The consumption of pasteurised dairy products is associated by some consumers with unpleasant symptoms that evidently arise from a food sensitivity or allergy. While these reactions can resemble one another, they are also often confused with lactose intolerance which is not a food sensitivity or allergy, but a straightforward problem with malabsorption.

To explain further, allergies produce a fast and pronounced immune response, such as anaphylaxis, due to a class of antibodies called IgE, while food sensitivity reactions are usually slow-acting and less dramatic. Of the first type, cow’s milk can be responsible for an immune reaction to casein or lactoserum, while goat’s milk is less allergenic overall.¹

In the second type, there are several kinds of reaction possible in response to either the proteins, fats or carbohydrates in milk and involve IgA or IgG antibodies. The symptoms are often mild but may include fatigue, headache, bowel upset and a general feeling of malaise. Milk sensitivity can also often cause a chronic increased secretion of mucus and catarrh of the airway, ears, sinuses and lymphatic system, something the old naturopaths called ‘mucus-forming.’

Due to genetic variations, the proteins in casein fall into two main types, A1 β-casein and A2 β-casein. A1 and A2 β-casein are digested in a slightly different manner, creating the possibility that the different break-down products might vary in immunogenic potency. In fact, A1 milk has been associated with an increased incidence of type 1 diabetes and coronary heart disease in animal models, thereby prompting the consumer interest in A2 milk; however, these associations have not been substantiated in human models.

Specific peptides are thought to be the cause of the immunological reactivity which result from the enzymatic breakdown of A1 β-casein, specifically β-casomorphin 7 (BCM7), an opioid peptide. These problematic peptides must first pass through the gut wall to trigger an immune reaction, so it is thought that a chronic state of inflammation must pre-exist, which makes the gut leaky. Importantly, raw unprocessed milk contains no BCMs whether A1 or A2 variant milk.

Just to make matters more difficult, ‘leaky gut’ and a state of altered bowel bacteria (dysbiosis) may result from a co-existing food sensitivity, allergy, infection or parasites, as well as the urban diet in general. For instance, modern staple foods typically consist of pasteurised milk, trans fats, refined sugars, synthetic additives and genetically modified grains, and therefore peptides may not necessarily be the direct cause of disorders such as irritable bowel disease, autism or type 1 diabetes for which milk is often blamed. Stress is also a major causative factor in the pathogenesis of leaky gut and dysbiosis regardless of diet; nevertheless, some people find A2 milk less difficult to digest than A1 milk.

Others will find a problem with pasteurised milk no matter what the type, and because raw milk is unavailable (unless the consumer keeps their own cows or goats), the sensitive patient is usually recommended a Paleo-style diet. This strategy avoids milk consumption entirely, and therefore any problem from the many potential sources of sensitivity whether it be protein, carbohydrate, fat, additives,  agri-chemical residues or other contaminants in the milk, along with a plethora of other ultra-processed factory foods, refined grains or their controversial products such as gluten.

Nevertheless, fermented milk products such as yoghurt and kefir have been prepared and consumed for thousands of years and been found to be more digestible than raw milk, as well as to confer additional health benefits because of their probiotic nature, in particular strains of Bifidobacterium and Lactobacillus. For example, cultured yoghurt has been found to improve the eradication of Helicobacter pylori bacteria in the treatment of peptic ulcer, gastritis and adenocarcinoma.²

The mechanism of action of probiotics on health is fourfold: probiotics modify the gut flora in a beneficial fashion by encouraging the colonisation of the gut with healthy bacteria; these bacteria competitively adhere to the gut wall and strengthen it; probiotics also regulate the immune system; and lastly, probiotics reduce inflammation and therefore leaky gut, probably the main cause of the trouble caused by immune sensitivity to pasteurised A1 milk.³

Cultured milk products (kefir, cheese, yoghurt) also contain less lactose due to fermentation by the probiotic bacteria. This is an advantage for the multitude who are, to a greater or lesser extent, lactose intolerant due to an age-related decline of the enzyme lactase which commences naturally after weaning.

References:

1.         Sanz Ceballos L, Sanz Sampelayo MR, Gil Extremera F, Rodríguez Osorio M. Evaluation of the allergenicity of goat milk, cow milk, and their lactosera in a guinea pig model. J Dairy Sci 2009;92:837–46.

2.         Sachdeva A, Rawat S, Nagpal J. Efficacy of fermented milk and whey proteins in Helicobacter pylori eradication: a review. World J Gastroenterol 2014;20:724–37.

3.         Plaza-Diaz J, Gomez-Llorente C, Fontana L, Gil A. Modulation of immunity and inflammatory gene expression in the gut, in inflammatory diseases of the gut and in the liver by probiotics. World J Gastroenterol 2014;20:15632–49.