Bowel Stimulants and Laxatives

What They Do
Generally speaking, all bowel stimulants fall under the category of laxatives.  A laxative is a term that is used for a substance that encourages defecation or the elimination of feces through stimulation of the intestines.  The actual term laxative usually refers to a mild substance, and more drastic substances are referred to as cathartics, purgatives, hydrogogues and drastics.  They are most commonly used to treat constipation (inability to have a bowel movement).  There are many different types of laxatives: stimulant, lubricant and saline laxatives are used to evacuate the colon for rectal and bowel examinations.  Unfortunately, laxatives can be addictive and are often abused by bulimics or anorexics.  Laxative abuse is a large problem because it is potentially very serious and can lead to problems such as intestinal paralysis, IBS and pancreatitis. When food and waste products are forced out of the intestinal tract too quickly, the body is deprived of vital substances, such as nutrients that are normally absorbed by the small and large intestines.  In addition to disrupting nutritional and digestive processes, laxatives reinforce the condition that they are meant to overcome.  If the intestines are purged dramatically, it could be several days before they can fill again with enough waste for a normal elimination.  If the goal is to eliminate every day with the use of laxatives, the necessary dose to achieve elimination becomes larger and larger.  For more information on laxative abuse, please see Digestion Health’s information on laxative abuse. 

There are several types of laxatives which may be in oral or suppository form: 

1. Bulking agents: compounds that increase the amount of bulk in the intestines either by withdrawing water from the body or increasing bulk when combined with fluids
2. Lubricants: softeners (emollient laxatives) or lubricants such as mineral oil which ease the passage of waste and counteract excessive drying of the intestinal contents.
3. Stimulants: laxatives that stimulate muscular action of the intestines (cascara sagrada, senna)

Bulking agents (fiber)
Bulking agents include dietary fiber and cause the stool to be bulkier and retain more water. These types of laxatives draw water from the body into the intestines, making it easier for peristaltic action (wave-like contractions of the colon) to take place.  Another type of bulking agent is a stool softener.  These cause fats and water to penetrate the stool through the intestines, making it much easier for the digestive material to move along.  Many types of bulking agents quickly prove ineffective with prolonged use.  With the use of saline, Epsom salt or Milk of Magnesia, this type of bulking agent (called a hydrating agent) causes the intestines to concentrate more water within, softening the stool.  Even though it is the most gentle of the laxatives, if not combined with fluids, bulking agents can lead to constipation.

Lubricants
Lubricants simply make the stool more slippery, which eases the passage of waste. This can also help counteract excessive drying of the intestinal contents.

Stimulants
As the name suggests, stimulants encourage peristaltic action (wave-like contractions of the colon).  The can be quite dangerous under certain circumstances and are the most severe among laxatives.

What’s in them?

There are two main sources or types of laxatives: anthraquinones and lactulose.  The chemical compounds that are called anthraquinones are naturally occurring stimulant laxatives that in small doses are safe and gentle for general use.   They are found in rhubarb root (Chinese laxative), senna leaf and pod (Middle Eastern laxative), cascara sagrada (North American laxative), buckthorn (European laxative and also known as frangula) and aloe (known worldwide).  There are also anthraquinones in vegetables such as cabbage and lettuce, and a particularly high count in beans (36mg/kg fresh weight). 

When it comes to the colon, anthraquinones act directly on the intestinal wall and help to speed the peristalsis of the bowel.  Anthraquinone laxatives increase fluid accumulation in the colon by changing the absorption and secretion of water as well as the retention of potassium through unknown actions. It is thought that laxatives work by irritating the intestinal mucosa and endothelial cells (cells that form the inner lining of blood vessels), but there may be a direct stimulation of peristaltic activity. 

For acute constipation, mirabilitrum (Epsom salt or magnesium sulfate) is often used along with rhubarb in the Chinese treatments.  In such cases, with the addition of mirabilitrum, the peristalsis is higher and produces a quicker action (within 2-3 hours instead of 6-8).  This is known as purgative therapy.

Over the years, chronic constipation has become increasingly prevalent.  The medical research and investigations that have been done on constipation have focused on constipation as secondary to a specific disease process, bowel malformation or a side effect of drugs.  Most commercial advertisements for over-the-counter laxative products as well as natural laxative products mention that laxatives are to be used for “occasional irregularity”, but in reality many people experience constipation much more often.  These patients feel it best to treat their constipation persistently with the use of laxatives. Studies of chronic constipation claim that the sedentary lifestyle that has become so incredibly prevalent in today’s society contributes greatly to constipation.  The absence of physical labor or vigorous exercise results in weak abdominal muscles, thus making eliminating waste a difficult task.  If the average person gets the recommended 20 minutes of walking per day, that means that that person spends 98% of the day inactive.  Except for the elite or disabled, such a low level of activity has never before been experienced in human history.  Lack of exercise also contributes to obesity, osteoporosis, heart disease, depression and is also associated with higher rates of colon cancer.  

In a medical study, published by Dr. Subhuti Dharmananda from the Institute of Traditional Medicine in Portland, Oregon, the importance of using laxatives as a last resort can be seen. 

Practitioners involved with natural health-care therapies often recommend various dietary supplements, including herbs, which will have a laxative effect. While these supplements can be quite helpful, it is important to put them into proper context and to be aware of potential problems from extended use of stimulant purgatives. Relying on laxatives to permanently replace exercise, fibrous foods, and water is inappropriate except in extreme cases where there are no other options (such as elderly patients with limited capabilities). While use of the laxatives as part of a changing lifestyle may be a valuable component of therapy leading towards alleviation of chronic constipation, it is inconsistent with the tenets of natural healing to recommend use of supplements only, particularly without a reasonable limit of duration.

The other type of laxative, called lactulose is a bulking agent.  It is a synthetic sugar that consists of the monosaccharides fructose and galactose. Lactulose is a prepared laxative or polyethylene glycol laxative and has a relatively quick effect.  The agent is taken in a does of about 10 grams each time, twice daily and can normalize stool within one to four weeks.  In a recent medical study, it was shown that lactulose is more frequently used laxative than the anthraquinone laxatives, although more dangerous.