What Are the Pros and Cons of Milk's Effect on Cancer?

PRO (yes)

Eunyoung Cho, ScD, Assistant Professor of Medicine at Harvard Medical School, et al., completed a study titled "Dairy Foods, Calcium, and Colorectal Cancer: A Pooled Analysis of 10 Cohort Studies," published July 7, 2004 in the Journal of the National Cancer Institute:

"Studies in animals have suggested that calcium may reduce the risk of colorectal cancer. We pooled the primary data from 10 cohort studies in five countries...

RESULTS: Milk intake was related to a reduced risk of colorectal cancer. CONCLUSION: Higher consumption of milk and calcium is associated with a lower risk of colorectal cancer."

July 7, 2004 - Eunyoung Cho, ScD 

Anette Hjartåker, PhD, Researcher in the Department of Biostatistics in the Institute of Basic Medical Sciences at the University of Oslo, et al., in their study "Childhood and Adult Milk Consumption and Risk of Premenopausal Breast Cancer in a Cohort of 48,844 Women - the Norwegian Women and Cancer Study," published June 16, 2001 in the International Journal of Cancer, wrote:

"When combining milk consumption as a child and as an adult we observed a clear negative trend in premenopausal breast cancer incidence rate with increasing milk consumption... Compared with women who reported no or low consumption of milk on both occasions, women with moderate milk consumption had a reduced incidence rate of breast cancer of about 25%, whereas women with a high milk consumption on both occasions had a reduced incidence rate of about 50%."

June 16, 2001 - Anette Hjartåker, PhD 

Joan Lappe, PhD, Director of Clinical and Pediatric Studies at Creighton University and co-author of a study titled "Vitamin D and Calcium Supplementation Reduces Cancer Risk: Results of a Randomized Trial," published June 2007 in the American Journal of Clinical Nutrition said:

"This is the first clinical trial to show that boosting vitamin D status can affect the overall risk for cancer - a proposition that has tremendous public health potential.

By choosing vitamin-D rich foods like milk and taking a supplement Americans can help improve their vitamin D levels and potentially impact their cancer risk."

June 2007 - Joan Lappe, PhD 

Peter Elwood, MD, Professor of Epidemiology at Cardiff University, in his study "Time to Value Milk," published July 18, 2005 in the International Journal of Epidemiology, concluded:

"Both animal and human studies have suggested a reduction in colon cancer by calcium supplements and by milk. An overview of 10 cohorts studies, which together reported almost 5000 incident cases, gave evidence of a lower incidence of cancer in the distal colon with increasing intakes of milk."

July 18, 2005 - Peter Elwood, MD 

Kana Wu, MD, PhD, Research Scientist in the Department of Nutrition at the Harvard School of Public Health, et al., in their study "Calcium Intake and Risk of Colon Cancer in Women and Men," published Mar. 20, 2002 in the Journal of the National Cancer Institute, concluded:

"Higher calcium intake is associated with a reduced risk of distal colon cancer. The observed risk pattern was consistent with a threshold effect, suggesting that calcium intake beyond moderate levels may not be associated with a further risk reduction."

Mar. 20, 2002 - Kana Wu, MD, PhD 

Bonnie Liebman, MS, Director of Nutrition at the Center for Science in the Public Interest (CSPI), in a July-Aug. 2001 article on the CSPI website titled "Preventing Prostate Cancer: So Far, No Clear Answers," wrote:

"Not all studies see a link between calcium and prostate cancer. And most men never reach the 'too-much-calcium' range... So it's still safe to shoot for the latest Recommended Dietary Allowances (RDAs)-1,000 mg a day for men 50 or younger and 1,200 mg for men over 50."

July-Aug. 2001 - Bonnie Liebman, MS 

Nutra Ingredients, a website about nutrition, included an article on Mar. 9, 2002 titled "Dairy Foods Could Lower Ovarian Cancer Risk," which stated:

"Women who consume a large amount of dairy foods may reduce their risk of ovarian cancer... Women with the highest intake of dairy products were 54 per cent less likely to be diagnosed with ovarian cancer than those who ate the lowest amounts of dairy products...

Women who consumed the most dairy products overall, including low-fat and skimmed milk, were the least likely to be diagnosed with ovarian cancer. Ethnicity had no effect on the results...

The [research] team explained that it was both the high intake of calcium and lactose that lowered the cancer risk. Lactose, the sugar in dairy foods, is thought to increase calcium absorption and promote the growth of bacteria that fight cancer-causing chemicals."

Mar. 9, 2002 - NutraIngredients.com 

Sai Yi Pan, MD, Senior Epidemiologist at the Public Health Agency of Canada, et al., stated in their Sep. 2004 paper "A Case-Control Study of Diet and the Risk of Ovarian Cancer" in Cancer Epidemiology Biomarkers and Prevention:

"We saw no evidence of any pattern of association of ovarian cancer risk with... any dairy product, including all milk, low-fat milk, low-fat and skim milk, cheese, and ice cream... Our study found that several dietary factors were associated with ovarian cancer risk... However, [our study] failed to find an association with any dairy products."

Sep. 2004 - Sai Yi Pan, MD 

CON (no)

Harvard School of Public Health distributed a press release on Apr. 4, 2000, "Higher Intake of Dairy Products May Be Linked to Prostate Cancer Risk," that described researchers' findings after tracking the Physicians' Health Study:

"New data from a long-term study suggest an association between consumption of higher quantities of dietary calcium and risk of prostate cancer... They [researchers] found a moderate elevation in risk of prostate cancer associated with higher intakes of dairy products and dairy calcium...

The researchers also found that men who drank more than six glasses of milk per week had lower levels of the potentially protective form of vitamin D than men who drank fewer than two glasses of milk per week."

Apr. 4, 2000 - Harvard School of Public Health 

Alison Stewart, Editor of the Consumer Health Journal, wrote in a Mar. 2004 article titled "Hormones in Milk Are Linked to Cancer," published in the Consumer Health Journal, that:

"One reason milk consumption may lead to cancer risk is insulin-like growth factor, IGF-1 (not to be confused with bovine growth hormone, rBGH). Milk contains IGF-1 for good reason: milk is designed for babies, and IGF-1 helps us grow. IGF-1 affects growth, as well as other functions, and is normally found in our blood. Higher levels of IGF-1, however, appear to stimulate cancer cells."

Mar. 2004 - Alison Stewart, MA 

Joseph Mercola, DO, osteopath and author, in an article on his website titled "Don't Drink Your Milk!" (accessed Sep. 17, 2007), wrote:

"BGH [Bovine Growth Hormone] causes an increase in an insulin-like growth factor (IGF-1) in the milk of treated cows. IGF-1 survives milk pasteurization and human intestinal digestion. It can be directly absorbed into the human bloodstream, particularly in infants.

It is highly likely that IGF-1 promotes the transformation of human breast cells to cancerous forms. IGF-1 is also a growth factor for already cancerous breast and colon cancer cells, promoting their progression and invasiveness."

Sep. 17, 2007 - Joseph Mercola, DO 

Ganmaa Davaasambuu, MD, PhD, physician, scientist and research fellow at the Harvard School of Public Health, gave a lecture at Harvard University on Dec. 4, 2006, as reported by Corydon Ireland in his Harvard News article, "Hormones in Milk Can Be Dangerous," where she stated:

"In the past 50 years in Japan, rising rates of dairy consumption are linked with rising death rates from prostate cancer - from near zero per 100,000 five decades ago to 7 per 100,000 today."

Dec. 4, 2006 - Ganmaa Davaasambuu, MD, PhD 

Stephen Walsh, PhD, Science Coordinator for the International Vegetarian Union, wrote in a Nov. 2001 article titled "Milk and Breast Cancer," posted on the VegSource website:

"Consuming milk increases levels of a growth hormone, IGF-1, in the body. Increased IGF-1 levels are strongly implicated in prostate cancer, colorectal cancer, premenopausal breast cancer and lung cancer. The effect of milk on IGF-1 may be due to absorption of IGF-1 from the milk or may simply be due to the high protein and zinc content of the milk."

Nov. 2001 - Stephen Walsh, PhD 

Pelayo Correa, MD, Anne Potter Wilson Endowed Chair in Cancer Research at the Vanderbilt-Ingram Cancer Center, concluded in his Sep. 1981 study "Epidemiological Correlations Between Diet and Cancer Frequency," published in Cancer Research:

"Strong and consistent correlations are reported between death rates of cancers of the colon and breast and the per capita consumption of total fat and of nutrients derived from animal sources, especially beef, pork, eggs, and milk."

Sep. 1981 - Pelayo Correra, MD 

Medicine Online, a medical and health news website, included an article on Aug. 5, 2005 titled "High Milk Intake May Boost Ovarian Cancer Risk," which stated:

"Three, large, well-designed studies in which dietary intake as assessed among cancer-free women who were followed up over time to see who developed ovarian cancer showed an increased risk of ovarian cancer among women with high intakes of milk and lactose...

If women took in a daily increase of 10 grams of lactose, about the amount in one glass of milk, their risk of ovarian cancer increased by 13 percent...

Exactly how the dairy foods may boost risk isn't known, but lactose produces galactose and glucose, and galactose has been thought to increase the risk by direct toxicity to the ovarian germ cells."

Aug. 5, 2005 - MedicineOnline.com 

Susanna Larsson, PhD, researcher in the Unit of Nutritional Epidemiology at the Karolinska Institute in Sweden, et al., concluded in their study titled "Milk and Lactose Intakes and Ovarian Cancer Risk in the Swedish Mammography Cohort," published in the American Journal of Clinical Nutrition, in Nov. 2004:

"Women who consumed greater than or equal to four servings of total dairy products per day had a risk of serous ovarian cancer twice that of women who consumed less than 2 servings per day. We observed a positive association between lactose intake and serous ovarian cancer risk.

Our data indicate that high intakes of lactose and dairy products, particularly milk, are associated with an increased risk of serous ovarian cancer but not of other subtypes of ovarian cancer."

Nov. 2004 - Susanna Larsson, PhD