Coffee, Tea, Cacao, Caffeinated Sodas & Breast Cancer: 5+ Cups/Day?! Study & Meta-Analysis Show, It May Take More Coffee Than Previously Thought to Ward Off Breast Cancer

While you don't have to bath in coffee, one cup per day is probably not enough to protect your mammary glands.
Initially today's SuppVersity post was just about coffee and breast cancer risk. Today, a couple of days and a hand full of news on other interesting papers that are piling up by dozens in my archive, I found that the paper has proliferated ;-o

Well, not exactly, but in conjunction with a recent meta-analysis on the potential anti-breast-cancer effects of coffee today's news certainly covers data from almost 380,000 women world-wide and will thus probably yield somewhat more reliable data on whatever relation may exist between a woman's coffee / caffeine consumption and her risk of developing breast cancer.

It takes Canadian women at least 5 cups of coffee to elicit significant reductions in breast cancer risk

Against that background, both the detailed 7-item sub-analysis of the data from the Women’s Diet and Health Study and the unique inclusion of information on the cytochrome P450 1A2 (CYP1A2; the enzyme that's responsible for the metabolism of caffeine) gene variant of the 25 to 74 year old women distinguish the soon-to-be-published epidemiological study by Elizabeth C. Lowcock and her Canadian (resident) who found that there is no general association with coffee and caffeine consumption on the one, and breast cancer risk on the other hand.
"[H]owever, a significant reduction in risk was observed with the highest category of coffee consumption [≥5 cups per day vs. never, multivariate-adjusted odds ratio (MVOR)=0.71, 95% confidence interval (CI): 0.51, 0.98]." (Lowcock. 2013)
Interestingly, the ~30% reduction in breast cancer risk the scientists observed in their cohort of Ontarian women, did not depend on the gene variant of the aforementioned caffeine metabolizing enzyme from the cytochrome P450 enzyme cascade. coffee consumption, but not total caffeine" (Lowcock. 2013) that's associated with a reduced risk of both estrogen receptor positive and post-menopausal breast cancers.
Figure 1: Multivariate-adjusted odds ratios for breast cancer and coffee, decaffeinated coffee and caffeine intake w/out correction for CYP1A2 (rs762551) genotype (Lowcock. 2013)
In conjunction with the actual data from the 7-item analysis, this observation supports the scientists hypothesis that it is "coffee consumption, but not total caffeine" (Lowcock. 2013) that's associated with a reduced risk of both estrogen receptor positive and post-menopausal breast cancers.

If that is true, i.e. if it's not the main active ingredient caffeine, but one of or the complete spectrum of polyphenols the dark brew has to offer, it seems logical that such an exuberant amount of coffee is necessary to benefit from the purported protective effects (remember we are still talking about associations of consumption and breast cancer incidence - not mechanisms) of coffee. Why? Well, despite the fact that a comparison on a mere weight-to-weight ratio is obviously overtly simplistic, the amount of whatever flavenoid or other ingredient may turn out to be responsible for the anti-cancer effect is almost certainly at least one, if not several magnitudes smaller than those 100-200mg of caffeine your "average" (whatever that may be today) cup of coffee has to offer.

2% risk reduction per two cups? Looks like more was really better.

The notion that "more helps more" is indeed supported by another a meta-analysis of 37 international studies, Wenjie Jiang, Yili Wu and Xiubo Jiang from the Medical College of Qingdao University in Shandong have conducted (Jiian. 2013).

Suggested read: "Only 'Real', Yet Not Decaffeinated Instant Coffee Increases Fatty Acid Oxidation. Plus: Revisited, Caffeine's Dose-Dependent Effect on the Exercise Induced Changes to the ratio of Testosterone to Cortisol" (read more)
According to the study, which is going to find it's way into one of the next issues of Gynecologic Oncology, the collective data of 966,263 study participants (59,018 breast cancer cases) does not warrant the conclusion that either coffee or caffeine consumption (yes vs. no) is associated with a significant reduction in breast cancer risk:
  • coffee -- 3% risk reduction, p = 0.09
  • decaffeinated coffee -- 2% risk reduction p = 0.55 
  • caffeine - 1% risk reduction,  p = 0.73
In fact, the p-value, i.e. the probability that a result is mere coincidence, passes the magic p < 0.05 (meaning there is a <5% chance of the observed association being mere coincidence) hurdle only in postmenopausal coffee concessionaires, whose risk of developing breast cancer is 6% lower than that of their non-coffee guzzling peers.

What's particularly intriguing, though, is the fact that Jiang, Wu & Jiang found a linear dose-response relationship for breast cancer risk with coffee and caffeine, with
"the risk of breast cancer decreas[ing] by 2% (P=0.05) for every 2 cups/day increment in coffee intake, and 1% (P= 0.52) for every 200 mg/day increment in caffeine intake, respectively." (Jiang. 2013)
If we do the math this yield a 10% reduction in breast cancer risk for the 5 cups which gave the Canadian women a 30% edge over their non-coffee drinking peers.

In view of the fact that the number of people consuming this amount of coffee on a daily base (3% in the Women's Diet & Health Study) is in epidemiological terms comparatively low, the "small" deviation of 20% is nothing that would negate the existence of a surprisingly profound protective effect of coffee on the development of breast cancer.

Bottom line: I don't want to be a spoilsport, but as a versed SuppVersity reader you should by now be aware that anything beyond 400-500mg of caffeine (for a woman, for a man maybe 500-600mg) can produce a couple of nasty heart and central nervous system related side effects in view of which the regular / chronic consumption of more than 5 cups of coffee is nothing I would suggest as a means of cancer protection. And since the currently available data does not confirm similar beneficial effects for decaffeinated coffee (see figure 1 red button for likely explanations), you should consider different means of breast cancer protection. Which means that would be? Well, ...
    Even one cup of hot chocolate per week could help reduce your risk of developing breast cancer by 15% (learn more about the health effects of cacao & chocolate)
  • cut your intake of caffeinated soft-drinks to zero and thus reduce your breast cancer risk (compared to drinking 2 cans per day) by 24% or a statistically hardly significant, but still worth mentioning -7% vs. consuming only one can per week (Lowcock. 2013)
  • drink some black tea for a change, and achieve a 13% reduction in breast cancer risk with 3-5 cups per day (Lowcock. 2013)
  • never pass on a delicious cup of cacao, even one cup of hot chocolate per week can decrease your breast cancer risk (due to the low number of cacao drinkers the -15% reduction is yet not significant, Lowcock. 2013)
  • lose weight and visceral fat to avoid the +107% increase in breast cancer risk non-hispanic white women with a BMI >30kg/m² have compared to their non-obese fellow females (Connor. 2013)
If you work out and stick to a whole foods diet, that's about as much as you can do for the health of your mammary glands. Well,... maybe aside from taking synthetic estrogen and progestin combos to battle the symptoms of menopause (read more about this in the SuppVersity Facebook news).

  • Connor AE, Baumgartner RN, Pinkston C, Baumgartner KB. Obesity and Risk of Breast Cancer Mortality in Hispanic and Non-Hispanic White Women: The New Mexico Women's Health Study. J Womens Health (Larchmt). 2013 Mar 26.
  • Jiang W, Wu Y, Jiang X. Coffee and caffeine intake and breast cancer risk: An updated dose-response meta-analysis of 37 published studies. Gynecol Oncol. 2013 Mar 24.
  • Lowcock EC, Cotterchio M, Anderson LN, Boucher BA, El-Sohemy A. High Coffee Intake, but Not Caffeine, is Associated with Reduced Estrogen Receptor Negative and Postmenopausal Breast Cancer Risk with No Effect Modification by CYP1A2 Genotype. Nutr Cancer. 2013 Apr;65(3):398-409.
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