"Overall, CR may improve aspects of reproductive longevity in the NHP, but the timing of when it occurs during the reproductive lifespan is likely critical."
BUFFALO, NY — June 24, 2025 — A new research paper was published in Aging (Aging-US) Volume 17, Issue 5 , on May 20, 2025, titled " Short-term moderate caloric restriction in the rhesus macaque attenuates markers of ovarian aging in select populations ."
In this study, led by first author Emma S. Gargus and corresponding author Francesca E. Duncan from Feinberg School of Medicine at Northwestern University , researchers explored how dietary changes impact ovarian aging in female rhesus macaques. They found that a three-year moderate reduction in caloric intake preserved a youthful distribution of ovarian follicles and reduced age-related tissue stiffness. These findings are relevant to women's health as they suggest that caloric restriction (CR) may help delay the decline in reproductive function associated with aging.
Ovarian aging, which leads to reduced fertility and hormone production, is one of the earliest signs of aging in women. This study investigated whether a 30% reduction in caloric intake could protect the ovaries from age-related damage in nonhuman primates (NHP), whose reproductive biology closely mirrors that of humans. Ovaries were collected from young (10–13 years) and old (19–26 years) rhesus macaques who were either on a diet of moderate caloric restriction or a control diet for three years.
"To test the effect of CR on follicle number, follicles were analyzed in histological sections from animals across experimental cohorts: Young Control, Young CR, Old Control, Old CR (n = 4–8/group)."
Although total follicle numbers still declined with age, caloric restriction helped maintain the types of follicles most associated with reproductive potential. In older monkeys who were still cycling, even if irregularly, caloric restriction preserved more primordial follicles, the key indicators of ovarian reserve, than in those on a normal diet.
The benefits of caloric restriction were also seen in the structure of ovarian tissue. Normally, aging leads to fibrosis, a stiffening of the ovarian environment caused by increased collagen and decreased hyaluronic acid. This study showed that caloric restriction reduced this fibrotic process, suggesting a more supportive environment for maintaining reproductive health.
While the diet did not stop the overall loss of follicles with age, it improved the proportion of younger, more viable follicles in aging ovaries. The timing of the dietary intervention also appeared to matter. Positive effects were more noticeable in older animals with irregular cycles than in those who had completely stopped cycling. This indicates that starting caloric restriction at a certain point in the reproductive lifespan may yield the best results.
This research is an important step to identifying lifestyle-based strategies that can extend reproductive longevity. Although further studies are needed to test these findings in humans, the work supports the potential of moderate dietary changes to delay ovarian aging and help preserve fertility later in life.
Read the full paper: DOI: https://doi.org/10.18632/aging.206253
