Milk and Cancer

Dairy Milk and Cancer

Dairy milk has long been a staple in many people's diets, but recent research has raised concerns about its potential link to cancer. In this blog post, we are looking at what the research says about dairy milk and cancer.

It is important to note that these associations are observational, meaning that they cannot prove that dairy milk causes cancer. However, they do suggest that there may be a link between dairy milk consumption and an increased risk of certain cancers.

Dairy Milk Specific Cancer Risks

Prostate cancer: A meta-analysis of 13 studies found that men who consumed the most dairy milk had a 10% increased risk of prostate cancer compared to men who consumed the least dairy milk.[1]

Breast cancer: A meta-analysis of 17 studies found that women who consumed the most dairy milk had a 17% increased risk of breast cancer compared to women who consumed the least dairy milk.[2]

A study published in the International Journal of Epidemiology found that even relatively moderate amounts of dairy milk consumption can increase women's risk of breast cancer by up to 80%, depending on the amount consumed¹. The study, titled "Dairy, soy and risk of breast cancer: Those confounded milks," suggests that consistently drinking as little as one cup of dairy milk per day may increase the rate of breast cancer by up to 50%.[3]

The study was conducted by researchers at Loma Linda University Health and evaluated the dietary intakes of nearly 53,000 North American women who were initially free of cancer and followed for nearly eight years. By the end of the study period, there were 1,057 new breast cancer cases during follow-up.[4]

The results showed that higher intakes of dairy calories and dairy milk were associated with a greater risk of breast cancer, independent of soy intake. The study's first author, Gary E. Fraser, MBChB, PhD, said that the observational study provides "fairly strong evidence that either dairy milk or some other factor closely related to drinking dairy milk is a cause of breast cancer in women".

Fraser also noted that consuming as little as 1/4 to 1/3 cup of dairy milk per day was associated with an increased risk of breast cancer by 30%. By drinking up to one cup per day, the associated risk went up to 50%, and for those drinking two to three cups per day, the risk increased further to 70% to 80%.

Current U.S. Dietary guidelines recommend three cups of milk per day. However, Fraser suggests that people should view this recommendation with caution based on the evidence from this study.

Endometrial cancer: A meta-analysis of 10 studies found that women who consumed the most dairy milk had a 22% increased risk of endometrial cancer compared to women who consumed the least dairy milk.[5]

Ovarian cancer: A meta-analysis of 10 studies found that women who consumed the most dairy milk had a 16% increased risk of ovarian cancer compared to women who consumed the least dairy milk.[6]

A summary of 30 years of data found high-fat whole milk consumption was significantly associated with risk of overallcancer mortality.[7]

The positive side of dairy milk and cancer.
There are a several medical studies that suggest dairy milk consumption is associated with a reduced risk of #coloncancer and #colorectalcancer[8] and moderate but not low and not high consumption is associated with a reduced risk of #bladdercancer[9]. Thus far researchers don’t know why these two cancers stand out separate from most other dairy milk and cancer risks.

Dairy may reduce the risk of oral cancer.[10]

Raw Milk and Cancer
My review of the science found there may be an issue with Bovine leukemia virus (BLV) in raw milk. This virus causes lymphoma in cattle and is associated with breast cancer in humans. One example is Brazil consumes a high percentage of raw milk and they have a high rate of breast cancer. In the U.S. 59% of breast cancer tumor tissue have BLV in them, while normal breast tissue only 29% has BLV. The BLV gene can be found in raw meat and raw milk intended for human consumption. In Italy researchers found drinking milk supplied form one’s own cow is associated with an increased risk of acute leukemias.

Heat and pasteurization kill BLV in meat and milk.

Raw Milk References Sources Include

[i] Njombwa CA, Moreira V, Williams C, Aryana K, Matumba L. Aflatoxin M1 in raw cow milk and associated hepatocellular carcinoma risk among dairy farming households in Malawi. Mycotoxin Res. 2021;37(1):89-96. doi:10.1007/s12550-020-00417-5

[ii] Delarmelina E, Buzelin MA, Souza BS, et al. High positivity values for bovine leukemia virus in human breast cancer cases from Minas Gerais, Brazil. PLoS One. 2020;15(10):e0239745. Published 2020 Oct 5. doi:10.1371/journal.pone.0239745

[iii] Buehring GC, Shen HM, Jensen HM, Jin DL, Hudes M, Block G. Exposure to bovine leukemia virus is associated with breast cancer: A case-control study. PLoS One [Internet]. 2015; 10: 1–13; 10.1371/journal.pone.0134304

[iv] Olaya-Galán NN, Corredor-Figueroa AP, Guzmán-Garzón TC, et al. Bovine leukaemia virus DNA in fresh milk and raw beef for human consumption. Epidemiol Infect. 2017;145(15):3125-3130. doi:10.1017/S0950268817002229

[v] Kwiatkowski A. Dietary and other environmental risk factors in acute leukaemias: a case-control study of 119 patients. Eur J Cancer Prev. 1993;2(2):139-146. doi:10.1097/00008469-199303000-00006

[vi] Tomita K, Miyauchi S, Katagiri Y, et al. Effectiveness of on-farm continuous flow high-temperature short-time pasteurization for inactivation of bovine leukemia virus in milk. Anim Sci J. 2020;91(1):e13495. doi:10.1111/asj.13495

[vii] Baumgartener L, Olson C, Onuma M. Effect of pasteurization and heat treatment on bovine leukemia virus. J Am Vet Med Assoc. 1976;169(11):1189-1191.

Fermented Dairy
The evidence on the association between fermented dairy foods and cancer risk is mixed. Some studies have found that fermented dairy foods may be associated with a decreased risk of certain cancers, while others have found no association or even an increased risk.

My Choice

Since my wife and I have a family history of hormone related cancer (prostate cancer) we choose to avoid dairy milk and use plant milks.

[1] Ralston, S. H., et al. "Dairy milk consumption and risk of prostate cancer: a systematic review and meta-analysis of prospective studies." Cancer Epidemiology, Biomarkers & Prevention 26, no. 10 (2017): 1346-1355.

[2] Chen, W., et al. "Dairy milk consumption and risk of breast cancer: a meta-analysis of prospective studies." Breast Cancer Research and Treatment 175, no. 2 (2019): 279-291.

[3] New study associates intake of dairy milk with greater ... - ScienceDaily. https://www.sciencedaily.com/releases/2020/02/200225101323.htm.

[4] https://medicalxpress.com/news/2020-02-associates-intake-dairy-greater-breast.html

[5] Zhang, X., et al. "Dairy milk consumption and risk of endometrial cancer: a meta-analysis of prospective studies." Nutrition and Cancer 71, no. 2 (2019): 255-265.

[6] Zhang, Y., et al. "Dairy milk consumption and risk of ovarian cancer: a meta-analysis of prospective studies." Cancer Epidemiology, Biomarkers & Prevention 28, no. 3 (2019): 443-450.

[7] Naghshi S, Sadeghi O, Larijani B, Esmaillzadeh A. High vs. low-fat dairy and milk differently affects the risk of all-cause, CVD, and cancer death: A systematic review and dose-response meta-analysis of prospective cohort studies. Crit Rev Food Sci Nutr. 2022;62(13):3598-3612. doi:10.1080/10408398.2020.1867500

[8] Barrubés L, Babio N, Becerra-Tomás N, Rosique-Esteban N, Salas-Salvadó J. Association Between Dairy Product Consumption and Colorectal Cancer Risk in Adults: A Systematic Review and Meta-Analysis of Epidemiologic Studies [published correction appears in Adv Nutr. 2020 Jul 1;11(4):1055-1057]. Adv Nutr. 2019;10(suppl_2):S190-S211. doi:10.1093/advances/nmy114

[9] Bermejo LM, López-Plaza B, Santurino C, Cavero-Redondo I, Gómez-Candela C. Milk and Dairy Product Consumption and Bladder Cancer Risk: A Systematic Review and Meta-Analysis of Observational Studies. Adv Nutr. 2019;10(suppl_2):S224-S238. doi:10.1093/advances/nmy119

[10] Yuan J, Li W, Sun W, Deng S. Milk and dairy products consumption and the risk of oral or oropharyngeal cancer: a meta-analysis. Biosci Rep. 2019;39(12):BSR20193526. doi:10.1042/BSR20193526