I was reading
a book over the summer that talked about the relationship between our lifestyles and the production of telomerase and therefore the length or our telomeres which determines the reproduction (rejuvenation) of our cells, and therefore our susceptibility to disease and early aging.
Loneliness and our social support was mentioned as a major factor in telomerase production. Several studies backed it up. She had a huge list of studies in the bibliography, although I didn't check any of them out.
I recommend this book, although what it tells you is stuff that you already know to be true:
