Fact Check: Does drinking milk increase the risk of breast cancer by up to 50 percent?

Claim: A post on the social media site Instagram claims that evidence suggests that consistently drinking as little as one cup of dairy milk per day can increase the risk of breast cancer by up to 50 per cent. The link to the post is here.

Fact Check:

The claim is False. There is no scientific evidence/study to support the statistics or the claim that drinking milk can increase the risk of breast cancer by up to 50 percent

What is Breast cancer?

According to the World Health Organization, ‘‘Cancer is a large group of diseases that can start in almost any organ or tissue of the body when abnormal cells grow uncontrollably, go beyond their usual boundaries to invade adjoining parts of the body and/or spread to other organs.”(1)

According to the American Cancer Society, “Breast cancer is a type of cancer that starts in the breast”. It can start in one or both breasts. Most breast lumps are benign and not cancer (malignant). Breast cancer can spread when the cancer cells get into the blood or lymph system and then are carried to other parts of the body. (2)

Some of the risk factors of Breast cancer may include:

1. Drinking alcohol

2. Being overweight or obese

3. Not being physically active

4. Birth control

5. Breast implants

Causes of Breast Cancer:

Speaking to Medical dialogues, Dr. Ferdinant J Consultant, Endocrine Surgery Apollo Adlux Hospital, explained the causes of breast cancer as 

"Genetic Mutations: Inherited mutations in genes like BRCA1 and BRCA2.

Age: Risk increases with age, especially in women over 50.

Family History: Having a first-degree relative with breast cancer.

Hormonal Factors: Prolonged exposure to estrogen, early menstruation, late menopause, or hormone replacement therapy.

Personal History: Previous breast cancer or certain non-cancerous breast conditions.

Dense Breast Tissue: Higher risk in women with dense breast tissue.

Excessive Alcohol Consumption: More than one alcoholic drink per day.

Obesity: Especially after menopause."

Milk and its nutritional components:

Milk is generally considered an important protein source in the human diet, supplying approximately 32 g protein/L. Its protein fraction can be divided into soluble and insoluble proteins. On average, bovine milk is composed of 87% water, 4% to 5% lactose, 3% protein, 3% to 4% fat, 0.8% minerals, and 0.1% vitamins. (3)

Does drinking milk increase the risk of breast cancer?

There is not much scientific evidence that Dairy consumption is associated with the increased risk of developing breast cancer. Also there is no scientific evidence in support of the specific claim that drinking milk can increase the risk of breast cancer by up to 50 percent.

On the contrary, there are many studies showing Dairy consumption is inversely related to the risk of developing breast cancer.

A Buenosvinos I et al. study found that Breast cancer and milk product intake were statistically and significantly inversely related. (4)

According to the cross-sectional study by Arafat HM et al. 2023, women who consume dairy foods have a lower risk of developing breast cancer than women who do not consume total dairy products. (5)

Having said that, a study by He et al. mentioned that dairy products have both pro- and anti-carcinogenic effects. Dairy products are rich in calcium, vitamin D, and conjugated linoleic acid, which affect cell proliferation and differentiation and can inhibit tumour development. Conversely, dairy products with high levels of fats, saturated fats, and possibly cancer-causing contaminants like pesticides, estrogen metabolites, and growth factors like IGF-1 may raise the risk of Breast cancer (6)

Expert Opinion:

Speaking to Medical dialogues, Dr H.K. Cheema, Professor & Head, Department of Obstetrics & Gynaecology, Punjab Institute of Medical Sciences Jalandhar, explained, "Till date, no research-based evidence has claimed or reported this myth/claim. However, lifestyle modifications, which include weight management with an adequate balanced diet along with regular exercises and early regular screening of high-risk cases of breast cancer and ovarian cancer, have been reported in families to help prevent Breast and ovarian cancer. This fact has also been endorsed by various international guidelines and the World Health Organisation."

Analysing the specific claim of 50% increase with the Medical dialogues team, Dr Smriti Uppal, Consultant Obstetrician and gynaecologist, clarified that " It would be very inappropriate to label that consistently drinking milk can increase the risk of breast cancer by 50%. Many studies have been conducted to find a relationship between dairy products and the incidence of cancers, specifically breast cancer, and many of them have shown an inverse relationship between the two, implying that milk is rather protective for breast cancer on the other hand, very few studies are there which have shown some correlation between the consumption of dairy proteins and increased incidence of cancer in general and many studies are still in progress."

Medical Dialogues Final intake:

This specific claim states that evidence suggests consistently drinking as little as one cup of dairy milk per day can increase the risk of breast cancer by up to 50 percent. The claim suggests evidence, but we couldn't find any scientific evidence claiming these statistics. On the contraary Many studies show dairy consumption is inversely related to the risk of developing breast cancer.

Hence, the claim that evidence suggests that consistently drinking as little as one cup of dairy milk per day can increase the risk of breast cancer by up to 50 per cent is False.

Reference:

1. https://www.who.int/health-topics/cancer#tab=tab_1

2. https://www.cancer.org/cancer/types/breast-cancer/about/what-is-breast-cancer.html#:~:text=Breast%20cancer%20is%20a%20type,%2C%20see%20What%20Is%20Cancer%3F)

3. Pereira, P. C. (2013). Milk nutritional composition and its role in human health. Laboratorio de Bioquímica, CiiEm - Centro de Investigação Interdisciplinar Egas Moniz, Egas Moniz, Cooperativa de Ensino Superior, C.R.L. Quinta da Granja, Monte de Caparica, Caparica, Portugal.

4. Aguilera-Buenosvinos I, Fernandez-Lazaro CI, Romanos-Nanclares A, et al.. Dairy consumption and incidence of breast cancer in the ‘seguimiento universidad de navarra’ (SUN) project. Nutrients. 2021;13(2):687.

5. Arafat HM, Omar J, Shafii N, Naser IA, Al Laham NA, Muhamad R, Al-Astani TAD, Shaqaliah AJ, Shamallakh OM, Shamallakh KM, Abusalah MAH. The association between breast cancer and consumption of dairy products: a systematic review. Ann Med. 2023 Dec;55(1):2198256. doi: 10.1080/07853890.2023.2198256. PMID: 37078247; PMCID: PMC10120447.

6. He Y, Chen P, Zhou F, et al.. The relationship between dairy product intake and breast cancer incidence: a meta-analysis of observational studies. BMC cancer. 2021;21(1):1109.