If you're an athlete, a fitness advocate or a dieter who routinely uses protein supplements, there's a good chance your supplement is made with a bad ingredient.
That ingredient is called casein.
So what exactly is casein?
Casein is the main protein in raw milk. It is typically extracted via acid heat processing and used as a common ingredient in protein products - powders, bars and drinks. You may have been told that casein supplementation is highly beneficial for your muscle and body, but I'm here to prove to you that nothing is further from the truth.
What's Wrong With the Typical Casein in Sport Nutrition Supplements?
The typical casein is an inferior protein, often drenched with toxic residues. In fact, it’s one of the worst proteins for your body.
If you're serious with your diet and training regimen, you owe it to yourself to know these facts before purchasing another casein-containing protein. You may have already been noticing some of the side effects involved with casein ingestion - heart burn, bad after taste, indigestion, allergies ... What you may not be aware of is that some protein manufacturers have been routinely taking advantage of dedicated consumers like yourself, who are in need for an affordable protein they can use on a daily basis. And in the case of casein …
They Sell You Nothing More Than Garbage With A Fancy Label
They Sell You Nothing More Than Garbage With A Fancy Label
Why garbage? Because they use the cheapest processing methods to maximize their profits. The casein is typically extracted with chemical acids found in fertilizers and household cleaning products. It costs them about 10 times less than what you pay. Their profits are around 10,000% - a huge margin, similar to that of drug companies - and all this on your account. And they don't just rip you off financially, they also jeopardize your health and rob you of your hard-earned gains.
This is one of the industry’s dirtiest secrets.
You won't be able to get this information anywhere else. The reason: the manufacturers of this protein are some of the biggest sponsors of the fitness media-magazines, radio, Internet, etc. One thing's for sure, they're not interested in your education.
They Don't Want You to Know the Truth About Casein
But you can't allow yourself to overlook this. You probably work hard to keep yourself in shape and you certainly need to know what you're putting in your body. Casein has obtained the reputation of a highly nutritious protein with distinct anabolic properties. It has been used as a common ingredient in sport nutrition products to support athletic performance, increase muscle mass, and prevent muscle breakdown.
But is casein as good as claimed?
Can it build your muscle?
And is it worth your money?
There are three types of casein - native whole milk casein, cheese casein and industrial casein. As you'll soon see except for a couple of good caseins most of these industrial proteins are low grade and potentially toxic.
Native Whole Milk Casein - Your Best Bet
Native casein is the primary protein in raw milk, accounting for nearly 80% of the milk's amino acid content. In its native form in raw milk, casein occurs along with whey to yield a most functional protein - naturally designed to nourish and promote healthy growth of the mammalian young. Raw milk casein is made out of a complex group of protein clusters called "micells," which are bound with calcium, phosphate and citrate ions and exist at a neutral pH of about 6.6 - about the same as your body's pH.
Native casein complements your body's acid-base balance and will not cause an overly acidifying effect. That's unlike most industrial caseins, which are highly acidifying and need to be chemically alkalized to be edible. But what's especially unique about native casein is its distinct anabolic properties.
Native Casein is One of the Most Effective Muscle-Building Proteins
It has the ability to form a clot in your stomach, which provides slow, sustained release of amino acids to your circulation for several hours. Note that it's the concentration of circulating amino acids (not cellular amino acid) that has been found to trigger muscle anabolism. This makes raw milk casein one of the most effective proteins for muscle retention and buildup. It can be used to keep your muscle in a sustained anabolic mode for a prolonged period of time - such as during the sleeping hours of the night.
Protein manufacturers have been trying to produce products that mimic native casein. The most notable ones are milk protein concentrate (MPC) and micellar casein.
Milk Protein Concentrate (MPC) -- As Close to Native Casein as You Can Get
Milk protein concentrate (MPC) is a whole protein produced by membrane filtration of milk. The ultrafiltration yields a protein end product that contains casein and whey - virtually the same as in the milk that it's derived from. MPC is outstandingly stable.
Milk protein concentrate has virtually the same properties of native raw milk.
It keeps the original ratio between casein and whey protein and maintains a neutral to alkaline pH in a stable, water-soluble state, which is highly resilient to damage by heat.
The best MPC products are those derived from raw milk of pasture-fed cows.
Raw milk products from pasture-fed cows, such as whey and milk protein concentrate, grant better integrity of the protein matrix as well as lipid composition. Raw milk protein concentrate keeps all fragile immuno-factors and amino acids intact and it's devoid of the enzyme xanthine oxidase (a byproduct of milk homogenization that has been linked to cardiovascular and degenerative diseases).
The other product that attempts to mimic native casein is micellar casein. Micellar casein is a relatively new product and considered to be the highest quality casein available. But is it indeed? We'll cover this product soon along with other types of industrial casein. We're still left with another type of whole milk casein - cheese casein.
Cheese Casein: Great Food for Your Muscle - Almost as Effective as Native Casein
Cheese casein is not the same as raw milk casein. During cheese manufacturing, the casein is enzymatically separated from the whey and cleaved out of an important peptide (glycomacropeptide), but the remaining curd is nevertheless a whole, complete protein. And similar to native casein, it has a slow and efficient nutrient delivery and thus can yield a long-lasting nitrogen retention and utilization in your muscle. Given this, cheese can be an ideal food for keeping your muscle in a sustained anabolic state during the sleeping hours of the night.
Next, we'll review industrial casein; there are several kinds of industrial casein that you need to take a look at.
Unlike whole milk caseins (native casein and cheese casein), all industrial caseins are protein isolates, most of which are extracted from pasteurized skim milk often via extreme acid/heat processing. The typical industrial casein is a deficient protein lacking the essential amino acid methionine and the conditionally essential amino acid cysteine, both of which are lost in processing. These sulfur-containing amino acids play key roles in sustaining your body's immune system.
This indicates from the start that industrial casein is inferior to native casein and cheese casein.
All industrial casein powders are derived from skim milk (a byproduct of cream manufacturing). In the processing, the cream is first separated from the milk by means of centrifuges and the remaining skim milk thus serves as the raw material from which industrial casein products are extracted.
Casein products are typically precipitated by means of acidification using chemical acids (hydrochloric acid or sulfuric acid) or natural acids (lactic acid). The acid precipitants cause destabilization of the micells in the milk, leading to coagulation of the protein. Some casein products are not precipitated via acid but rather via enzymes or microfiltration. These are called rennet casein and micellar casein, respectively. Let's review the different kinds of industrial casein and see how viable they are in respect to their protein integrity and nourishing potential.
Acid Casein - An Insoluble, Inedible Protein
There are two kinds of acid casein - chemical acid casein and lactic acid casein - both are insoluble in water. Since most applications of casein require them to be water soluble, manufacturers treat acid casein with alkalies to yield a water-soluble product with a higher pH called caseinate.
Chemical Acid Casein - The Cheapest And Worst Casein
Chemical acid casein is precipitated with chemical acids - hydrochloric or sulfuric acid - both are products of the chemical industry and used mainly due to their cheap cost. Even in New Zealand, which has a very small chemical industry, manufacturers extract casein with sulfuric acid - a chemical produced in comparatively large quantities by the fertilizer industry.
Chemical acid casein is probably the "dirtiest" among all commercial proteins.
What casein manufacturers fail to tell you is that the residues of these chemicals remain in the final casein product even after the washing and milling of the curd - which explains the typical acid aftertaste of many casein products.
Note that sulfuric acid is a highly toxic substance found in acid rain and mine drainage.
It is considered an industrial hazard that causes skin burns, erosion of teeth, chronic damage to the respiratory tract, depletion of vitamin B12 and possibly neural damage. The other precipitant, hydrochloric acid, is used as detergent for household cleaning as well as a chemical reagent in the production of vinyl chloride for PVC plastic. The chemical hydrochloric acid has a corrosive effect on human tissues with potential damaging effects on the respiratory organs, eyes, skin and intestines.
These are some of the facts casein manufacturers do not want you to know -- and there are even more reasons for you to be concerned with the processing of this product.
After the casein has been precipitated by acid, the mixture is heated again. This causes the protein to further thermolyze and degrade into smaller components ("a nitrogen soup"), which agglomerate together to form clumps of curd. The curd is then dewatered via pressing or high-sheer centrifuging. At this point, the casein is pretty much "beaten" by acid, heat and high-sheer centrifuging, which literally destroy the integrity of the protein matrix.
What remains is a protein mess contaminated with toxic chemicals that are used to clean toilets or manufacture fertilizers.
This protein then goes through a drying process where it's even more thermolyzed by hot air (via several drying treatments) followed by milling, shifting, blending and bagging. As a protein consumer you need to know this. You need to know what kind of stuff you're putting in your body.
Lactic Acid Casein - A Cleaner Version But Nevertheless Inferior
Lactic acid casein is a byproduct of milk fermentation. In this case, the casein is extracted via natural processing. The skim milk goes first through pasteurization and then is cooled and inoculated with several strains of lactic-acid-producing bacteria known as "starters." The milk is fermented for a period of 14-16 hours during which much of the lactose in the milk is converted to lactic acid and the pH is reduced to about 4.6, causing coagulation of the casein.
The problem with this processing is in the fermentation of the milk. It has been commonly assumed that milk fermentation is healthy and beneficial due to the fact that it yields probiotic/digestive-supporting properties. But the fact is that milk fermentation is not as "simple and healthy" as commonly thought.
Milk fermentation damages fragile immuno peptides and amino acids and creates MSG.
And if that's not bad enough, the protein matrix is further "cooked" and thermolyzed by means of heat exchanger and steam injection. Following the heat treatment, the resultant curd is washed, dried and milled in a similar manner to chemical acid casein. Lactic acid casein is not as "contaminated" as chemical acid casein, but it is nevertheless damaged by fermentation and thermolyzation - yielding a deficient protein with MSG.
Caseinate - A Water-Soluble Version of Acid Casein With Even More Defaults
To be commercially viable, all acid caseins must be treated with alkalies. This process yields a water-soluble product - called caseinate. The most common caseinates are calcium caseinate and sodium caseinate - treated with the chemicals calcium hydroxide and solium hydroxide, respectively. The problem with chemical alkalies is that they act like "anti-nutrients" - damaging or suppressing nutrient absorption.
In Dutch chocolate for instance, the alkali causes destruction of antioxidant polyphenols rendering the product nutritionally deficient. And there is another problem with this protein -- Caseinates are ultra-thermolyzed by extreme heat.
The processing of caseinates requires the use of extremely high heat of 95ºC, which is near boiling temperatures. The exposure to high heat is a cheap way to decrease the viscosity of the caseinate and improve its solubility.
However cheap processing is often fatal to quality. The extreme heat treatment renders the caseinate an ultra thermolyzed protein drenched with MSG (a byproduct of protein thermolyzation).
Note that ultra thermolyzed casein has been linked to increased risk of colon cancer. Thermolyzed casein is a highly denatured protein that can't be fully digested by your stomach, causing undigested protein residues to "escape" your stomach and reach your colon - where they're fermented by colonic bacteria into highly carcinogenic phenolic compounds that promote colonic tumors and cancer.
Products Containing Caseinates
Following are common caseinate-containing products
||Coffee whiteners and creamers
|Ice creams and frozen desserts
||Soups and gravies
Rennet Casein – Better Than Acid Casein But Lower Grade Than Cheese Casein
Next is a natural casein product that is not precipitated with acid. Called "rennet casein," it's extracted via milk clotting enzymes, also called rennet enzymes.
Rennet casein is generally less damaged than acid casein. It isn't exposed to the low pH as acid casein, but it's nevertheless a protein isolate, derived from pasteurized skim milk. Here is how rennet casein is processed …
Following the pasteurization, the skim milk is cooled to a setting temperature, where calf rennet or microbial rennet enzymes are added and mixed thoroughly until the protein coagulates. This process is virtually the same as that of cheese manufacturing.
And as with cheese manufacturing, the enzymatic precipitation cleaves a most important part of the casein protein called glycomacropeptide. This peptide is a highly beneficial component of native casein - being a great source of immune supportive and satiety-enhancing nutrients.
This is how the protein cleavage technically occurs.
Casein is made out of three kinds of proteins:
α - casein
- ß - casein
- k - casein
K-casein works like a stabilizing agent, keeping the native casein protein matrix in a stable, water-soluble state. During the first state of renneting, the enzymes specifically cleave one of the bonds in k-casein, releasing part of the protein chain - glycomacropeptide - into the whey liquid. This action destabilizes the casein micells, which then form a clot with some of the calcium ions of the milk.
What's left is a casein curd devoid of its glycomacropeptides, which is then cooked and thermolyzed similar to acid casein. This means that on final evaluation rennet casein is a low-grade protein subjected to protein cleavage and thermolyzation.
And note that the casein's glycomacropeptides are "donated" during the processing to the whey liquid, which ironically increases the biological value and nutritional properties of the whey on the account of the original casein donor.
Next we'll take a look at casein hydrolystate. This product is highly popular these days due to its "easy to digest, fast to assimilate" properties. But is it better than other caseins?
Casein Hydrolystate - an Inferior Protein Drenched With MSG
Casein hydrolystate, also known as hydrolyzed casein, is a predigested protein treated with proteolytic enzymes. It is generally used in nutritional and pharmaceutical applications as easily digestible, fast-assimilating protein. Unlike other casein products, hydrolyzed casein has a fast assimilation rate similar to whey protein. Nonetheless, this protein has virtually the same problems as the other casein products.
Hydrolyzed Casein is an Inferior Protein Isolate, Drenched With MSG Byproduct of Hydrolyzation
Recent studies have shown that hydrolyzed casein is no match to whey protein. Researchers found that whey protein outperforms all casein products including hydrolyzed casein in the capacity to promote muscle protein accretion after meal ingestion. This means that in spite of being as fast assimilating as whey protein, hydrolyzed casein has a "weaker" anabolic effect - most likely due to an inferior protein content.
Finally, let's take a look at micellar casein. Micellar casein, also referred to as native phosphocasein, has been promoted by the sport nutrition industry as the epitome protein for building muscle and preventing muscle waste. But is it as superior as claimed?
Micellar Casein - Premium Casein However with Poor Functionality and Low Stability
Micellar casein is processed similar to milk protein concentrate, but in this case the casein micells are separated from the whey via microfiltration. The main problem with micellar casein is in its functional properties.
Micellar casein has poor functionality due to poor solubility in water.
Let me explain.
It's important that the functionality of the protein is retained during drying, storage and reconstitution (mixing with fluid). Generally the protein powder needs to be dispersed and dissolved to be fully functional and edible as an ingredient. Micellar casein has poor reconstitution - which means poor capacity to dissolve in water at low temperatures.
The cheapest way to address this problem and increase the casein solubility is the use of high heat or high sheer. This is apparently what manufacturers use in the case of canned protein production. Additional methods include heat treating prior to membrane filtration, and the addition of salt, sodium caseinate or polydextrose - all of which increase the solubility of the powder on the account of the protein integrity.
The other problem with micellar casein is instability, as micellar casein tends to deteriorate with increased storage time.
Microstructural analysis shows that with increased storage time, the casein micells interact with each other and deteriorate. Micells' interactions lead to cross-linking of proteins, migration of fat particles to the surface, and degradation of the casein. This means that though micellar casein is acclaimed to be superior to other industrial caseins, it is yet unstable and thus inferior to native casein and cheese casein. And it may contain undesirable additive residues, such as salts, sodium caseinate, and polydextrose.
Do your own investigation before purchasing a micellar casein product. Ask the product provider for an updated certificate of analysis (CofA) and an independent lab report that proves the product's protein integrity.
Final Notes and Conclusions
- Whole casein such as in raw milk, milk protein concentrate and aged cheese, is superior to all casein isolates. Whole casein has a very effective nutrient delivery and can be used to yield a steady, long-lasting anabolic effect on your muscle.
- Fresh cheese casein such as in cottage cheese is also a viable whole protein, high in muscle-building BCAA and leucine - albeit with a lower pH and lower nutritional value than native casein and raw aged cheese casein. The main advantage of cottage cheese is its high ratio of protein to fat. Pound for pound, you simply get more protein from cottage cheese than from milk or aged cheese.
- The worst casein is chemical acid casein. All products in this category should be avoided as they're degraded and drenched with dangerous chemical residues.
- All caseinates are ultra-thermolyzed and thus present a serious health risk. Consumption of thermolyzed casein has been linked to increased incidence of colonic tumors and cancer.
How to Get the Best Out of Casein, Cheese and Whey
To get the best out of casein and whey, incorporate the following protocol: During the day, use quality whey protein for muscle nourishment and post-exercise recovery. At night, use casein such as in quality cheese to keep your muscle in a sustained anabolic mode during the sleeping hours.
The reasons: during the day and after exercise your muscle needs fast-assimilating protein and immuno factors such as in quality whey to counteract the catabolic effect of daily stressors and physical exercise on your muscle and grant protein deposit toward recovery and growth.
Slow proteins such as casein have shown to be less effective than whey protein in supporting your body's immune defenses and promoting muscle protein synthesis after exercise. Nonetheless, cheese casein has the anabolic advantage in the long term, and that's due to its ability to induce a slow steady release of amino acids to your muscle for several hours at a time. Therefore cheese casein can serve as an ideal muscle food during the sleeping hours of the night.
Your quality cheese products should come from premium, preferably raw aged cheese such as cheddar, colby, gouda, swiss and emmanthal, or fresh cheese such as organic cottage cheese from pasture-fed cows.
Avoid dietary products containing casein hydrolystates. Read the labels of sports drinks, ready-made protein drinks, protein powders and protein bars - many of these items are made with casein hydrolystate as a main ingredient and are therefore drenched with MSG.
The A1-A2 Milk Issue
There have been concerns that casein from A1 milk presents a health risk - apparently due to yielding a metabolic byproduct (opioid peptide) called beta casomorphine, which has been arguably linked to brain disorders and disease particularly among babies and infants.
Most U.S. dairy products are from A1 milk unless stated that they're produced from A2 milk such as of Guernsey or Jersey cows. European dairy products, however, (which include French, Swiss and Italian cheeses) are mostly derived from A2 milk. It has been recommended as a precautionary step to choose dairy products from A2 milk.
But let's put things in perspective. There is no conclusive evidence yet to the A1 casein issue, and if there is indeed a proven problem with A1 milk, most likely the same problem will apply to A2 milk as well.
The truth is that even A2 cows like Guernsey produce about 50% A1 milk. So if the A1 milk risk exists, it will apply to all kinds of casein products.
As a final note, be aware that historical epidemiology has been indicating great benefits of dairy products (milk, cheese and whey) on human health, particularly in the areas of weight management, cardiovascular health and muscle conditioning.
Ori's new book Unlock Your Muscle Gene is now available at Amazon.com and bookstores nationwide.
Unlock Your Muscle Gene: Trigger the Biological Mechanisms that Transform Your Body and Extend Your Life
- Southward, C.R. (2008). Casein Products. New Zealand Institute of Chemistry. Retrieved September 12, 2011 from nzic.org.nz/ChemProcesses/dairy/3G.pdf
- Ahmad, S., Piol, M., Rousseau, F., Grongnel, J.F., Gaucheron, F. (2009). Physiochemical changes in casein micells of buffalo and cow milks as a function of alkalinisation. Dairy Science and Technology, 89, 387-403.
- Anema, S.G., Pinder, D.N., Hunter, R.J., Hemar, Y. (2006). Effects of storage temperature on the solubility of milk protein concentrate. Food Hydrocolloids, 20, 385-393.
- Bastier, P., Dumay, E., Cheftel, J.C. (1993). Physiochemical and functional properties of commercial caseinates. Lebensmittel-Wissenschaft and Technologie, 26, 529-537.
- Blazey, N.D., Knights, R.J., Wu, C. (2000). Membrane filtered milk proteins varying in composition and functional attributes. Patent W000/51440.
- DeKruif, C.G., Holt, C. (2003). Casein micelle structure, functions and interactions. In P.F. Fox, & P.L.H. McSweeney (Eds.), Advanced dairy chemistry - I. Proteins (3rd ed.). (pp. 233-276) New York, NY, USA: Kluwer Academy.
- Farrell, H.M., Brown, E.M., Hoagland, P.D., Malin, E.I. (2003). Higher order structures of the caseins: a paradox? In P.F. Fox, & P.L.H. McSweeney (Eds.), Advanced dairy chemistry - I. Proteins (3rd ed.). (pp. 203-231) New York, NY, USA: Kluwer Academy.
- Gaiani, C., Scher, J., Schuck, P., Hardy, J., Desobry, S., Banon, S. (2006). The dissolution behavior of native phosphocaseinate as a function of concentration and temperature using a rhetorical approach. International Dairy Journal, 16, 1427-1434.
- Gaiani, C., Schuck, P., Scher, J., Errhardt, J.J., Arab-Tehrany, E., Jaquot, M., et al. (2009). Native phosphocaseinate powder during storage; lipids released onto the surface. Journal of Food Engineering, 94, 130-134.
- Havea, P. (2006). Protein interactions in milk protein concentrate powders. International Dairy Journal, 16, 415-422.
- Jeanier, R., Schuck, P., Six, T., Andre, C., Delaplace, G. (2010). The influence of stirring speed, temperature and solid concentration on the rehydration time micellar casein powder. Dairy Science and Technology, 90, 225-236.
- Jimenez-Flores, R., Kosikoswki, F.V. (1986). Properties of ultrafiltered skim milk retentate powders. Journal of Dairy Science, 69,329-339.
- Schuck, P., Briard, V., Mejean, S., Davenel, A., Piot, M., Famelart, M.H., et al. (1999). Dehydration by desorption and spray-drying of dairy proteins: influence of mineral environment. Drying Technology, 17, 1347-1357.
- Schuck, P., Davenel, A., Mariette, P., Briard, V., Mejean, S., Piot, M. (2002). Rehydration of casein powders: effects of added mineral salts and salt addition methods on water transfer. International Dairy Journal, 12, 51-57.
- Shukla, A., Narayanan, T., Zanchi, D. (2009). Structure of casein micells and their complexation with tannins. Soft Matter, 5, 2884-2888.
- Udabage, P., McKinnon, I.R., Augustio, M.A. (2000). Mineral and casein equilibria in milk: effects of added salts and calcium-chelating agents. Journal of Dairy Research, 67, 361-370.
- Walker, G.P., Williams, R., Doyle, P.T., Dunshea, F.R. (2007). Seasonal variation in milk production and cheese yield from commercial dairy farms located in northern Victoria is associated with pasture and grazing management and supplementary feeding practice. Australian Journal of Experimental Agriculture, 47, 509-524.
- Walstra, P. (1990). On the stability of casein micells. Journal of Dairy Science, 73, 1965-1979.
- Walstra, P. (1999). Casein submicells; do they exist? International Dairy Journal, 9, 189-192.
- Schokker, E.P., Church, J.S., Mata, J.P., Gilbert, E.P., Puvanenthiran, A., Udabage, P. (2011). Reconstitution of properties of micellar casein powder: effects of composition and storage. International Dairy Journal, 21, 877-886.
- Corpet, D.E., Ya, Y., Zhang, X-M., Remesy, C., Stamp, D., Medline, A., Thompson, L, Bruce, W.R., Archer, M.C. (1995). Colonic protein fermentation and promotion of colon carcinogenesis by thermolyzed casein. Nutr. Cancer, 23(3), 271-281.
- Pennings, B., Boirie, Y., Senden, J.M-G., Gijsen, A.P., Kuipers, H., van Loon, L.J.C. (2011). Whey protein stimulates postprandial muscle protein accretion more effectively than do casein and casein hydrolysate in older men. Am. J. Clin. Nutr., May, 2011; 93(5): 997-1005.
- Phillips, S.M. (2011). A comparison of whey to caseinate. Am. J. Physiol. Endocrinol. Metab., March, 2011; 300(3):E610.
- Grufferty, M.B., Fox, P.F. (1985). Effect of added NaC1 on physiochemical properties of milk. Irish Journal of Food Science and Technology, 9,1-9.
- Hall, C.W., Hedrick, T.I., (1966). Quality control and sanitation. In C.W. Hall & T.I. Hedrick (Eds.), Drying milk and milk products (pp. 197-231). Westport: The APC.
- Jost, R. (1993). Functional characteristics of dairy proteins. Food Science and Technology, 4, 283-288.
- Shalabi, S.L., Fox, P.P. (1982). Influence of pH on the rennet coagulation of milk. Journal of Dairy Research, 49, 153-157.
- Bloore, C., Boag, I. (1982). The effect of processing variables on spray dried milk powder. New Zealand Journal of Dairy Science and Technology, 17, 103-120.
- Dalgleish, D.G. (1982). Milk proteins. Chemistry and physics. In P.F. Fox & J.J. Condon (Eds.), Food proteins (pp. 155-178), London; Applied Sciences Publisher.
- Sun, Z., Cade, J.R. A peptide found in schizophrenia and autism causes behavioral changes in rats. Autism. 1999. 3(1):85-89.
- McLachlan. ß-casein A1 ischaemic heart disease mortality, and other illnesses. Medical Hypotheses. 2001. 56(2):262-272.
- Tailford, K.A., Berry, C.L., Thomas, A.C., Campbell, J.H. A casein variant in cow's milk is atherogenic. Atheroscerosis. 2003. 170(1):13-19.
- Elliott, R.B., Harris, D.P., Hill, J.P., Bibby, N.J., Wasmuth, H.E. Type I (insulin-dependent) diabetes mellitus and cow milk: casein variant consumption. Diabetologia. 1999. 42(3):292-296.
- New Zealand Food Safety Authority. Beta casein A1 and A2 in milk and human health. 2004. Cited 2010 February 3.
- Corpet, D.E., Yin, Y., Zhang, X.M., Remesy, C. Stamp, D., Medline, A., Thompson, L., Bruce, W.R., Archer, M.C. Colonic protein fermentation and promotion of colon carcinogenesis by thermolyzed casein. Nutr. Cancer. 1995:23(3), 273-281.
- Armstrong, B., Doll, R. Environmental factors and cancer incidence and mortality in different countries with special reference to dietary practices. Int. J. Cancer. 1975:15;617-31.
- Zhang, X.M., Stamp, D., Minkin, S., Medline, A., Corpet, D.E. et al. Promotion of aberrant crypt foci and cancer of rat colon by thermolyzed protein. J Natl Cancer Inst. 1992 Jul 1;84(13):1026-30.
- Bone, E., Tamm, A., Hill, M. The production of urinary phenols by gut bacteria and their possible role in the causation of large bowel cancer. Am. J. Clin. Nutr. 1976;29:1448-1454.
- Boutwell, R.K., Bosch, D.K. The tumor promoting action of phenol and related compounds for mouse skin. Cancer Res. 1959:19;413-424.