Cow’s milk allergy or lactose intolerance?

mill consumption during infancy

When we think about milk, it’s difficult not to imagine a bowl of cereals or a simple glass of milk. However, have you ever wondered how many foods do also contain it? Milk and/or its components are widely spread across all kinds of foods. 

 

Dips and salad dressings, chewing gum, paté, tuna fish, and sausages are some of the surprising foods that commonly contain milk or its components (e.g. milk proteins like casein). It’s hard to imagine, but milk is everywhere! The question is, has it always been around? The answer is no.

When did we start consuming milk?

Historically, routine consumption of dairy products had a geographically limited distribution. In fact, cow’s milk consumption is a novel behaviour that ranges from 8,000 years to only a few years or decades, depending on the population and geography.

History of milk consumption
History of milk consumption. Photo credit: UndeniableDairy.

Proof of milk consumption being a novel behaviour from an evolutionary perspective is that there is well-documented evidence of genetic variability across human populations with respect to the ability to digest lactose (milk sugar).

Apart from this, there is the curious fact that milk being produced for infants of one species supports the growth and development needs of infants of that species (calves) and not others (e.g. humans).

Milk for everybody!

I did mention that milk or its components are spread across all kinds of foods, but how could not? The production of this nutrient-rich liquid food has grown by more than 63%, increasing from 500 million tons in 1983 to 819.3 million tons in 2016. This translates into more than 6 billion people consuming milk and milk products.

Per capita milk consumption is relatively high (>150 kg/capita/year) in most developed countries like the U.S. or the U.K. In contrast, in developing countries, the average consumption of dairy products doesn’t often exceed 30 kg/capita/year.

Either to a greater or lesser extent, milk and/or its components are present in most countries worldwide.

Milk has an excellent nutritional density, being a good source of proteins, vitamins, and minerals that support growth and development. Advances in production techniques and logistics have contributed enormously to a worldwide glut of milk. Accordingly, milk can now be considered a staple food.

Thanks, science!

OK… Maybe not for everybody

Yep, not all are cool facts when referring to milk. I mentioned earlier in this blog post that milk consumption is a novel practice from an evolutionary perspective, and that is demonstrated at the physiological level by means of milk intolerance or allergenicity. It’s essential to tell the difference between these two, as they are both significantly different.

Contrary to milk allergy, milk intolerance does not involve an immune response when consumed. Although it produces symptoms related to milk allergenicity, it is not so dangerous. It is said to be intolerance because there is a disorder in digestion, absorption, or metabolism due to a particular milk component. A typical example is a lack of the enzyme lactase, responsible for hydrolysing (i.e. degrading) lactose, a disaccharide highly present in milk.

Molecular structure of the lactose disaccharide. Photo credit: ScienceABC.

On the other hand, milk allergy does involve an immune response and can be extremely dangerous. Normally, symptoms appear instantly or within 2 hours after the intake of milk. Symptoms used to be different from milk intolerances, affecting the skin, the respiratory system, and the gastrointestinal tract.

In a worst-case scenario, the allergic reaction may affect more than one organ/system and even cause death!

What is science doing about milk allergenicity?

Usually, there are no treatments at all for food allergies, and consequently, the main recommendation for prevention relies mostly on the total avoidance of the offending foods. 

Nevertheless, there’s been huge efforts going on during the last two decades to find out and standardise approaches aimed at reducing the allergenicity of milk. Conventional and non-conventional procedures have been reported.

Conventional approaches for decreasing allergenicity include thermal treatment, enzymatic hydrolysis, glycation reactions, fermentation, and in vitro protein digestion.

Ultra-high temperature food processing facilities
Ultra-high temperature food processing facilities. Photo credit: Tetra Pack.

On the other hand, some non-conventional innovative procedures reported are gamma ultraviolet, infrared, and microwave irradiation; high hydrostatic pressures; and genetic modification.

Genetic modification can be used for decreasing allergenicity in foods. Photo credit: World Atlas.

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