Laxatives: An Unlikely Ally In The Battle Against High Ph Levels?

Laxatives are medicines that treat constipation by softening stools or stimulating the bowels. They are available in various forms, including pills, powders, liquids, suppositories, and enemas, and can be purchased over the counter or with a prescription. While laxatives can provide relief, they should be used sparingly and only when necessary as they can cause side effects such as abdominal cramps, dehydration, and electrolyte imbalances. Some common types of laxatives include bulk-forming laxatives, osmotic laxatives, stool softeners, lubricants, and stimulants.

A study by R L Bown et al. published in the journal Gut in 1974 investigated the effects of lactulose and other laxatives on ileal and colonic pH using a radiotelemetry device. The study found that lactulose significantly reduced the pH in the proximal colon but had less consistent effects in the distal colon. Combining lactulose with other laxatives did not result in a more uniform reduction of pH along the length of the colon.

The effects of lactulose on ileal and colonic pH

Lactulose is a versatile pharmaceutical agent used to treat chronic constipation. It is a non-absorbable synthetic disaccharide that reaches the large bowel unchanged. In the colon, bacteria metabolize lactulose into monosaccharides, volatile fatty acids, hydrogen, and methane. This process reduces intestinal ammonia production and absorption in three ways: by promoting increased ammonia uptake by colonic bacteria, reducing intestinal pH, and decreasing intestinal production of ammonia.

The effect of lactulose on ileal and colonic pH has been compared with that of other laxative agents, such as sodium sulphate and magnesium sulphate. Lactulose produced a marked acidification of proximal colonic contents, but this effect was not consistently maintained into the distal colon. Sodium sulphate, on the other hand, acidified distal rather than proximal colonic contents. Combining these laxatives did not produce a more uniform reduction of pH along the length of the colon compared to lactulose alone. Magnesium sulphate had little effect on luminal pH except in the rectum, where a significant rise occurred.

In a study on rats with minimal hepatic encephalopathy (MHE), lactulose decreased the pH value of the colon to below 6.0, which can reduce ammonia absorption and promote the growth of healthy bacteria. This effect was similar to that of a probiotic compound, Golden Bifid, which is a highly concentrated combination of Bifidobacterium longum, L. bulgaricus, and Str. thermophilus.

The impact of other laxatives on colonic pH

Laxatives are medicines that help resolve constipation or empty the bowel of faecal matter before procedures or surgery. There are several different types available, each working in a particular way. Some soften or loosen up the stool, while others increase how frequently the large colon contracts, helping to move the stool along the bowel.

Lactulose is an osmotic laxative that lowers colonic pH, thereby stimulating the large bowel. It is very sweet and may be unpalatable to some patients. It commonly causes flatulence, abdominal cramps and bloating. It must be taken regularly for up to three days before an effect is seen.

Magnesium salts are laxatives that result in rapid bowel evacuation. If given in large doses, defaecation may occur within one to two hours. These laxatives are reserved for bowel clearance prior to surgical procedures and are not suitable for regular use.

Bulk-forming laxatives, such as psyllium, polycarbophil and methylcellulose, add "soluble" fibre to the stool. This causes the stool to absorb more water, creating larger, softer stools that help trigger the bowel to contract and move the stools out.

Emollient stool softeners, such as docusate, moisten and lubricate the stool, making it easier to pass.

Stimulant laxatives, such as bisacodyl and sennosides, are the harshest type of laxatives. They cause the bowel to squeeze or contract to move the stools out. They should not be used for more than a few days. When these laxatives are taken for a long time, the bowel can lose its muscle tone and forget how to push the stool out on its own.

The human intestine harbours both lactate-producing and lactate-utilising bacteria. The effect of different initial pH values on lactate metabolism was studied using fecal inocula from healthy volunteers. The results suggested that lactate accumulated at a pH of 5.2 because production was maintained but utilisation was markedly reduced.

The safety of long-term laxative use

Laxatives are medicines used to treat constipation and empty the bowel of faecal matter before medical procedures. They are available over the counter without a prescription and can be taken by mouth or rectally. However, laxatives should be used sparingly and only when necessary. They are not meant for long-term use unless under medical supervision.

Laxatives are meant to be used occasionally and for short periods of time. Long-term use of laxatives can lead to several health complications:

• Electrolyte disturbances: Prolonged use of laxatives can cause imbalances in electrolytes such as potassium, which are necessary for the proper functioning of nerves and muscles, including the colon and heart.
• Dehydration: Laxatives can cause dehydration, which can lead to lightheadedness, headaches, darker urine, tremors, weakness, blurry vision, and even kidney damage in extreme cases. It is important to drink plenty of fluids, such as water, tea, or soup, while using laxatives.
• Intestinal obstruction: Excessive use of laxatives can lead to large and dry stools, resulting in intestinal obstruction.
• Laxative dependency: The colon may stop reacting to usual doses, requiring larger and larger doses over time.
• Internal organ damage: Long-term use can stretch the colon and thin the muscle wall, causing damage to internal organs.
• Increased risk of colorectal cancer: Non-fibre-based laxative use has been linked to an increased risk of colorectal cancer, although more research is needed to confirm this association.
• Interference with medication absorption: Laxatives can interfere with the absorption of certain medications, so it is important to consult a doctor if taking other drugs.
• Nutrient deficiencies: Long-term use of laxatives can lead to nutrient deficiencies, especially if they cause diarrhoea, as this can result in the malabsorption of essential vitamins and minerals.

It is important to note that laxative misuse is relatively common, especially among individuals with eating disorders. Misuse can lead to health complications and contribute to an eating disorder diagnosis. Therefore, it is crucial to use laxatives as directed and only when necessary. If constipation persists or worsens, it is important to consult a doctor, as it may be a warning sign of a more serious condition.

Laxatives as a treatment for constipation

Laxatives are a type of medicine that can treat constipation. They are often used if lifestyle changes, such as increasing fibre intake, drinking more fluids, and exercising, have not helped. Laxatives are available to buy over the counter in pharmacies, grocery stores, and online. They may be labelled as laxatives, stool softeners, or fibre supplements.

There are several types of laxatives that work in different ways. The main classes of laxatives are:

• Bulk-forming laxatives: These increase the "bulk" or weight of the stool, which stimulates the bowel. They are generally considered the gentlest type of laxative and are often recommended as the first option. They include Metamucil, Citrucel, Fybogel, and more.
• Osmotic laxatives: These draw water from the body into the bowel to soften the stool and make it easier to pass. They also stimulate the muscles that line the gut, helping to move the stool along. Osmotic laxatives include Movicol, Laxido, Milk of Magnesia, and more.
• Stool softener laxatives: These increase the water and fat that the stool absorbs, softening it. They include Colace and docusate.
• Lubricant laxatives: These coat the colon, making it slick and preventing the colon from absorbing water from the stool. Lubricant laxatives include mineral oil.
• Stimulant laxatives: These activate the nerves that control the muscles in the colon, forcing it to move the stool along. They include Dulcolax, Senokot, and more.

Laxatives are usually taken orally in the form of pills, capsules, powders, liquids, or syrups. However, some laxatives are administered rectally as suppositories or enemas. It is important to follow the instructions when taking laxatives to prevent side effects such as bloating, gas, stomach cramps, and dehydration. Laxatives should only be used occasionally and for a short period, as long-term use can lead to side effects and worsen constipation.

The different types of laxatives available

Laxatives are a type of medicine used to treat constipation. They are available over the counter in pharmacies, grocery stores, and online, as well as on prescription from a doctor. They can be taken orally or rectally. It is important to take laxatives as directed to prevent side effects such as bloating, gas, or stomach cramps.

There are several different types of laxatives, including:

Bulk-forming laxatives

Also known as fibre supplements, these work in the same way that fibre in the diet does. They increase the bulk of stools by getting them to retain liquid, which encourages the bowels to push them out. They usually take 12–24 hours to start working and are generally considered the gentlest type of laxative. Bulk-forming laxatives include:

• Psyllium (Metamucil)
• Polycarbophil (FiberCon)
• Methylcellulose (Citrucel)
• Calcium polycarbophil (Equalactin, FiberCon)
• Wheat dextrin (Benefiber)

Osmotic laxatives

Osmotic laxatives draw water from the rest of the body into the bowel to soften poo and make it easier to pass. They may take up to 2–3 days to start working. Osmotic laxatives include:

• Polyethylene glycol (Gavilax, MiraLAX)
• Magnesium hydroxide solution (Dulcolax, Ex-Lax, Phillips' Milk of Magnesia)
• Glycerin (Colace Glycerin, Fleet Pedia-Lax)
• Lactulose (Duphalac, Lactugal)
• Macrogol (Movicol, Laxido, CosmoCol, Molaxole, Molative)
• Magnesium citrate (Citroma)
• Magnesium sulfate (Epsom Salt)
• Sodium biphosphate/sodium phosphate (Fleet Enema)

Stool softener laxatives

Also called emollient laxatives, these increase the water and fat that poo absorbs, softening it. Stool softeners include:

Docusate (Colace)

Lubricant laxatives

Lubricant laxatives coat the colon, making it slick. The coating prevents the colon from absorbing water from the stool, so it stays soft. Lubricant laxatives include:

Mineral oil (Kondremul)

Stimulant laxatives

Stimulant laxatives activate the nerves that control the muscles in the colon. They force the colon into motion so it moves the stool along. They usually take effect within 6–12 hours. Stimulant laxatives include:

• Bisacodyl (Dulcolax, Correctol, Feen-a-Mint)
• Senna (Fletcher's Laxative, Senokot, Ex-Lax, Senokot S, Senexon, Swiss Kriss, etc.)
• Prunes (dried plums)

Frequently asked questions