Oocyte (egg) quality has a major influence on female fertility and pregnancy outcomes, and scientists are trying to find ways to improve or preserve oocyte quality in women. Two recent papers from Australian researchers have addressed whether a particular supplement, nicotinamide mononucleotide, or NMN, can improve egg quality in women.
One study focussed on testing whether NMN could prevent the loss of eggs by women undergoing treatment for cancer. Cancer treatments, such as radiation and chemotherapy, cause the loss of the ovarian follicles (primordial follicles) that contain the oocytes, leading to ovarian insufficiency and premature menopause. The authors hypothesized that treatment of young mice with NMN, a precursor of the well-known cofactor NAD+, would protect their eggs from the cancer therapies. Unfortunately, intraperitoneal administration of NMN could not protect oocytes from either radiation or a chemotherapy agent under the experimental conditions used. It is likely that one action of cancer therapies is to inflict DNA damage in the eggs, so unless the damage is repaired quickly, the egg will die. The authors suggest that further research should investigate whether different NMN formulations could protect against DNA damage in oocytes during cancer treatment.
Another study addressed the problem of declining egg quality with ageing, an important problem as many women wish to fall pregnant later in life when their oocyte number and quality is rapidly declining. The authors showed that treating old mice with NMN in the drinking water could restore egg quality and subsequent fertility, and that this was recapitulated by treating eggs recovered from old mice in vitro. This exciting finding suggests that NMN supplementation could be a promising approach to preserve fertility in older women, but independent verification will be required. The authors caution against the immediate use of NMN supplements by patients until further research establishes how this treatment actually works.