfortunately there aren't many foods that naturally contain Vitamin D (it is found in substantial levels mainly in fish). So your best bet is to take a supplement - make sure you go for a good quality make and follow the recommended dosage.
Vitamin D levels are also very important in children - doctors are actually seeing an increase in the number of children with rickets, which causes bone weakness, bowed legs, and other skeletal deformities, such as stooped posture - so keep an eye on their Vitamin D intake too!