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 stucture 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.

References

  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.
  13. http://www.foodsci.uoguelph.ca/dairyedu/homogenization.html.

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.

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38 thoughts on “Milk Homogenization and Heart Disease

  1. The study on homoginazition of milk is very interesting. I feel that there is more to it than is said, unless I am a layman and it went over my head. Somehow I feel thet th fracturing of fat modules in milk leaves it in jagid form and smaller in size allowing it to enter the blood stream to cause scoring of the inside of the vessel, therefore celestoral is needed to try to hold the vessel together or rather try to repair the damage.
    Please reply

    Ted Carter

    • I posed your comment to Sally Fallon Morell, who replied, “Even after homogenization, the fat globules are still way too big to be absorbed. The globules must be broken down, and the triglycerides broken down into individual fatty acids before absorption can take place. That doesn’t mean that homogenization is benign, it probably oxidizes the fatty acids and it disrupts the membrane material.” Hope this helps.

      • Anyone with even just an elementary knowledge of gut physiology knows that the size of globules of fat present in food has little or no effect on its digestion. One of the important functions of the liver is to secrete bile when fatty food enters the small intestine. Bile contains copious quantities of detergent-like bile salts, whose primary function is to emulsify various types of fatty substances. This elmulsification is the biological equivalent of the mechanical process of homogenisation – in other words large globules of fat are converted to millions of tiny droplets, less than 1 micron in diameter, that fat-digesting enzymes (various lipases produced by the pancreas) can then more readily work on.

        The resultant micelles, aggregations of trigycerides (from the digested fats) and a substances called lecithin, are then absorbed through the microvilli of the epithelial cells lining the cell walls of the small intestine, and thence reach the bloodstream.

        It therefore makes no difference to its subsequent digestion whether milk is homogenised or not, and it is complete nonsense to contend that homogenised fats in milk pass into the bloodstream at a greater rate or in greater amounts than un-homogenised fats, or indeed whole fats such as vegetable oils, lard, suet or whatever.

        It has also been conclusively demonstrated over the past 3 decades that the xanthine oxidase theory is also seriously mistaken. This substance, implicated in cardiovasular damage, is supposedly released during the homogenisation process from fat globules and then absorbed into the bloodstream. However, the results of numerous investigations have shown that xanthine oxidase is not absorbed by the gut wall at all.

        I would rather rely on actual research data than the idle speculation spouted by “armchair scientists” who seem to possess very limited knowledge (or maybe they just ignore it).

        • 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.

        • 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?

  2. It is a sad fact that ‘academia’ in the United States means that the side with the most money can hire the ‘academics’ to support their economic necessity to be ‘consistent’ with the science for which the intentionally ‘dumbed-down’ American education leaves the American people unable to cope with this double-talk. The fact is that Dr. Oster had irrefutable data that backed up his assertions that homogenized milk contributes significantly to the narrowing of the arteries. The data carefully quantified both milk consumption rates and homogenization rates in all all the major milk consuming countries.
    These same ‘academics’ chime in for the highest bidder to support GMOs, to negate Global Warming, Darwin’s theory of evolution, and would if necessary, and did in the past, that the earth is flat and the center of the universe. These people should not be considered academics, but ‘guns for hire.’

  3. If homogenization of milk is not the issue then what caused the rise in incidence of atherosclerotic heart disease during the time after the homogenization process began being used?

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  5. If the mechanical process of homogenization with cows milk causes the free radical Xanthine Oxidase to be released which can cause damage to your heart can the unnecessary but sometimes practiced mechanical process of homogenization with goat’s milk cause the same health issue?

    Thanks

  6. During my surgical residency 1946-1951, I started the day with 3 post/coronary arteriosclerosis 3 to 4 per 100. Cook County Hospital, Chicago. Homogenization brings forth “acid” which burns the endothelium, which is repaired by covering with LDL. When this happens daily a progressive process results. I have not seen a disease in farmers’ animals that in 65 years who drink raw milk that demands or needs pasteurization. Farmers should be able to sell raw milk.

    • Bill I am amazed that someone of your claimed education is virtually illiterate. You are unable to write understandable english and yet you comment on a scientific subject such as this. You do people a disservice and promote distrust of what should be a serious discussion on an important subject as your comments cannot be taken seriously as being those of an educated, informed person. At least get a professional sub-editor to check your work.

      • Since his surgical residency ended 62 years ago, I assume he is rather elderly now–at least late 80s–and may have difficulty typing/seeing the computer screen well. I retyped his comment so that it is not in all caps. It still needs editing, but few people have an editor at home to check the comments they leave on websites.

      • You are a very rude person! How can you speak to an elderly person with such disdain! It’s a sad era of time when the young look on the elderly as idiots! Lets see how well you type when your into your eighties! I understood what he was trying to say, and I greatly value his opinion, which is very relevant to the topic, especially as a “first hand eye witness”, to the changes in people’s health during the time he was a surgeon.
        ” Do unto others a you would have them do to you. “

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  11. Hey there, back in the mid 1960’s there was an article in Time magazine by some medical doctor who had made a connection between people with heart disease and their drinking homogenized milk. There was nothing in the article about the heart and artery tissue that should contain plasmalogen often contained none. Or, that it is well known that atherosclerosis begins with a small wound or lesion in the wall of the artery and that the initial lesion was caused by the loss of plasmalogen from the cells lining the artery, leading to the development of plaque. His hypothesis was, that instead of digested butter fat in the form of triglyceride, along with fatty acids, the clumped together butter fat molecules which are too big to pass into the bloodstream were separated by homogenization and the individual, undigested fat molecules were able to pass into the bloodstream with the resulting damage to the arteries. Therefore, can you tell me if whole fat molecules, butter fat, or other fats, can pass into the bloodstream or only digested fats? Thank you in advance for your reply.

    • From Sally Fallon Morell: “I just don’t know. My guess is that unless you have leaky gut, only free fatty acids pass through. But even if whole triglycerides pass through, I don’t think it matters because the free fatty acids are reconfigured into triglycerides in the bloodstream. Sally”

  12. I’ve found that homogenized milk in me promotes erectile dysfunction.
    The causes with erectile dysfunction which I can make happen, are with homogenized milk(pasteurization is alright with my body, raw causes more flatulence,.. it’s the homogenization, and, ultra-pasteurization, which my body does not process as well), potatoes, and white flour products. Also, apples have some some effect in that direction too, especially baked apples.
    Eat fundamentally, and with what you’re body responds well with and processes well, as can be demonstrated by each person’s own results, and in appropriate amounts, not over eating, not eating too frequently all the time,… and you should have best chance of thriving all-around.

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  16. This article is well written and interesting, as are the comments. I read about this problem years ago and was researching it today. Since reading about the issue, I have wondered why we still homogenize milk. Yes, there will still be some fat in the milk, but why can’t we just shake the carton? I do wish there was an economical alternative.

    • 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.

  17. 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.

  18. 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.

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  21. 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.

  22. 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.

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