prolactin’s functions and benefits in women’s health
“Hormonal, hormonal mess, out-of-whack hormones, hormonal rollercoaster.” Our hormones have gotten a bit of a bad rep. But did you know that, for example, healthy prolactin levels not only are crucial for your fetility but also support healthy hair and skin?
Though menstruation and (peri)menopause come with their challenges, often the real issue is not that our hormones are out of whack, but that our lifestyle, diet, or level of stress are out of balance. This creates imbalance in different areas of our lives, like our health and hormone levels, causing or exacerbating “hormonal symptoms.”
In this series about hormones, I’d love to take you on a journey that will help you see that our hormones aren’t bad. They can do amazing things for us! And by giving your hormones the support they need to remain balanced, you can enjoy their benefits. In this article, we’ll dive deep into prolactin, a hormone with over 300 biological functions,
Keep in mind that science has only recently started to seriously consider that a woman’s body functions differently from a man’s body. Proper research into women’s health is still relatively new, and a lot more cool stuff will be discovered in the years to come.
But read on to find out what we know already!
Do you first want a little refresh on the natural flow of your cycle? Then go here first.
What is Prolactin?
Prolactin is another hormone that is generated by your pituitary gland. It is mainly known for its role in milk production after pregnancy, but it does way more than that! It is involved in more than 300 biological functions in your body. Let’s take a look at the most important ones.
Prolactin’s Essential Role in Female Fertility and Reproduction
Prolactin is produced by both men and women all the time. Men produce slightly less than women. Women’s basal level is normally quite low, but rises significantly during pregnancy or when breastfeeding. Its synthesis follows a circadian rhythm with levels going up during sleep.
For men, its main function is to modulate testosterone, influencing libido. In women, the hormone is also produced in the ovaries themselves, where it influences follicle development and ovulation. Though only small amounts are produced when you aren’t pregnant or breastfeeding, they are still a vital part of fertility. Prolactin helps balance other hormones, and too high levels (hyperprolactinemia) is one of the leading causes of infertility in women.
Prolactin and Lactation: The Science of Milk Producton
When pregnant, the placenta produces massive amounts of estrogen and progesterone. High estrogen increases prolactin, which causes the development of mammary glands that can generate milk. Milk flow, however, remains blocked by the high levels of progesterone. After giving birth, both these hormones drop drastically. Without the blocking action of progesterone, and with the support of oxytocin, milk can now flow.
After giving birth, it is no longer estrogen that drives prolactin production. Prolactin signals the body to make more prolactin. Also, the suckling of your baby sends nerve signals to your hypothalamus, which then instructs your pituitary to produce prolactin.
And not only a baby sucking your nipple triggers prolactin — any nipple stimulation does, but to a lesser degree. What also stimulates production are eating, and having sex, and physical stresses like pain or exercise.
Prolactin’s Influence on Maternal Instincts and Bonding
Prolactin influences the brain and promotes our maternal instincts. It makes birds create nests, motivates certain fish to keep their eggs safe in their mouths until they hatch. For us humans, prolactin works together with oxytocin to create that special bond between mother and child.
Hyperprolactinemia: Symptoms and Causes of High Prolactin Levels
When not pregnant or lactating, your ovaries and pituitary still produce small amounts of prolactin, which is thought to support follicle development. After ovulation, it rises slightly, which led to the idea that prolactin also helps maintain the corpus luteum and thus progesterone production.
High prolactin levels suppress GnRH release from the hypothalamus. During pregnancy, when it is normal to have high prolactin, GnRH suppression limits FSH and LH, making sure new menstrual cycles don’t start while you already have a baby growing in your uterus.
When your prolactin is very high when you aren’t pregnant or have a newborn, the same happens: your cycle shuts down. This is called hyperprolactinemia, and it can be caused by long-term stress, medication, or pituitary tumors (prolactinomas), as well as hypothyroidism, issues with the liver or kidneys that inhibit prolactin clearance, and estrogen excess.1
Understanding Macroprolactinemia
There is also a form of “false” hyperprolactinemia where prolactin binds to immunoglobulins, forming “macroprolactin.” This larger molecule stays in your system longer, so levels increase. This shows in a blood test as hyperprolactinemia; however, this molecule is too big to enter tissues. It doesn’t exert the same effects as unbound prolactin. It can cause no to only mild symptoms and doesn’t require the same treatment. So in case you ever test for hyperprolactinemia, make sure the test is done right.
Prolactin Levels During Perimenopause and Menopause
During perimenopause, prolactin levels can fluctuate a little due to other hormones changing. As women transition into menopause, they stabilize and become slightly lower. Post-menopause, levels usually equal those of men, which are slightly lower than women’s levels during reproductive years.2
Beyond Reproduction: Other Cool Prolactin Functions in the Body
Though prolactin affects many systems in your body, most of its functions still link back to baby benefits. During pregnancy and breastfeeding, prolactin soars and its effects are very active. Outside of these life events, when you only have small amounts of this hormone, its effects are still there but far more subtle.
Prolactin’s Role in Water, Electrolyte, and Calcium Balance
Water follows the flow of salts and other ions. Prolactin influences the movement of ions that we call electrolytes in tissues like your breasts, colon, and endometrium. By doing this, it affects fluid and electrolyte balance — for example, in mother’s milk or the uterine environment.
Research has also shown that it influences calcium absorption. Calcium comes from your diet and gets absorbed in the small intestine. We need calcium for many things, like:
- bone strength
- nerve and muscle function
- milk production
- fetal skeletal development
Prolactin increases calcium absorption and reduces its excretion via the kidneys. When levels rise during pregnancy, this supports the calcium needs of the growing baby.
The hormone is also involved in bone turnover — breaking down bone to release calcium (when needed) and creating new bone cells.
Scientists have noted that younger people’s response to prolactin is much stronger. The body may become less sensitive to prolactin as we age.3
How Prolactin Influences Metabolism, Insulin, and Weight Gain
Increased levels of this hormone also affect your metabolism to support pregnancy. Prolactin increases appetite so you consume enough calories to create a baby and produce milk. It enhances fat storage and fluid retention during pregnancy and, after giving birth, mobilizes fat and fluids to make milk.
It also affects insulin production and makes your cells slightly resistant to insulin. This ensures that you take up a little less glucose so more is available for your baby.
High prolactin levels when not pregnant can thus contribute to insulin resistance, blood sugar issues, and weight gain. Many women experiencing PCOS also deal with insulin resistence and links have been made between hyperprolactinemia and PCOS.4
Prolactin and the Immune System: Regulation and Autoimmunity Links
Research has shown that certain immune cells produce prolactin. They also have prolactin receptors and can thus be affected by changing hormone levels.
Prolactin can both stimulate and inhibit your immune system, depending on the context and the type of immune cells involved. In stress situations, for example, prolactin rises and can limit cortisol’s inhibiting effect on the immune system.
It also makes sure that a mother’s body won’t reject a growing fetus. The uterus itself creates prolactin, preventing a strong inflammatory response that would otherwise break down and expel the baby.
But this hormone can also activate your immune system. This study shows there are options to use prolactin in Covid treatment.
Though it’s great that prolactin can help ramp up immunity when needed, chronic high levels of prolactin can exacerbate immune responses and have been linked with autoimmune conditions like lupus.6
Prolactin and Vasoinhibins: Regulating Blood Vessel Growth
Prolactin can be broken down into smaller parts called vasoinhibins that regulate blood vessel growth. In the uterus and placenta, prolactin supports proper blood vessel growth to nourish the developing fetus. In the breast, it helps create the rich blood supply needed for milk production.
Overall, prolactin supports cell differentiation, growth, and multiplication. Breast cells express a lot of prolactin receptors, which is one of the reasons this hormone has strong effects on the breasts. Receptors are also found in the brain, and prolactin seems to support brain plasticity as well as repair, especially during pregnancy and after brain injury.7
Prolactin’s Complex Link to Cell Growth and Tumor Risk
But when you tip off balance, prolactin can support out-of-control cell growth and thus tumour growth. Keep in mind that prolactin is not the only substance your body generates to enhance or inhibit cell differentiation and growth. Also, not all research shows the same results, and some even propose that under certain conditions prolactin can be protective or, in a tumour-generating environment, support the creation of a less dangerous tumour.
Yes, hormones and other bodily substances often don’t function in a black-and-white way. They don’t just do good or bad. What happens around them influences their behaviour.
Prolactin’s Effects on Healthy Skin and Hair Follicle Cycling
Prolactin also influences hair follicle cycling, aka the cycle of growth, rest, and shedding. Proper levels will support healthy hair growth, whereas too much prolactin can cause excess shedding and thus hair thinning.
High prolactin levels can also contribute to oily skin, as the hormone stimulates the skin’s sebaceous glands that produce oil.
The Post-Orgasm Chill: Prolactin’s Role in Relaxation
That good and relaxed — even sleepy — feeling after orgasming? Prolactin has something to do with it! Its levels rise sharply after an orgasm for women, men, and non-binary people. It is responsible, together with dopamine, for this feeling of satisfaction and utter relaxation in which new arousal is out of the question for most people.
But not to worry, having a lot of orgasms shouldn’t induce hyperprolactinemia. What happens here are natural short-term spikes, while hyperprolactinemia is more a constant high level of the hormone.
Prolactin: Involved in Over 300 Biological Processes
As mentioned, this hormone is involved in about 300 processes in our body. It supports eye development, it is thought to be involved in taste perception and sleep, and many more wonderful things. Above, I have mentioned what I think are the most relevant and fun functions of prolactin.
How to Naturally Support and Balance Prolactin Production
Prolactin’s release isn’t caused by the previously discussed cascade of hormones starting with kisspeptin. Neither does it follow a monthly pattern like, for example, progesterone does. Prolactin’s production is more stable. It gets released in pulses every few hours, increases shortly after you fall asleep, rises during the night and drops after waking.
It is quite uncommon to have too-low prolactin levels. Generally, this hormone starts to create problems when it reaches high levels when someone is not breastfeeding or carrying a baby.
Balancing Prolactin with Dopamine and Other Neurotransmitters
Continuously, its release is inhibited by dopamine, a neurotransmitter that supports feelings of peace and motivation. When dopamine lowers, prolactin goes up. Increasing serotonin can make prolactin go up directly or indirectly because it can decrease dopamine levels.
Natural fluctuations of these neurotransmitters shouldn’t create problems for your prolactin levels. However, if your dopamine is chronically lowered — for example, due to taking certain antidepressants or antipsychotic drugs (that mess with your serotonin and dopamine) — you can increase prolactin levels.
Thyroid Health, Stress (Cortisol), and Prolactin Balance
Oxytocin, estrogen, TRH, and cortisol all increase prolactin too. Oxytocin increases during childbirth and initiates uterine contractions. It is linked to intimacy, trust, and social bonding and supports milk flow when breastfeeding. It is a hormone that can also act as a neuromodulator and can even support cardiovascular health.
TRH (Thyrotropin-Releasing Hormone) increases when your thyroid is underfunctioning and directly stimulates prolactin production. People with hypothyroidism often also have mild hyperprolactinemia.
Cortisol can be chronically elevated when we are stressed long term. This — not the occasional stressful moment — can cause unbalanced prolactin. Now, your body also sees having no food and blood sugar crashes, or the blood sugar rollercoaster, as stressful. They can increase cortisol and prolactin and wreak havoc on your fertility and full-body wellbeing.
Estrogen and Prolactin: Managing High Estrogen Levels
Estrogen is the hormone that signals the initial prolactin increase during pregnancy. When it goes up, prolactin goes up. High estrogen that is not linked to pregnancy comes with a set of other issues. It can cause heavy flow, is linked to endometriosis and fibroids, and can increase breast cancer risk.
So keep xenoestrogens out of the house! (Xenoestrogens are synthetic substances that mimic estrogen in your body. They can be found in some plastics, pesticides, and chemical cleaning products.)
Dietary Support: Vitamins, Minerals, and Foods to Balance Prolactin
Prolactin is a peptide, and its synthesis therefore requires protein, zinc, magnesium, manganese, and vitamin B6. Neurotransmitters like serotonin and dopamine also need vitamin B12, folate, vitamin C, and copper, and the thyroid really loves iodine and selenium.
But your body wants all the vitamins, minerals, enough protein, carbs, fats, fibre, water — and it also loves treats like quercetin, polyphenols, and all those cool medicinal compounds that are hidden in our food. A balanced diet is the way to go for a full-body healthy experience.
Focus on a diet low in processed foods, rich in fresh veggies and fruits, some fish, nuts, seeds, and whole grains. Minimize the wheat, meat, and dairy, which are more difficult for the body to handle and can limit its daily detoxing mechanisms.
For specific diet tricks like balancing estrogen or supporting your thyroid, you can reach out to me and we can make a plan that fully supports your unique needs.
Images
Baby suckling: Blond Fox, Unsplash
Grandmother: Ekatarina Shakharova, Unsplash
Sonogram: Omar Lopez, Unsplash
Pregnant woman: Unsplash
Medical Disclaimer