Research has documented the psychological benefits of being in a high-quality relationship — but the benefits may be physical as well. Scientists in California have now found that sexual intimacy is associated with longer telomeres, the protective end caps on our DNA.

A preliminary study published online March 24, 2017, in the scientific journal Psychoneuroendocrinology found that women who reported having sex with their partner during the course of the week tended to have significantly longer telomeres.

“Past research has found that high quality, satisfactory relationships and sexual intimacy are good for physical and mental health,” explained lead researcher Tomás Cabeza de Baca of the University of California, San Francisco. “Based on this body of research, we wanted to explore whether there was a health-enhancing relationship between sexual intimacy, telomere length, a biological index of systemic aging and health, and telomerase, an enzyme produced by cells to lengthen telomeres. We also examined whether there was an association between relationship satisfaction, positive/negative partner interactions and our two measures of health (telomere length and telomerase activity).”

“Some quick background: Telomeres are nucleoprotein caps that protect the chromosome from fraying and maintain the integrity of DNA,” Baca told PsyPost. “Although normal life-course processes, such as aging and cellular replication, shorten telomeres, sustained psychosocial stress accelerates this process. Over time, shortened telomeres may contribute to chronic degenerative diseases and premature mortality.

“One internal mechanism organisms are equipped with to overcome telomere shortening is telomerase. We wanted to examine whether sexual intimacy, within the context of a committed long-term relationship, may offer protective benefits to these markers of general health.”

The study of 129 women found that recent sexual intimacy was positively associated with two measures of telomere length, even after controlling for other relevant factors.

“We measured telomere length and telomerase activity via blood draw. Of the three measures of telomere length, two were statistically significant – whole blood telomere length and Peripheral Blood Mononuclear Cell (PBMC) telomere length. Women who reported being sexually active during the week had significantly longer telomere length across whole blood and PBMC than women who were not sexually active,” Baca explained.

“The relationship held when we controlled for our measures of relationship quality, perceived stress, and other important confounders. Telomere length and telomerase activity was not associated with relationship satisfaction and positive/negative partner interactions.”

The study provides the first evidence that sexual intimacy is linked to telomere length. But the research has some limitations.

“Our findings, although important, were largely exploratory,” Baca explained. “Our results were amassed from a small cross-sectional sample of 129 partnered women who were either caregivers to a child with autism or to a neuro-typical child. As such, there are three major caveats: (1) causation cannot be inferred from the results of our cross-sectional study, (2) we can only generalize these findings to partnered mothers in a long-term relationship, and (3) there may be a “self-selection” bias whereby inherent health and functional variation between sexually active women and non-sexually active women may be confounding results (e.g., healthy women with longer telomere length may be more likely to be sexually active).”

“However, based on the promising results in our study, we hope that the next step in this research will be to collect data on a larger more diverse sample designed to specifically explore the longitudinal effects of sexual intimacy on telomere length.”

The physical mechanisms that link intimacy to health benefits are also unknown.

“There are so many exciting questions to ask regarding sexual intimacy’s role in health!” Baca told PsyPost. “One major question that needs to be addressed involves hypothesizing how the effects of sexual intimacy may translate to better health. There are many physiological and psychosocial mechanisms that may mediate the sex-telomere relationship. For instance, we proposed that sexual intimacy may dampen the effects of stress by down-regulating stress response systems and up-regulating immune response. Over time, these patterns of stress function should result in longer telomere length.”

“The research was collected on only a sample of women. Future research should examine if these associations are found in men. Examining this in both sexes may point us to what the possible protective mechanisms of sexual intimacy are.”

The study, “Sexual intimacy in couples is associated with longer telomere length“, was also co-authored by Elissa S. Epel, Theodore F. Robles, Michael Coccia, Amanda Gilbert, Eli Puterman, Aric A. Prather.