When thinking about fertility, insulin is not often considered relevant, however in the hierarchy of hormones, insulin is the Mother hormone. It is one of 2 top tier hormones from which vital reproductive hormones are made. Dysfunction, even mild, can impact downstream, disrupting the fine balance of baby making.
What exactly is insulin?
Insulin is a hormone, produced in the pancreas and is responsible for the metabolism of carbohydrates, fats and protein, by promoting the uptake of glucose (carbohydrates) into the liver and fat cells. It’s actions are activated by a feedback mechanism via Beta cells in the pancreas. It is also the precursor to DHEA, which converts to testosterone and oestrogen and pregnenolone which converts to progesterone.
Sources of dysglysemia
In this article I am not looking at disease such as diabetes, but dysglysemia, the more common day to day dysregulation of insulin caused by diet and exercise.
Ideally blood sugars operate within a fairly generous range, with an upper limit and a lower limit. Once glucose drops below or rises above this range then a response is activated.
Things that will affect blood sugars include;
- The balance of macros in a meal (carbs/fats/protein)
- Fibre in a meal
- Timing of meals
- Eating late at night
- Shift work
- Chewing gum
- Artificial sweetners
5 ways fertility is affected
The chart above shows the hierarchy relationship between insulin and reproductiove hormones. When it comes to fertility these affects can have a sub clinical impact, not necessarily showing up on a blood test, but enough to create dysfunction.
5 of these affects are;
Excess glucose is stored initially in the liver where it is readily available for conversion to energy. However once that storage site is at capacity, glucose is stored by insulin as fat, in particular visceral fat, found around the middle of the body and around internal organs. This mechanism of action is why belly fat is difficult to get rid of through calorie restriction as reduced calories can make the situation worse. It is not necessary to be clinically obese in order to have visceral fat. Oestrogen is stored in body fat, so when there is excess body fat, visceral in particular, there can be excess oestrogen stored.
It is normal for men to have some oestrogen but it should be in balance with testosterone. An imbalance between the two can lead to low sex drive and diminished sperm production, leading to infertility.
Oestrogen hormone makes women curvy; round breasts, narrower waist, broader hips. Women naturally have high levels of oestrogen and it has a significant impact on the menstrual cycle alongside progesterone. An imbalance of oestrogen causing oestrogen dominance can lead to irregular menstrual cycles, failure to ovulate and short luteal phases potentially leading to early miscarriage.
When blood sugars are consitently high and the body is constantly trying to store glucose beyond the liver’s storage capacity, a condition callled Insulin Resistance may develop, where cells no longer respond to insulin in the bloodstream and fail to accept glucose into storage. This causes additional insulin to be produced, energy gets low and food cravings increase. Too much insulin can cause chronic low grade inflammation affecting hormone balance, egg quality and sperm quality.
Egg and sperm quality
The second tier steroid hormone Dehydroepiandrosterone (DHEA) is involved in egg quality and supports the growth of the follicle prior to ovulation. Lower levels of DHEA are seen in women with dimished ovarian reserve. Sperm motility (ability to swim) is also supported by DHEA. Chronic dysglysemia can affect the production of DHEA and subsequent production of oestrogen, progesterone and testosterone. Low levels of testosterone in men affect sperm generation. In women low progesterone islinked to anovulatory cycles, luteal phase defects and miscarriage.
The thyroid impacts virtually every organ in the body. Each cell has receptor sites for thyroid hormone
allowing the thyroid to hold influence over the functions of every cell and every tissue.
The thyroid’s main job is to regulate heart rate, blood pressure, and body temperature but it also impacts things
like weight, fertility, menstruation, skin tone, energy levels, sleep, memory, and digestion. It is particularly crucial in early pregnancy as the developing embryo differentiates cells very quickly and needs thyroid hormone to support rapid growth. Dysglysemia can cause thyroid dysfunction leading to symptoms such as irregular or heavy period and miscarriage
Optimizing your fertility
It is a rare day when I don’t encounter some level of dysglysemia in my new fertility clients and that brings an immediate opportunity to start optimizing their fertility. Even when there is an identified fertility issue, such as low AMH, the fundamentals of good blood sugar balance are always relevant. From this foundation all other improvements can be built.
The entire Module 1 in the Now Baby Programme is devoted to establishing the eating habits of a metabolically healthy individual and this is backed up weekly with a new and delicious meal plan designed with both fuel and fertility nourishment in mind. And because nothing happens in isolation we come back around to a variety of topics such as stress, sleep, shift work and exercise throughout the programme, underpinning the work started in Week 1.
So when your goal is to optimize your fertility for either a natural conception or to improve your IVF success, look to your plate !