One of Britain's most prominent scientists says the growth in use of electronic tablets and smartphones is causing people to spend so much time indoors that they need to take regular vitamin D supplements to make up for the lack of sunlight they receive naturally.

Speaking at the Hay Literary Festival in Wales, one of Britain's leading annual publishing industry events, geneticist Steve Jones said he himself was a convert to the cause and urged others to follow his lead.

"I never thought I would be a person who would take vitamin supplements, I always thought it was absolute nonsense, it's homeopathy. I now take vitamin D every day. Today, because I knew the sun wasn't going to shine, I took an extra one," he said.

Children are now spending one hour less outdoors each day than they did a decade ago, he said, blaming the rise of technology. The problem is particularly acute in Scotland, where children receive less sunlight than in any other country in the world.

"Scotland is still the sick man of Europe. The Scots are the palest people in the world … and that's because their entire body systems are crying out for vitamin D," he said, adding that life expectancy in Scotland is two years shorter than in England or Wales. Multiple sclerosis, a medical condition which is rarely encountered in tropical countries, is also higher in Scotland than in England.

Jones admitted that concerns over the damaging effects to skin of prolonged exposure to the sun were valid, but said sunlight was healthy and necessary for the human body, and could help with lowering blood pressure.

"If you lie out on the beach in your bikini, or without anything on, for an hour you will drop your blood pressure by about 10 points, because it relaxes your blood vessels. So get out in the sun while we still can."

Jones's latest book, Here Comes the Sun, looks at the scientific and medical impact of exposure to sunlight.

Vitamin D helps with the absorption of calcium, which helps keep bones strong, and he said the fact that the bone disease rickets was making a comeback in Britain after nearly 50 years was another sign of how changing behavior patterns were taking a physical toll.

"It's coming back and at some speed. It is coming back because of a shift in human behavior which we never thought would happen," he said.

Many people are missing out because of a dietary deficiency in vitamin D. Fatty fish and substances such as cod liver oil are some of the best sources, and it can also be found in shellfish and egg yolks.

There was also "overwhelming" evidence, he said, that vitamin D deficiency had a "drastic" effect on health. "It can help tackle infectious disease, it changes mood, if you have a shortage you're more likely to get kidney disease … it is really, really important stuff," he said.