A large-scale ten-year study conducted by the Institut Pasteur on a thousand individuals has shed new light on steroid hormones. Levels of these molecules, which play a crucial role in our health, vary over time – sometimes to a significant extent – influenced by sex and lifestyle factors. The results of this research were recently published in Science Advances.
Steroid hormones, or steroids, are a large family ranging from corticosteroids, such as cortisone, to sex hormones like progestogens, estrogens and androgens. It is well known that they play a crucial role in our health, regulating our metabolism, immune system, the development and maintenance of sex characteristics and the reproductive system, and stress resistance.
Levels of these steroids can vary significantly according to genetics, sex and time of life, though scientific research on the topic remains relatively limited in terms of when levels of these hormones are likely to rise or fall and in what proportions.
Levels of 17 hormones investigated
To fill this gap in scientific knowledge, two teams at the Institut Pasteur conducted a ten-year longitudinal study of the same individuals. This was led by two Institut Pasteur scientists – Darragh Duffy, Head of the Translational Immunology Unit and Molly Ingersoll, Head of the Mucosal Inflammation and Immunity Joint Unit (with the Institut Cochin).
Nearly a thousand healthy individuals, aged 20 to 69, were recruited to form the Milieu Intérieur cohort. Half of them were women and the other half were men. Changes in 17 steroid hormones in these subjects were measured by mass spectrometry. This is the first study to analyze such a large number of hormones in a broad healthy population.
Oral contraception and smoking have a significant impact
The main finding from the study published in March 2025 (1) is that levels of virtually all steroids vary with individuals' genetics, age and sex. However, numerous lifestyle-related factors are also at play.
The key factor for women is oral contraception, with contraceptive pill use significantly affecting 12 steroid hormones. "Estrogen, androgen and progestogen levels in women taking oral contraceptives are very low – lower than those seen in menopausal women," explains Molly Ingersoll.
Sex hormones are not the only ones affected – levels of several corticosteroids are much higher in women taking contraceptive pills.
Smoking affects levels of numerous steroids in men. In male subjects, there is also a link between falling androgen levels (including testosterone) and various diseases as individuals get older. "This suggests that these hormones could play a role in the development of certain diseases," explains Darragh Duffy.
The importance of lifestyle
Other lifestyle choices also have an impact on hormonal balance. "Unexpected correlations emerged from the study, including a correlation between consumption of fast food and levels of cortisone and cortisol," outlines Léa Deltourbe, PhD student in Molly Ingersoll’s team, and one of the three co-first authors of the study, along with Elizabeth Maloney (phd student) and Jamie Sugrue (postdoc) both in Darragh Duffy’s team
All these data provide a basis of reference for understanding normal hormone variations and their health implications. "They highlight the importance of tailoring treatment for hormone-associated diseases to sex, age and behaviors, including gendered behaviors," conclude the scientists.
The team is already planning to investigate links between hormone variations and disease development.
(1) Steroid hormone levels vary with sex, aging, lifestyle, and genetics, Science Advances, march 28, 2025.
