Medichecks chief medical officer Dr Sam Rodgers said the increase in vitamin D was constant in both men and women.
He told PA: “The data is robust and shows a marked increase in vitamin D in the summer of 2020, common in both men and women.
“The conclusions we can draw from this are that the shift to work from home, which means less travel and time off, offered more opportunities to spend time outdoors in the sun than was possible in 2019.
“We should also consider the possibility that more people are following NHS guidelines and choosing to supplement vitamin D.
“Both of these are positive developments because maintaining good vitamin D levels is important for keeping bones, teeth and muscles healthy.”