Health effects: allergy and cancer link

Health Effects

We have looked into the possibility of creating a hypo-allergenic cheese which for those allergic to cheese.

• Blog Post 2021 - Milk allergy, caseins and the journey to a hypoallergenic real vegan cheese

Some humans have brought up that casein has been linked to cancer. There are actually two issues being brought up:

• That casein may cause cancer
• That animal protein in general may cause cancer

In both cases, it seems that people's concern can be traced back the book The China Study and three papers, all by T. Colin Campbell.

Alternative Milks and Milk Allergies

Which alternative milks are recommended for people with cow’s milk protein allergies? Let’s do a multiple sequence alignment of the corresponding casein proteins, and see what they have in common.

• Cow's milk protein allergy in children: a practical guide

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2823764/ Mammalian milks are not nutritionally adequate. Goat's milk commonly provokes clinical reactions in more than 90% of children with CMPA [23], donkey's milk in about 15% [24,25] and has a high cost.

• Soy formulas and nonbovine milk. https://pubmed.ncbi.nlm.nih.gov/12487214/

Vegetable formulas obtained from soy and milk derived from other mammals, such as mare or donkey, homemade preparations, and elemental diet may represent valid alternatives for children with cow's milk allergy.

• Allergenicity of mare's milk in children with cow's milk allergy. https://pubmed.ncbi.nlm.nih.gov/10808187/

These data suggest that mare's milk can be regarded as a good substitute of cow's milk in most children with severe IgE-mediated cow's milk allergy.

• Alternatives to Cow’s Milk-Based Infant Formulas in the Prevention and Management of Cow’s Milk Allergy.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8997926/ Excellent review! Camel, donkey, and horse milk may, however, provide a better alternative for CMA management due to the lower protein homology and hence lower cross-reactivity to counterpart cow’s milk allergens.

“Let’s do something about camel's milk”

• https://camelculture.org/

• Nutritional and Therapeutic Characteristics of Camel Milk in Children: A Systematic Review https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4700900/

• Nutritional, antimicrobial and medicinal properties of Camel’s milk: A review https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8117040

• Camel milk: an alternative for cow's milk allergy in children https://pubmed.ncbi.nlm.nih.gov/21703103/

• Cross-over clinical trial for evaluating the safety of camel's milk intake in patients who are allergic to cow's milk protein https://pubmed.ncbi.nlm.nih.gov/29223706/

• Camel Milk: Are There Health Benefits? https://www.webmd.com/diet/health-benefits-camel-milk

• Camel Milk - an overview https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/camel-milk

• A comprehensive review on health benefits, nutritional composition and processed products of camel milk, Food Reviews International, 39:6, 3080-3116, (2023) https://doi.org/10.1080/87559129.2021.2008953

• Circadian Variation in Human Milk Composition, a Systematic Review -“Significant circadian variation is found in tryptophan, fats, triacylglycerol, cholesterol, iron, melatonin, cortisol, and cortisone. This may play a role in the child’s growth and development in terms of the biological clock.” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7468880/

The China Study

I (Juul (talk)) have not yet read the book. It would be better if we could read the actual research papers that the book seeks to explain, since the book makes several controversial claims and is not itself peer-reviewed. Hopefully the book makes no new claims, since a professor making health claims outside of peer-reviewed literature would be somewhat incriminating. There is a long and fairly thorough critique of the book here. Based on the critique it seems that Campbells conclusions about animal protein are somewhat questionable. It seems that he is repeatedly forgetting to control for important and obvious factors, neglecting to mention other more likely explanations for the data, and ignoring data that doesn't fit his narrative. To be blunt it all in all sounds like a very large and impressive research study that has been used uncritically by Campbell to prop up his pre-existing notions about nutrition. The author of the critique does however find the Casein studies convincing or at least she does not point out any serious flaws.

ToDo Investigate the china studies conclusions about casein.

Casein and cancer

There have been at least three studies linking casein and cancer, all by Campbell, the author of The China Study.

• Dietary protein level and aflatoxin B1-induced preneoplastic hepatic lesions in the rat by Dunalf and Campbell (1987)
• The sustained development of preneoplastic lesions depends on high protein intake by Youngman and Campbell (1992)
• Long-term intake of a low-casein diet is associated with higher relative NK cell cytotoxic activity in F344 rats by Bell, Golemboski, Dietert and Campbell (1994)

We'll discuss these papers separately.

Dunaif 1987

The paper uses aflatoxin injected into the stomach of the rats through a tube. There is mention of 8 control rats that received the same treatment without the aflatoxin, but the important data is missing from the paper. This makes it impossible to tell if there is some compounding effect from the method of delivery of aflatoxin. I find it odd, but not _quite_ suspicious that this data was left out.

I am not well-versed in cancer research, so maybe this aflatoxin method is normal and well-accepted, but it seems to me that if you're using a method like this you should do two studies with different carcinogens to minimize the chance that aflatoxin is acting in unusual concert with casein to cause these effects.

More interesting is the fact that it was not reported what type of casein was used in the study. It may simply be that they fed the rats cow casein and that rats have a serious problem with cow casein. We already know that there can be health problems associated when humans eat certain animal caseins. What about purity and form? Did the casein contain trace amounts of other components of milk like lactose? Was it in its micellar form or was it denatured?

Lastly, the amounts of casein that correlate with heightened levels of cancer are pretty insense. The first heightened levels of cancer appear when the rats receive 6% of their total caloric intace via casein. Let's compare that number to humans. Americans in 2000 ate about 593 pounds of dairy products per year. That's probably less than 10% casein (ToDo calculate this more accurately) so around 271 kg casein per year. Casein contains about 3.56 calories per gram, so the average american receives around 97 kilocalories from casein per year out of 3,770 total kilocalories. That's about 2.6% of total calories from casein. Even if humans have the same reaction as the rats in the study, they would have to get somewhere between 1.5 to 2.3 times the the average amount their calories from casein to have a measurable increase in cancer risk for this specific type of cancer. ToDo find more data on casein consumption to know how many are currently above this level and check if there is any data on a casein cancer link in humans.

Youngman 1992

ToDo

Bell 1994

ToDo

Animal protein and cancer

ToDo