New research reveals factors influencing steroid hormone levels in healthy adults

Steroid hormone levels in healthy adults are influenced by oral contraceptives and smoking, as well as other lifestyle choices and factors such as biological sex and age, according to new research that has just been published in leading international journal Science Advances.

The objective of the research was to expand knowledge and understanding of steroid hormone levels, including corticoids and sex hormones, in healthy women and men over a broad age range. This is the first study to analyse such a large number of hormones in nearly 1,000 healthy people, filling a major gap in the knowledge of molecules that are important for our day-to-day well-being.

The work was conducted by members of the Milieu Interieur consortium and led by Dr Darragh Duffy (Institut Pasteur) and Dr Molly Ingersoll (Institut Pasteur and Institut Cochin (Inserm U1016, CNRS, Université Paris Cité). Dr Jamie Sugrue, a Trinity College Dublin graduate, now a Marie Curie-funded postdoctoral researcher at the Institut Pasteur, is the co-first author. Dr Sugrue also worked with Trinity's Professor Cliona O'Farrelly to secure a Research Ireland Ulysses grant, which kickstarted the ongoing collaboration between Trinity researchers and the Pasteur and Milieu Interieur consortium teams.

The team involved in this current study found that hormone levels vary according to an individual's age and sex, but that they are also associated with many other factors, such as genetics and common behaviors. 

Notably, many steroid hormone levels, beyond sex hormones, are influenced by oral contraceptive use in women, while in men, smoking was associated with altered levels of nearly every steroid hormone measured.

Additionally, measurement of hormones in the same donors 10 years after the original visit showed that decreases in specific androgens were associated with diverse diseases in aging men, implying that these hormones – which are associated with physical characteristics, and supporting strong bones and red blood cell production – play a role in disease development.

This finding – among others – gives the team numerous avenues to pursue in future research.

Dr. Sugrue said: "Even in healthy people, immune responses can vary dramatically. As a first step towards understanding how hormones impact immunity, we worked to understand how hormones themselves vary among people. Our study provides a significant resource for the research community, and generates many new hypotheses for further research. Our next steps will focus on understanding how variation in hormone levels contribute to differences in the immune response between people." 

"My current project is specifically focused on variation in antiviral immune responses in healthy people, and in many ways is a continuation of work that I started during my PhD with Prof. Cliona O'Farrelly at Trinity, where we worked on how antiviral immune system variation can confer resistance to hepatitis C virus infection. By incorporating the hormone measures into my current analysis I hope to uncover exciting new insights."

If the COVID pandemic taught us anything it was how different all our immune systems are, and being part of the Milieu Interieur collaboration is giving us Trinity researchers a wonderful opportunity to study the molecular and genetic mechanisms responsible for these differences at scale."

Cliona O'Farrelly, Professor of Comparative Immunology in Trinity's School of Biochemistry and Immunology

Co-first author, Dr Léa G Deltourbe, Institut Pasteur & Institut Cochin, added: "This study brings much needed data to a subject that is receiving a lot of interest in the mainstream news and on social media platforms, providing a strong basis for investigating the role of steroid hormones in health and disease, including the impact of endocrine disruptors, the link between stress and cortisol, and the role of sex hormones on our well-being." 

As one example, understanding the potential effects of the contraceptive pill on physical and mental health should lead to a better quality of life for women choosing to use this form of medication.

The exciting results in this paper were first presented to an international audience at the Sex Differences in Immune Health conference recently hosted by Trinity College Dublin.