The majority of our vitamin D is made by the body when our skin comes into contact with sunlight.
In the summer months, exposing our face and arms to the sun for a few minutes each day should be enough to ensure we make enough of the vitamin to maintain our bone health.
However, there is often insufficient sunlight and it is therefore important to eat the right foods as well.
Alan Silman, medical director of Arthritis Research UK, explained that vitamin D is "essential" to build and maintain strong, healthy bones.
"The country may have changed its clocks to British Summer Time but it will be a few more months before the sun's UV levels are strong enough over Britain for our bodies alone to make enough vitamin D," he observed.
"In less sunny months, we recommend that people top up the vitamin D in your diet by eating more oily fish, such as salmon, tuna, trout, mackerel, pilchards and sardines, and foods 'fortified' with vitamin D, such as breakfast cereals and some margarines."
The expert added that people may also want to consider taking a vitamin D supplement.
In the UK, the government advises people in at-risk groups - including children aged six months to five years, pregnant and breastfeeding women, and over-65s - to take daily vitamin D supplements.