Day 1 of your menstrual cycle is the first day of bleeding. Bleeding, or the shedding of your uterine lining, is caused by the drop in your progesterone levels.
Day 1 is also the start of your follicular phase. It's the phase leading up to ovulation and is usually about 2 weeks long - but can last anywhere from 7 to 21 days. If you have a longer cycle it is usually due to having a longer follicular phase (keep in mind it can also be due to not ovulating). Long follicular phases can be caused by stress, under-eating, illness or possibly PCOS.
The follicular phase is also the final phase of your follicles growth on their way to ovulation (remember their entire journey is about 100 days long!).
Follicle-stimulating hormone (FSH) stimulates your follicles to make estradiol. Estradiol levels fluctuate throughout your cycle, and even throughout the day. Your estradiol levels gradually rise throughout the follicular phase, peak right before ovulation, drop and then rise again during the luteal phase.
Estrogen: the good and the bad
Estrogen definitely can get a bad rap since estrogen dominance can cause a host of issues which I'll cover in a second. But, estrogen also serves several very important purposes in your body:
- boosts serotonin and dopamine
- enhances your sensitivity to insulin and in-result helps to prevent insulin resistance
- stimulates the uterine lining to grow and thicken in preparation for pregnancy
- stimulates the production of fertile mucus (which helps sperm to survive)
Estrogen has some pretty important roles in your body, right? A lack of estrogen can cause pain during sex, light periods and no fertile mucus.
But what happens when you have too much estrogen? Or unopposed estrogen?
Estrogen dominance can happen when your body is producing higher levels of estrogen, or when you have normal levels of estrogen but low levels of progesterone (read more about the cause of low levels of progesterone here,).
When you have high levels of estrogen or normal estrogen but low progesterone it can result in symptoms like heavy periods, short cycles, PMS and breast tenderness.
Higher estrogen can be due to higher production by your ovaries (more common during perimenopause), or impaired estrogen metabolism or detoxification.
Estrogen metabolism is the removal of estrogen from your body. To simplify it, estrogen metabolism is a two part process that involves the liver inactivating estrogen and then the elimination of estrogen through your bowel. What this means is, in order for estrogen metabolism to take place you need to have a healthy, good functioning liver and a healthy gut microbiome (a healthy balance of good bacteria living in your gut). If not, your estrogen won't be metabolized and will recirculate in the body.
Your liver needs nutrients such as vitamin B6, B12, zinc, selenium, folate and protein to function well (and not have too much burden on it, such as excess alcohol). And in order to maintain healthy gut bacteria the best way to do so is to avoid anything in excess that kills the good bacteria, such as antibiotics or other drugs and alcohol.
So in order to have healthy hormone levels, we also need a healthy gut microbiome and liver. (Nothing in the body works alone!)