How caffeine affects hormones

Many people use caffeine to fuel their lives. It’s a standard morning routine to wake up, have a cup of coffee, then start your day. While common, this substance isn’t innocuous. It interacts with certain prescriptions, and research shows that your cup of joe can also affect your hormones—most significantly estrogen in women. Here’s what you need to know about caffeine and hormones.

Does caffeine affect hormones?

Observational studies find an association between caffeine intake and changing hormonal levels. Meaning, there’s a link, but there’s no proof that caffeine causes changes in hormones. It’s possible that some other behavior or inherent trait, common in people who consume more caffeine, is responsible for the differing hormone levels. Hormone levels change with diet, exercise, sleep, stress, and supplement use. The potential impact varies by type of hormone.

Estrogen

Caffeine appears to affect estrogen differently in different racial groups. Furthermore, estrogen differs in every woman and changes throughout her monthly cycle. One study showed that higher caffeine consumption was associated with higher estrogen levels for Asian women. However, the exact reverse effect was found for white women—higher caffeine intake was associated with lower estrogen levels. In Black women, there was a slight rise in estrogen levels, but it wasn’t statistically significant. Meaning, the differences in estrogen level may be insignificant and random. 

There are some studies suggesting a decreased risk of breast cancer in those who drink coffee.  Conversely, other studies have shown no difference. Having conflicting reports on how caffeine affects estrogen levels in women of different races, makes it difficult for medical providers to accurately predict risk. This may be because caffeine does not change the risk of developing breast cancer.

There is also the issue of how fluctuating hormonal balances affect women’s mental health. While there is evidence of caffeine affecting hormonal balance in women, and this could possibly affect mental health, direct causation has not been proven. The recommendation is that moderate caffeine intake is not harmful.   

Progesterone

“I’m not aware of direct association of caffeine and progesterone,” says Oladimeji Oki, MD, a family attending physician at Montefiore Medical Center in New York. “Of course if estrogen levels are altered, the estrogen/progesterone ratio will also be altered.” When there is an imbalance of these two hormones, it can have negative health effects for women.

“Drinking caffeine can increase estrogen levels in women, sometimes leading to an estrogen dominant state,” says Odelia Lewis, MD, a medical contributor to ABC News Medical Unit. “Estrogen dominance is associated with premenstrual syndrome, heavy periods, fibrocystic breasts, and even certain breast cancers. Estrogen dominance is usually associated with low progesterone levels.” 

In other words, even if caffeine doesn’t directly affect progesterone, because it impacts the relationship with estrogen, it can be important to consider. More research is needed.

Testosterone

A small randomized, controlled trial suggested caffeine may increase testosterone in men and lower estrogen, but it was not a statistically significant difference.There is no direct relationship between caffeine intake and testosterone levels. However, it seems to decrease testosterone in women. Women with low testosterone levels may experience sluggishness, muscle weakness, fatigue, sleep disturbances, reduced sex drive, decreased sexual satisfaction, weight gain, fertility issues, irregular menstrual cycles, vaginal dryness and loss of bone density. There is, however, limited research in this area. When there are small trials or trials that are not statistically significant, more robust trials and research are needed to show causality.  

Cortisol

Caffeine seems to increase cortisol levels, especially when combined with other stressors. The body naturally produces adrenaline in response to stress. Cortisol, the stress hormone, increases excess sugar in the bloodstream and enhances the brain’s use of the sugars. In the short term, elevated cortisol levels can lead to increased heart rate and energy level—part of the body’s “fight or flight” response. However, prolonged elevation in cortisol levels, which can occur under chronic stress or with a cortisol-producing tumor, can lead to other symptoms: decreased metabolism, weight gain, poor immune response, increased blood pressure, muscle weakness, fatigue, brain fog, difficulty concentrating, headaches, easy bruising, and poor wound healing.

Serotonin

Caffeine seems to decrease serotonin levels, which could affect mood in the long-term. Serotonin levels affect a range of body functions like orgasm, sleep, bladder and bowel functions, and mood, so it is difficult to attribute changes exclusively to serotonin levels. The levels can manifest in changes in mental and physical health. Mental health symptoms can be mood instability, depression, anxiety, schizophrenia, memory issues, sleep changes, sexual function, attention and hyperactivity. Physical health symptoms can be movement issues, premature ejaculation/orgasms, digestive difficulties, or incontinence. 

Dopamine

Caffeine seems to increase dopamine levels. Dopamine is used in our reward pathways and also movement. It has a direct effect on neurological, cognitive, and behavioral functions. Imbalance in dopamine levels is hard to detect and can manifest in many ways. High dopamine levels can increase your concentration, your energy, your sex drive, and your ability to focus. It can also lead to competitive, aggressive behavior and cause symptoms including anxiety, trouble sleeping, and stress. 

Oxytocin

Caffeine may increase levels of oxytocin, often called the love hormone. This may facilitate bonding and feelings of happiness and calm—a good reason to go on a coffee date.

How does caffeine affect men versus women?

More research is needed. However, caffeine’s effects on hormones in women seem to be more significant, specifically estrogen levels. There needs to be more studies on the source of caffeine as in caffeine from coffee versus tea, soda, or an energy drink. It’s currently unclear if they trigger different responses in the body. Decaffeinated coffee seems to have significantly less association with effects on hormones based on the few available studies.  

Symptoms of hormonal imbalance

“Signs of a hormonal imbalance tend to be very vague,” Dr. Oki says. “I also tend to avoid using this term as there are so many hormones in the body and each has their own profile of symptoms.” Symptoms can include:

• Fatigue
• Irritability
• Unexpected weight changes
• Changes in skin and hair including acne
• Changes in cycle including heavy menstrual bleeding or irregular/infrequent menstrual cycles

However, there are many other medical conditions that can cause these same changes so seeing a trusted medical provider is advised.  

The bottom line: Does caffeine mess with your hormones?

Maybe. The link between caffeine and hormones is a very complex one. It’s hard to give advice on whether to drink or abstain. There are studies suggesting caffeine may aid in preventing diabetes, unwanted weight gain (via appetite suppression), and breast cancer. There have also been studies suggesting caffeine may be detrimental to health. 

“I advise pregnant women to avoid caffeine mostly because we try to limit what we expose a growing fetus to,” Dr. Oki says. “In general, for those who drink coffee, rather than trying to figure out what it’s doing to their body, it’s worth trying to figure out why they are drinking the coffee in the first place. If you are using it to compensate for poor sleeping habits or poor dietary habits, those are more likely to cause you harm in the long term.”

Maintaining a healthy diet, exercise regimen, and sleep routine while drinking coffee in moderation—one to two cups a day—is likely best. It’s also smart to pay attention to what you’re adding to your coffee. Cream and sugar introduce a lot of calories, which can have negative effects on your body. If you have a health condition or are experiencing unexplained symptoms after drinking coffee, consult with your provider.