Study Finds Hormone Therapy May Restore Immune Health After Menopause

Researchers at Queen Mary University of London have found evidence that hormone replacement therapy (HRT) may help reverse immune system changes triggered by menopause. Published in Aging Cell, their study shows that menopause significantly alters immune function in women, increasing vulnerability to infections.

The research offers the first detailed analysis of how aging and sex differences affect monocytes, a type of white blood cell that acts as a first responder to infections. Blood samples from adults under 40 and those aged 65 and older revealed that post-menopausal women develop more inflammatory monocytes, which are less effective at eliminating bacteria. This shift was linked to reduced levels of complement C3, a protein that supports monocyte activity in clearing microbes. Men of similar age did not exhibit these immune changes, highlighting menopause as a unique factor in immune decline for women.

To explore whether HRT could influence immune health, the team examined peri- and post-menopausal women using HRT. These participants showed fewer inflammatory monocytes and stronger infection-fighting capacity compared to age-matched controls. Levels of complement C3 were also higher among HRT users, approaching those seen in younger women. Lead author Emma Chambers said, “Our findings highlight menopause as a critical turning point for women’s immunity… hormone therapy seems to restore key aspects of immune health, offering benefits that go beyond easing menopausal symptoms.”

Menopause usually occurs between ages 45 and 55, preceded by a peri-menopausal phase that can last up to a decade. Symptoms such as hot flushes, joint pain, fatigue, and brain fog can significantly affect daily life. In the U.K., over four million women fall within this age range, and women over 50 represent a growing segment of the workforce. Menopausal symptoms can contribute to workplace disruption, making effective management strategies important.

While HRT is already used to address menopausal symptoms, this study suggests it might also help sustain immune health and potentially reduce infection risk. However, the authors stress that more research is needed to determine whether HRT lowers infection rates in real-world conditions and to assess how different types or delivery methods of HRT influence the immune system. They advise that HRT should not be prescribed solely for immune health until these questions are answered.