Summary of general beneficial health findings:  

• An inverse association between daily coffee consumption of 3-4 cups/day and all-cause mortality has been observed.  In other words, when people drink up to 4 cups of coffee per day, there are lower rates in all causes of death.   
• Coffee appears to lower the risk of heart disease, congestive heart failure, high blood pressure, degenerative neurologic disease, liver disease, inflammatory disease, and cancer.  
• Improvements in diabetes, metabolic syndrome, depression, obesity and asthma have been observed.  
• A meta-analysis found an inverse association of coffee/caffeine with breast cancer risk in postmenopausal women.  
• Several studies indicate that caffeine consumption reduces the relative risk of various cancers.

Summary of beneficial health findings, specific to estrogenic activity of coffee:  

• Some of the compounds found in coffee (caffeic acid, chlorogenic acid, and vanilic acid) have estrogenic activity and have shown promise for bone protection and in the treatment of osteoporosis.  
• Nicotinic acid is associated with protection of the cardiovascular system through estrogenic activity. 
• Caffeic acid, caffeic acid phenethyl ester, ferulic acid, sinapic acid, stigmasterol, and theophylline demonstrate estrogenic action and may help relieve menopausal symptoms.  
• Caffeine, gallate (octyl), serotonin, beta-sitosterol, and gamma-tocotrienol show mostly estrogenic action and seem to offer protection to the neurologic system.

While there are many studies that support coffee’s health benefits, there are also studies that show negative health effects. 

Summary of negative findings on general health:   

• Coffee can increase the risk of anxiety, insomnia, headaches, tremors, and palpitations, especially in heavy users.   
• There is evidence that coffee can increase blood pressure in people who already have hight blood pressure for approximately 3 hours after consumption.
• High coffee consumption (4+ cups daily) was associated with a small reduction the bone density of women, but that did not translate into an increased risk of fracture. 
• Coffee has shown to increase risk of low birth weight, and preterm birth during pregnancy in a dose dependent fashion.  

Summary of negative health findings, specific to estrogenic activity of coffee:   

• Caffeic acid at low doses and trigonelline seem to exert unfavorable effects on bone, though it is thought that low estrogen levels are required for this to happen. 
• Trigonelline, a natural component in green coffee beans and other unidentified compounds, was found to be mutagenic (cause damage to cell DNA), especially after roasting.  
• Excessive estrogen can potentially cause endocrine disruption, and reproductive dysfunction. These effects were reported for coffee extracts, hippuric acid, humic acid, lecithin, and β-sitosterol.  
• Acrylaminde, a substance formed during the roasting process at high temperatures in the Maillard reaction, may have carcinogenic activity.  

The health effects of coffee can be traced back to each biologically active compound, such as caffeine. Though the research specific to estrogenic activity is interesting, it is likely premature to gain any solid clinical implications from it.  

Coffee consumption is generally safe within usual levels of intake, with estimates indicating the largest risk reduction for various health outcomes at three to four cups each day, and more likely to benefit health than harm it. 

However, some people, including those with high blood pressure or anxiety, may be more likely to experience the negative effects of caffeine. Some evidence suggests that it may be prudent for pregnant women to limit coffee consumption to 3 cups per day. Women at increased risk of fracture (possibly due to low estrogen levels), may also be more vulnerable than the general population. 

Although it is not discussed in any of the studies I read, coffee may impact cortisol and adrenalin levels.  For people struggling with adrenal fatigue, it may not be recommended.

Research is ongoing, because people love their coffee, and more information will continue to be released.  So if you fall into one of the groups that coffee may benefit, then moderate consumption (3-4 cups per day) is okay.