Dairy intolerance

Dairy is a common food allergy and intolerance in children. There are two components in dairy that can result in a sensitivity to dairy: lactose and beta-casein. 

Lactose is a sugar. It requires the enzyme lactase to break it down in the human digestive tract. A lactose intolerance can almost immediately lead to symptoms such as change in bowel movements, gas, pain and bloating. Primary lactose intolerance due to insufficient production of lactase is not commonly seen in infants. Secondary lactose intolerance can be due to intestinal injury (due to allergy or infection) or inflammation. Identifying and addressing the cause of secondary lactose intolerance is important, and lactose can also be removed from the diet to prevent symptoms.

Casein is a protein in milk of which there are two types, A1 and A2. The difference between A1 and A2 is a single amino acid in the protein chain at position 67: A1 contains histidine whereas A2 contains proline. 

In general, milk produced by Jersey and Guernsey cows, human milk and other milks such as sheep and goats contain the A2 beta casein. Milk from the Holstein Friesian, the most common breed in Western countries contains mostly A1 beta casein, hence it is the most commonly available milk on shelves. A1 casein protein can be problematic for some as it can be broken down into an inflammatory compound beta-casomorphin-7 which activates inflammation and opioid receptors throughout the body. In other individuals casein may only be partially broken down in the digestive tract, enter the bloodstream and can cross the blood brain barrier causing a cascade of reactions. 

Some children who cannot tolerate A1 casein can tolerate A2 casein, while other children are not able to tolerate any casein protein.

Dairy can play a role in many conditions but the most common symptoms seen are all sorts of tummy issues like constipation, diarrhoea, reflux, bloating, wind, softer acidic stools and tummy aches. While dairy intake may not be the cause of the digestive symptoms, removing dairy from the diet or switching to A2 milk can reduce the stress on the gut and immune system. This can also improve sleep and mood as the gut affects the brain through the gut-brain axis.

It should be noted that while there have been some studies on A1 and A2 milk and its effects, there are not a lot of human studies. However, if dairy is a problem for some children it is worthwhile trying the A2 milk to see if it has the same effect as a milk containing mostly A1 casein. Generally, A2 milk is labelled as such on supermarket shelves.

To rule out a dairy allergy you can speak to your GP or paediatrician. However, in most cases you would already know if your child has a milk allergy as it generally produces a severe and sometimes life-threatening reaction.

A dairy intolerance can be determined by eliminating all dairy for a period of time (6 weeks is best) and seeing how your child responds. If it is too hard to eliminate dairy for 6 weeks, start off by eliminating A1 dairy. Switch to an A2 milk, use goat and sheep cheese and yoghurt, or use coconut yoghurt. I leave it up to clients as to whether they wish to eliminate butter. Butter contains virtually no casein or lactose so side-effects from its consumption are rare.

If you do go off dairy for 6 weeks, reintroduce one product at a time to see how your child responds. You can search online and follow the dairy ladder or receive guidance from your health professional. Also, it is important to note that with dairy there is a tolerance level – consuming a little bit here and there might be ok, but consuming a little bit every single day might cause a problem.

Most children outgrow a dairy intolerance between ages 3-5. If you reintroduce dairy at an earlier age and find they still cannot tolerate it, remove it from the diet again, continue to focus on maintaining a healthy gut and try again in 6 months to a year.

Cheese

Soft aged cheeses are better than younger, harder cheeses. Harder cheeses contain a lot of casein. Making aged cheese such as brie and camembert involves the addition of a group of enzymes called rennet, one of which is a proteolytic enzyme that breaks down proteins such as casein.

Cream

Heavy cream contains very little casein, though very sensitive people may still experience an adverse reaction to it. Cream is made from curds which is the thick fat layer that separates from a clear liquid layer (whey) when you let milk stand for some time. Generally, once someone is symptom free, cream is usually safe to consume.

Yoghurt

Yoghurt is a healthy snack and can contain a range of beneficial microorganisms to help maintain intestinal flora balance. When making yoghurt beneficial bacteria are added which act on lactose to produce lactic acid. Lactic acid then works on the proteins in yogurt such as casein, making them more digestible and less likely to cause an adverse reaction. However, most yoghurt on the market is not fully cultured and contains milk sugars such as lactose that have not been consumed by beneficial microorganisms and can result in adverse reactions.

Milk kefir

Milk kefir (fermented milk) is made with kefir grains full of bacteria. These bacteria feed on the sugars in milk and produce lactic acid. Lactic acid and the bacteria in the kefir grains work on the proteins in milk making them more digestible and less likely to cause tummy problems. In addition, through the fermentation process a wide variety of bacteria become available in the milk kefir. Research supports the idea that ingesting milk kefir should have minimal adverse effects in those with a dairy intolerance and a small daily consumption will provide a range of bacteria that may improve tolerance to dairy.

There are lots of foods other than dairy that provide a good source of calcium such as tinned fish with bones, almonds, tahini, cannellini beans, and green leafy vegetables. If it is hard to get your child to eat a variety of calcium-containing foods then it may be worthwhile to supplement. Book an express consult if you have specific questions around dairy, calcium and you or your child’s health. Alternatively, book an initial standard consult for a complete health assessment.

For educational purposes only. If you suspect you have a medical problem, please see a physician.

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Jianqin, S., Leiming, X., Lu, X., Yelland, G. W., Ni, J., & Clarke, Andrew J. (2016). Effects of milk containing only A2 beta casein versus milk containing both A1 and A2 beta casein proteins on gastrointestinal physiology, symptoms of discomfort, and cognitive behavior of people with self-reported intolerance to traditional cows’ milk. Nutrition Journal, 15(35), 35–35. https://doi.org/10.1186/s12937-016-0147-z

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