We’ve all heard the saying “the cream rises to the top” in reference to the idea that something good won’t go unnoticed for long.  It is interesting that this saying is still used because it is referencing the way cream performs in non-homogenized milk – something many people have never seen first-hand due to today’s widespread practice of homogenization.  In the past, higher fat milk meant healthier and happier cows.  Consumers would actually look for the cream at the top of the milk jug to know they were getting a quality product.  Nowadays, homogenized milk is the norm and many people have no idea that milk naturally separates.   

Whole milk naturally separates into two portions – the watery milk portion which is a mixture of water, lactose, and milk proteins such as casein, and the cream portion which is mostly fat and rises to the top because fat is less dense than water.  Homogenization forces whole milk through a high-pressure, high-temperature system that shreds the normally large fat globules into much smaller globules.  Due to the laws of chemical attraction, the fat globules in milk naturally attract protein molecules to their surface.  Smaller globules have more surface area than larger globules, which gives more space for protein to attach to.  This allows more protein to attach to the small globules of fat, which makes them heavier and allows the globs to blend or “homogenize” into the watery portion of the milk.  This causes the processed milk to retain a uniform texture, unlike fresh milk which will have a cream portion that rises to the top.

So what’s all the fuss?  Homogenization may be useful for presenting a product that is uniform in appearance, but it is not without its side effects.  Casein makes up approximately 87% of the protein found in milk, with the remainder attributed to whey protein.  Casein is one of the more allergenic molecules in milk and the fact that smaller fat globules in homogenized milk expose the consumer to more milk protein (namely casein) may be part of why modern day milk allergies are so widespread.  It may also be why makers of non-homogenized dairy products receive calls from customer after customer reporting with surprise that they do not experience an allergic response after drinking non-homogenized milk.

When non-homogenized milk is ingested the large fat globules are processed in the digestive system and the small amounts of casein attached to their surface are broken down by digestive enzymes and stomach acid.  When milk fat is homogenized, the small globules become “delivery capsules” which allow allergenic milk proteins such as casein to be absorbed directly into the blood stream without being broken down prior.  This absorption of undigested protein is strongly linked to increased allergies, because the immune system will attack undigested foreign proteins.  In conventionally produced milk, this delivery system may be of even more concern because it allows compounds such as hormones and antibiotics to pass into the body with greater ease.

Modern dairy processing practices have turned whole natural milk, one of nature’s most healthy foods, into a processed and allergenic food.  Fortunately there are still a few traditional dairies who stick to a standard of producing milk that is true to what nature intended.  If the saying holds true, it won’t be long until this superior way of creating milk products “rises to the top.”

In today’s world of nutritional confusion, many of us believe that saturated fats must be completely avoided in order to prevent disease. If we would take a look at ourselves on a microscopic level, however, we would see a completely different picture: approximately half of each of the tiny membranes surrounding your individual cells is made of saturated fat!

Saturated fat is so important to good health that if our bodies are deprived of it in the diet, they will start to manufacture it from carbohydrates. It is still better, though, to obtain saturated fat from whole food sources such as coconut, dairy, grassfed meat, and egg yolks. Requiring your body to make saturated fat from carbohydrates requires the release of insulin to digest the carbohydrates, while fat digestion does not. Over time, excess insulin release may lead to premature aging, weight gain, and blood sugar problems such as hypoglycemia or diabetes.

An average glass of whole milk contains about 8 grams of fat, with slightly over half of that fat as saturated fat1. The term “saturated” refers to the arrangement of carbon and hydrogen in the structure of the fat – a saturated fat is “saturated” with hydrogen because it has a hydrogen molecule at every available location. Saturated fat is an important building block for brain tissue – especially in children – and it also serves as an important ingredient for making hormones. A recent study found that women who choose low-fat dairy products over full-fat dairy products are more likely to experience anovulatory infertility2, which is an inability to become pregnant due to lack of ovulation.

Dairy fat in particular contains two types of saturated fat with amazing health benefits: butyrate and CLA. Butyrate, a specific type of saturated fat found in dairy, serves as the primary food for colon cells3. This fat is made through a fermentation process by the healthy bacteria in the gut. This fat can also be found in abundance in butter and whole milk yogurt. Butyrate has been shown to play a preventive role in formation of colon cancer4. CLA (conjugated linoleic acid) is another important saturated fat found in dairy fat, with approximately five times more CLA in the milk of cows that are fed grass (their natural food) as opposed to grain. CLA is currently the focus of much research for its anti-cancer properties. In fact, a 2005 Swedish study found that “high intakes of high-fat dairy foods and CLA may reduce the risk of colorectal cancer”5. CLA also encourages the body to use calories to build muscle instead of storing them as fat which is especially important in children who are developing rapidly6,7.

With all of this said, it is important to remember that pesticides, artificial hormones, and other harmful substances tend to lodge in the fat portion of a food. So, as you begin to increase the dairy fat content of your diet please be mindful of the source of your food and choose milk from healthy, chemical-free cows.

References:

1. USDA Food Composition Database
2. J.E. Chavarro et al., “A Prospective Study of Dairy Foods Intake and Anovulatory Infertility.” Human Reproduction 2007;22(5):1340-7.
3. E. Hijova et al., “Short Chain Fatty Acids and Colonic Health.” Bratisl Lek Listy 2007;108(8):354-8.
4. J.M. Wong et al., “Colonic Health: Fermentation and Short Chain Fatty Acids.” Journal of Clinical Gastroenterology 2006;40(3):235-43.
5. S.C. Larsson et al., “High-fat Dairy Food and Conjugated Linoleic Acid Intakes in Relation to Colorectal Cancer Incidence in the Swedish Mammography Cohort.” American Journal of Clinical Nutrition 2005;82(4):894-900.
6. B.A. Corl et al., “Conjugated Linoleic Acid Reduces Body Fat Accretion and Lipogenic Gene Expression in Neonatal Pigs Fed Low- or High-Fat Formulas.” Journal of Nutrition 2008;138(3):449-54.
7. C.S. Berkey et al., “Milk, Dairy Fat, Dietary Calcium, and Weight Gain: A Longitudinal Study of Adolescents.” Archives of Pediatric Adolescent Medicine 2005;159(6):543-50.