Chronic stress, comfort eating and fertility

Stress is supposedly a common facet of modern life, although anyone who studies history will be able to tell you that modernity has nothing to with it. There are not many people who would swap their stressful 21st Century lives the 19th Century agricultural or factory drudgery that included the very real stresses of grinding poverty, ill health and lack of hope.

That said, stress IS something that we all have to manage, and there is no doubt that a diagnosis of infertility is uniquely stressful. Recognizing this, when we talk about stress we generally consider two aspects of the condition:

–     The perception of pressure e.g. the ‘stimulus’ of danger, threats and uncomfortable situations

–     The body’s response to that stimulus

The body’s automatic response to stress is known as the fight or flight response. This triggers a cascade of hormones, including adrenaline and cortisol, speeding up the heart rate and blood circulation, mobilising glucose for immediate energy, and preparing the muscles for action.

Of course, in bygone days such as when we had to run from a sabre tooth tiger or an enraged bison, the stress response was extremely useful and probably was a major factor in keeping the human race from extinction!

Nowadays with our more sedentary lives, there are plenty of downsides to the fight or flight response. It was never meant to solve issues such as job stress, traffic jams, anger management, marital issues or the unique and powerful mental and emotional pressures that infertility challenges bring.

The problem with the stress response is that it generally takes some time for the body to calm down after it is initiated, and it has been shown that prolonged or repeated arousal of the stress response can have harmful physical and psychological consequences, including heart disease and depression.

None of this is helpful in terms of dealing with infertility. In addition, researchers at RMIT University in Melbourne, Australia, have now uncovered a new link between chronic stress and reproductive problems. A pre-clinical study has highlighted the role of a hunger-triggering hormone ghrelin that is also released as part of the stress response.

Ghrelin is a hormone that makes mammals feel hungry and increases food intake and promotes fat storage. It’s also released when we are stressed and is part of the reason we comfort eat when we feel emotional or anxious.

The RMIT University researchers found that by blocking the ghrelin receptor in female mice, they were able to reduce the negative effects of chronic stress on a key aspect of ovarian function: the primordial follicle reserve, which represents immature follicles.

A small proportion of these immature follicles will eventually develop further to become pre-ovulatory follicles, and this means the fewer immature ones you have, the fewer mature follicles later in life that can release an egg cell for fertilisation.

However the study found that female mice exposed to chronic stress had significantly fewer primordial follicles. The role ghrelin plays in this process became clear when the researchers blocked it and found that the number of primordial follicles remained normal, even when the experimental mice were exposed to stress.

These findings could have future implications for those with underlying fertility issues. Dr Luba Sominsky, senior co-author of the study said, “Stress is an inseparable part of our lives, and most of us deal with it quite efficiently, without major health problems. This means young and otherwise healthy women may experience only temporary and probably reversible effects of stress on their reproductive function. But for women already suffering from fertility problems, even a minor impact on their ovarian function may influence the chance and timing of conception.”

Sominsky says that although this work is exclusively in mice, there are many similarities to humans in stress responses, as well as in many phases of reproductive development and function. She continued, “Our findings help clarify the intriguing role of ghrelin in these complex connections, and point us on a path towards future research that could help us find ways of mitigating the effects of stress on reproductive function.”

Associate Professor Sarah Spencer, co-author on the study, noted the study also indicated there could be a relationship between eating, stress and reproductive function.

Professor Spencer said, “Because ghrelin is so closely linked to hunger and feeding, these findings very broadly suggest that our eating habits may be able to modify the effects of stress on fertility, although we need to do more work to fully assess this.”

The researchers conclude that getting a better understanding of the role of ghrelin in all of this brings us an important step closer to developing interventions that can keep these critical parts of the reproductive system healthy. It may be that, in the future people with infertility concerns may have to pay more attention to what and when they eat as a result of stress.