There are a lot of people who always have problems with eating cheese and milk, in fact, experts have shown that about 70% of the world's population have lactose malabsorption which you also know as lactose intolerance. So let's have a sugary milky post ahead.
Lactose is a double sugar (disaccharide) molecule basically glucose and galactose, and that is why when it gets into the body system, it breaks down into glucose and galactose. Glucose is a stable molecule responsible for energy production in the body, while galactose is a less stable molecule that is converted to glucose and other molecules. If you are talking about lactose, you can find it in almost all dairy food, from cheese, butter, milk, and so on.
When we take these dairy products, the lactose in the body is broken down via the enzyme lactase and it is produced by the lactase gene. The gene is very important in infants as it is always functioning to help break down lactose since our food then is milk but when infants are introduced to other types of food (weaning), the gene begins to produce less lactase or even a complete zero stage which is what leads to lactose intolerance. Why lactose intolerance mechanism isn't completely known, scientists have an explanation at least.
Lactose intolerance is often referred to as Lactase Non-persistence or Lactose malabsorption. While approximately two-thirds of the world's population is lactose intolerant, some individuals have lactase persistence, meaning their lactase gene continues to produce lactase. This persistence is a result of specific genetic variations, such as single nucleotide polymorphisms in the MCM6 region located before the lactase gene on chromosome 2, which sustain lactase production.
The lactase is produced in the small intestine where it is activated at the lumen, with humans producing lactase-phlorizin hydrolase. So when lactose is consumed, and the lactase gene produces lactase, then the lactase converts it to galactose and glucose which is then absorbed into the body to be used but if the gene isn't producing lactase, the lactose goes through the stomach, then the small intestine, and makes its way to the large intestine and it is assumed as waste.
At the ileocecal valve, it goes into the cecum, then the ascending and transverse colon, after which it goes to the descending colon, then to the sigmoid colon which then takes it to the rectum. In the large intestine, there are a lot of bacteria that break down lactose into glucose and galactose thereby creating short-chain fatty acids, carbon dioxide, hydrogen, and methane gas. These waste and the gases stretch out the large intestine which then stimulates peristalsis which is why people with lactose intolerance experience bloating, flatulence, diarrhea as a result of water going into the intestine to dilute the solute waste, and abdominal pain from large intestine cramp. When these occur, the patient can experience nausea which is the body reacting to the symptoms., ,
Though lactose intolerant individuals may want to avoid dairy altogether, research suggests that non-persistence individuals can tolerate small amounts of milk, around 250ml, without experiencing severe symptoms. However, some individuals may still prefer to avoid all dairy products due to the discomfort they experience. If you suspect lactose intolerance, it's essential to consult your doctor for guidance and personalized advice on managing your dietary choices,