A Tropical Pitcher Plant and Enzymes for Gluten Digestion
A Pitcher Plant and Gluten Digestion in Humans
Pitcher plants are carnivorous organisms that trap and digest prey. They bear cup or tube-like containers made from modified leaves. These containers, or pitchers, contain digestive fluid. Animals and other organic material that fall into a pitcher are broken down and their components used by the plant.
There are many different types of pitcher plants. A tropical species named Nepenthes ampullaria may have an important benefit for humans. Researchers have discovered that enzymes made by the plant can digest gluten, a protein complex present in certain grains.
In people with celiac disease, the presence of gluten in the small intestine triggers an immune system response that damages the intestinal lining. This can lead to some very serious symptoms. The plant enzymes may be able to digest gluten in the acidic conditions of a patient's stomach, preventing the protein from entering and damaging the small intestine.
Why Are Pitcher Plants Carnivorous?
Pitcher plants are interesting and intriguing organisms. They're found in several families. The pitchers of different species may look different and have different features, but they all serve the same function.
Like other plants, pitcher plants carry out photosynthesis to produce food and also absorb nutrients from the soil. The soil in which they grow is poor in nitrogen, however. This element is needed to make DNA, RNA (which is necessary in order for DNA to perform its job), and proteins. DNA, or deoxyribonucleic acid, contains the genes of an organism.
Pitcher plants solve the problem of insufficient nitrogen by trapping and digesting animals. Other nutrients in the animals are also used. The animals that are caught are generally insects, although sometimes larger animals fall into the pitchers and are digested.
Some pitcher plants digest feces that's dropped into the pitchers by rodents. The animals feed on nectar produced at the rim of the pitcher. The relationship is beneficial for both organisms, although occasionally an accident happens and a rodent falls into the pitcher.
Pitfall Traps and Prey Digestion
The pitchers of carnivorous plants are also known as pitfall traps. They are deep containers in relation to the size of the intended prey. They often have a lid, or operculum, that reduces the dilution of the digestive liquid by rain water.
Pitchers generally have special features to attract prey. These include the presence of sweet nectar or of colours that are significant for insects. The traps have special precautions to prevent the escape of an animal once it falls into the liquid. The interior walls of the pitcher are usually slippery, for example. In addition, the digestive liquid that covers trapped insects makes it impossible for them to fly.
Pitcher plants produce an array of digestive enzymes. They are able to break down the entire body of an insect, including the chitin that forms the outer covering. Some of the enzymes may be useful for humans.
Nepenthes Ampullaria and Other Species in a Plant Nursery
Nepenthes ampullaria can be bought in some plant nurseries and kept as a cultivated plant.
The Nepenthes Ampullaria Plant
Nepenthes ampullaria is a climbing plant that grows on the forest floor in Borneo, Sumatra, Malaysia, Thailand, Singapore, and New Guinea. The plant does trap and digest insects, but unlike many of its relatives it also feeds on leaf litter that falls into the pitchers. This means that it's both a carnivore and a detritivore (an organism that feeds on detritus, or small fragments of dead creatures).
The leaves of the plant are long, narrow, and pointed. Some of them have a tendril at their tip. The lower leaves are borne in rosettes while the upper ones are spread out. The plant becomes woody as it matures.
The plant bears small flowers arranged in a structure called a panicle, which is shown in the photo below. Each flower in the panicle is yellow-green in colour. The fruit is a capsule that changes from green to brown as it ripens.
Nepenthes ampullaria produces both aerial pitchers and terrestrial ones. The pitchers are attractive and have a variety of colours. They are green, yellow-green, red, speckled red and green, or speckled red and yellow. They have a small operculum that is folded backwards.
An aerial pitcher is attached to a tendril that extends from the tip of a leaf's midrib. The plant also produces a cluster of pitchers that spread over the ground and are referred to as terrestrial or basal pitchers. These pitchers are produced by an underground stem known as a rhizome.
The digestive fluid of Nepenthes is acidic, like the fluid in our stomach. In addition, it contains a large bacterial population. These bacteria may help to digest food, just like the bacteria in our intestine. The plant's similarity to our digestive tract is interesting and could be significant with respect to disease treatment.
Species in the genus Nepenthes are sometimes known as monkey cups. The name arose from the idea that monkeys fed on the liquid in the pitchers.
What Is Celiac Disease?
Untreated celiac disease is a serious condition. The small intestine is the site of most of the food digestion in the body and of nutrient absorption. In some people, gluten activates the immune system inappropriately and causes inflammation of the intestinal lining. In addition, villi are damaged and flattened. The villi are tiny folds on the intestinal lining that absorb nutrients. When the villi are flattened, the ability to absorb nutrients from food is greatly reduced. Another problem is that people with untreated celiac disease have an increased risk of intestinal cancer.
There are many possible symptoms of celiac disease. Diarrhea and abdominal pain are frequent effects, but patients may have additional or different symptoms. Since nutrients are hindered in their passage through the intestinal lining and into the bloodstream, problems may appear in many areas of the body.
The treatment for the disease is to eliminate gluten from the diet. This generally allows the villi to regenerate and symptoms to disappear. As described below, however, it's a challenge to follow a truly gluten-free diet. This is one reason why the search for suitable digestive enzymes is important.
Celiac Disease Explained for Adults and Children
Gluten in Grains
Gluten is found in all forms of wheat, including kamult and spelt. It's also a popular food additive. It gives elasticity and binding power to baked goods and stops them from crumbling. Wheat gluten is actually a complex of two types of proteins—the gliadins and the glutenins. The gliadins are believed to be responsible for the problems in celiac disease. The word "gliadins" is sometimes used in the singular to refer to the entire group of chemicals.
Rye contains secalins, which are related to gliadins, and barley contains related hordeins. Both types of chemicals trigger intestinal damage in people with celiac disease. Rye and barley are generally said to be gluten-containing grains, even though the relevant chemicals are different from those in wheat.
Avenins in oats are also related to gliadins but are thought to be safe for people with celiac disease. Oats that are certified gluten-free (that is, not contaminated by wheat, rye or barley) are available in some stores, especially health food markets. Someone with celiac disease should check with their doctor about the advisability of eating these oats, however, because there is some debate about the safety of the grain.
Rice, corn, millet, buckwheat, amaranth, quinoa, sorghum, and teff contain no gluten and are suitable grains or grain substitutes for people with celiac disease.
A Gluten-Free Diet
Someone with celiac disease must elimate all wheat, rye, and barley from their diet as well as any product containing added gluten. In addition, a patient must avoid items that have come into contact with unsuitable food, such as utensils and kitchen surfaces. Even being in a room with flour in the air can be dangerous if the flour contains gluten.
In reality, it's hard to reach a zero gluten level due to contamination of food at some point in its harvest and/or preparation. In North America, a food must contain less than 20 ppm (parts per million) of gluten in order to be labelled gluten-free.
It's important that someone with celiac disease does their best to eliminate gluten from their diet in order to reduce the chance of continual low-level inflammation in their intestine.
Potential Problems With Following a Gluten-Free Diet
The gluten-free diet is sometimes difficult to follow, for a variety of reasons.
- A person must be constantly vigilant about their diet and about food contamination.
- Food contamination with gluten is impossible to detect visually.
- Going to restaurants may be a risky pursuit because ingredients are often unknown.
- Even when it's certain that food in a restaurant meal normally contains no gluten, it may have been contaminated in the kitchen.
- Travelling requires careful planning because suitable food may be unavailable.
- Wheat, rye, and barley (and oats) are nutritious foods. It's important to compensate for the missing nutrients when the grains are eliminated from the diet.
- Gluten-free products are often more expensive than the equivalent ones containing gluten.
- There is often a wider choice of healthy processed food that contains gluten than of healthy processed food without the substance.
- The widest variety of gluten-free foods is found in health food markets, which are not as common as general markets.
Though it's certainly possible to follow a healthy dIet while avoiding gluten, it's easier to do this when the substance doesn't need to be avoided. Enzymes that destroy gluten in the stomach before it reaches the small intestine and causes harm would be very useful. Pitcher plant enzymes might be able to perform this task.
Pitcher Plant Enzymes for Gluten Breakdown
The research into digestion of gluten by pitcher plant enzymes was led by David Schriemer. He's a biochemist and associate professor at the Cumming School of Medicine. The school is part of the University of Calgary in Alberta.
Enzymes that break down gluten have already been discovered. According to Schriemer, however, a major problem is that an amount of enzyme almost as large as the amount of food is required in order to remove gluten. This treatment isn't practical for people with celiac disease.
The research team found that the combination of two enzymes made by Nepenthes ampullaria and by a hydrid form of Nepenthes can digest gliadin. The enzymes can be used in much smaller quantities than other ones. The pitcher plant chemicals are called nepenthesin and neprosin. The latter substance was discovered during the research.
The plant chemicals digested gluten in both lab equipment and animal stomachs. Very significantly, mice sensitive to the substance showed no intestinal inflammation when eating gluten-containing food and the enzyme combination.
Remarkably low doses enhance gliadin solubilization rates, and degrade gliadin slurries within the pH and temporal constraints of human gastric digestion. Potencies in excess of 1200:1 (substrate-to-enzyme) are achieved.— University of Calgary Research Team
Nepenthes Ampullaria Pitcher Development
The enzymes from pitcher plants sound very promising, but more research is needed. It's important to check that the chemicals cause no harm to humans and that they consistently digest all gluten before it reaches the intestine. The ratio of enzyme to ingested food is an important consideration. It's also important to check that the continual use of the chemicals prevents both inflammation and villi flattening.
The research explored the breakdown of gliadin in wheat. We need to know whether the related chemicals in rye and barley are also digested. Although wheat gliadin seems to be the major instigator of intestinal damage in celiac disease, rye and barley also play a role, at least according to our current understanding of the disease.
Availability of the Enzymes
David Schriemer has established a commercial company with the aim of bringing the plant enzymes to market. He says that this will be a multi-year project. Scientists need to fully understand the actions of the chemicals and to solve any problems before clinical trials take place in humans. The production of sufficient quantities of the enzymes for celiac disease patients is also an important problem to solve.
The use of nepenthesin and neprosin could eventually make food choices much easier for people with celiac disease. It would be interesting to know whether other enzymes from pitcher plants have benefits for us.
Information about tropical pitcher plants (genus Nepenthes) from the San Diego Zoo
Celiac disease information from the Mayo Clinic
Sources of gluten: A list from the Celiac Disease Foundation
Enzymes from a carnivorous plant can digest gluten: A news release from the University of Calgary with links to the original research reports
Questions & Answers
© 2016 Linda Crampton