Fiber Laxatives: Diarrhea Risk?

Fiber is an essential part of a healthy diet, but it can be tricky to find the right balance. While fiber is well-known for relieving constipation, it can also cause diarrhea. This is because there are two types of fiber: soluble and insoluble. Soluble fiber dissolves in water to form a gel-like substance, which helps to slow digestion and soften stools. Insoluble fiber, on the other hand, remains intact as it passes through the digestive system, bulking up stools and speeding up transit time. For those suffering from diarrhea, increasing soluble fiber intake can help to solidify stools, while insoluble fiber may be beneficial for those experiencing constipation. However, it is important to note that everyone's fiber needs are different, and it is always best to consult a healthcare professional before making any significant changes to your diet.

Fiber and IBS

Irritable bowel syndrome (IBS) is a common chronic gastrointestinal disorder that affects 10-20% of the adult population worldwide. It is characterised by abdominal pain and abnormal bowel habits such as constipation, diarrhoea, or a combination of both, as well as bloating, distension, and excessive flatulence.

The amount of dietary fibre consumed can play a role in managing IBS symptoms and normalising bowel habits. Too much or too little fibre can affect IBS symptoms, and certain types of fibre may be better tolerated than others.

Types of Fibre

Fibre is the non-digestible, carbohydrate component of plant foods. It can be soluble or insoluble. Soluble fibre dissolves in water, pulls water into the stool, and forms a gel-like substance that helps move contents down the gastrointestinal tract. Insoluble fibre bulks up stools and acts like a brush, sweeping through the bowels to keep things moving.

Fibre and IBS-D

For those with IBS-D (irritable bowel syndrome with diarrhoea), consuming more fibre may worsen symptoms by increasing the frequency or urgency of bowel movements. Short-chain soluble and highly fermentable dietary fibre, such as oligosaccharides, can result in rapid gas production that can cause abdominal pain, bloating, and flatulence.

Fibre and IBS-C

Those with IBS-C may have tried a high-fibre diet and/or fibre supplement and felt worse. However, this may be due to excessive FODMAP intake, which can worsen symptoms such as bloating, gas, and abdominal pain.

Recommended Fibres for IBS

Psyllium is a recommended fibre for IBS as it has been shown to help normalise stools and reduce symptoms. It is minimally fermented and forms a gel that is preserved during its passage through the large bowel. It is also safe and effective in improving IBS symptoms overall.

Other recommended fibres for IBS include:

• Partially hydrogenated guar gum (PHGG) or Sunfiber
• Acacia fibre or acacia gum
• Methylcellulose
• Calcium polycarbofill
• Wheat dextrin or Benefiber

Tips for Getting Enough Fibre

Despite recommendations that adult women consume 25g of fibre per day and men consume 38g per day, the average fibre intake is just 16g per day.

• Snack on fruits such as raspberries, rhubarb, kiwifruit, mandarin, strawberries, passionfruit, and oranges
• Include vegetables with meals such as carrots, green beans, potatoes, corn, and eggplant
• Check food labels when buying bread and cereal products and opt for higher fibre options such as quinoa flakes, brown rice, gluten-free multigrain bread, rice bran, sourdough spelt bread, and porridge (oats)
• Add canned lentils or chickpeas to casseroles or salads
• Snack on nuts such as macadamias, almonds, and peanuts
• Add rice bran or linseeds/flax to breakfast cereal

Fiber and weight loss

Fiber is an important nutrient that can help with weight loss. It is a type of carbohydrate that cannot be digested by the gut and is found in all plant-based foods. There are two types of fiber: soluble and insoluble. Soluble fiber dissolves in water and forms a gel-like substance in the digestive system, while insoluble fiber does not dissolve and acts as a bulking agent for stool.

Soluble fiber has been linked to weight loss, specifically in reducing belly fat. It does this by encouraging the growth of gut bacteria, which are linked to a lower risk of conditions like type 2 diabetes, insulin resistance, and heart disease. Soluble fiber also helps to reduce appetite by slowing the movement of food through the gut, which can lead to a reduced sense of hunger. Additionally, soluble fiber may help to regulate hormones involved in appetite control, increasing the production of hormones that make you feel full.

A study published in the Annals of Internal Medicine found that eating 30 grams of fiber each day helped participants lose weight, lower blood pressure, and improve their response to insulin. This was compared to the American Heart Association's (AHA) diet for preventing heart disease, which includes eating more fruits, vegetables, high-fiber foods, fish, and lean protein while cutting back on salt, sugar, fat, and alcohol. The participants in the high-fiber diet group lost slightly less weight than those on the AHA diet, but both groups were able to maintain their weight loss for 12 months.

It is important to note that increasing fiber intake should be done gradually, as doing so too quickly can cause side effects such as abdominal discomfort, cramps, and diarrhea. It is also recommended to get fiber from food sources rather than supplements, as the health benefits of whole plant foods are more significant.

Fiber and cholesterol

Fiber is a non-digestible carbohydrate found in all plant-based foods, including fruits, vegetables, grains, nuts, and seeds. It is essential for human health and plays a crucial role in maintaining a healthy digestive system and promoting regular bowel movements. There are two types of fiber: soluble and insoluble.

Soluble fiber and cholesterol

Soluble fiber, found in oat bran, nuts, seeds, beans, lentils, peas, and some fruits and vegetables, forms a gel-like substance in the digestive system. This gel helps to keep stools soft and slows down the digestive process. In doing so, soluble fiber traps fats in the intestines, preventing them from being absorbed into the body. This leads to lower cholesterol levels in the blood.

Insoluble fiber and cholesterol

Insoluble fiber, found in wheat bran, whole grains, and the peels of fruits, acts as a natural laxative. It bulks up the stool and speeds up the passage of food through the stomach and intestines. While insoluble fiber does not directly lower cholesterol levels, it helps maintain a healthy digestive system, which is essential for overall health, including maintaining healthy cholesterol levels.

Recommended fiber intake

The American Heart Association and the FDA recommend a daily intake of at least 25 grams of dietary fiber. However, it is estimated that most Americans consume less than 20 grams of fiber per day.

Sources of fiber

Soluble fiber can be found in oatmeal, beans, lentils, and many fruits. Insoluble fiber is present in whole grains, beans, lentils, and most vegetables. It is important to consume a variety of fiber-rich foods to ensure adequate intake of both soluble and insoluble fiber.

Benefits of fiber

In addition to lowering cholesterol, a high-fiber diet offers numerous health benefits. It is associated with lower weight, blood pressure, blood sugar, and a reduced risk of diabetes, heart disease, strokes, and certain types of cancer. Fiber also promotes a healthy gut by increasing the number of good bacteria in the intestines.

Fiber and gut health

Fiber is a non-digestible carbohydrate found in all plant-based foods. It is essential for human health and plays a critical role in maintaining a healthy digestive system and promoting regular bowel movements. There are two types of fiber: soluble and insoluble.

Soluble fiber

Soluble fiber forms a gel in the digestive tract by pulling in water. This slows digestion and reduces the absorption of some nutrients like starch and sugar. It is commonly used in over-the-counter laxatives and can be found in psyllium husk, pectin, and the soft parts of fruits, dried beans, and peas. Soluble fiber has been shown to improve glucose tolerance in people with diabetes and may help prevent heart disease and stroke by lowering cholesterol levels.

Insoluble fiber

Insoluble fiber, found in fruit peels, acts as a natural laxative that speeds up the passage of food through the stomach. It adds bulk to stool and helps it move quickly through the gastrointestinal tract.

Benefits of fiber for gut health

• Prevents and treats constipation: Fiber increases stool size and makes it softer, which helps keep bowel movements regular. Insoluble fiber bulks up stool and acts like a brush to keep things moving, while soluble fiber absorbs water to form a gel-like substance that helps stool pass smoothly through the bowels.
• Improves gut bacteria: The fermentation of soluble fiber, known as prebiotics, in the large intestine can increase the number of good bacteria in the gut, which may reduce the risk of type 2 diabetes, heart disease, and obesity.
• Reduces the risk of certain diseases: A high-fiber diet may help prevent and treat various conditions, including gastrointestinal disease, hemorrhoids, high cholesterol, heart disease, stroke, diabetes, and some forms of cancer.
• Aids weight loss: Soluble fiber may help with weight loss by increasing feelings of fullness and reducing appetite.
• Improves insulin sensitivity: Soluble fiber can improve glucose tolerance and lower insulin and blood sugar levels in people with diabetes.
• Reduces inflammation: Soluble fiber is associated with reduced inflammation and a lower risk of death, particularly in people with kidney disease.

The recommended daily intake of fiber is 25 to 35 grams. However, most people do not meet this recommendation, with estimates suggesting that the average intake is between 12 and 18 grams per day.

Precautions when increasing fiber intake

While fiber is essential for gut health, it is important to gradually increase fiber intake to avoid side effects such as gas and bloating. Additionally, excessive fiber intake can lead to intestinal blockage in rare cases. It is always advisable to consult a healthcare professional before making significant dietary changes.

Fiber and constipation

Fiber is the indigestible part of plants and carbohydrates. It can be found in all plant foods, including fruits, vegetables, grains, nuts, seeds, and legumes. Chitin, a form of fiber, is also found in the shells of crustaceans like crab, lobster, and shrimp.

There are two types of fiber: soluble and insoluble. Soluble fiber is found in oat bran, nuts, seeds, beans, lentils, and peas, as well as some fruits and vegetables. Insoluble fiber is found in wheat bran, vegetables, and whole grains. Most fiber-rich foods contain a mixture of both types.

Fiber is often recommended for people experiencing constipation. Constipation is characterized by less than three bowel movements a week, with stools that are hard, dry, and difficult to pass.

Fiber helps with constipation in the following ways:

• It increases stool size and makes stools softer, which helps keep you regular.
• Insoluble fiber, in particular, adds bulk to stools and acts like a brush, sweeping through the bowels to keep things moving.
• Soluble fiber absorbs water and forms a gel-like substance, aiding in smooth stool passage and improving its form and consistency.
• Soluble fiber also promotes the growth of good bacteria in the gut, which may reduce the risk of type 2 diabetes, heart disease, and obesity.

The recommended daily fiber intake for adults is 25-38 grams for men and 25-21 grams for women, depending on age. However, most people eat less than half of this amount, consuming only 12-18 grams per day.

For those with constipation, gradually increasing fiber intake over a few days can help get back to a more regular bowel movement schedule. It is important to note that increasing fiber intake should be done gradually to avoid gastrointestinal symptoms like gas, cramping, or bloating.

While fiber is generally recommended for constipation, it may worsen the condition in certain cases. If constipation is not due to insufficient fiber intake, adding more fiber may not help and could even make the problem worse.

Additionally, for people with irritable bowel syndrome (IBS), high-fiber foods that are also high in FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) can worsen IBS symptoms.

In such cases, a low-fiber or no-fiber diet may be recommended, or non-fermentable, soluble fiber supplements may be beneficial.

Best Types of Fiber for Constipation Relief

For those with chronic constipation or experiencing symptoms like pain, wind, bloating, and gas, non-fermentable, soluble fiber supplements may be the best option. Examples include psyllium husk, methyl cellulose, glucomannan capsules, and inulin.

Prunes are also an effective natural laxative due to their high fiber content and the presence of sorbitol, a natural laxative.

Other Strategies for Constipation Relief

In addition to increasing fiber intake, other strategies to relieve constipation include:

• Increasing fluid intake: Water is essential to helping fiber work effectively, as it is needed for fiber to sweep the colon and move stool out of the body.
• Exercise: Physical activity helps stimulate bowel movements.
• Hot beverages: Drinking hot liquids, especially caffeinated ones like coffee or tea, can speed up digestive motility and stimulate the bowels.
• Natural laxatives: Commercially available constipation supplements with psyllium husks or guar gum are generally safe for occasional use. However, caution is advised with other herbal supplements, as they may be poorly researched and regulated.

Frequently asked questions