Temperatures are dropping, and the days are getting shorter. Shorter days mean less sun and vitamin D. So, in addition to pulling out the wool sweaters, we need to winterise our diets to make sure we get the vitamin D we need this season.

The role of vitamin D

Vitamin controls body functions. It helps bones and teeth absorb calcium. Both calcium and vitamin D are important for bone health and muscle strength, which may explain why we need more as we age and our muscles weaken and the tendency for falls becomes greater. We produce less vitamin D from the sun's ultraviolet (UV) rays as we age. Vitamin D deficiency causes aching bones.

The sunshine vitamin

Sunshine is a good source of vitamin D. Our skin produces vitamin D when exposed to UV rays. This process requires direct sun exposure without sunscreen. 10-15 minutes of strong sunshine on your arms and face at least twice a week should meet your vitamin D needs.

Food sources of vitamin D

Multivitamins, many calcium supplements, and some fortified foods contain vitamin D. Without vitamin D, the body cannot absorb dairy's calcium. Under 50s can get enough vitamin D from two cups of fortified milk. Fatty fish oils and salmon, sardines, and tuna are also good sources of vitamin D, as are fortified soy milks, margarines, cereal, eggs, and orange juice.

To make sure you are getting plenty of vitamin D this winter:

• Enjoy the natural sunlight. A brisk walk outside can lift your mood

• Take your daily multivitamin

• Eat plenty of fish

• Enjoy vitamin D-fortified foods such as low-fat milk, cereal, and orange juice