You have probably heard of the term “lactose intolerant” used to describe someone who has difficulty digesting milk, or negative symptoms associated with ingesting dairy products. But do you know how proteins play a role in this problem?
One of the many functions of proteins is to catalyze reactions, breaking things down or building things up as necessary. This is the key to digestion, as all of the food and drinks that humans consume are made up of the same peptides that make up our proteins and must be broken down into their simple components to be used by the body. (Insert figure diagraming how food is just protein amino acids broken down into essential parts). The protein that breaks down lipids and carbohydrates in milk and dairy products is known as lactase. Lactase is an enzyme that adds a water molecule to the carbohydrate lactose, breaking it from a repeating chain of glucose and galactose to individual molecules of glucose and galactose. It is essential to the digestion of milk fat and other dairy products. When it is properly functioning, the reaction mechanism resembles this chemical reaction:
So what causes some people to have what is known as lactose intolerance? In some cases, this can occur when the protein lactase stops functioning properly. However, as explored further in the following article, there is more than one cause of lactose intolerant symptoms.
Many people experience food sensitivities and intolerances. There are methods of diagnosing these problems, but most associate negative symptoms with a food group and tend to avoid it. But what if you could know for sure that you can’t have dairy? This paper outlines the results of a clinical study on 158 people claiming to be lactose intolerant. The participants are described as patients with functional bowel disorder, and the tests conducted are designed to determine if this disorder is truly due to lactose intolerance (LI).
A clinical study is a scientific article that focuses on the patient outcomes to an experiment. This means that participants in the study were exposed to something (milk products) designed to test whether they have a reaction. The results of the tests are patient answers to questions and other interpretable results from the tests conducted.
Lactose intolerance (LI) is characterized by a digestive discomfort caused by ingesting lactose in food. This is often described as the result of lacking the functional protein enzyme lactase to break down lactose. The paper explains that lactose intolerance (LI) can itself be categorized into 2 different types: lactose malabsorption (LM) and lactose sensitivity (LS). The differences and causes of each one are summarized here:
- Lactose malabsorption (LM) – a result of LI, LM indicates the lack of lactase and an abundance of lactose that has not been broken down
- Lactose makes its way to the colon to be processed instead by fermentation by gut bacteria that are present – this causes production and build-up of hydrogen, carbon dioxide, and methane in the large intestine and is why some complain of gas and bloating after consuming lactose.
- Lactose fermentation in the colon also causes an increase in water uptake in the small intestine, causing symptoms such as bloating, pain, gas, nausea, and diarrhea.
- Lactose sensitivity (LS) – an overabundance of gut bacteria fermenting products and causing the sensations described in the small intestine would lead to the same symptoms, but not necessarily caused by lactose
- The initial symptoms may be brought on by lactose or first noticed after consuming dairy, but the true cause could be small intestinal bacterial overgrowth (SIBO) and increase the likelihood of LI.
- Treating SIBO with probiotics could reduce symptoms of LI not brought on by lack of lactase enzyme.
The researchers have outlined that patients who self-diagnose with lactose intolerance (LI) could be suffering from a lack of the protein lactase to break it down, or they could be experiencing symptoms of an entirely different problem: too much bacteria in the small intestine. Fortunately, there is a way to determine the cause of such indigestion.
Remember how the enzyme lactase works? The disaccharide lactose is broken into its two components: glucose and galactose. So when the protein is functioning properly, there should be more glucose released into your bloodstream. There are effective methods of measuring blood glucose levels, and so the team of scientists came up with an experiment to test the patients for lactose intolerance. The volunteer patients were asked to fast overnight, and then given a sample of lactose to consume. Samples of their blood were taken over time to evaluate how well their bodies broke down the lactose. Here is what they were looking for:
- If a patient did not show signs of significantly increasing their glucose content (i.e. not breaking down lactose) then they were considered lactose malabsorptive (LM).
- If a patient reported negative digestive symptoms, then they were considered lactose sensitive (LS) because it caused their symptoms to flare up.
- If both were true, then the patient was considered LM and LS.
As an interesting report, here are the results of testing 158 patients according to these specifications:
How Proteins are Important
So what’s the big deal about a study like this? It shows that there are different ways that your body responds to food and beverages, and how you should treat negative symptoms as they arrive. Patients who are lactose malabsorptive can take a protein supplement (Lactaid) that breaks down lactose for them when they lack the protein. On the other hand, patients who are lactose sensitive may also need antibiotics to repress their gut bacterial growth and fight fermentation, and protein supplements may not work for them. Before you give up the dairy, check with your doctor!
The other important thing to note from this study is the importance of proteins in experiments and clinical tests. To test for glucose in the blood, something had to break it down and release it (because when was the last time you ingested pure glucose?). Proteins made this study work, and they play a role in many clinical and basic research experiments. The next time you enjoy ice cream, yogurt, or cream in your coffee, thank your lactase proteins for making it possible!