The Recent Evolutionary Introduction of Milk and Dairy
One of the rewarding benefits of having written a diet book that has become internationally known is the opportunity to travel the world and speak to tens of thousands of people about this engaging and life changing subject. My signature lecture, “Origins and Evolution of the Western Diet: Health Implications for the 21st Century” is based upon a scientific paper I wrote of the same name and published in The American Journal of Clinical Nutritionin 2005 (24). In this lecture, I trace the chronological introductions of all the food groups and foods that have become part of the contemporary U.S. and western diet. When I lecture, I like to engage the audience so it becomes not just a solitary presentation by me, but rather a mutual give and take conversation amongst us all. When I get to the part about milk and dairy products, I pose a question to everyone, “How do we know that our hunter gatherer ancestors never ate this food group?” Some people furl their brows, scratch their heads and clearly are lost for words. In the ensuing pregnant pause before some raised hands can blurt out the correct answer – I flip to the very next slide. Immediately appears a ferocious, unruly herd of about 30 African Cape buffalo (both cows and bulls), snorting and pawing the earth with powerful hooves supporting their one ton bodies crowned by enormous menacing horns.
Enough said? Have you ever tried to approach a wild animal? How about milking one? Indeed – this is an impossible task to say the least. Until the dawn of agriculture 10,000 years ago and the subsequent domestication of dairy animals (6, 18, 50); milk, butter, cheese and yogurt were never part of our ancestors’ menu (24, 35).
Although 10,000 years ago seems unimaginably distant compared to a single human lifespan, it is very, very recent on an evolutionary time scale. Only 333 human generations have come and gone since we first domesticated animals (cows [6], sheep [18] and goats [50]) and began to consume their milk. Consequently, as a species we have had scant evolutionary experience to adapt to a food that now comprises about 10 % of the calories in the U.S. Diet (24, 45). As such, milk and dairy products have an enormous potential to disrupt our health and wellbeing through a variety of means that I barely touched upon in my first book, The Paleo Diet. If you had any prior doubts about whether you should eat dairy foods, the information contained in this article should help you make an informed decision in the best interest of your health.
Milk and dairy products only became part of the current western diet during the period known as the Neolithic or “New Stone Age” which began about 10,000 years ago and ended 5,500 years ago. The figure below shows just how recent dairy foods and other staples of the western diet really are when evaluated on an evolutionary time frame.
Unless you are lactose intolerant, have an allergy to milk and dairy products, or have been a devoted follower of The Paleo Diet, most people don’t give a second thought about whether or not they should consume a food group that seems to be found nearly everywhere in the western diet. Your favorite dairy foods may include ice cream, chocolate milk, cheese, fruit flavored yogurt, kefir or fancy imported cheeses. You may even think that you are doing your body a favor by eating these calcium rich foods. Nevertheless, the bottom line is this: we are the only species on the planet to consume another animal’s milk throughout our adult lives. Humans don’t have a nutritional requirement for the milk of another species, nor do any other mammals.
An increasing body of scientific evidence supports the evolutionary caution that this dietary practice is not necessarily harmless. The table below shows the sources and amounts of dairy foods in the U.S. diet (data from 45).
These figures don’t entirely tell the full story, as dairy products are put into almost all processed foods. Take some time to read labels. If you are a milk chocolate addict, you are eating dairy – same for latte lovers. Non-fat milk solids, a major ingredient in chocolate, are also put into candy, cereal, bread, salami, bologna, sausages, baked goods, salad dressings, chips, condiments, soft drinks and literally any food that comes in a can, jar, bottle, bag or plastic wrapper. Even though these tiny residues of milk in processed foods seem to be trivial, you may want to reconsider. Later in this article I’ll show you how milk proteins and peptides (the building blocks of proteins) at even small concentrations have potential to promote allergies, inflammation, autoimmune diseases and other health problems.
The Milk Mustache Advertising Hype
Before I even get into the extensive science underlying milk’s unfavorable effect upon our health and wellbeing, let’s take a step back and look at the vast, hype advertising campaign that the milk processing industry has shoved down our throats for nearly 20-30 years. This glitzy promotional crusade called “Got Milk” depicts movie stars, sports personalities, politicians and just about any public figure you can imagine with a wet, white film of what appears to be milk on their upper lips. Implied in magazine ads, TV and radio commercials, and now social networks is the notion that all public figures with “milk mustaches” endorse dairy products, presumably because they are a healthy and nutritious food. Whoa! Let’s stop for a minute and touch bases with reality.
I haven’t drank a glass of milk in nearly 40 years, but if I were to, I certainly wouldn’t spill it all over my upper lip. I imagine that world class athletes, dancers and actresses with far better hand to eye coordination than I have, also would not make this clumsy maneuver. However, this issue really doesn’t matter and simply is part of the industry’s advertising strategy – if the movie stars and sports heroes do it, so should you. But more importantly, why would a Wimbledon tennis champion, an Oscar winning actress, or an Indy 500 race car driver blindly support a product they know virtually nothing about?
These public personas have spent their lifetimes honing talents, skills and knowledge specific to their life’s callings. But when it comes to understanding milk’s intricate influence upon our metabolism, hormonal function and long term health, most of these people are novices operating completely out of their areas of expertise without knowledge or understanding of the facts. You can’t really fault them for endorsing a product they know little or nothing about. Like the public at large, they have bought into the milk processing industry’s ad campaign portraying milk right along with motherhood, apple pie and the American way.
This is exactly the message the milk processing industry wants to convey to the general public because it sells more milk and dairy products – plain and simple. Is there a conspiracy by dairy industry middlemen, executives and CEOs to sabotage our health and promote disease? Of course not. These people by and large, just like the movie stars and sports figures who endorse milk, are uninformed and blindly believe in their product. They represent tiny cogs in a wheel that rolls directly in the face of at least 2.6 million years of evolutionary wisdom. To them, the “Got Milk” and “Milk Mustache” advertising campaigns simply represent a logical corporate tactic to increase sales and maximize profits of a supposedly nutritious and healthful product.
As was the case with saturated fats, whether or not people should consume dairy products is divisive within the scientific community because the human experimental and epidemiological evidence is not necessarily conclusive and still can be interpreted in a variety of ways. Does milk prevent disease, or does milk promote disease? Or is the answer somewhere in between? In an ideal world, this question could be decisively answered by well controlled human experimental studies conducted over entire lifetimes. Unfortunately, these hypothetical lifelong experiments in real people will never be carried out because they would be impossible to control, incredibly expensive and unethical. In lieu of these studies, conventional nutrition researchers are left with the four basic scientific procedures to unravel the milk drinking dilemma: 1) observational epidemiological studies, 2) animal studies, 3) tissue studies, and 4) short term human experiments.
Unfortunately, traditional nutrition researchers are unaware of, or don’t appreciate the most powerful research tool in all of biology. This concept could point them in the right direction when it comes to deciphering the conflicting information about dairy products and human health. By now you know what I’m talking about – the evolutionary template. Anybody who doesn’t use it, just as well may be running uphill in a football or soccer game or doing calculations with pencil and paper rather than a computer. When the evolutionary template is employed together with the four basic procedures scientists use to establish causality between diet and disease, then we can make sense of all the contradictory data and be pointed in the right direction of arriving at a correct answer.
Frank Oski, M.D.: A Pioneer Milk Researcher
Before I go any further, I’d like to bring up a quote that has influenced my thinking about science, biology, diet and life in general for most of my adult life:
“Those who cannot remember the past are condemned to repeat it.”– George Santayana105
I certainly am not the first scientist to recognize that milk and dairy consumption may have adverse effects upon our health. One of the most vocal opponents to milk drinking was a physician, Frank Oski M.D. (1932-1996) who served as the Department Chairman of Pediatrics at the State University of New York, Syracuse from 1972 until 1985 and as the Department Chairman of Pediatrics at Johns Hopkins University from 1985 until 1996. He was a member of the National Academy of Sciences and the author or co-author of about 300 academic papers and 20 books. A book he wrote in 1977 called “Don’t Drink Your Milk” (86) was decades ahead of its time. Here is a quote from this book which dovetails nicely with this article:
“The fact is: the drinking of cow milk has been linked to iron-deficiency anemia in infants and children; it has been named as the cause of cramps and diarrhea in much of the world’s population, and the cause of multiple forms of allergy as well; and the possibility has been raised that it may play a central role in the origins of atherosclerosis and heart attacks… In no mammalian species, except for the human (and the domestic cat), is milk consumption continued after the weaning period [the period of breast-feeding]. Calves thrive on cow milk. Cow milk is for calves.”
Evolutionary Clues to Cow Milk Consumption
When you apply the evolutionary template to milk drinking, it becomes absolutely clear that cow’s or any other mammal’s milk was never intended to nourish another species (i.e. humans) throughout their entire adult lives. Rather it was specifically designed by natural selection to encourage rapid growth, support immune function, and prevent disease in young suckling animals. New born calves, like most mammals are nearly helpless for the first few hours after birth. They are unable to stand up, much less sprint away from potential predators. For the first few days and weeks after birth, they can’t forage for food and are almost entirely dependent upon mother’s milk for nourishment.
Milk is designed to make young animals grow rapidly and to prime their immune systems and prevent disease by allowing hormones and other substances in their mother’s milk to enter their bloodstreams. This is a brilliant evolutionary strategy to encourage survival for young suckling animals at the beginning of their lives, but is a formula for disaster when adult animals (us) consume a food intended only for the young of another species.
One of the telltale signs that there may be something just a little awry with milk drinking is that about 65 % of all people on the planet can’t do it without experiencing gas, bloating and digestive distress (60). Maybe we should be listening to our bodies? Many of you may have these symptoms and already know why they occur after drinking milk or eating dairy products, but let me explain the basic concept for those who don’t know (80,116).
Milk is a mixture of carbohydrate, protein and fat. Most of the carbohydrates in milk occur in the form of a sugar called lactose which in turn is made up of two simple sugars: glucose and galactose. When we consume milk, ice cream and other dairy products rich in lactose, it must first be broken down into these two simple sugars by an enzyme in our guts called lactase. As I mentioned earlier, about 65 % of the world’s people haven’t inherited the genes to make lactase and are therefore lactose intolerant (60). The notable exception to this rule is people from Northern Europe and their descendants (80, 116). Because Northern Europeans maintain high gut lactase activity as adults, they can metabolize lactose into its two simple sugars and don’t experience gastro-intestinal upset after drinking milk. In the figure below you can see that the percentage of people with Northern European ancestry who can digest lactose without discomfort is much higher than almost all the other world’s people (80, 116).
The evolutionary explanation for the information in this figure is quite simple. Most people on the planet can’t drink milk without gastrointestinal upset because their genes simply haven’t had enough time to adapt to this newcomer food (60, 80, 116). Milk represents foreign fare which lactose intolerant people reject, as should we all, whether we can digest lactose or not. The lactose evidence is like a canary in a coal mine, and hints at even greater health problems with milk and dairy consumption.
Milk and Dairy: Nutritional Lightweights
Based upon the dairy ad campaigns, bovine (cow) milk consumption appears to represent nothing less than an extraordinary food to perk up our health and avoid illness. This milky white liquid, served cold is touted as “Good for Everybody” and high in nine nutrients including calcium and vitamin D as listed on the milk processing industry’s website: www.whymilk.com. If the truth be known, milk is a lousy source of vitamin D as well as the top 13 nutrients most lacking in the U.S. diet. Let’s take a look at the facts.
In a paper published in The American Journal of Clinical Nutrition, (24) my research group and I pointed out how dairy products were nutritional lightweights when compared to lean meats, seafood, fresh fruits and vegetables. Based upon the 13 vitamins and minerals most lacking in the U.S. diet, our analysis showed that whole milk ended up near the bottom of the stack for all food groups. The highest source of these 13 nutrients were 1) fresh vegetables, followed by 2) seafood, 3) lean meats, 4 ) fresh fruits, 5) whole milk, 6) whole grains, and 7) nuts and seeds.
To even suggest that milk is a good source of vitamin D is a total stretch of the facts. In 2010 the official (Institute of Medicine) daily recommended intake for vitamin D increased from 400 IU to 600 IU per day for most people (32). Although this advice represents a substantial raise, it still falls far short of human experimental evidence showing that at least 800 to 2,000 IU per day is required to keep blood levels of vitamin D at the ideal concentration of 50 ng/ml (13, 14, 129, 130). An eight oz glass of raw milk (280 calories) straight from the cow without fortification gives you a paltry 3.6 IU of vitamin D (76, 128). At this rate, you’d have to drink a ridiculous 167 eight oz glasses of milk just to achieve the 600 IU daily recommendation. Because most of the milk we drink is fortified with vitamin D, then an 8 oz glass typically yields 100 IU of this nutrient (128). However, even with fortification, you would have to drink six 8 oz glasses (1,680 calories or ~ 75 % of your daily caloric intake) of whole milk to meet the daily requirement for vitamin D. If you wanted to reach the 2,000 IU level as suggested by the world’s best vitamin D researchers (13, 14, 129, 130), you would have to drink 20 eight oz glasses of fortified whole milk amounting to 5,600 calories. No one in their right mind would drink 20 glasses of milk a day, even if they could. As you can see from these simple calculations, whether fortified or raw, milk is an abysmal source of vitamin D. The best way to get your vitamin D is not by drinking milk, but rather by getting a little daily sun exposure as nature intended (131,132).
Milk, Dairy and Heart Disease: The Early Days
The history of modern medicine is full of starts, stops, and reversals in strategy for treating disease. One of the more remarkable tales in recent medical history involves peptic ulcers. This is a chronic condition in which the linings of the stomach or small intestine are eroded away causing painful internal wounds. Complications include bleeding and perforation of the gastrointestinal tract, which are potentially life threatening.
For the better half of my adult life, peptic ulcers were routinely attributed to excessive stomach acid production caused mainly by stress, or spicy foods or too much gum chewing. Even as recently as the mid 1980’s, ulcer patients were advised to take antacids, make lifestyle changes to reduce stress, cut back on spicy foods and stop chewing gum. However, as we will soon see, this advice didn’t do much to alleviate symptoms or cure the problem.
One of the more unusual ideas that surfaced to treat peptic ulcers came from an early 20th century physician, Betram Sippy (M.D.). Dr. Sippy authored an influential paper that appeared in the Journal of the American Medical Association in 1915 (112) suggesting that peptic ulcers could be effectively treated by feeding patients milk and cream on a regular basis throughout the day. The good doctor’s advice became known as the “Sippy Diet” and was employed widely across the United States to care for patients with ulcers even as recently as 25-30 years ago (127)
One of the downsides to the Sippy Diet, first recognized in 1960 by Dr. Hartroft and colleagues at Washington University in Saint Louis (17, 52) was that it noticeably increased fatal heart attacks in ulcer patients. In Dr. Hartroft’s study three groups were examined at autopsy: 1) subjects with peptic ulcers who followed the Sippy Diet, 2) subjects with peptic ulcers who didn’t follow the Sippy Diet, and 3) subjects without peptic ulcers. The fatal heart attack rate was similar between subjects without peptic ulcers and those with peptic ulcers who hadn’t been on the Sippy Diet. However, the fatal heart attack rate in ulcer patients who had adhered to the Sippy Diet was a staggering 42 %. Think about these statistics. Close to half of all ulcer patients following the Sippy Diet had succumbed from heart attacks! Thank goodness to us all that the medical community no longer recommends the Sippy Diet for peptic ulcers.
The reason that physicians no longer recommend the Sippy Diet or any other dietary regime for the treatment of ulcers is one of the most incredible and unlikely tales in all of modern medicine. For almost 100 years, peptic ulcers were looked upon as a disease of excessive stomach acid production caused by stress, spicy food – whatever. No one ever considered that this condition might be caused by an infectious organism. That is, until the publication of two revolutionary papers in 1983 and 1984 by two Australian scientists, Barry Marshall and Robin Warren, showing that 70 to 90 % of peptic ulcers resulted from infection by the bacterium Helicobacter pylori (74,75). At first, these innovative publications were generally dismissed and discredited by the medical community. However, it didn’t take long for practicing physicians to realize that ulcers could be effectively cured simply by giving their patients a good dose of antibiotics. Unfortunately, it took about a decade for these brilliant scientists’ ideas to be accepted worldwide. Now, because of their ground-breaking insights, antibiotics are routinely used to successfully treat and cure almost all peptic ulcer cases. In 2005 Drs. Marshall and Warren were awarded the Nobel Prize in medicine for their discoveries (133).
A forgotten piece of the peptic ulcer story is that milk and dairy consumption significantly increased the risk for cardiovascular disease and heart attacks. The information about Sippy Diets and heart attack risk has been buried in the scientific literature for nearly 50 years and is virtually lost to contemporary scientists. OK. Fair enough. I would no longer necessarily hang my hat upon 50 year old studies than I would drink a cup of milk. However, the knowledge, wisdom and insight of our parent’s, grandparent’s and great grandparent’s generations shouldn’t just be swept under the rug. Is it possible that they were actually on to something?
Milk, Dairy and Heart Disease: Contemporary Science
The data from the early 1960’s studies on milk and heart attacks certainly bear further scrutiny. As we move forward from the past, numerous studies support the view that milk and dairy products may not be heart healthy and “Good for everybody”. A 1993 epidemiological study by Drs. Artaud-Wild and co-workers (7) involving 40 countries worldwide demonstrated that milk and its components (calcium, protein and fat) had the highest relationship with cardiovascular death rates for any food or nutrient examined. Similar results implicating milk consumption with high mortality from heart disease were reported by Drs. Renaud and De Lorgeril in 1989 (100), by Dr. Appleby and co-workers in 1999 (8), by Dr. Segall (107, 108) and by Drs. Moss and Freed in 2003 (78). Epidemiological studies are notorious for conflicting results. Here’s a perfect example. In a recent 2011 meta analysis (114), scientists at the Harvard School of Public Health showed that dairy food didn’t affect heart disease risk one way or another. Milk and dairy didn’t make things worse for our cardiovascular systems, but they also didn’t make them any better (114).
Good scientists almost always let you know the weak points and shortcomings of their experiments because these limitations are an integral part of the scientific method which allows us all to glimpse the “truth”. The authors of this Harvard study expressed an important concern about the validity and generalizability of their experiment that you need to know. These kinds of details often get swept under the rug as milk industry lobbyists promote their products, and as governmental agencies make dietary recommendations. Let me quote the scientists who conducted this analysis:
“Conclusions from this meta-analysis only apply to the small proportion of analyzable study populations included in this work, within milk intakes of ~200-600 ml/d. Moreover, the internal validity of the different studies included in the meta-analysis (e.g., methodology and confounding factors) also determines the quality of the present meta-analysis.”
For those of you that may not completely understand this scientific admission, here’s what it means. The amount of milk in this analysis only ranged from 200 to 600 ml. This total represents a modest quantity which translates to only one to three 8 ounce glasses of milk per day. In other words the amount of milk in this study was too low to know if higher milk intakes increase heart disease risk. If we go back to the 1960s study of ulcer patients following the Sippy diet, they drank two to three times this much milk, and nearly 42 % died from heart attacks (17, 52).
Milk is a lot like a moving target with more than one bull’s-eye. Scientists aren’t completely sure which element or elements may underlie its adverse effects upon our cardiovascular systems (30, 37, 73). Milk simply isn’t just a creamy white liquid that is “Good for everybody” but rather is a complex mixture of many substances suspected of causing heart disease including its high calcium content, fatty acids, lactose and certain proteins. Because milk contains so many compounds that could potentially promote heart disease, it is difficult or impossible for epidemiological studies to sort out all the facts. Let’s take a closer look at some specific elements in milk which may promote heart disease.
Decomposing Milk and Heart Disease
Unless you haven’t watched TV or read a newspaper or magazine in the past 20 years, most people know that milk and dairy products are one of our best sources of calcium. The dairy manufacturing industry has pounded this message into our brains for decades – so much so that many women fear they will develop osteoporosis if they don’t consume dairy foods. Until just recently, the prevailing knowledge was that if a little calcium was good for us, then more certainly must be even better. Not necessarily so. If we look at the evolutionary evidence, it becomes immediately clear that it would be virtually impossible to achieve governmental recommended calcium intakes without eating dairy products. In 2002, I wrote a scientific paper covering this topic, and my analysis showed that modern day Paleo Diets provide us with only about 70 % of the daily recommended calcium intake (23). Given this evolutionary clue, then it is not be surprising to find that the supra-normal intakes of calcium that can be achieved by milk and dairy consumption may just cause unexpected health problems.
A recent 2010 meta analysis published in the British Journal of Medicine by Dr. Bolland and colleagues from the University of Auckland confirmed the health hazards of too much calcium. Their comprehensive analysis involving 26 separate studies and more than 20,000 subjects revealed that calcium supplementation significantly increased the risk for heart attacks and sudden death (16). High blood levels of calcium are likely involved in the artery clogging process (atherosclerosis) (99) because too much calcium may promote the formation and fragility of the plaques which block our arteries (134).
Interestingly, high dietary calcium also tends to cause imbalances in magnesium (5, 34, 110) and this mineral is generally protective against heart disease for many reasons. As far back as 1974, Dr. Varo at the University of Finland pointed out that high dietary calcium to magnesium ratios were a better predictor of heart disease than high calcium intake alone (120). Meaning – that if you got too much calcium and not enough magnesium in your diet, it puts you at an increased risk for heart disease. Because milk’s calcium to magnesium ratio is quite high (about 12:1) (128), the inclusion of dairy products in our diets can easily raise the overall calcium: magnesium ratio to about 5:1 (120), thereby reducing cellular magnesium stores and promoting heart disease. Note that our studies of contemporary “Paleo”diets confirm that the dietary calcium to magnesium ratio was much lower and close to 2:1 (23).
Supplementation studies of magnesium show that it reduces heart disease risk via multiple mechanisms. It improves blood lipid profiles (47, 97), prevents heart beat irregularities called arrhythmias (57), improves insulin metabolism (82) and lowers markers of inflammation (82). If you decide to consume dairy products, you effectively negate these therapeutic effects of magnesium either fully or in part. If milk’s high calcium and low magnesium ratio was not bad enough, let’s consider just a few other nutritional features in milk which further promote heart disease.
In the 1950’s and early 1960’s when nutritional researchers were just beginning to understand how atherosclerosis and heart attacks developed, it was assumed to be a simple plumbing problem. Eat too much saturated fat and cholesterol, and your total blood cholesterol levels skyrocketed which clogged your arteries thereby predisposing you to a heart attack or stroke. Unfortunately, these simplistic views did not standup well to the test of time, as hundreds of studies starting in the late 1980s showed beyond a shadow of a doubt that inflammation and immune reactions were just as important or more so in the artery clogging process (atherosclerosis) than either consumption of saturated fat or cholesterol (79, 84, 135, 136).
So this brings us to a larger question. What elements in diet may be responsible for causing chronic low level inflammation now known to underlie not just heart disease, but also cancer and autoimmune disease? The evolutionary template once again brings us back to foods which we never consumed in our ancestral past. Is there any possibility that these Johnnie- come-lately foods such as, milk and dairy, grains and legumes may cause chronic low level inflammation and promote immune responses that lead to heart disease?
Milk is an incredible amalgamation of nutrients, proteins and hormones that have only recently been discovered and appreciated. It certainly is not the pure white liquid, high in calcium, vitamin D and other vitamins and minerals portrayed by milk manufacturers and their lobbyists. You may not know it, but milk is essentially nothing more than filtered cow’s blood. As such, it contains almost all of the hormones, immunological factors, and body altering proteins that are found in pure cow blood (11, 64, 65). However, let’s don’t get too alarmed at this information. Most of these compounds in milk have very short half-lives and are spontaneously degraded within minutes or hours after the manufacture of modern dairy foods. Consequently, they should not enter our bloodstreams. Further, a healthy human gut lining rarely allows intact, large proteins such as those found in milk hormones to bypass its protective barrier. So why should we worry? Are there proteins or hormones in cow milk which bypass the gut barrier and eventually get into our bloodstreams to wreak havoc with our immune systems and promote atherosclerosis?
Milk, Insulin Resistance and the Metabolic Syndrome
I’ve briefly touched upon the glycemic index, but let me get into a bit more detail about how this indicator of a food’s blood sugar response relates to milk and dairy. As many of you may already know, the glycemic index gauges how much a food raises our blood glucose concentrations. Processed foods such as white bread, candies, breakfast cereals, cookies and even potatoes have high glycemic indices because they cause rapid and marked increases in our blood glucose levels (38). As such, these foods tend to promote the Metabolic Syndrome which includes diseases of insulin resistance such as type 2 diabetes, hypertension, cardiovascular disease, obesity, gout and detrimental blood chemistry profiles (24, 31, 117). Real foods such as lean meats, fish, eggs, fresh fruits and veggies typically have moderate to low glycemic indices and are not associated with the Metabolic Syndrome (24).
Normally, when our blood sugar levels soar after we consume high glycemic index carbohydrates, our blood insulin concentrations also rise in tandem. This is the usual response. Shortly after the glycemic index was developed in the early 1980’s, it was discovered that milk, yogurt and most dairy foods had low glycemic responses (38). Presumably, these foods should be healthy and help to prevent the Metabolic Syndrome. However, about 5-10 years ago experiments from our laboratory and others unexpectedly revealed that low glycemic dairy foods paradoxically caused huge rises in blood insulin levels (42, 55, 59, 87), even when milk is added to mixed meals (70). The table below shows that despite their low glycemic indices, dairy foods maintain high insulin responses similar to white bread.
This information posed a challenge to nutritional scientists. It was unclear if milk’s insulin stimulating effect but low glycemic response was healthful or harmful. To date only one human study conducted in 2005 has addressed this question. Dr. Hoppe and colleagues at The Royal Veterinary and Agricultural University in Denmark put 24 eight year old boys on either a high milk or high meat diet for seven days. The high milk diet worsened the boys’ insulin response nearly 100 %, and the entire group became insulin resistant in just a week’s time. In contrast, the high meat eating group’s insulin levels did not change, and their overall insulin metabolism remained healthy (58). The results of this experiment are alarming, particularly if future studies also demonstrate this effect in teenagers and adults. As insulin resistance is the fundamental metabolic defect underlying the Metabolic Syndrome, it would not be surprising to discover that milk drinking may cause other diseases of insulin resistance.
Milk and Acne
Until 2002 the official party line of the mainstream dermatology community was that diet had nothing to do with acne (22, 25). This viewpoint was expressed time and again in all of the major dermatology textbooks and became the doctrine taught to newly minted dermatologists. If you didn’t know any better, you might think that this perspective was based upon hundreds or even thousands of carefully controlled scientific studies. When I first started to examine the link between diet and acne more than 10 years ago, this is exactly what I had expected. How wrong I was! As it turned out, the dogma that diet didn’t cause acne was based solely upon two poorly conceived experiments conducted in 1969 and 1971 (25). In a series of papers from 2002 to 2006 (22, 25, 26), I pointed out this flawed assumption to the dermatology community.
My research rekindled the entire diet/acne debate, but more importantly we showed that acne was completely absent in two non-westernized populations who didn’t drink milk or eat processed foods (22). We suspected that both milk and foods with high glycemic indices caused blood insulin levels to rise steeply and remain high all day long. In turn, elevated insulin levels set off a hormonal cascade that triggered the known cellular events which caused acne (22, 25). My hypothesis that milk, in part, caused acne was verified by a series of epidemiological studies from scientists at the Harvard School of Public Health (1-3). Even more convincing was an experimental study carried out by Dr. Neil Mann and colleagues at the Royal Melbourne Institute of Technology showing that low glycemic index, high protein diets improved acne symptoms (113) as did a more recent randomized controlled trial by Kwon and co-workers (138).
As it has been less than 12 years since my study in The Archives of Dermatology (2002) revived the diet/acne debate, scientists worldwide have not completely worked out how milk drinking promotes acne. Some researchers share our view that milk’s exaggerated insulin response along with high glycemic index carbohydrates sets off a hormonal cascade that causes acne (137). Others suggest that hormones found in cow milk may be responsible (1-3, 139), whereas some scientists believe that both mechanisms or perhaps others are involved (140).
Hormones in Milk
Milk may be advertised as a squeaky clean white liquid, high in vitamin D and calcium, but if the truth be known, it is filtered cow’s blood and as such contains almost all of the hormones and bioactive peptides (protein building blocks) found in blood itself (10, 11, 33, 36, 39, 40, 51, 64, 65, 91, 92, 95, 96, 111) . Take a look at the table below (which is only a partial listing), and you can see the incredible profusion of biologically active substances found in milk.
Growth Hormones
Insulin, Insulin like growth factor 1 (IGF-1), Insulin like growth factor 2 (IGF-2)
Insulin like growth factor binding proteins, 1 to 6 (IGFBP-1, 2, 3, 4, 5, 6),
Betacellulin (BTC), Growth hormone (GH), Growth hormone releasing factor (GHRF), Transforming growth factor alpha (TGF α), Transforming growth factor beta 1 (TGF-β1), (TGF-β2), Platelet derived growth factor (PDGF)
Steroid Hormones
Estrogens (Estrone, Estradiol-17β, Estriol and Estrone sulfate), Progesterone, 20 alpha-dihydropregnenolone, 5α androstanedione, 5 α pregnanedione, 20α- and 20β-dihydroprogesterone, 5α-pregnan-3β-ol-20-one, 5α-androstene-3β17β-diol, 5α-androstan-3β-ol-17-one, androstenedione, testosterone, and DHEA acyl ester
Bioactive Proteins and Peptides
Relaxin, Thyrotropin releasing hormone (TRH), Luteinizing hormone releasing hormone (LHRH), Somatostatin (SIH), Gastrin releasing peptide (GRP), Calcitonin, Adrenocorticotropic hormone (ACTH), Prolactin, Thyroid stimulating hormone (TSH), Lysozyme, Lactoperoxidase, Lactoferrin, Transferrin, Immunoglobulins (IgA, IgM, IgG), Proteose-peptone, Glycomacropeptide, Plasmin, α Casein, β Casein, κ Casein, α Lactoglobulin, β Lactoglobulin, Bovine serum albumen (BSA), Gastric inhibitory polypeptide (GIP), Glucagon-like peptide-1 (GLP-1), Antitrypsin, Plasminogen activator inhibitor-1, α(2) antiplasmin , Butyrophilin, Xanthine oxidase, Mucin-1, Mucin-15, Adipohilin, Fatty acid binding protein, CD36, Periodic acid Schiff 6/7
Bioactive Peptides formed in gut from Milk Proteins
Casomorphins, α Lactorphin, β Lactorphin, Lactoferroxins, Casoxins, Casokinins, Casoplatelins, Immunopeptides, Phosphopeptides.
The trick for any of these elements to wreak havoc with our health and wellbeing is for them to end up fully intact and present in our bloodstreams. To accomplish this feat, these hormones, proteins and peptides must first survive pasteurization (the quick heating of milk to destroy microorganisms), homogenization and other processing procedures applied to dairy foods. Next they must survive the digestion process and resist breakdown by our gut enzymes. Finally, they must cross the intestinal barrier which normally blocks entry of whole proteins, hormones and large peptides into our bloodstreams. As unlikely as this series of events may first appear, it now seems quite probable that cow hormones in milk indeed enter our bloodstream, particularly if we have a leaky gut.
For a young suckling calf, it is a good thing for its mother’s hormones, peptides and immune factors to cross the intestinal barrier. This process assures the calf will get a healthy start in life, grow rapidly and develop resistance to disease. To insure that mother’s hormones and peptides are not degraded in the calf’s gut by various enzymes, milk contains substances called protease inhibitors which prevent this breakdown (91, 96, 141). The downside of milk’s protease inhibitors is that they also prevent our own gut enzymes from destroying cow hormones and peptides. So the stage is set. Many hormones and bioactive peptides in milk survive pasteurization and food processing. They also resist enzymatic breakdown in our guts because inherent compounds in milk protect them. Ultimately, in order to adversely affect our health, these substances must then bypass the gut barrier and enter our bloodstream.
It is apparent that this final hurdle is routinely overcome because so many people have allergies and immune reactions to milk and its various protein components (21, 29, 54, 61, 72, 85, 86, 118, 119, 142, 143). When intact hormones, proteins or peptides cross the intestinal barrier, the immune system takes immediate steps to neutralize or destroy any particle that is perceived as a foreign invader. Part of this process is to form antibodies against milk proteins which later may be involved in allergic and autoimmune reactions. Many of the proteins and substances I have listed in the table above show up as specific milk allergens. Meaning – that they had to either cross the gut barrier and interact with the immune system or via another body interface.
Unsafe Milk Hormones
Of all the milk hormones and bioactive peptides I have listed in the table above, very few have been examined directly in human experiments. Nonetheless, evidence from animal, tissue and epidemiological studies suggest that consumption of cow, goat or sheep milk by humans and the subsequent ingestion of hormones and bioactive substancs at best may be unwise and at worst may be responsible for a number of life threatening diseases. Let’s take a look at the most problematic of these hormones.
Insulin
The regular, everyday milk you buy at the supermarket is loaded with bovine insulin (51, 64, 65). This cow hormone not only survives your gut’s digestive enzymes, but it seems to frequently cross the gut barrier and make its way into the bloodstream, as revealed by telltale signs from our immune systems (72, 118, 119). Because the structure of bovine insulin varies from the human form, if it enters circulation, it is immediately recognized as a foreign particle and flagged as such by the immune system. The large number of children who display immune system flags (antibodies) to bovine insulin means that it has likely crossed the gut barrier intact and has caused an immune reaction. Although the mechanism is not entirely clear, the presence of bovine insulin antibodies in our children’s bloodstreams is associated with a greatly increased risk for Type 1 diabetes (72, 118, 119).
Type 1 diabetes is an autoimmune disease in which the immune system destroys beta cells in the pancreas, so that it can no longer make insulin. Type 1 diabetic patients then must take insulin injections for the remainder of their lives. This devastating disease most frequently strikes children before their teen years. Epidemiological studies have time and again identified cow’s milk as a major risk factor for the disease, particularly if children are exposed to milk or milk containing formula before the age of three (66, 69, 72, 118, 119, 121). The bottom line: milk is a potentially lethal toxin for infants and young children, but also for adults as you shall soon see.
Insulin like Growth Factor 1 (IGF-1)
Another hormone found in cow’s milk that may have disastrous effects upon our health and wellbeing is called insulin like growth factor 1 (IGF-1). As implied from its name, this hormone encourages growth. Unfortunately it not only promotes growth in healthy tissues and organs, but also in cancerous growths (104, 115). Like all milk hormones, IGF-1 is a large protein molecule that normally should not breach the gut barrier and get into our bloodstreams. Nevertheless, recent meta analyses of 15 epidemiological studies and 8 human dietary interventions by Dr. Qin and colleagues at Soochow University have shown without a doubt that milk drinking robustly elevates IGF-1 in our bloodstreams (92). This effect may occur directly from the additional ingested bovine IGF-1 that crosses our gut barriers, or via indirect mechanisms. You recall that milk drinking causes our blood insulin levels to rise sharply. Whenever blood insulin concentrations increase, a series of connected hormonal events simultaneously cause IGF-1 to increase. Over a 24 hour period, blood insulin concentrations are a good marker for IGF-1 concentrations. When one increases so does the other (144).
Whether IGF-1 in our blood is increased either directly from ingested bovine IGF-1 or indirectly from milk’s insulin raising effects doesn’t really matter, as the end result is the same – milk raises our total blood levels of IGF-1 (92). This particular consequence of milk drinking is especially ominous because it encourages the growth of many types of cancer. Numerous worldwide, meta analyses over the past 40 years show beyond a shadow of a doubt that high blood levels of IGF-1 strongly increase the risk for prostate and breast cancer (104,115). If this outcome doesn’t alarm you, perhaps additional meta analyses will. These comprehensive studies show that milk drinking also increases the risk for ovarian cancer in women (44, 68). If you or any close relatives have a history of cancer, one of the best lifestyle changes you can make to reduce your risk of these life threatening diseases is to wipe your upper lip clean of the milk mustache and get milk and dairy completely out of your life!
Estrogens
By now you can see that milk isn’t simply an innocuous high calcium food that builds strong bones, but rather is a concoction of body altering hormones, enzymes and proactive peptides whose wide ranging effects may promote cardiovascular disease, insulin resistance, cancers, allergy and autoimmune diseases. Another hormone in milk which may operate in tandem with other bovine hormones, proteins and peptides to promote cancer is estrogen. It is present in bovine milk in a variety of forms including estrone, estradiol-17β, estriol, estrone sulfate and progesterone (36, 40, 95).
Before we go any further, you need to know how modern dairy farmers maximize milk production from their cows. Dairy farmers are in the business to make money, and the more milk they can get from a single cow in a year, the more money they make. Female cows, like all mammals only produce milk during the latter half of pregnancy and during the suckling period. So the trick for modern dairy farmers is to get cows to make high amounts of milk during the early months of pregnancy when milk is normally not produced. Dairy farmers achieve this goal by artificially inseminating cows within three months after they have just given birth. In effect, these cows become pregnant once again while they are still nursing the young of their previous birth. This contrived interference by humans causes the mother cow to produce milk 305 days out of the year. From an economic perspective, this strategy makes perfect sense – more milk means more money. From a dietary and health perspective, this practice may increase the estrogen content in the milk we drink (36, 40, 95). For men, milk drinking (whether be it from added estrogen or other mechanisms) greatly increases your risk for prostate cancer (43, 67, 93, 94, 103, 126).
Betacellulin
So far we have only closely examined three hormones found in milk. You can see from my table that we have barely touched the tip of the iceberg. Because most of these substances have been so infrequently studied in humans, we simply don’t know how they may influence our health and wellbeing. Nevertheless, at least one additional hormone in milk called betacellulin is worth examining.
Betacellulin was only recently identified in cow milk in 1999 (33). It survives pasteurization and occurs in milk, cheese and whey proteins (10). Tissue studies of a molecularly similar hormone (EGF) demonstrate that it likely survives our digestive enzymes (96) . A low ph, such as may be found in the gut, does not impair or prevent BTC from binding its receptor (146). Further betacellulin doesn’t have to worry about getting past the gut barrier. It gains easy access to our bloodstream by binding a structure in the gut lining called the epidermal growth factor receptor (EGF-R) (26, 56, 90, 145). This structure is found throughout most cells in our body, and when the EGF-R becomes over stimulated, it is intimately associated with the development and progression of almost all types of cancers (53, 81). Tissue experiments show that betacellulin powerfully stimulates the EGF-R – more so than any other hormone (145). Further, pharmaceuticals which block EGF-R stimulation act as powerful anti-cancer agents in humans and animals (28, 46, 81, 83, 88, 109).
It will take many more experiments and years of research to conclusively show whether or not the betacellulin in milk contributes to the cancers associated with milk drinking and dairy consumption. But you don’t have to wait that long. By eliminating milk and dairy products from your diet, you will immediately reduce your risk of these cancers, as well as allergy, heart disease, and autoimmune disease.
Milk and Dairy: More Health Problems
The list of adverse health effects known to arise from milk drinking is seemingly endless. Let me briefly point out some additional conditions and illnesses in which milk and dairy products have been implicated.
Food Allergies
The table below lists the eight most common food allergies in the U.S. population.
These foods account for 90 % of all food allergies, and notice that milk tops this list (85). Milk is also the most common childhood food allergy, where it afflicts between 2-3 % of children between the ages of 1 to 3. Symptoms include: stomach pain, diarrhea, skin rashes, hives, wheezing, infantile colic and anaphylactic shock which can be life threatening. By age 3 most (85-90 %) children grow out of their milk allergy. So at first, this change appears to be a good thing, but the down side to childhood milk allergy is that it predisposes the child to other food allergies for the rest of their lives. A study by Dr. Høst at the University of Southern Denmark (54) alarmingly revealed that 50 % of all infants and young children who were allergic to milk later developed allergies to a wide variety of other foods before puberty. As was the case with Type 1 diabetes, early exposure to milk proteins is the key to whether or not your child will develop allergies. The crucial period for restricting cow’s milk is from birth until at least age 2 or 3.
One of the more interesting disorders related to milk allergy is infantile colic. If you are planning on having children, or know someone who is, you may want to bookmark this paragraph. When a healthy baby cries, screams or fusses intensely for more than three hours a day, three days a week, it probably has colic. Continual infant crying is considerably more than just a parental annoyance. Crying and its associated exhaustion to parents and infants may cause serious problems including stress to your marriage, breastfeeding failure, and shaken baby syndrome, which frequently results in infant death.
Today it is almost universally recognized by pediatricians that infants should never consume milk (except mother’s milk) or dairy products until at least age one or beyond. A series of human infant experiments carried out in the 1980’s revealed beyond a shadow of a doubt that whey proteins in milk were largely responsible for colic. A powerful experiment known as a double blind crossover conducted by Drs. Lothe and Lindberg at the University of Lund in Sweden (71) demonstrated that colic symptoms disappeared in 89 % of all infants when they were given a cow milk free diet.
OK, this is good news, but you may ask why this information is relevant in 2014 when cow milk is no longer recommend by pediatricians until after about 1 year of age for infants. An often forgotten, but important offshoot of these 1980’s double blind crossover experiments was that they were also repeated in milk drinking mothers who breastfed their infants. Not surprisingly, infants who’s Moms drank milk became colicky, indicating that certain elements in cow’s milk may have caused an immunological response in the nursing mothers that was transferred to their milk which in turn was transmitted to their babies, making them cry (21, 61). Any food that causes such distress in infants should be a warning to us. It may be possible that our babies are more in tune with their bodies than we are.
Excessive Mucus Production
Too much milk consumption has long been associated with increased mucus production in the respiratory tract and incidence of asthma. I have a memory a few years back of going to a high school cross country meet and watching these young athletes cross the finish line. I noticed a few runners were literally “foaming at their mouths” because they had so much mucus being produced from their respiratory system. I wondered if milk drinking had anything to do with it, but at the time, the science hadn’t yet caught up with my observation and those of others. An intriguing new (2010) hypothesis by Drs. Bartley and McGlashan, otolaryngologists from New Zealand (9) may have found the answer.
Go back to my table of all the hormones and bioactive substances found in milk. You will notice under the category, “Bioactive Peptides formed in gut from Milk Proteins”, a substance called casomorphins. These compounds are produced in our guts from the breakdown of the milk protein, casein. One of these casomorphins, beta-casomorphin-7 directly stimulates mucus production from specific glands (MUC5AC) located in the gut. If the gut becomes leaky, which it invariably does on a typical western diet, beta-casomorhin-7 can then enter our bloodstream and travel to our chests where it stimulates mucus production from MUC5AC glands located in our lungs and respiratory tracts. A final piece of this puzzle is that beta-casomorphin-7 is much more likely to trigger mucous production if the lungs and respiratory tract are inflamed by asthma.
Parkinson’s Disease
Parkinson’s disease is a nervous system disorder that primarily affects areas of the brain controlling movement. Disease symptoms include tremors, stiffness and difficulty moving. You may best know this disease through its two most famous victims, Muhammad Ali and Michael J. Fox. Although the cause of Parkins