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# 3.8 Age and the menopause

The composition of the gut microbiome changes with age, and this is particularly noticeable after the age of 65 years. The changes that occur can reflect the physical fitness, frailty, and longevity of the individual. In healthy ageing, there is consistently a depletion of some of the core bacterial groups, particularly Bacteroidetes. In contrast, individuals assessed as having a higher degree of frailty have an increase in the levels of Bacteroidetes (Wilmanski, 2021). The decrease in Bacteroidetes seen in healthy ageing also appears to be associated with longevity, and individuals over 100 years of age typically have fewer Bacteroidetes and an increase in rare bacterial groups.

Often these changes in gut microbiome diversity reflect the environmental and personal factors that an individual has been exposed to during their lifetime. As we age, there is age-related decline in the structural integrity of the gut wall, to our internal physiology, and there are many molecular and cellular changes, such as epigenetic changes, all of which can have an impact on the gut microbiome. As a result, an important area of scientific research is exploring the impact of environment, diet, exercise, disease, medication and societal factors and their impact on the ageing gut microbiome (Ghosh, 2022). A better understanding of these factors will hopefully help to promote better health and longevity in ageing (Figure 23).

Figure 23 (a) Ernestine Shepherd and (b) Toshisuke Kanazawa, body builders aged 80 and 81 years, respectively, at the time of these photos, demonstrate that it is possible to maintain good physical health and fitness in the later decades of life

One particular period of life that affects females is the menopausal period.

## Fun fact: are perimenopause and menopause the same thing?

In everyday language, the two terms are often used interchangeably, however, the scientific terminology is more precise. From the age of approximately 40–44 years onwards, most females will enter the perimenopause, which is a transitional period which can last several years. During perimenopause, hormone levels fluctuate and there are often changes in the pattern of menstruation. The menopause is a specific moment in time, defined by the NHS as being when there has been no menstruation for a year in females over 50 years, or for two years, if under 50 years of age. The average age of the menopause in the UK is 51 years of age.

There is a sex-related difference in the microbiomes of males and females, however, during the perimenopause and post-menopausal period there is a reduction in diversity and the gut microbiome in females becomes more similar to males (Peters, 2022). At present, there is very little research into the changes in the gut microbiome during the menopausal period, and how hormonal changes contribute to this alteration in bacterial diversity. There are many health-related risks associated with the menopause, and it is unclear whether modification of the gut microbiome after the menopause may help to reduce the risk of developing some of these conditions. Therefore, more research into this area will be essential to try to improve the health and wellbeing of post-menopausal females.

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