Lactose Intolerance

Lactose Intolerance

Approximately 17% of the British nation is diagnosed with lactose intolerance, the number is thought to be much greater in those that don’t realise they are intolerant. A common misconception of lactose intolerance is that firstly, it is an allergy. False- it is an intolerance it will induce no symptoms of an allergic shock.

Secondly that it is an intolerance to all dairy, again false- it’s an intolerance to the sugar lactose in dairy.

What is lactose intolerance? What are the symptoms?

Lactose intolerance is categorized under ‘Carbohydrate Metabolic disorders’, which describes the inability to absorb and metabolise certain carbohydrates. In the case of lactose intolerance it is ‘lactose’ sugar. The absence of the enzyme Lactase it the culprit for the symptoms of the disorder. In a person without this disorder lactase is present in the small intestine. This is where majority of the disaccharide Lactose is broken down into glucose and galactose. Instead, people with lactose intolerance fail to break down lactose and this moves into the large intestine. Within the large intestine the undigested sugar ferments and creates typical symptoms of the disorder [2]. These are:

  • Bloating
  • Diarrhea
  • Abdominal Cramps
  • Flatulence

These symptoms can occur from 15 minutes post-lactose consumption or up to 2 hours afterwards. This will of course depend on the individual and the type of food consumed.

What is the cause of lactose intolerance?

Previously discussed the Lactase enzymes, or lack thereof is the cause. However, lactose intolerance can be present from birth or develop later in life. Much like the root cause of any disorder, genes are to blame, the LCT gene to be precise. The disorder named ‘Primary Lactose Intolerance’ is caused by a slow decrease of lactase production. As we age the gene LCT is under stimulated leading to lower expression of the Lactase enzyme. On the other hand, congenital lactose intolerance is caused by a mutation of the LCT gene which means that lactase enzyme is not correctly produced and therefore impairs the ability to digest milk from birth [3]. Secondary Lactose intolerance is caused by a disease or injury to the small intestine or bowel that prevents digestion of lactose, such as Celiac disease or IBS [2].

In some cultures the consumption of milk post-maternal breastfeeding is uncommon. This can lead to a developed disuse of the Lactase enzyme. Those cultures that are typically lactose intolerant are of Arab, Jewish, Greek, West African, East Asian, and Italian descents [3].

What are the common deficiencies in people with lactose intolerance?

Due to the exclusion of many dairy foods, people with lactose intolerance are frequently deficient in Vitamin A, B2, B12, D, Iodine and Calcium.[4]

Vitamin A is found abundantly in milk, per 200ml of whole milk there is approximately 62mcg of Vitamin A (Retinol). Due to Vitamin A being a fat soluble vitamin, the Vitamin A content reduces as the fat content of milk decreases. Vitamin A is required for the health of our vision, mucous membranes, and immune system. Furthermore, it is responsible for the metabolism of Iron and cell differentiation. Non-lactose alternatives include sweet potato, kale, carrots, fish oils, egg yolks, and supplementation.

Vitamin B2, also known as Riboflavin I one of the most abundant vitamins found in dairy foods. In one singular 200ml glass of semi-skimmed milk, there is 45% of a person’s daily recommended requirement for Vitamin B2. The primary use of Riboflavin in the body is for the metabolism and production of energy. Vitamin B12 is only found in animal sources, there are no natural plant sources of this vitamin. Dairy is one of the main sources, of Vitamin B12 providing 100% of its daily requirement in just one glass. Vitamin B12 is also used for energy, but its most prominent benefit is its protection of nerve cells and its contribution to the production of new cells, particularly red blood cells [5]. Vitamin B12 and B2 can be consumed together in a B-Complex tablet, however, they can also be found in whole grains, yeast, lean meats fish and egg yolks.

Iodine is a trace mineral but is found abundantly in non-organic milk. Children are often given milk as it was thought to help them “grow big and strong’. This is correct as Iodine can provide 96% of a child’s daily requirement for Iodine and up to 44% of adults [5]. Alternatively, Iodine can be found in fish, seafood, sea kelp, and Iodine tablets (Potassium Iodide).

Vitamin D and Calcium are the most well-known components of dairy foods. However, exclusion diet and removal of dairy can reduce the primary dietary source for many people. Vitamin D is used to aid the absorption of Calcium. Calcium is a structural component of our bones and teeth. Evidence has shown that reduced dietary intake of Vitamin D and Calcium can lead to disorders such as Osteopenia and Osteoporosis. Other dietary sources of Vitamin D include fish oils, salmon, sardines, plant oils and sunlight. Whereas Calcium sources are more difficult to come by, they include kale, spinach, nuts, tofu, fortified foods or supplementation.

People who develop Lactose intolerance may also be deficient in Magnesium, Zinc, Potassium, Phosphorous.

How else to improve symptoms of the disorder…

  • Be label savvy- watch out for hidden lactose in crisps, sweets, bread and dressings
  • Monitor your symptoms to connect it to a certain food that causes particularly painful symptoms
  • Do not self-diagnose as it could be another disorder such as IBS.
  • Avoid foods such as ice cream, milk, chocolate etc. However, do try to find 'lactose free' and Calcium fortified versions of the same foods.
  • Try supplementing what you have lost from excluding dairy foods.
  1. The Dairy Council. (2016). Lactose intolerance: prevalence, symptoms and diagnosis. Available:
  2. Cafasso,J. (2016). What causes lactose intolerance? 4 possible conditions. Available:
  3. GHR. (2016). Lactose Intolerance. Available:
  4. NHS. (2016). Lactose Intolerance. Available:
  5. The Dairy Council. (2016). Vitamins in Milk. Available:
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