HOME > Doctor’s Health Advice > Cow’s milk consumed by humans: Necessary for health or silent purveyor of disease?

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Doctor’s Health Advice

Doctor’s Health Advice

Food, Nutrition, and Exercise for Healthy Living


Cow’s milk consumed by humans: Necessary for health or silent purveyor of disease?

Many Americans consume large amounts of dairy products from cow’s milk. Historically, cow’s milk was utilized in times of food scarcity, particularly among northern Europeans, who lived in a poor climate that did not lend itself to growing food for much of the year.  This tradition persisted over time and eventually it became assumed by almost all consumers that dairy products are healthy and part of the overall approach to eating well.  Thanks to the United States Department of Agriculture’s dietary recommendations, it is assumed by the unsuspecting consumer that dairy food is actually not just a good thing, but essential to health, particularly for the growth and maintenance of bones and teeth, among others, due to calcium and to a lesser extent protein.  This message has been almost entirely perpetuated due to the dairy industry’s influence and efforts to ensure that their industry would remain financially viable, even with receiving heavy government subsidies for dairy farmers to operate.  Along with lobbying efforts, the dairy industry has invested heavily in marketing its products on television and other forms of media, particularly toward children, to ensure that its message is heard, e.g., “Got Milk?” and “Milk:  It does a body good.”  These messages have had a powerful influence on consumer purchasing behavior, resulting in a preponderance of people buying their products from milk to yogurt to all kinds of cheeses.

Besides culture, history, and industry influence through lobbying and marketing, most people apparently consume dairy products because they either like the taste (due to added sugar and other flavors) and/or because they are ignorant of the actual science. On the surface, it would appear like eating dairy products is a good thing to do because it is high in calcium and protein with the perception of being “wholesome.”  However, when you consider that we are the only species on the planet that drinks the milk of another mammal as adults, the veil begins to fall down.  From an evolutionary perspective, it makes no sense that we would require the milk of another species to be healthy.  In a dire situation of food scarcity, you could argue that consuming dairy products is necessary for survival, but how does that compare to trying to optimize one’s health?  Additionally, one could argue that humans would have never evolved to where we are today if it some point in our history we required the milk of another species to advance to a next stage in our development.  Unfortunately, it would appear that these concepts have not been considered by the average consumer or else the dairy industry would have collapsed a long time ago.

It is not arguable that cow’s milk lacks nutrition. Obviously it is nutritious (for baby cows), as it contains calcium, vitamin D, protein, fat, carbohydrate, lactoferrins, and immunoglobulins, among others, just like the milk of all mammals, only in different ratios depending on the species.  Cow’s milk contains 59 different pituitary, thyroid, hypothalamic, pancreatic, parathyroid, adrenal, sex, and gastrointestinal hormones, which ultimately explains the growing body of literature that suggests consuming dairy products is problematic and increases the risk of chronic diseases, such as various forms of cancer and heart disease, substantially due to the insulin growth factor-1 and casein found in all dairy products.  A very comprehensive and revealing article was written a few years ago linking the consumption of dairy products with an increased risk of many chronic diseases of Western societies due to milk’s enormous impact on the growth hormone, insulin, and insulin growth factor-1 axis.  This axis is critically responsible for regulating cellular growth throughout the body.  If that mechanism becomes dysfunctional and does not properly enable the elimination of dying, mutating cells, then the proliferation of those cells is indicative of eventual chronic disease through the processes of oxidative stress, carcinogenesis, and atherogenesis, among others.  Thus, in that sense, combining dairy products and their high level of exogenous hormones with our endogenous hormones is essentially like throwing gasoline on a fire.  That fire burns brighter and brighter with increasing amounts of dairy products and hormones consumed.  By the way, it makes no difference if the dairy products are organic, as cows still produce hormones, even if they are not treated with hormones, like recombinant bovine somatotropin, or other drugs to make them grow faster and produce more milk.  Thus, consuming organic dairy products does not lessen the risk of proliferative diseases like cancer and heart disease.

Speaking of diseases, the literature is replete with many studies showing correlational relationships between the consumption of dairy products and risks of many chronic diseases, such as cardiovascular disease, stroke, obesity, dyslipidemia, hypertension, and diabetes, particularly type 1 for infants who were exposed to cow’s milk protein before 1 year of age. Higher intake of dairy products is associated with greater risk of cancers of the breast, colon, and prostate among others, likely in part due to its content of insulin growth factor-I, which is a very potent and efficient cellular growth promoter and proliferator.  One study even found that poor cognitive function and memory was associated with eating dairy foods.  Consumption of dairy has been shown to cause intestinal bleeding in infants.  Allergy has long-been associated with lactose intolerance, but it is also due to the protein in milk as well.

If all of those links between consuming dairy products and various diseases and disorders were not dire enough, perhaps the worst affront to the dairy industry’s message is the one involving osteoporosis. We have all been told that if you do not eat dairy products then you will succumb to osteoporosis at some point in life.  Are you someone who believes that?  What does the science say?  First of all, you will take care of your bones better if you remember that preventing osteoporosis is an issue of calcium balance, not calcium intake.  Second, diets high in protein, especially animal compared to vegetable, cause an excess amount of calcium to be excreted.  The inability to compensate for animal protein-induced calciuric response is a risk factor for the development of osteoporosis.  Third, persons who eat the most fruits and vegetables have denser bones because their diets are lower in protein, these foods are rich in potassium (K+), magnesium (Mg+), and calcium (Ca+), and they do not induce urinary calcium loss.  Fourth, countries that eat the lowest amount of protein per capita have the lowest rates of osteoporosis and hip fractures, and this relationship remains true even in countries with low calcium intake.  Data from a 12-year prospective study indicate that higher dairy and calcium intakes in middle-aged women do not provide protection against hip or forearm fractures.  Women consuming the greatest amounts of calcium from dairy foods had significantly increased risks of hip fractures, while no increase in fracture risk was observed for the same levels of calcium from non-dairy sources.  Wow!  The data from the literature are completely opposed to the dairy industry’s standard message.  It is difficult to suggest to anyone that eating dairy products is the way to maintain bone health.  In fact, the data suggest the exact opposite.  Likewise, I am not aware of one clinically controlled trial showing that consuming dairy products equates to healthier bones.

In conclusion, the data suggest that dairy products should not be included as part of a healthy diet.  It begs the question as to why dairy products are even included in governmental dietary recommendations to the public at-large.  It makes no sense once you read the relatively large number of peer-reviewed studies that show not only the poor health value of dairy products, but provide evidence of increased risk of chronic diseases due to their consumption.  These findings are derived across the board from clinical studies of humans, experimental animal studies, and population-based human behavior.  Unfortunately, dairy products are widely consumed today, but I hope the information in this article provides an impetus to reconsider your decision the next time you think about drinking a glass of milk or eating a slice of cheese.  Not only might you feel better in the short-term by ridding your daily routine of dairy products, e.g., your bowel will function much better, but you might greatly reduce your long-term risk of chronic diseases like diabetes, cancers, and cardiovascular disease.  Eat no dairy foods for 3 days and pay careful attention to how differently you feel.  I am certain you will quickly notice a difference in your health.


John E. Lewis, Ph.D.

John E. Lewis, Ph.D.
Associate Professor, University of Miami

Associate Professor of Psychiatry and Behavioral Sciences at the University of Miami Miller School of Medicine
Director of Research for the Center for Complementary and Integrative Medicine at the University of Miami Miller School of Medicine
Advisor, Diplomat, and Faculty member of the Medical Wellness Association

1990 B.S., Business Administration, University of Tennessee
1992 M.S., Exercise Physiology, University of Tennessee
1995 Ph.D., Education and Psychological Studies, University of Miami

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