Coffee Estrogen LinkSeptember 29, 2010 Written by JP [Font too small?]
A friend of the site recently posed an interesting question. She wondered whether drinking coffee adversely affects sex hormone levels in women. In particular she inquired about supposed estrogenic elements in coffee which may lead to an excess of estrogen or “estrogen dominance” in women. Ultimately, her concern was that regular coffee consumption could confer similar side effects as hormone replacement therapy.
Coffee does, in fact, contain phyto or plant estrogens. Studies dating back to the 1980’s have identified “weakly estrogenic” components in coffee. A paper published in the August 2008 issue of the Journal of Agricultural Food Chemistry found that coffee and tea contained up to 20 mcg/100 g of lignans, a type of phytoestrogen. While beer contained significantly more lignans – 71 mcg/100 g. These are obviously minute quantities of plant-derived estrogens. However, the authors of the study noted: “As these beverages are commonly consumed, they are a main source of dietary lignans”. Furthermore, emerging research is discovering previously unknown phytoestrogens in coffee which may alter “the actions of estradiol” and activate estrogen receptors. (1,2,3)
The best way to accurately assess the affects of coffee consumption and its impact on estrogen levels is to directly examine the medical literature. I’ve identified five studies that have scientifically evaluated this very topic. Here’s what they have to say:
- The June 2009 issue of the journal Cancer examined the relationship between “caffeine, coffee, decaffeinated coffee and tea” and plasma concentrations of various sex hormones in 524 premenopausal and 713 postmenopausal women. In the premenopausal women, caffeine intake was associated with significantly lower levels of estradiol (a form of estrogen). The postmenopausal women demonstrated a positive association between caffeine and coffee intake and SHBG (sex hormone-binding globulin). However, this did not translate into any significant alteration in hormone levels. (4)
- The October 2001 edition of the journal Fertility and Sterility investigated the hormonal influence of alcohol, coffee and tobacco in 498 women with ages ranging from 36 – 45 “who were not currently pregnant, breast feeding, or using exogenous hormones”. Coffee consumption of more than 1 cup per day was associated with higher estradiol levels. Up to a 70% increase in “early follicular phase E2 (estradiol)” was found in women consuming over 500 mg of caffeine/day vs. those consuming <100 mg/day. (5)
- A 1998 publication in the journal Nutrition and Cancer studied the relationship between caffeine-containing beverages (black tea, coffee, cola, green tea and oolong tea) and serum estradiol and SHBG concentrations in 50 premenopausal women. Specifically, the researchers examined any hormonal alterations occurring on days 11 and 22 of the women’s menstrual cycles. Blood samples and food frequency questionnaires revealed that a higher intake of caffeine correlated to increased SHBG (sex hormone binding globulin). SHBG may inhibit estradiol-induced breast cancer cell growth and spread. Perhaps that’s why the conclusion of the study states that “consumption of caffeine-containing beverages appeared to favorably alter hormone levels associated with the risk of developing breast cancer”. (6,7)
- A 1996 study involving 728 postmenopausal women noted “significant inverse associations between caffeine intake and bioavailable testosterone”. Two or more cups of coffee or > 4 cans of caffeinated soda per day was also correlated with higher estrone and SHBG levels. The downside of this examination (“The Rancho Bernardo Study”) is that it didn’t differentiate between coffee and soda intake. (8)
- The May 1992 edition of the Annals of Epidemiology reported that “coffee intake, ascertained at the 26th week (of pregnancy), was found to be negatively related to pregnancy E2 (estradiol) levels”. This is believed to be one of the reasons why caffeinated coffee should be avoided during pregnancy as lower estrogen levels have been correlated with lower birth weight. (9,10,11)
Coffee Consumption May Decrease Cardiovascular Related Morbidity and Mortality
Source: American Journal of Clinical Nutrition, Vol. 83, No. 5, 1039-1046 (link)
There simply haven’t been enough well-designed studies to know with certainty what effect coffee is likely to have on estrogen concentrations in women during varying stages of life. But there is other information available which may assist in forming a more well-rounded perspective on this issue. Hormone replacement therapy (HRT) has been documented as increasing the incidence of breast cancer, endometrial cancer, heart attacks and strokes. If coffee truly provokes significant elevations in estrogen levels, it would seem likely that it too would increase the risk of the same health concerns.
A current review of the topic of coffee and cancer clearly states that, “There appears to be no association with breast, pancreatic, kidney, ovarian, prostate, or gastric cancer”. It goes on to reveal that, “For hepatocellular (liver) and endometrial cancers, there appears to be a strong and consistent protective association”. This summary point of view is largely supported by the latest population studies pertaining to both breast and endometrial cancer in relation to coffee consumption. But beware, adding sugar to coffee may negate the protective effect and even lead to a greater risk of endometrial cancer. (12,13,14,15,16,17,18)
The picture is even rosier when it comes to the coffee-cardiovascular issue. Three recent population studies involving approximately 200,000 participants have generally found a protective effect of moderate coffee consumption of between 12% to 55%. What’s most interesting is that some of the data points to gender-specific protection. For instance, a study carried out in the Netherlands concluded the following: “Coffee consumption was inversely associated with IHD (heart attack) mortality in women only”. A Japanese investigation came to a similar finding. “Our results suggest that coffee may have favorable effects on mortality due to all causes and CVD (cardiovascular disease), especially CVD, in women”. (19,20,21)
So what’s the answer to the question that originally inspired this column? It seems that caffeinated coffee can affect hormone levels, but it doesn’t do so in a predictable manner. If this is a concern for you, you might look at the studies above to determine which group of women you most closely resemble. Your hormonal response *may* be similar to theirs. However, I think what’s more important is to look at the end result of coffee consumption. The evidence that’s currently available suggests that coffee is unlikely to predispose women to the same health threats brought about by synthetic hormone replacement therapy. On the flip side, it’s also important to keep in mind that coffee is unlikely to yield the same health benefits of HRT as well.
Note: Please check out the “Comments & Updates” section of this blog – at the bottom of the page. You can find the latest research about this topic there!
Tags: Coffee, Estrogen, Phytoestrogens
Posted in Food and Drink, Nutrition, Women's Health