Category: Lactose Intolerance

Lactase can digest the sugar molecule lactose into simpler molecules called galactose, which is widely utilized to help digest milk and dairy products. Lactose intolerance occurs when a person’s body produces only a small amount of lactase. Lactase is naturally produced by cells arranged and bacteria living in the small intestine. People needs lactase can get it by taking supplements, drugs or probiotics. What are the sources of lactase?

Lactose intolerance begins at different ages. Lactose intolerance can affect children at 2 years age or older. And it is more common for adults. One way to treat is to avoid drinking dairy products. However, this can lead to a lack of important nutrients and vitamins such as calcium, vitamin D, riboflavin and protein. Some people use lactose-free milk or milk substitutes such as soy or rice syrup.

Human milk contains a large amount of lactose, which is digested by lactase into glucose and galactose. However, 75% of adults in the world suffer from lactose intolerance, which means they experience varying degrees of diarrhea, nausea, abdominal pain and flatulence after lactose intake. Lactase is produced by cells arranged in the small intestine. It attaches to the membrane of these cells and is exposed to the digested food of the intestines. Infants born on time produce large amounts of lactase and can easily digest milk. However, when they become adults, their small intestines can completely stop producing lactase, leading to lactose intolerance.

In addition to intestinal cells, certain bacteria that live in the gut also produce lactase. Lactose that has not been digested by human lactase will be digested by bacterial lactase. When bacteria are ingested as part of a food (yoghurt), lactase survives in the acidic stomach because it is protected by the bacterial cell wall. Once it enters the small intestine, the bacteria release lactase to digest lactose. The complete bacterial cell wall and lactase release rate around the entire bacteria are two factors that determine yogurt intake to treat lactose intolerance.

People with lactose intolerance can obtain lactase by taking pills or chewable tablets. WebMD recommends taking tablets containing 6,000-9,000 IU (International Units) at the start of the meal. It is also recommended to add 500 IU of liquid lactase to a 500 ml milk cup before drinking. One disadvantage of lactase pills is that not all lactase preparations – pills, liquids and brands – have the same enzyme concentration.

In addition to taking lactase, one can also obtain lactase by eating a lactase-producing bacterium. The US Food and Drug Administration defines probiotics as ‘living microorganisms that, when administered in sufficient amounts, confer a health benefit to the host.’ These bacteria are not pathogens, so they won’t make people sick. The three common genera (plural genus) of probiotics are Lactobacillus, Bifidobacterium and Enterococcus. Representative species of each genus are Lactobacillus acidophilus, Bifidobacterium longum and Enterococcus faecalis.

Quite a lot of people are actually lactose intolerant and that means that they can not have milk or almost any other dairy because their bodies can not digest the sugar in dairy that is called lactose. Researches and studies show us that being lactose intolerant has a lot to do with genetics, age and gender. Doctors can test you lactose tolerance by using the lactose tolerance test that is done by a glucometer that can exactly tell you how much lactose there is left in your body after having something such as an intake of milk. Being lactose intolerant can cause lots of discomforts such as abdominal pain, nausea, bloating, gas, vomiting and others. So it is very good to know if you are lactose intolerant or not so you can choose what your body intakes are wisely.

The Cohort study, that I reviewed, divided the people who they wanted to test into two different age groups, one with people under the age of 50 and the other group were people that are over the age of 50 and these studies showed us that the rate of people under 50 that are lactose intolerant are around 29.7% and the rate for people over the age of 50 was 42.9%. From these results we can clearly see that lactose intolerant people over 50 is almost twice as much of the people that were tested and were under 50 years of age. Also, I found some really interesting facts, such as roughly 34.6% of individuals living are actually lactose intolerant and that is a significant and eye catching number.

Generally Lactose intolerance happens when there is not enough enzyme (lactase) in your small intestine to digest milk sugar which is also known as lactose. Lactase usually turns milk sugar into two simple sugar such as glucose that is absorbed through the intestinal lining into the bloodstream. If you are deficient in lactase, instead of being processed and consumed, lactose in your diet passes into the colon. Dairy is an important food for us because they contain calcium and vitamin D but how should lactose intolerant people get these important food factors? Well, they can actually use other foods such as fish, green vegetables and soy to get the calcium and vitamin D their body needs to function and be healthy.

Studies have shown that the rate of people being lactose intolerant differs with locations. People from Africa and Asia are actually in higher risk of being lactose intolerant than lets say people that live in northern Europe. There are lots of children that are born with this disorder and is very important for the parents to know about this and to place their child on a good and healthy diet based on the way their bodies are.

One thing that caught my attention was that almost all of the studies on being lactose intolerant or not were tested by only milk and not other dairy products and I wonder if the statistics would change if there was a change in the food substance and by trying other dairy products or foods which contain lactose. There should be a difference because the amount of lactose in each substance is different to the other one. Therefore, further research on this issue is needed.

β-galactosidase is a bacterial enzyme. Study of this enzyme allowed researchers to develop operon model and determine the role of the enzyme in regulating gene expression. Besides this historic significance, β-galactosidase also have essential enzymatic functions, including to hydrolyze lactose into glucose and galactose, to synthesize allolactose by transgalactosylation of lactose, and to produce monosaccharides by cleaving allolactose . Ability of β-galactosidase to hydrolyze lactose is vital for energy production. Resulting products of lactose hydrolyzes enter glycolysis and are converted to ATP, energy source used by organisms. This hydrolyze process is turned on when there is lack of glucose and presence of lactose in the environment. In the absence of glucose, β-galactosidase is essential for energy production and thus survival of the organisms. In addition to enzymatic functions, β-galactosidase is also used significantly in molecular biology. It acts as a reporter marker to monitor gene expression and is use to distinguish recombinant plasmid through blue and white screening (Juers et al., 2012).

β-galactosidase can be purified by first introducing β-galactosidase gene into plasmid, which is then introduced into Escherichia coli culture. This will allow for increase in concentration of the enzyme. Then, the cells are lysed to break the cell membrane and release cell content, including β-galactosidase. After, the cell content must go through various separation steps to purify β-galactosidase from other proteins. This could be achieved by (NH4)SO4 fractionation, size exclusion chromatography using Sepharose G-75, and DEAE chromatography (Hu et al., 1959).

During (NH4) SO4 fractionation, addition of salt results in “salting-in,” where solubility of protein increases. With addition of more salt “salting-out” occurs, where solubility of protein decreases and precipitation occurs. The precipitation, containing β-galactosidase, can then be separated by chromatography. β-galactosidase is a tetramer with molecular weight of 540 kDa. Since, Sepharose G-75 has exclusion limit of 80 kDa, β-galactosidase will elute out of the column without entering resin pores, along with other protein of similar size. Thus, the sample must further be filtered to separate β-galactosidase from other proteins. The final separation occurs through DEAE chromatography. In this step, the elution from size exclusion chromatography is added to the column, resulting in binding of β-galactosidase to the resin. All the unbound protein are wash off while, bound protein remains, which can be eluted by increasing ionic strength of NTM elution buffer (Hu et al., 1959). The purity and identity of each separation steps can then be analysed using SDS-PAGE and Western Blot analysis.

In humans, lactase, small intestine enzymes, are responsible for digesting lactose. However, when there is low concentration of lactases, lactose begins to buildup. They eventually move from small intestine to large intestine. In large intestine, these lactose are digested by microorganisms, resulting in production of gaseous by-products. These gaseous by-products cause the symptoms of lactose intolerance including bloating, cramps and accumulation of water in the large intestine. Since lactose intolerance affects ~70% of the world’s adult population, modifying β-galactosidase for safe and more efficient use is essential (Lehman and Wolyniak, 2015).

Currently, treatment of lactose intolerance includes adding β-galactosidase to lactose-containing products and β-galactosidase supplements. β-galactosidase is added to products containing lactose, including yogurt, sour cream, milk and some cheese, during production (Saqib et al., 2017). The result is creation of lactose-hydrolysed products with low concentration of lactose (Saqib et al., 2017). Although, lactose-hydrolysed products are effective, recent study shows that lactose are not hydrolyed 100% and there is still low concentration of lactose in products, even after treatment with β-galactosidase (Rosolen et al., 2015). Thus, studying the structure of β-galactosidase can provide solution for successfully achieving 100% hydrolysis of lactose in lactose products.

Another treatment of lactose intolerance involves ingesting β-galactosidase capsules before consuming lactose-containing products (Lehman and Wolyniak, 2015). Supplement have shown to prevented symptoms of lactose intolerance (Lehman and Wolyniak, 2015). However, research shows supplements being degraded due to the low pH level of the stomach (O’Connell and Walsh, 2006). O’Connell and Walsh studied four main commercial lactases used as treatment for lactose intolerance (2006). They found that all four lactases functioned at maximum activity of 55 to 65% at 37°C and at pH level of 3.0 to 6.5 (O’Connell and Walsh, 2006). But all lactases significantly lost their activity in in vitro digestive environment, and only 0 to 65% of their original activities was retained (O’Connell and Walsh, 2006). They also found that the most effective lactase out of the four, cleaved only 2.7 g of lactose per tablet (O’Connell and Walsh, 2006). Thus, lactases not only loss significant amount of their activity but many lactase tablets is required for effective treatment.

Furthermore, a study on mutant strain of E. coli revealed β-galactosidase with higher activity than normal (Martinez-Bilbao et al., 1991). This mutant was discovered to have its’ Gly-794 replaced with Asp (Martinez-Bilbao et al., 1991). Due to this substitution, activity of β-galactosidase increased significantly, especially with lactose as a substrate. This study by Martinez-Bilbao and team also revealed this β-galactosidase to be heat-sensitive in comparison to normal β-galactosidase (1991). Based on the result of this study, structure of the purified enzyme can be examined and ways of replacing Gly-794 with Asp, while maintaining the heat-tolerance of normal enzyme, can be determined.

Purifying β-galactosidase will allow for analysis of the structure and specific parts of the structure that are involved in the process of cleaving lactose into glucose and galactose. The structural information can be used to increase efficiency and effectiveness of current treatment for lactose intolerant.