THE BLOG
07/31/2015 12:50 pm ET Updated Jul 31, 2016

Raise a Glass? The Story Behind Alcohol and Breast Cancer

When it comes to alcohol and health, the take-home advice can get confusing. On the one hand, women hear that it's good for the heart: Studies have shown that a moderate amount of alcohol can lower blood pressure levels and protect against heart disease. (1, 2)

But research shows that alcohol can raise your chances of developing breast cancer (3). One review of 53 studies involving more than 153,000 women published in the British Journal of Cancer found that women who sipped two to three alcohol beverages a day were 20 percent more likely to have breast cancer than those who rarely drank. The researchers also showed that for each alcoholic drink per day, the relative risk of breast cancer increased by seven percent. (7)

Meanwhile, alcohol's effect on breast cancer patients and survivors is less than clear cut: Some data suggests that it can increase the risk of recurrence or death, while other studies shows that it doesn't. (4-6)

So, what are we to make of all of these mixed messages? Should you cut back at happy hour for the sake of your health? Or, should you banish wine, beer, and cocktails entirely, given that one in eight women will develop breast cancer sometime during her lifetime? (9) Here, we'll examine the research covering the topic -- so you can have all the information you need to make the best choices for your body.

How Alcohol Increases Breast Cancer Risk

While scientists haven't yet pinpointed the exact role alcohol plays in the development of breast cancer, they have identified a number of different ways that it may set the stage for the disease. One key factor is estrogen, the female sex hormone. It's established that having high levels of estrogen stimulates the growth of breast cancer cells and estrogen-responsive tumors, raising the risk of developing breast cancer. (9)

Research shows that alcohol can increase the amount of estrogen circulating in the bloodstream. (8) According to a review of 13 studies involving more than 6,000 post-menopausal women conducted by the University of Oxford's Endogenous Hormone and Breast Cancer Collaborative Group in England and published in the British Journal of Cancer, women who consumed the equivalent of two alcoholic beverages a day had higher levels of estrogen circulating than those who didn't drink at all. (8)

Another way that alcohol may encourage the growth breast cancer is because of its harmful effect on cellular DNA. One study published in Alcoholism: Clinical & Experimental Research revealed that a byproduct of alcohol called acetaldehyde damages DNA. This, in turn, was shown to trigger a response associated with the growth of breast cancer. (10)

To make matters worse, alcohol can deplete levels of folate, a vitamin that helps repair DNA in the body. Case in point: A study involving nearly 33,000 women published in the Journal of the National Cancer Institute revealed that women who sipped at least one alcoholic beverage a day had lower levels of folate and a greater risk of breast cancer. (11) And research, including a study from Australia's Cancer Epidemiology Centre (12) revealed that consuming high levels of folate and folic acid (the synthetic form of the vitamin) mitigated that effect. In fact, the study authors concluded, "An adequate dietary intake of folate might protect against the increased risk of breast cancer associated with alcohol consumption." (12)

So, how much folate should you get? According to the National Institutes of Health (NIH)'s Recommended Dietary Allowances, women should consume 400 micrograms (mcg) of folate a day. (13) Fortunately, the vitamin is found in multivitamins and common foods such as spinach, rice, and asparagus, just to name a few. But keep in mind that you can get too much of a good thing: The NIH advises getting no more than 1,000 mcg per day.

Alcohol and Breast Cancer Patients and Survivors

Taking into account all of these factors, it's natural to assume that breast cancer patients and survivors should avoid alcohol at all costs. But the research shows that the reality is more nuanced.

In a study of 1,897 people published in the Journal of Clinical Oncology, early-stage breast cancer survivors who drank three to four alcohol drinks a week were 35 percent more likely to experience a recurrence and 51 percent more likely to die of the disease than their teetotaler counterparts. (14) The scientists also found that alcohol was associated with a reduced risk of all-cause mortality, potentially because of its heart-protective benefits. (14)

On the other hand, a study involving 3,088 breast cancer survivors from the University of California, San Diego's Cancer Prevention and Control Program showed that light to moderate alcohol intake -- consuming less than one drink per day -- was not associated with breast cancer recurrence. (15) The researchers speculate that antioxidants in beer and wine may have a protective effect, writing, "Bioactive constituents in beer and wine, such as flavonoids and polyphenols, have been hypothesized to reduce mortality risk after cancer." (15)

Experts say that age may play a role in whether alcohol raises the risk for breast cancer recurrence. In a 10-year study published in the Journal Cancer Epidemiology, Biomarkers & Prevention, researched tracked 9,329 women who had stage one to three breast cancer. (16) They found that those who average about half an alcohol drink per day -- or about three to four a week -- had no greater risk of having a recurrence of the disease than non-drinkers, except... postmenopausal women who drank that amount were 19 percent more likely to have a recurrence (16).

What's the Bottom Line?

What does this all mean? It all largely depends on your own personal risks for breast cancer and comfort level. Alcohol's effect on breast cancer risk does exist, although more studies are needed to fully define just how much. Speak with your health care provider. You'll want to weigh your risk for breast cancer and heart disease with your enjoyment of the occasional glass of wine, beer, or cocktail.

References:

1. Fuchs CS, Stampfer MJ, Colditz GA, et al. Alcohol consumption and mortality among women. N Engl J Med. 332(19):1245-50, 1995.

2. Forman JP, Stampfer MJ, Curhan GC. Diet and lifestyle risk factors associated with incident hypertension in women. JAMA. 302(4):401-11, 2009.

3. Hamajima N, Hirose K, Tajima K, et al. for the Collaborative Group on Hormonal Factors in Breast Cancer. Alcohol, tobacco and breast cancer--collaborative reanalysis of individual data from 53 epidemiological studies, including 58,515 women with breast cancer and 95,067 women without the disease. Br J Cancer. 87(11):1234-45, 2002.

4. Kwan ML, Kushi LH, Weltzien E, et al. Alcohol consumption and breast cancer recurrence and survival among women with early-stage breast cancer: the life after cancer epidemiology study. J Clin Oncol. 28(29):4410-6, 2010.

5. Flatt SW, Thomson CA, Gold EB, et al. Low to moderate alcohol intake is not associated with increased mortality after breast cancer. Cancer Epidemiol Biomarkers Prev. 19(3):681-8, 2010.

6. Kwan ML, Chen WY, Flatt SW, et al. Postdiagnosis alcohol consumption and breast cancer prognosis in the after breast cancer pooling project. Cancer Epidemiol Biomarkers Prev. 22(1):32-41, 2013.

7. Hamajima N, Hirose K, Tajima K, et al. for the Collaborative Group on Hormonal Factors in Breast Cancer. Alcohol, tobacco and breast cancer--collaborative reanalysis of individual data from 53 epidemiological studies, including 58,515 women with breast cancer and 95,067 women without the disease. Br J Cancer. 87(11):1234-45, 2002.

8. Key TJ, Appleby PN, Reeves GK, et al. for the Endogenous Hormones and Breast Cancer Collaborative Group. Circulating sex hormones and breast cancer risk factors in postmenopausal women: reanalysis of 13 studies. Br J Cancer. 105(5):709-22, 2011.

9. American Cancer Society, http://www.cancer.org/cancer/breastcancer/detailedguide/breast-cancer-risk-factors

10. Jessy Abraham, Silvia Balbo, David Crabb and Phillip J. Brooks. Alcohol Metabolism in Human Cells Causes DNA Damage and Activates the Fanconi Anemia-Breast Cancer Susceptibility (FA-BRCA) DNA Damage Response Network. Alcoholism: Clinical & Experimental Research, 2011

11. Zhang SM, Willett WC, Selhub J, et al. Plasma folate, vitamin B6, vitamin B12, homocysteine, and risk of breast cancer. J Natl Cancer Inst. 95(5):373-80, 2003.

12. Baglietto L, English DR, Gertig DM, Hopper JL, Giles GG. Does dietary folate intake modify effect of alcohol consumption on breast cancer risk? Prospective cohort study. BMJ. 331(7520):807, 2005.

13. National Institutes of Health, https://ods.od.nih.gov/factsheets/Folate-HealthProfessional/

14. Kwan ML, Kushi LH, Weltzien E, et al. Alcohol consumption and breast cancer recurrence and survival among women with early-stage breast cancer: the life after cancer epidemiology study. J Clin Oncol. 28(29):4410-6, 2010.

15. Flatt SW, Thomson CA, Gold EB, et al. Low to moderate alcohol intake is not associated with increased mortality after breast cancer. Cancer Epidemiol Biomarkers Prev. 19(3):681-8, 2010.

16. Kwan ML, Chen WY, Flatt SW, et al. Postdiagnosis alcohol consumption and breast cancer prognosis in the after breast cancer pooling project. Cancer Epidemiol Biomarkers Prev. 22(1):32-41, 2013.