People often think it's the quality of their friendships that counts as opposed to the quantity, but a new study shows that the number of friends we have when we're young has a significant impact on our health later in life. As we get older, the quantity appears to matter less, and it's the quality of our relationships with those we hold dear that confers the most benefits as we age.

Researchers from the University of Rochester in the US have conducted the latest chapter of an ongoing 30-year study looking at the social interactions of female students who once went to school there. Lead author Cheryl Carmichael got in touch with students who participated as 20-year-old undergraduates in a Rochester social interactions study in the 1970s, then again as 30-year-old adults a decade later. Having tracked down 133 of the original 222 participants, she was able to gauge the possible links between their social lifestyles when they were young and their mental and physical well-being in middle age.

The findings, published in Psychology and Aging, suggest that our friend count does actually matter, but only while we're young. According to Carmichael, a greater frequency and volume of social interactions when we're 20 years old is beneficial as we get older because the experiences give us a broader social tool set that we can draw upon later, and this in turn benefits our health and overall longevity.

"It's often around this age that we meet people from diverse backgrounds, with opinions and values that are different from our own, and we learn how to best manage those differences," she said in a press release.

However, keeping lots of pals around by the time we're 30 is moot as far as our physiological health later is concerned, but participants who reported intimate and satisfying relationships with their friends in their 30s also reported high levels of well-being in middle age.

Interestingly, while the research draws a benefits link between quantity of friendships for 20-somethings and quality of friendships for 30-somethings, one doesn't necessarily follow on from the other. The researchers were surprised to find that the socially active 20-year-old students with high friend counts weren't necessarily successful in finding quality relationships a decade later.

What's particularly important, regardless of how old you are, is to surround yourself with as many good friends as you can find, as a wide body of research links poor social connections with early mortality.

"In fact, having few social connections is equivalent to tobacco use," said Carmichael, "and it's higher than for those who drink excessive amounts of alcohol, or who suffer from obesity."

Speaking of departures, it's not the end of the road for this epic social study either. Despite the experiment already having run for some 30 years, Carmichael suggests even more stands to be discovered by tracking the original group as they proceed into their advancing years.

"It would be interesting to see if beneficial social activity during college years and early on in adulthood continues to have an effect, in terms of longevity, mortality, and other specific health outcomes as these participants get older," she said. "I would absolutely love to keep following these people."