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Lactose Intolerance

We’ve all heard of lactose intolerance, but do you really know what it is? There’s a good chance that you think it is the medical term for a dairy allergy, but the two are in fact completely unrelated conditions. This blog will look at the definition and various forms of lactose intolerance, as well as its implications.

What is Lactose Intolerance?

Before explaining what causes lactose intolerance, let’s distinguish it from a milk allergy. A milk allergy generally appears within a child’s first year of life, and can be life threatening. It is caused when the body sees one or more of the proteins in milk as an unwelcome foreign invader, most commonly S1-casein. Consuming milk with a milk allergy can cause a person to go into anaphylactic shock, which can be fatal.

On the other hand, lactose intolerance relates to lactose, a sugar found in milk. There are two ways complications can cause symptoms. The first is that the small intestine does not produce enough lactase, which breaks lactose down into two separate sugars: glucose and galactose. The second way is malabsorption, where the body cannot absorb what has been broken down. This can happen as a result of lactase deficiency, or for other underlying medical reasons.

Types of Lactose Deficiency

Although most cases of lactose intolerance involve a lactase deficiency, there are four different ways this can manifest. The most common type is primary lactase deficiency, which is when the body’s ability to produce lactase gradually declines over time. This can begin at any age, often starting as young as two years old. Regardless of the starting point of the decline, most people will not experience symptoms for a number of years. This means that in many cases, people are unaware that they are lactose intolerant for years, which is why many people may go undiagnosed until their late teens.

Secondary lactase deficiency is when damage to the small intestine inhibits the production of lactase. The damage can be a result of anything from trauma to infection, and in many cases, addressing the root cause can improve symptoms.

Developmental lactase deficiency occurs in children who are born prematurely, and usually disappears as the child grows.

Congenital lactase deficiency is the rarest form. As the name implies, it is a genetic disorder inherited from one of the parents. The result is that little or no lactase is produced at all throughout the person’s life.


Symptoms of lactose intolerance are mainly confined to the abdomen and digestive tract. They include bloating, pain, gas, and diarrhoea, and usually appear within two hours of consuming lactose. Rashes or irritated skin are also common, as is nausea. The severity of these symptoms will depend on the amount of lactose consumed, as well as the extent of the individual’s intolerance. Symptoms can range from very mild to temporarily incapacitating, but the condition is not fatal.

In terms of quality of life, lactose intolerance should have no major effect. The most important step to ensure that you stay healthy is to find suitable substitutes to give you the nutrients found in milk, particularly calcium and vitamin D. Fortunately, there are now many lactose-free forms of dairy and other diet alternatives that can help you achieve this without any major issues. Cod liver oil, salmon, and tuna are great sources of vitamin D. Salmon is also a good source of calcium, which can be found in beans, leafy vegetables (such as spinach), nuts, oatmeal, and more. There are many ways people can get all their necessary nutrients without ever touching dairy, rendering lactose intolerance more of an inconvenience than concern for most people.