Milk Homogenization and Heart Disease

Health-MilkHomogenization-600x626By Mary G. Enig, PhD

One widely held popular theory singles out homogenization as a cause of the current epidemic of heart disease. The hypothesis was developed by Kurt A. Oster, MD and studied from the early 1960s until the mid 1980s. In studying and comparing the structure and biochemistry of healthy and diseased arterial tissue, Oster investigated plasmalogen, an essential fatty component of many cell membranes in widely scattered tissues throughout the human body. Plasmalogen makes up a substantial part of the membranes surrounding heart muscle cells and the cells that make up the walls of arteries. It is also present in the myelin sheath surrounding nerve fibers and in a few other tissues. But it is not found in other parts of the human anatomy.

Oster discovered that heart and artery tissue that should contain plasmalogen often contained none. It is well known that atherosclerosis begins with a small wound or lesion in the wall of the artery. Oster reasoned that the initial lesion was caused by the loss of plasmalogen from the cells lining the artery, leading to the development of plaque.

The big question was what caused the lack of plasmalogen in the heart muscle and the tissue lining the arteries. Oster believed that the enzyme xanthine oxidase (XO) has the capacity to oxidize, or change, plasmalogen into a different substance, making it appear that the plasmalogen had disappeared. The body makes XO, but XO and plasmalogen are not normally found in the same tissue; the heart, therefore, normally contains plasmalogen but not XO. In a paper published in 1974, Oster argued that the presence of XO in the liver and in the mucous membrane of the small intestine was directly responsible for the natural absence of plasmalogen from the cell membranes at these sites.1 If XO somehow made its way to the heart and its arteries, that might explain the absence of plasmalogen in the surgical specimens and autopsy tissues from pathological hearts.

What was the source of the XO found in the autopsy tissues? Normal human serum (the fluid part of the blood) does not contain XO. Oster and his partner Ross considered two possible sources. One was liver cells; patients with acute liver disease showed increased serum levels of xanthine oxidase, and those with chronic liver disease occasionally showed moderate elevations. Another potential source was cow’s milk, “…presently under investigation in this laboratory since it has been shown that milk antibodies are significantly elevated in the blood of male patients with heart disease.”2

Cow’s milk is the most widely consumed food containing high levels of XO. Thorough cooking destroys XO, but pasteurization destroys only about half of the XO in milk. Knowing this, Oster now looked for a link between XO in milk and the loss of plasmalogen in arteries and heart muscle tissue.

He knew that people have drunk milk for upwards of 10,000 years, and that milk and milk products were central in the dietaries of many cultures. But the epidemic of atherosclerosis was recent. These facts argue against traditional milk and milk products being the culprit. But the homogenization of milk became widespread in America in the 1930s and nearly universal in the 1940s—the same decades during which the incidence of atherosclerotic heart disease began to climb. Oster theorized that the homogenization of milk somehow increased the biological availability of xanthine oxidase.

According to Oster, XO that remains in pasteurized, unhomogenized milk is found on the exterior of the membrane of the milk fat globules, where it is broken down during digestion. XO in raw milk is similarly digested. Oster postulated that because homogenization reduces the fat globules to a fraction of their original size, the XO is encapsulated by the new outer membranes of the smaller fat globules which form during the homogenization process. He believed that this new membrane protected the XO from digestive enzymes, allowing some XO to pass intact within the fat globules from the gut into the circulatory system when homogenized milk is consumed.3 He referred to these fat globules as liposomes and argued that the liposomes carrying XO were absorbed intact. After entering the circulation, they travel to the capillaries, where the lipoprotein membranes appear to be digested by the enzyme lipoprotein lipase, thus freeing the XO for absorption into the body, including the heart and artery tissues, where it may interact with and destroy plasmalogen.

In essence, Oster’s theory replaces cholesterol as the cause of heart disease with another mechanism, summarized as follows:

Homogenization causes a supposedly “noxious” enzyme called xanthine oxidase to be encapsulated in a liposome that can be absorbed intact.

XO is released by enzymatic action and ends up in heart and arterial tissue where it causes the destruction of a specialized protective membrane lipid called plasmalogen, causing lesions in the arteries and resulting in the development of plaque.

Neither the opponents nor the proponents of the xanthine oxidase/plasmalogen hypothesis have presented convincing evidence in all of their writings. However, the more scientific reviews questioned the validity of Oster’s hypothesis, and pointed to some of the inconsistent findings.

A fundamental flaw in Oster’s theory involves the difference between a fat globule and a liposome. Fat globules basically contain triglycerides and cholesterol encapsulated in a lipid bilayer membrane composed of proteins, cholesterol, phospholipids and fatty acids. They occur naturally in milk in a wide range of sizes. The fat globules in unhomogenized bovine milk are both very small and very large, ranging in size from 1000 nanometers to 10,000 nanometers. After homogenization, the average globule size is about 500 nanometers with a range from 200 nanometers to 2000 nanometers.

Oster considered homogenization of cow’s milk to be a “procedure which foists unnaturally small particles on our digestive tracts.”4 Yet sheep’s milk fat globules are reported to be “very small. . . [and consequently]. . . easier to digest” and in fact globules from this milk are described as “naturally homogenized.”5 The milk fat globule membrane from sheep’s milk does not separate and butter cannot be made from such milk even though there is twice as much fat in sheep’s milk as in cow’s milk. The fat globules from goat’s milk are similarly small. Once again, goat’s milk is considered easier to digest than cow’s milk for this reason. So there is nothing unnatural about small milk fat globules.

Fat globules of all sizes are broken down during digestion, releasing the hundreds of thousands of triglycerides as well as any enzymes they contain. (Milk fat globules actually contain more than seven enzymes, of which XO is one. The other major ones are NADH2, iodonitrotetrazolium, 5-nucleotidase, alkaline phosphatase, phosphodiesterase and gamma-glutamyltranspeptidase.) These enzymes are broken down into individual amino acids (enzymes are specialized proteins) and the triglycerides are broken down into individual fatty acids and monoglycerides.

Although Oster described these small milk fat globules in homogenized milk as liposomes, several researchers have pointed out that liposomes are very different in basic composition. Liposomes are typically 200 nanometers or less in size and do not contain complex protein components. Liposomes do not occur in nature but were developed by scientists as a way of delivering components such as drugs to the cells in the body. They are composed of a phospholipid layer in which the phosphorus moiety is on the outside and the lipid moiety is on the inside. The layer encapsulates a watery liquid, not fatty acids. A liposome is not broken down during digestion. For this reason, scientists have looked at liposomes as a way of delivering compounds taken orally to the cells. In fact, a 1980 study led by Oster’s colleague D. J. Ross reported that liposome-entrapped insulin effected blood sugar-lowering in diabetic rats.6 Ross claimed that this proved that large molecules could be absorbed.

A team led by A. J. Clifford looked carefully at Oster’s theories. In a study published in 1983,7 they noted that “neither liposome formation during homogenization of milk nor absorption of intact liposomes from the gastrointestinal tract has been demonstrated.” In reviewing the major published findings, Clifford reported that “absorption of dietary xanthine oxidase has not been demonstrated.” Clifford’s team cites studies showing lack of activity of serum xanthine oxidase from pigs and humans fed diets that included milk or were without milk8,9 Further, Clifford’s team noted that “a relationship between intake of homogenized ‘dairy foods’ and levels of xanthine oxidase activity in the blood has not been established.”

There was even one study which showed an increase in serum xanthine oxidase when corn oil was fed, whereas milk and cream showed no such increase.10 Oster had argued that homogenization came into widespread use during the 1930s and 1940s, the same years during which heart disease incidence went up dramatically. But these were the same years in which vegetable oils came into widespread use. (And if Oster’s theories are correct, then only those who drink modern milk would get heart disease, a conclusion that is obviously untrue.)

As for Ross’s study on insulin, Clifford argued that recent evaluation by others showed the insulin phenomenon to be an artifact of the methods used and not due to the delivery of insulin to the cells. Thus one of Oster’s published proofs turned out to be erroneous. (In fact, scientists have subsequently tried to use liposomes in humans as a way of delivering insulin taken orally to the cells but without success. However, liposomes have been used successfully to deliver an enzyme needed for the treatment of Gaucher disease.) When the Clifford team examined the electron micrograph presented in Ross’s 1980 paper, he reported that it did not match the typical liposome structure as reported by a noted authority in liposomes.11

In the second part of his theory, Oster maintains that XO causes the destruction of plasmalogen. However, Clifford’s team reported that “a direct role for xanthine oxidase in plasmalogen depletion under physiological conditions has not been established.” They cite animal studies where bovine xanthine oxidase was given intravenously in large doses.12 This treatment failed to deplete plasmalogen in the arteries or in the coronary tissue, nor did it introduce formation of plaque.

The fact that Oster’s theory has been disproven does not mean that the homogenization process is benign. During homogenization there is a tremendous increase in surface area on the fat globules. The original fat globule membrane is lost and a new one is formed that incorporates a much greater portion of casein and whey proteins.13 This may account for the increased allergenicity of modern processed milk.


  1. Oster, K., Oster, J., and Ross, D. “Immune Response to Bovine Xanthine Oxidase in Atherosclerotic Patients.” American Laboratory, August, 1974, 41-47
  2. Oster, K., and Ross, D. “The Presence of Ectopic Xanthine Oxidase in Atherosclerotic Plaques and Myocardial Tissues.” Proceedings of the Society for Experimental Biology and Medicine, 1973.
  3. Ibid.
  4. Oster KA. Plasmalogen diseases: a new concept of the etiology of the atherosclerotic process. American Journal of Clinical Research 1971:2;30-35.
  5. Sheep’s milk
  6. Ross DJ, Sharnick SV, Oster KA. Liposomes as proposed vehicle for the persorption of bovine xanthine oxidase. Proceedings for the Society of Experimental Biology and Medicine. 1980:163;141-145.
  7. Clifford AJ, Ho CY, Swenerton H. Homogenized bovine milk xanthine oxidase: a critique of the hypothesis relating to plasmalogen depletion and cardiovascular disease. American Journal of Clinical Nutrition. 1983:38;327-332.
  8. McCarthy RD, Long CA. Bovine milk intake and xanthine oxidase activity in blood serum. Journal of Dairy Science. 1976:59;1059-1062.
  9. Dougherty TM, Zikakis JP, Rzucidlo SJ. Serum xanthine oxidase studies on miniature pigs. Nutrition Report International. 1977:16;241-248.
  10. Ho CY, Crane RT, Clifford AJ. Studies on lymphatic absorption of and the availability of riboflavin from bovine milk xanthine oxidase. Journal of Nutrition. 1978:108;55-60.
  11. Bangham AD. Physical structure and behavior of lipids and lipid enzymes. Advances in Lipid Research. 1963:1;65-104.
  12. Ho CY, Clifford AJ. Bovine milk xanthine oxidase, blood lipids and coronary plaques in rabbits. Journal of Nutrition. 1977:107;758-766.

Mary G. Enig, PhD

Mary G. Enig, PhD was an international expert in lipid biochemistry. She headed a number of studies on the content and effects of trans fatty acids in America and Israel, and successfully challenged government assertions that dietary animal fat causes cancer and heart disease. Recent scientific and media attention on the possible adverse health effects of trans fatty acids brought increased attention to her work.

She was a licensed nutritionist, certified by the Certification Board for Nutrition Specialists, a qualified expert witness and nutrition consultant, contributing editor to a number of scientific publications, fellow of the American College of Nutrition and president of the Maryland Nutritionists Association. She was the author of over 60 technical papers and presentations. She served as vice-president and board member of the Weston A. Price Foundation (WAPF) and scientific editor of Wise Traditions, the Foundation’s quarterly journal. She is the author of Know Your Fats: The Complete Primer for Understanding the Nutrition of Fats, Oils, and Cholesterol and Eat Fat Lose Fat (with Sally Fallon Morell) and co-author of the bestselling cookbook Nourishing Traditions. Her three healthy children were brought up on whole foods including butter, cream, eggs and meat.

25 thoughts on “Milk Homogenization and Heart Disease

  1. Hi, I wonder if you can help me with a question. As you know there are many noxious substances that attack the tight junctions of the gut including glutin, lectins, medication and chemicals. Is it possible that liposomes or fat micro globules in homogenized milk migrate thru the enlarged junctions and enter the blood stream where they will raise triglyceride levels. These in turn are related to cardiovascular disease.
    Thank you
    Paul von Kulmiz

    • Sally Fallon Morell responds: This is entirely possible although I know of no study to confirm this. Certainly proteins warped and distorted by pasteurization get through. And there is some evidence that pasteurized milk contributes to heart disease.

  2. As a person who has recently had a heart attack, I can attest that I avoided vegetable fats, I enjoyed butter, cheese and more recently took to drinking kefir made from full fat homogenized milk, 2-3 glasses a day.
    I couldn’t drink homogenized milk without getting acid problems, and thought that the kefir got around this and for quite a while it did appear to agree with me. I thought that the pre-digestion by bacteria, enzymes and yeasts rendered it more easily digestible. I’m assuming that the lactic acid may have burned the lining of my arteries, it certainly felt like it was burning me, especially my lungs felt like I was inhaling hot smoke instead of cold damp sea air.

    Could lactose intolerance be more widespread that we think it is?

  3. “These findings support the hypothesis that xanthine oxidase is a major source of oxygen-free radicals produced during reperfusion of the ischemic small bowel.”

    “Plasmalogens are often considered as antioxidant molecules that protect cells from oxidative stress. Their vinyl ether bond could indeed be among the first targets for newly formed radicals.”

    “When a hydroxyl radical reacts with a protein, lipid, or DNA molecule, it snatches an electron to itself then sinks back into the sublime stability of water, But of course the act of snatching an electron leaves the reactant short of an electron, just as a mugger leaves a victim short of a handbag. In the case of the hydroxyl radical, another radical is formed, this time part of the protein, lipid or DNA. It is as if having your handbag snatched turns you into a mugger yourself, restless until you’ve snatched someone else’s bag. This is a fundamental feature of all free radical reactions – one radical always begets another, and if this radical is also reactive, then a chain reaction will ensue. Thus the cardinal feature of a free radical is an unpaired electron, while the cardinal feature of free radical chemistry is the chain reaction.”
    “Oxygen”, The molecule that made the world. Nick Lane, Oxford University Press.

    So, if plasmalogen is reactive Dr Oster is right.

  4. I read his book in 2001 and quit using milk shortly thereafter, 10 years later my new doctor was quite concerned about my cholesterol test. My HDL was 15 and LDLs were 90, both exceptionally low. Almost 10 years hence and those values are still similar. I don’t recall those test values from prior testing but around 200 for LDLs seems about right when I was in my 30s. I’m 63 years old now, take no RX drugs, have pulse around 65 and BP in the 105/65 range consistently. I am going to continue to heed this advice since it seems to be working for me. I also seem to be able to out pace those much younger that I work around with ease. I live at 1,100 feet but was able to hike 2500 feet of elevation change to 10,000 feet in the Rockies last summer without much difficulty, can’t say the same for my companions.

  5. weather is that exact theory, the fact it is changing the fat molecules to a much smaller size, makes it easier to get directly absorbed into the bloodstream which I think is the basis of the issue, The fact that are changing something from the way is naturally.

  6. You are almost right, been studying this for years, basically it allows the much smaller fat molecules to directly ether the bloodstream more readily. Since milk has calcium and is absorbed in the fat molecules, these can not get into the bloodstream much easier, then the fat molecules dissolve and leave calcium deposits. now this process is completely different than eating natural foods containing calcium since not directly absorbed into the blood stream in those instances. This is at least one therogy, Heart disease correlates with the onset of when homogenization of milk began. And issues with lactose intolerance did not become a big issue until after homogenization. Never could really tolerate Milk when growing up, Mom only liked Skim Milk and although did not like as well did not bother me as bad as whole milk. later in life on and off tried drinking milk, each time I would get heavy mucus build up and constantly coughing up. As soon as started trying non homogenized milk once it never bothered me, moved and could not get tried regular milk and issues came back, ever since been drinking non-homogenized milk, no issues.

    • Thanks Mike. You hit an interesting note with me. When I was a youngster, I could glug down a pint of gold top channel full fat milk, which was pasteurized, without any problems. I was a milk monitor in primary school and I used to help the milk man deliver milk to the door as a youngster. Yet for some reason, the milk became very acid-causing and I would have to take ant-acids for relief until I realised I could no longer tolerate drinking milk. I’m 63 now so this would have been around 1964

      Add to this the fizzy drinks introduction, which would instantly turn your stomach and intestines from a relaxed low pressure environment into a gas pressurised system that could explain how fat globules are given a helping hand into the blood stream.

  7. one major item overlooked, before homogenization most fat molecules in cows milk does past easily into the bloodstream, after homogenization these fat molecules are small enough that most are directly absorbed into the blood stream. The one thing most US milk is fortified with is Calcium, this gets infused into those smaller fat molecules and once in the blood stream can get deposited. I noticed many years ago after drinking any homogenized milk I would cough up a large amount of mucus/phlegm. I thought was just milk, but no other dairy would do this. After some time I was in an area where shopping at a local farmers market was getting raw milk or at least non homogenized milk and realized was not having the issue. one day I ended up buying homogenized milk and the issues came back immediately. Since I have interviewed many others that exhibited the same symptoms, and of those who had gotten to try non homogenized milk their issues also completely went away. That is direct evidence that something is wrong with homogenization of milk period!

  8. Mark McAfee and Dr. Dale Jacobson (DC) had a full-length conversation on homoginization and related aspects of milk that I produced as a DVD: “Raw Milk: The Whole Truth”. Contact me for a copy:

  9. I used milk quite often for the last of my 62 years that I can remember. I am not overweight or smoke or drink alcohol heavy. I have been recently told that I need 4x CABG. After reading this article and comments I will stop using grocery store milk. Thank you for keeping the article on the www for all this time.

  10. I am more interested by the last couple of sentences regarding casein and whey proteins increasing in % when reforming the fat globule in homogenized milk. This may well be the issue with increased allergenicity and decreased tolerance. Also, as commercial dairy production increases, cows are bred for the amount of milk they produce, not the quality. Enter the Hostein. They produce almost entirely A1 casein milk, which is more difficult to digest, due to its chemical structure. As far as heart disease, I think milk is part of the issue, but by no means the whole issue. There are hormones in milk that increase size and insulin response, so the link may be more to do with the increase in diabetes, which contributes to heart disease. Add to that the vegetable oils, chemical preservatives, artificial colors and flavors, and massive increase in sugar consumption, and you have a recipe for disaster.

  11. In spite of the comments from some of the more “learned” commentators, I still subscribe to Oster’s theory due to his accompanying charts showing the amount of milk consumed per person in various countries, the % of milk that’s homogenized, and the rate of atherosclerosis. Finland, which had nearly double the U.S. consumption of cow’s milk, had only a slightly higher occurrence of atherosclerosis than the U.S. due to their lower % of homogenization whereas Italy, which had a much lower consumption of milk per capita, had a greater than expected rate of ath’sis as well as a high % of homogenization. One commentator admitted that, unless one has leaky gut, fats don’t get into the bloodstream. From what I’m learning, leaky gut has become a fairly common problem among Americans, thereby adding credence to Oster’s explanation. I wouldn’t rule out the role of dietary oils, though. The addition of oils into our food supply, especially canola/rapeseed and soy, (margarine, salad dressings, peanut butter, cereals, breaded fish, Ensure/Boost, you name it) is another monumental problem IMHO. Time to start reading labels before you buy.

    • Do not have to have leaky gut, homogenization causes the fat molecules to become small enough to be directly absorbed into the bloodstream through the intestinal walls.

  12. They homogenized it so multiple batches of milk can be mixed so consumers get consistent quality and it also makes it easier to make low fat milk.

  13. This does not address the claim by the late Dr. Enig that the increased surface area of the homogenized globules allows a greater percentage of (potentially) allergenic bovine casein proteins to be transported into the bloodstream without proteolysis.

    The same could be said about sheep and goat’s milkfat globules—already ‘homogenized’—but are their caseins equally potentially allergenic?

  14. Says Mary Enig is the mother of three healthy children brought up on whole foods including butter, cream, eggs and meat.

    Cream is not homogenized. So regardless of how safe homogenized milk may be, she didn’t feed it to her kids.

    • As mentioned elsewhere, I cannot drink homogenized milk causes all kinds of issues so have never drank much at all, but can drink non homogenized milk from the farmers market all day without issues. I eat a ton of cheese and other dairy, I mean a lot, use to be a block of cheddar a day on average. recent heart tests and echo cardiogram shows no issues. Now my brother who regularly drinks a large glass or more a day of homogenized milk has had many blockages. Too many studies focus on the trees too much, does not correlate all the data, not seeing the forest.

  15. I would rely on what my indicates to me,… and clearly I find I do better with non-homogenized milk than with homogenized milk.
    I find homogenized milk promotes lowered sexual vitality/lowered sexual stamina, with me,.. and which is an indicator of other less than preferable processes going on in my body due to the ingestion of significant quantity of homogenized milk,.. as a staple in my diet. Homogenized milk being more likely to ‘gunk up’ ones system more so than unhomogenized milk.
    I let my body prudently direct.
    People as you, perhaps, can blithely rely on science and disregard their body,.. beause they don’t care as much about their physical integrity.

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