Coffee influences health in multiple ways. It acts as a stimulant, increasing cortisone and adrenaline production. However, moderate coffee intake appears to protect against heart disease, on balance. Coffee has also been linked to reduced risks of type 2 diabetes, gallstone development, and Parkinson's disease. On the other hand, drinking coffee, especially unfiltered coffee, can raise cholesterol levels.
Fertility may be impaired for some coffee drinkers. In addition, caffeine consumption has been reported to be associated with higher risks of osteoporosis and benign fibrocystic breast disease (although not all studies are in agreement).
Coffee and cancer risk generally
Cafestol, caffeine, chlorogenic acid, ferulic acid, hydroxyl hydroquinone, kahweol, the phytoestrogen trigonelline, and various other polyphenols and aromatic volatile compounds are thought to contribute to the cancer-related effects of coffee consumption.
Coffee is associated with decreased risks of liver, kidney and colorectal cancers, as well as non-Hodgkin lymphoma. The coffee diterpenes cafestol and kahweol have been shown to offer some protection against mutagenic damage by heterocylic amines (HCAs) and aflatoxin B1 in laboratory animals. Human consumption of these coffee components has been associated with lower rates of colon tumors. On the other hand, drinking coffee has been shown to be associated with a marginally increased risk of lung cancer in smokers. Childhood malignant central nervous system tumors have also been reported to be associated with maternal coffee drinking during pregnancy.
Coffee can influence effectiveness of breast cancer treatment
Coffee might increase the treatment effects of tamoxifen
Regularly consuming at least two cups of caffeinated coffee per day has the potential to heighten the effectiveness of tamoxifen treatment, according to one study. Another study reported that coffee cooperates with tamoxifen to induce cell-cycle arrest and programmed cell death. Caffeine is necessary, but not sufficient, for this effect, indicating that at least one other coffee compound is involved.
Coffee might reduce effectiveness of anthracycline & taxane chemotherapy
Coffee might reduce the effectiveness of Adriamycin (doxorubicin) and other anthracycline chemotherapy as a result of its caffeine content. Decaffeinated coffee incorporates approximately 5% to 10% of the caffeine of regular coffee, or approximately 7 mg per 8-ounce cup. As such, modest amounts of decaffeinated coffee probably can safely be consumed during anthracycline chemotherapy (however, check with your oncology team).
There is also evidence that coffee could reduce the effectiveness of Taxol (paclitaxel) and other taxane chemotherapy as a result of its caffeic acid content. Decaffeinated coffee can contain even more caffeic acid than regular coffee and should not be used as a substitute by those undergoing taxane chemotherapy.
Breast cancer-related effects of drinking coffee
Overall findings
Coffee drinking has variously been reported to have small positive, small negative, or no association with breast cancer risk in the general population. For example, a large 2020 prospective study of postmenopausal women found no association between caffeinated or decaffeinated coffee intake and breast cancer risk. The same study reported that coffee was not associated with risk of hormone receptor positive (which was defined as ER+ and/or PR+) or hormone receptor negative (ER−/PR−) breast cancer.
Another large 2021 study reported that higher post-diagnostic coffee consumption was associated with lower rates of breast cancer-specific death compared to no coffee intake during up to 30 years of follow up. Those drinking over three cups per day experienced a 25% lower risk of death from breast cancer compared to non-drinkers.
However, the body's reaction to coffee can vary for different women based on genetic differences and other factors. Large population studies tend to mask such differences by combining results of subgroups for whom coffee drinking may reduce risk of breast cancer or its recurrence with subgroups for whom coffee may increase such risks.
Breast cancer risk by ER status
Studies that have attempted to determine the possible influence of coffee consumption on risk of breast cancer according to hormone receptor status have produced inconsistent results. One major 2023 study reported that coffee was associated with lower risk of breast cancer, especially among lean women and for ER- breast cancer. A Swedish study reported that coffee consumption is associated with reduced risk of ER+/PR- disease.
Relatively high caffeine intake has been found to be associated with ER-/PR- breast cancer, as well as with breast tumors greater than 2 cm in size, among women with benign breast disease. The implication is that coffee drinking should be limited or avoided by women with benign fibrocystic breast disease.
Breast cancer risk by menopausal status
Studies that have attempted to determine the possible influence of coffee consumption on risk of breast cancer according to menopausal status have also produced conflicting results. Some studies have reported an association between coffee drinking and increased premenopausal breast cancer risk. Other studies have reported a neutral or beneficial effect of coffee drinking among postmenopausal women. Several studies have reported a possible association between heavy coffee drinking and increased risk of ER- breast cancer in premenopausal women. Other studies have reported that coffee drinking is associated with reduced risk of ER- breast cancer or no association with risk in postmenopausal women.
However, coffee consumption has been found to increase the risk of breast cancer among postmenopausal women who previously used hormone replacement therapy (HRT).
Breast cancer risk according to body weight
One Swedish study found that coffee consumption was associated with a reduction in breast cancer risk among lean women, whereas it appeared to have the opposite effect in heavy women. As noted above, a major 2023 study reported that coffee was associated with lower risk of breast cancer, particularly among lean women.
Breast cancer risk by genetic factors
Coffee and harmful BRCA mutations
Several studies have reported that heavy coffee consumption is linked to significantly reduced breast cancer risk among women with harmful BRCA1 or BRCA2 gene mutations. However, an earlier 2013 study reported increased breast cancer risk among BRCA1 carriers who were heavy coffee drinkers.
Breast cancer risk depends in part on CYP1A2 genotype
The effect of coffee consumption on breast cancer risk depends in part on a person's CYP1A2 genotype, regardless of whether a harmful BRCA mutation is present. The CYP1A2 gene plays a crucial role in the metabolism of both estrogen and coffee. Regular heavy coffee consumption increases the expression of the CYP1A2 gene, which encodes a member of the cytochrome P450 family of enzymes. Coffee has been found to protect C-allele carriers against breast cancer by reducing breast volume. Coffee consumption has also been shown to slow the growth of ER+ tumors in women with the CYP1A2*1F A/A genotype.
Like BRCA1 and BRCA2 mutations, a woman's CYP1A2 genotype can only be determined through genetic testing. Such this testing is not normally available.
Breast cancer risk from acrylamide
Acrylamide, a chemical byproduct of the coffee bean roasting process, is a suspected carcinogen. Acrylamide is also found in other roasted, fried, and baked foods such as potato chips, French fries, bread and smoked almonds. Levels can vary greatly for a given type of food. A small bag of potato chips can contain two or more times the amount of acrylamide as a cup of coffee.
The majority of the studies that have examined the association between acrylamide and breast cancer have reported negative or inconclusive results. However, a 2020 study reported that breast cancer risk increased in proportion to acrylamide intake once it reached 20 μg/day (approximately seven 8-oz cups) among premenopausal women. A 2021 meta-analysis of data from 18 previous studies found that high acrylamide intake was associated with increased breast cancer risk among premenopausal (but not postmenopausal) women. Also, a 2024 study reported that DNA damage caused by acrylamide exposure was exacerbated by obesity in a mouse model of breast cancer.
In addition, several large Scandinavian studies have found a link between high acrylamide intake and increased breast cancer risk. For example, one large Danish study reported that relatively high pre-diagnostic acrylamide levels (based on acrylamide-related markers in the blood) were associated with increased mortality among women who subsequently developed ER+ breast cancer. Note that Scandinavians typically have far higher coffee intake than U.S. residents.
Acrylamide levels are lower in darker coffee roasts compared to light roasts since acrylamide production hits its highest point early in the heating process and then declines. Therefore, the potential risk of breast cancer associated with acrylamide in coffee is highest for light roasts.
Instant coffee has higher acrylamide content than coffee made from roasted beans. One 2019 study reported that while there was no association between overall coffee drinking and breast cancer risk, women who consumed instant coffee experienced significantly increased risk.
Breast cancer risk according to coffee preparation method
Aluminum moka pots should not be used to brew coffee
Coffee should not be brewed using an aluminum moka pot since this has been shown to introduce significantly higher aluminum concentrations into the beverage. Aluminum exposure has been linked to increased breast cancer risk.
Coffee pods may contain estrogenic compounds
One 2021 study reported that coffee brewed using coffee machines that accept single-serve coffee pods, K-Cups or capsules may possess weak estrogenic activity. Six different coffee samples were tested and found to be positive for estrogenic chemicals which had migrated from the packaging, including bisphenol A (BPA), bisphenol F, benzophenone, 4-nonylphenol, dibutyl phthalate, and dimethyl terephthalate.
Bottom line
Based on the available evidence, light to moderate coffee consumption appears to be safe for most postmenopausal women, including breast cancer survivors. The potential risks of heavy coffee intake appear to outweigh the potential benefits for most premenopausal women and it would appear prudent for them to limit coffee consumption. Drinking coffee may be beneficial for those undergoing treatment with tamoxifen. However, coffee should not be consumed during most types of chemotherapy used for breast cancer. Women with benign breast disease should avoid coffee consumption.
These are tentative conclusions. More research is needed to clarify the association between coffee drinking and breast cancer risk and prognosis.
Additional comments
Organic coffee is a better choice than non-organic coffee since coffee is often grown using high levels of pesticides.
High coffee consumption has been linked to reduced bone health, although study findings are inconsistent. One 2018 Chinese study reported that drinking four or more cups of coffee per day was associated with a higher hip fracture risk, while a moderate intake appeared to reduce the risk in postmenopausal women.
Coffee has been shown to be an iron chelator (containing compounds that remove iron from the body), which may be helpful in reducing iron for some women (since high iron stores might contribute to breast cancer risk), but could negatively impact women with marginal iron stores.
Sources of information provided in this webpage
The information above, which is updated continually as new research becomes available, has been developed based solely on the results of academic studies. Clicking on any of the underlined terms will take you to its tag or webpage, which contain more extensive information.
Below are links to 20 recent studies concerning coffee and its components. For a more complete list, including less recent studies, please click on coffee.