Dairy Hazards Cow’s milk
Epidemiology study found that, among women previously diagnosed with breast cancer, those consuming one or more servings of high-fat dairy products (e.g., cheese, ice cream, whole milk) daily had a 49% higher breast cancer mortality, compared with those consuming less than one-half serving daily, while low-fat dairy products were not associated with an increased risk. Research funded by the National Cancer Institute, the National Institutes of Health, and the World Cancer Research Fund, found that women who consumed 1/4 to 1/3 cup of cow’s milk per day had a 30% increased chance for breast cancer, while there was no change in risk associated with cheese or yogurt.
Milk and other dairy products are the top source of saturated fat in the American diet, contributing to heart disease, type 2 diabetes, and Alzheimer’s disease. Studies have also linked dairy to an increased risk of breast, ovarian, and prostate cancers.
Bone Health
Research shows that dairy products have little or no benefit for bone health. According to an analysis published in the British Medical Journal, most studies fail to show any link between dairy intake and broken bones, or fractures.3 In one study, researchers tracked the diets, exercise, and stress fracture rates of adolescent girls and concluded that dairy products and calcium do not prevent stress fractures.4 Another study of more than 96,000 people found that the more milk men consumed as teenagers, the more bone fractures they experienced as adults.
Cancer
Research has linked the high fat content and hormones in milk, cheese, and other dairy products to breast cancer.
A 2017 study funded by the National Cancer Institute that compared the diets of women diagnosed with breast cancer to those without breast cancer found that those who consumed the most American, cheddar, and cream cheeses had a 53% higher risk for breast cancer, while yogurt was associated with a lower risk, suggesting that the high saturated fat content in cheese may play a role.6
The Life After Cancer Epidemiology study found that, among women previously diagnosed with breast cancer, those consuming one or more servings of high-fat dairy products (e.g., cheese, ice cream, whole milk) daily had a 49% higher breast cancer mortality, compared with those consuming less than one-half serving daily.7
Research funded by the National Cancer Institute, the National Institutes of Health, and the World Cancer Research Fund, found that women who consumed 1/4 to 1/3 cup of cow’s milk per day had a 30% increased chance for breast cancer. One cup per day increased the risk by 50%.8
High intakes of dairy products including whole and low-fat milk increase the risk for prostate cancer, according to a meta-analysis that looked at 32 studies.9 In another study, men who consumed three or more servings of dairy products a day had a 141% higher risk for death due to prostate cancer compared to those who consumed less than one serving.10
But avoiding dairy products and eating a more plant-based diet may help protect the prostate. A study published in the American Journal of Clinical Nutrition found that men who followed a vegan diet had a 35% lower prostate cancer risk than those following a nonvegetarian, lacto-ovo-vegetarian, pesco-vegetarian, or semi-vegetarian diet.
Dairy – Cows milk
Cows milk’s relationship with hormones—specifically estrogen and IGF-1 (Insulin-like Growth Factor 1)—is a major point of modern scientific debate regarding breast cancer risk.
Most modern dairy cows are milked throughout their pregnancies, a time when their natural estrogen levels are at their peak.
- The Hormones: This milk contains small amounts of naturally occurring estrogens (estrone and estradiol).
- The Risk: Some studies, including a major 2020 study from Loma Linda University, found that women who consumed even 1/4 to 3/4 of a cup of dairy milk per day had a 30% to 50% increased risk of breast cancer.
- The “Why”: The theory is that these exogenous (external) estrogens can stimulate the growth of hormone-sensitive breast tissue.
Milk is designed by nature to make things grow—fast. It contains IGF-1, a hormone that tells cells to divide.
- For Bones: IGF-1 is a “pro-bone” hormone. It stimulates the osteoblasts (bone-builders) to deposit calcium.
- For Cancer: Elevated levels of IGF-1 in the blood are a known risk factor for breast, prostate, and colorectal cancers because it can tell “bad” cells to divide just as easily as “good” ones.
The “Protective” Dairy Alternatives – “Safer” Calcium:
- Soy Milk (Organic) – High Calcium / High Protein – Lower (Isoflavones may actually protect breast tissue). Unlike cow’s milk, soy contains phytoestrogens. These are “weak” estrogens that can sit in your estrogen receptors, blocking the “stronger” estrogens (from your own body or meat/dairy) from attaching. Mineral-Set Tofu – High protein for bone “scaffolding” without the IGF-1 spike of dairy.
- Almond Milk (Fortified) – Moderate Calcium, Rich in magnesium, which helps the “locking” process.
- Chia & Sesame – Very High Minerals – Protective (High Fiber helps flush excess estrogen)
A very common and highly debated topic in wellness circles is that cow’s milk leaches the calcium from human bone. It makes the body acidic, so the body pulls calcium from bones to neutralize it, leading to bone loss. Large reviews and cohort studies show a mixed picture: overall, drinking more milk does not reliably translate into fewer fractures, and in some big groups (e.g., women in a Harvard cohort, and a Swedish study) higher milk intake was actually linked with more hip fractures or higher mortality. If milk was a “bone-builder,” shouldn’t those countries have the strongest bones? This “paradox” suggests that dairy isn’t the savior it was marketed to be. The reasons likely include:
- Lack of Vitamin K2: without K2 (which is low in most modern pasteurized dairy), the calcium doesn’t know how to get into the bone.
- High Vitamin A: Some fortified dairy is high in Vitamin A, which in excessive amounts can actually stimulate the cells that break down bone.
- D-Galactose: Milk contains a sugar called galactose. In animal studies, high levels of galactose are linked to inflammation and “oxidative stress,” which can weaken bone structure over time.