The Real Story of Homogenized Milk, Powdered Milk, Skim Milk and Oxidized Cholesterol

Milk has been through a lot in the past 100 years. First it was subjected to pasteurization, then homogenization, then oxidation. Will the -ations ever end?

The question for us milk drinkers is of course: when does a change cause a nutritional problem?

Some say that pasteurization already kills too many healthy enzymes; see more on the different kinds of milk pasteurization in yesterday’s post.

Related: Sweetened Condensed Milk

Is Homogenized Milk Dangerous?

I joined the crowd warning of the health dangers of homogenized milk when I talked dairy fats in the fall. This post is an important update to that one!

There’s a theory out there, propagated by Kurt Oster, that says that the process of breaking the fat globules into such small pieces that they remain suspended in the milk, homogenization, is a leading cause of arteriosclerosis and heart disease. I’ve even seen it listed as one of the top three causes of heart disease, along with trans fats and chlorinated water. 1

However, even Mary Enig, co-author of Nourishing Traditions and author of Eat Fat, Lose Fat disagrees with Oster’s findings. She says:

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.

Translation: the fats damaged by homogenization can be passed through the walls of the digestive system directly into the circulatory system, where they “scratch” the artery walls, making a problem area to which cholesterol flocks (cholesterol is like the ambulance or mechanic in your circulatory system, repairing issues in the arteries). This forms plaque and causes heart disease, and it’s all because the fat globules got too small.

But.

He was wrong.

Mary Enig says so here, and I also spoke with a professor in the department of Food Science & Human Nutrition and Department of Animal Science at my favorite agricultural college, Michigan State University. Dr. John Partridge is a Dairy Food Extension Specialist, and he had this to say about concerns about oxidation of homogenized milk:

Homogenization is done by forcing milk through a small geometry valve at very high pressures (1500-2500 psi). The effect of this treatment is to break the natural fat globule (average size ~10 micrometers) into  much smaller fat globules (average size <2 micrometers). In doing this the fat globule membrane is broken and the surface area of the new fat globules is much larger than the native globules.

Within the first 10-20 seconds after homogenization, proteins and segments of the original membrane form a new membrane on the surface of the smaller fat globules. The addition of the protein to the surface of the fat globules and the reduction in the size of the globules results in the reduction in the ability of the globules to float to the top of the milk. During this process, the milkfat is not exposed to air as the process is done in an air tight system containing only milk. Milkfat is made up of 98% triglycerides, which are extremely stable to changes during processing. The only way that milk will spoil faster after homogenization is if the homogenizing system is not properly cleaned and sanitized.

Another factor that may be thrown out is the xanthine oxidase. Dr. K. Oster proposed a theory in 1971 that xanthine oxidase released from the milk fat globule membrane during homogenization was a contributor to atherosclerosis. To this end, I would have you read the following review article.

There is not much if any support for this theory but a lot of people are still using it to scare customers into paying higher prices for cream-line milk.

Dr. Partridge drinks homogenized store milk himself, although he said he has to take the jugs from the back to avoid the “light oxidized flavor that is prevalent in milk stored under direct fluorescent lighting.” This is not a man who drinks milk without consciousness.

Dr. Mary Enig finishes with this, although I’d like to see more foundation for her claims:

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. This may account for the increased allergenicity of modern processed milk.

With all that under my belt, I’m much less afraid of homogenized milk than I used to be. I have some distrust in it, because it is quite a man-made process, so when I can stick to the natural, I will. I won’t, however, pay double price for unhomogenized milk unless there are other upgraded benefits from the store milk! (See this milk descriptions post for what all the terms on the jugs mean.)

Does Skim Milk Contain Powdered Dry Milk?

The Weston A. Price Foundation says, “All reduced-fat milks have dried skim milk added to give them body, although this ingredient is not usually on the labels.” I’ve seen this claim in multiple other places as well, but it’s incredibly outdated and plain wrong.

I’m the type of person who calls companies to ask questions (in case you haven’t already noticed that). When I realized that the claim of “industry standard” might be incorrect, I decided to call a few brands that sell milk to see what I could find out.

From Meijer:

I had not heard of that being an industry standard, and I can tell you that none of Meijer’s dairy suppliers add anything to the milk.

From Bareman’s, a local Michigan dairy:

Non-fat dried milk (skim milk powder)  is not currently added to our, or any of our direct competitors lowfat or fat free milks (skim milk) and, any direct addition of a dried milk powder would require it to be included on the label to meet current United States labeling requirements. In the 1950’s and 60’s many states required nonfat dried milk to be added to lowfat (<1% butterfat) and fat free milks (skim) under the guise of making it a nutritionally superior product to the unfortified product but, in reality its real purpose was to help support a higher demand for non-fat milk powder and ultimately a higher total milk price for the producer. Eventually, pressure from industry, regulators and nutritionists prevailed and all states who had “solids fortification” requirements in their dairy laws repealed them.

I would like to see the WAPF update their position on this issue, as their information clearly was correct decades ago but is sorely outdated.

Does Powdered Dry Milk Contain Oxidized Cholesterol?

The reason for the scare about powdered milk being added to skim and lowfat milk is this:

A note on the production of skim milk powder: liquid milk is forced through a tiny hole at high pressure, and then blown out into the air. This causes a lot of nitrates to form and the cholesterol in the milk is oxidized… Oxidized cholesterol contributes to the buildup of plaque in the arteries, to atherosclerosis. So when you drink reduced-fat milk thinking that it will help you avoid heart disease, you are actually consuming oxidized cholesterol, which initiates the process of heart disease.

Here’s the hole in that argument: nonfat dry milk has little to no cholesterol to begin with, so consuming any “oxidized” cholesterol that may or may not be present there is probably no more hazardous to your health than eating an apple that is starting to brown (that process is oxidation, too).

Here is a a conversation with an animal science trained former farm gal on oxidized cholesterol with her convincing arguments.

I had been making my yogurt with store whole milk since coming around to the idea of full fat dairy. Once I decided there was no inherent problem drinking skim milk, other than the fact that it’s missing the fat, I began making my yogurt with skim milk and added cream from our grassfed raw milk. I figured that even if homogenization isn’t as bad as it’s being made out to be, I can still get the fat to be organic, which helps my family avoid most of the potential toxins and hormones, which tend to collect in the fat.

Tomorrow I’ll tell you a bit about how I came to the decision to drink raw milk.

1. Natural Cures “They” Don’t want you to Know About by Kevin Trudeau

Photo from Flickr.com

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