They are the nutrition top-up of choice for millions of people, but if you think swallowing multivitamins will help you live a day longer than otherwise, you’re probably wrong. A team of US doctors and scientists studied around 300,000 people over 20 years and found taking the would-be elixirs “was not associated with a mortality benefit.” “Multivitamin use to improve longevity is not supported” by their research, the team said, in findings published by JAMA Network Open, an American Medical Association journal. Despite multivitamins making little apparent difference to longevity, including am…