What is Prolactin?

            Prolactin is a hormone that mammals secrete from their pituitary gland (the part of the brain where all of our hormones come from) and promotes lactation and mammary gland development (1). Lactation is the ability to produce milk to feed our babies, and mammary glands are the milk production sites within breast tissues. Prolactin levels increase during pregnancy and breastfeeding, then decrease after delivery and weaning (2). This is an interesting evolutionary advantage because breast milk contains so many different beneficial ingredients beyond nutrition, including vital immune-system boosters, molecules needed for organ growth and development, and microbes to colonize our gut, forming the gut microbiome (3). Several types of milk exist, but “What Is The Healthiest Milk?”  

            Many foods are high in prolactin. Prolactin has many different interactions in our body and, as a whole, is not well understood. We know prolactin has some effects on digestion, interactions with dopamine and serotonin in the brain, and some functions in metabolism and fat storage (4). Research is ongoing, but some fascinating discoveries are likely coming soon that will clarify these diverse effects. It seems the function of prolactin goes far beyond lactation and breastfeeding.

The Primary Function of Prolactin

            Currently, our best understanding of prolactin lies in the female reproductive system. Prolactin plays a significant role in the stimulation of pregnancy, fertilization of eggs in the ovaries, ovulation, and mammary gland development and maintenance during and shortly after pregnancy (5). Studies in mice have even found that prolactin has a role to play in maternal behavior. When prolactin was not present, mice did not develop normal maternal behavior such as feeding, grooming, and care of their pups. During pregnancy and lactation, the mice developed new neurons in the forebrain, which migrated to the olfactory bulb (the part of our brain right at the front, near the nose). Researchers suggest that the addition of these new neurons likely helped the new mother adapt to the needs of her pups, increasing the likelihood of their survival, though details on this are still being worked out (5).

            So, we can see that prolactin isn’t as simple as “a lactation aid” and has many roles. The majority of research so far on prolactin has been on its effect during conception, pregnancy, and early stages of post-birth infant development.

When Prolactin Does Work

            Prolactin has been tested as a treatment for lactation insufficiency before in women who cannot produce enough milk. Breastfeeding is encouraged for newborns where it is a feasible option (some women cannot breastfeed due to medical conditions or treatments such as radiation). Prolactin has shown in preliminary studies to be a potential treatment if lactation is not sufficient for a newborn (6).

When Prolactin Doesn’t Work

            Several documented disorders occur when prolactin levels are either too high or too low. These disorders can happen to men and women but are more common in women. One reason why these disorders develop is a pituitary gland tumor. Other changes in prolactin can be the result of lactation during breastfeeding, pregnancy, stress, or even intense exercise (7, 8). This is a good reminder of why you should always consult your healthcare provider if you are significantly changing your lifestyle or notice small changes in your body (as a result of stress or other life changes).

Where You Can Find Dietary Sources of Prolactin

            While prolactin supplements and pills are available, your first choice should always be getting additional prolactin through a diverse and healthy diet (although, if your doctor recommends a pharmaceutical source of prolactin, you should follow this advice). So, without further ado, here is our list of:

10 foods high in prolactin:

Chickpeas and garlic

Much of the data on chickpeas is from anecdotal studies that watch participants consume chickpeas in the form of hummus (a blended dip of chickpeas, olive oil, tahini, garlic, and lemon juice). Together they form a healthy, energy-packed snack that seems to promote lactation and prolactin (9).

Oats, brown rice, and barley

Oats, brown rice, and barley are all high in beta-glucan, a form of fiber found in the outer shell (called the kernel). To learn more about beta-glucan, take a look at the “World’s Healthiest Rice Varieties.” This fiber helps with digestion and has many health benefits. Among the lesser-known benefits is a recent study performed in cells that showed beta-glucan stimulated prolactin secretion. Of course, further studies in animal and human models are needed, but this fiber may hold the key to maintaining healthy prolactin levels.

Brown rice also has some effect on serotonin, increasing serotonin levels in the brain (10). Serotonin has been noted to increase prolactin levels, but it is unclear why (11).

Alfalfa

            Alfalfa consumption also seems to affect increasing milk supply and is assumed to increase prolactin, but the research remains to be seen. Participants who eat more alfalfa seem to have healthier milk levels, but much more research remains here (11).

Asparagus

            Asparagus seems to increase prolactin, thus increasing lactation and milk production, in some studies (12). However, how this occurs and why remains a mystery under investigation. In rats, those given asparagus extract had a higher prolactin level than those that did not receive the extract. This also suggests that some component of asparagus may be responsible for prolactin level increases, but it is unclear why (13).

Dates, apricots, and papaya

            These three fruits are high in vitamin A, C, potassium, calcium, and fiber, and are a great addition to your diet, and are good for prolactin levels, too! Similar to many of the foods on our list, it is unclear why they are prolactin-promoting. One potential reason has been suggested that dopamine requires vitamin C to release prolactin, which was determined in pituitary cells (14). Animal and human studies are pending to see if this is the case and if there is more to the story.

We’ve now seen why prolactin is essential for good health and what happens when this misunderstood hormone is too much or too little. Beyond pregnancy and breastfeeding (which are extremely important on their own), this hormone may have a variety of other functions in mental health (interacting with serotonin and dopamine), metabolic disorders (seeming to have some interactions with our gut microbiome and diabetes development), and a number of other body functions. Prolactin remains a topic of debate and research, as scientists continue to try to determine all of the applications and functions of this mysterious hormone.

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