Scientists have discovered that people who stay away from sun exposure, or have insufficient vitamin D in their diet, are more likely to develop genetic damage linked with ageing and age-related illnesses.
According to researchers at the King's College, London, 90 per cent of the body's intake of vitamin D is created by exposure to the sun.
The outcome of the harm is so great that those who lack vitamin D are biologically five years older than those with the highest levels.
"These results are exciting because they demonstrate for the first time that people with high levels of vitamin D may age more slowly than people with lower levels," the Telegraph quoted lead researcher Dr Brent Richards, as saying.
"This helps to explain how vitamin D has a protective effect on age-related illnesses such as heart disease," he added.
Co-author Prof Tim Spector said the study established that people should increase their exposure to the sun and eat more vitamin D rich foods such as fish, eggs, fortified milk and breakfast cereals, or take supplements.
"There are scares about melanomas, which do affect several thousand people per year. But vitamin D deficiency is making hundreds of thousands of people ill with potentially fatal diseases," Spector said.
However, cancer campaigners are of the view that too much exposure to the sun could cause skin cancer.
"It doesn't take much time in the sun to make vitamin D, and always less time than it takes to redden or burn," Henry Scowcroft, of Cancer Research UK, said.