Social isolation increases the risk of premature death from every cause for every race, a new study finds.

For white people (unlike other groups), solitude was found to significantly increase the risk of cancer.

For black people, being lonely doubles the risk of early death (it increases 60-84 percent for white people).

For everyone, it's clear that social interaction is essential for survival: without human contact our blood pressure rises, inflammation ramps up - and many of us turn to unhealthy habits, that only serve to accelerate those issues.

The study by the American Cancer Society, published today, hammers home the true dangers of loneliness - which can feel exacerbated by the holiday season, a time where many feel that they should be surrounded by loved-ones.

The study by the American Cancer Society, published today, is the largest to date on all races and genders. It hammers home the true dangers of loneliness, which can feel heightened by the holiday season (file image)

Social isolation is different to loneliness. Loneliness is a temporary scenario (whether it feels that way or not). Social isolation is a prolonged lack of contact with other people or society.

The research is one of the first to confirm the tangible risks of social isolation to every racial group.

Previously, the only studies connecting social isolation with mortality risk showed a risk for white people but nobody else.

This research, a new prospective cohort study, sought to clarify whether there was a real difference - and there wasn't, really.

Human contact is key to survival.

Over the last century, our understanding of the evolutionary importance of physical and social interaction has developed dramatically. For centuries we've known it doesn't feel good, but recent studies have shown social isolation could be as dangerous as cigarette smoking.

But now, epidemiologists are peeling back the layers further to understand as precisely as possible what solitude does to our bodies, and how different bodies might respond.

As with most areas in medicine, one of the most glaring gaps in social isolation research was race. Specifically: we know isolation damages the health of white people, but there wasn't data to confirm that the same was true for everyone.

To investigate, a team led by Kassandra Alcaraz, director of research into health disparities at the American Cancer Society, analyzed data from 580,182 adults enrolled into Cancer Prevention Study-II in 1982/1983, who were followed for mortality up until 2012.

The 30-year study collected information on various social factors for each person - how many close friends or relatives they had, how often they saw them, whether they were married or divorced or single, whether they had children, how often they were alone.

Using that information, the researchers gave each person a social isolation 'score', ranging from 0 (the most lonely) to 5 (the most social).

They then looked at whether there was a correlation between that score and their general health. The team looked at the age of death, and how they died (first looking at all causes of death, and then zooming in on the two biggest killers for Americans: heart disease and cancer).

The correlation was unequivocal. The most socially isolated had the highest risk of death any way they cut it.

Every risk increased for everyone, including heart disease.

White people were the only ones that saw an increased risk of cancer - a factor which the team say they cannot yet explain but hope to look at more closely down the line.

Crucially, the study showed the importance of clarifying that there is a higher risk for all races: the researchers found losing human contact appears to have more drastic implications for African Americans than any other race.

Social isolation was more common among black people in their cohort than among any other race. It was least common among white people.

Among black people, the least social were two times more likely to die early compared to the most social - and that was the same regardless of gender.

Meanwhile, social isolation increased the risk of early death by 60 percent for white men and 84 percent for white women.

'[C]urrent findings indicate that a composite measure of social isolation is a robust predictor of mortality risk among men, women, blacks, and whites,' write the authors.

'Lack of interpersonal connections seems particularly detrimental.'