A high fiber diet that includes a variety of sources of fiber reduces several major risk factors for heart disease and other medical conditions and could help you live longer. Fiber does a heart good, and 25 grams per day is needed to reap significant benefits. In the U.S. it's been estimated that the average adult eats only about 10 to 15 grams of fiber a day. In addition, fiber could help with weight loss and help reduce cholesterol levels. Foods containing strong-gelling fibers reduce food intake by stimulating a feeling of satiety or fullness.
   People who get a lot of fiber in their diet lower their odds for type 2 diabetes.

Definition: Dietary fiber is the term for parts of plants a body can't digest. Dietary fibers are non-starch polysaccharides which are derived from vegetables, whole grains, legumes and other plants and absorb water when consumed. Natural dietary fiber contains cellulose, lignin, waxes, chitins, pectins, beta-glucans, inulin and oligosaccharides.

Classification: Fiber is classified as soluble or insoluble. Both types of fiber are present in all plant foods. Soluble fiber undergoes metabolic processing via fermentation, yielding end-products that influence health. Insoluble dietary fiber attracts water and increases bulk, softens stool and maintains regularity.

Fiber supplement pill and powder
There are a number of types of fiber supplements sold over the counter. They come in pill or powder form. I prefer you get your fiber directly from foods. However, if you are not able to do so easily, then it would be quite acceptable to take fiber supplements. Or, you could take them only at a meal which happens to have little fiber. For instance a meal of meat and potatoes or a snack such as pie or ice cream.

Most common or popular fibers are:
Psyllium is one of my favorite fiber supplements, I use half or one teaspoon of the powder daily with breakfast, lunch or dinner. You also have the option to take psyllium capsules rather than the powder.
Glucomannan is a dietary fiber becoming more popular in the USA. Glucomannan has been studied in terms of weight reduction.

Less common:
Apple pectin fiber. Although present in the cell walls of most plants, apple and orange peel are the two major sources of commercial pectin due to the poor gelling behavior of pectin from other sources.
   Zhonghua Yi Xue Za Zhi. 2014. Clinical benefits after soluble dietary fiber supplementation: a randomized clinical trial in adults with slow-transit constipation/ Four-week pectin soluble dietary fiber use accelerates colon transit time and alleviates clinical symptoms in patients with slow-transit constipation. Additionally, supplementary fiber offers protective effects on gut microbiota by increasing the population of healthy microflora.
Prebiotics such as inulin fiber. You can purchase inulin fiber supplement over the counter.
Beta-glucan is a soluble fiber derived from the cell walls of algae, bacteria, and fungi. Beta glucan supplements are available to be purchased.
Grapefruit pectin fiber information and supplement product.
Modified citrus pectin supplement is an example of a healthy fiber.
Agar fiber is found often in form of a powder.
Chitosan fiber has been promoted for weight loss but studies have not shown chitosan to be of benefit for the purposes of losing weight.

High fiber food - source
Most plants and foods have a combination of soluble and insoluble fiber.
   Foods high in soluble fiber include whole grains, oat bran, oatmeal, cereals, beans, peas, rice bran, barley, citrus fruits, strawberries and apple pulp. Oats have the highest proportion of soluble fiber of any grain. Soluble fibers that dissolve or swell when put into water include pectins, gums (gum arabic, guar gum, locust bean gum), mucilages, and some hemicelluloses.
   Insoluble fiber is important in normal bowel function. Foods high in insoluble fiber include whole-wheat breads, wheat cereals, wheat bran, rye, rice, barley, most other grains, cabbage, beets, carrots, Brussels sprouts, turnips, cauliflower and apple skin. Insoluble fiber cannot be digested by enzymes in the human gastrointestinal tract. Insoluble fiber is considered a "noncarbohydrate carbohydrate" since the components that make it are lignins, cellulose, and hemicelluloses. All of these compounds form the structural parts of plants and do not readily dissolve in water and are not metabolized by intestinal bacteria. Bran fiber is rich in hemicelluloses, while a cotton ball is pure cellulose. Insoluble fiber is important because it provides mass to the stool, helping to ease elimination and reduce constipation. The fiber absorbs water and holds onto it in the intestine. When enough fiber is consumed, the water-retaining property helps to enlarge and soften the stool. As a result, less pressure is required to expel the stool.
   Flax seeds are wonderful for bowel regulation. Chia seeds which work similar to psyllium in having a high fiber content and being able to absorb a lot of water and help regular bowel function.

Overall benefit
Fiber present in food keeps the gastrointestinal system moving, improves feelings of satiety thus helping in weight management, reduces the risk of some forms of cancers and helps the trillions of beneficial microbes living in the gut and intestines.

Anti-aging benefit
Researchers from the U.S. National Cancer Institute report eating a high amount of fiber makes you live longer and reduces the of developing heart disease and respiratory, some cancers, diabetes and obesity. In addition, fiber helps bowel movements and lowers cholesterol levels, blood sugar and blood pressure. It also promotes weight loss and reduces inflammation. Guidelines recommend bout 25 grams of fiber a day. The researchers found that men and women who ate the most fiber were 22% less likely to die over the nine years than people who ate the least fiber. Fiber from grains, but not from fruits, was associated with reduced risks of dying. The report is published in the Feb. 14 online edition of the Archives of Internal Medicine.

Appetite reduction
Adding a dietary fiber derived from seaweed to a meal-replacement drink may reduce feelings of hunger. Researchers from Unilever's Research and Development in the Netherlands compared the effects on hunger after drinking a meal-replacement drink with alginate at two different strengths and without it. The higher concentration alginate drink reduced hunger longest -- up to nearly five hours after drinking it.

Arthritis and osteoarthritis benefit
Consumption of dietary fiber at the recommended average intake of 25 g per day is associated with lower risks of developing symptomatic knee osteoarthritis and moderate or severe knee pain in two separate analyses of Osteoarthritis Initiative participants conducted by investigators at Boston University in 2016.

Colon cancer risk reduction
A diet with lots of fiber decreases the chances of dying from colon cancer. In people treated for non-metastatic colon cancer, each five grams of fiber added to their diet reduces the risk of dying by almost 25 percent, according to Dr. Andrew Chan, associate professor in the department of medicine at Harvard Medical School; Nov. 2, 2017, JAMA Oncology, online.

Cholesterol lowering
When eaten regularly as part of a diet low in saturated fat and cholesterol, soluble fiber has been shown to help lower blood cholesterol. But how does it work? Three major biological mechanisms have been proposed to explain the cholesterol-reducing effects of soluble dietarby fibers: prevention of bile salt re-absorption from the small intestine leading to an excess fecal bile salt excretion; reduced glycemic response leading to lower insulin stimulation of hepatic cholesterol synthesis; and physiological effects of fermentation products, mainly propionate.

Estrogen levels
Women who get the recommended amount of fiber in their diets may have lower estrogen levels and ovulate less often than women who eat less fiber.  American Journal of Clinical Nutrition, October 2009.

Fiber and gallstones
High-fiber diet reduces the risk for gallstones.

Fiber and hemorrhoid treatment
Most kinds of fiber are beneficial for hemorrhoids, particularly psyllium.

IBS
Increasing intake is beneficial in certain cases of irritable bowel syndrome.

Weight Loss
Foods containing strong-gelling fibers reduce food intake by stimulating a feeling of satiety or fullness. The average fiber intake of adults in the United States is less than half recommended levels and is lower still among those who follow currently popular low-carbohydrate diets, such as Atkins and South Beach. Increasing consumption of dietary fiber with fruits, vegetables, whole grains, and legumes across the life cycle is a critical step in stemming the epidemic of obesity found in developed countries. The addition of functional fiber to weight-loss diets should also be considered as a tool to improve success.
   If a person consumes a high-insoluble-fiber cereal rather than a low-fiber cereal, they are likely to consume fewer calories and this reduced energy intake is often not replaced at lunch.

Eat more fiber at breakfast
A breakfast cereal  that has a high fiber content contributes to a cumulative reduction in breakfast and lunch energy intake, possibly due to its high satiety value. A short-term benefit of a high fiber cereal breakfast, compared with a low fiber cereal, is lower blood sugar concentration before and immediately after lunch.

Fiber, weight loss, and cholesterol reduction study
If you have been a long term reader of my newsletter, you are aware of about my hesitancy in using statin drugs for cholesterol reduction, or the use of pharmaceutical drugs for weight loss. Drugs should be reserved when safer methods fail. Here I present a study done in Spain that found the use of two simple and inexpensive fibers, psyllium and glucomannan, to be helpful not only in weight reduction, but also in lowering cholesterol levels. It's sad that doctors prescribe statin drugs to their patients with mild cholesterol level elevations when there are are simple and safe alternatives. I can understand using statin drugs when all natural options fail, but most doctors don't even suggest additional fiber supplements. They are quick to the draw to write a prescription for a statin drug such as Lipitor or prescription weight loss drugs.

Effect of two doses of a mixture of soluble fibers on body weight and metabolic variables in overweight or obese patients: a randomised trial.
Br J Nutr. 2007.
The purpose of this study was to compare the benefit of a mixture of fibers on body weight-loss, satiety, lipid profile and glucose metabolism. For a period of 16 weeks, 200 obese individuals consumed fiber consisting of3 grams Plantago ovata (psyllium husk) and 1 gram glucomannan twice daily, or three times daily or placebo. Weight loss tended to be higher after both doses of fiber than placebo. Postprandial satiety increased in both fiber groups compared to the placebo. The differences between groups in LDL-cholesterol levels were significant, with greater reductions in the two fiber-supplemented groups. A similar pattern was observed for changes in total cholesterol / HDL-cholesterol ratios. Interventions were well tolerated and had no effects on HDL-cholesterol, glucose and insulin concentrations, glucose tolerance or high-sensitivity C-reactive protein. In conclusion, a 16-week dietary supplement of soluble fiber in overweight or obese patients was well tolerated, induced satiety and had beneficial effects on some cardiovascular risk factors, the most important of which was a significant decrease in plasma LDL-cholesterol concentrations.

A study of nearly 6,000 men and women found that the higher the participants' fiber intake, the lower their risk of being overweight or having elevated blood pressure or cholesterol. Fiber from different sources had somewhat different effects. Fiber from whole grains, for example, was linked to lower body mass index (BMI), blood pressure and levels of a blood protein called homocysteine, which is connected to heart disease risk. Fruit fiber was associated with lower blood pressure and less abdominal fat, while fiber from vegetables appeared to lower the risk of high blood pressure and high homocysteine concentrations. And fiber from nuts, dried fruit and seeds was linked to a lower BMI, a lesser risk of abdominal obesity and lower blood sugar levels. These findings all point to the importance of getting fiber from a variety of sources. The results also suggest that adults would do well to get more than the recommended fiber intake of roughly 25 grams per day. In the study, each 5-gram increase above that was linked to a greater decrease in the risks of being overweight or having high blood pressure or high cholesterol. People can generally have fiber intakes of up to 70 grams a day without having digestive symptoms such as bloating and cramping. Study participants with highest total fiber intake had a 30 percent lower risk of being overweight. They had similarly lower risks of high blood pressure and elevated cholesterol compared with their peers who ate the least fiber. American Journal of Clinical Nutrition, December 2005.

Fiber and C reactive protein
In a study of 524 healthy adults, investigators found that those with the highest fiber intake had lower blood levels of C-reactive protein (CRP) than those who ate the least fiber. The findings support the general recommendation that adults get 20 to 35 grams of fiber per day, in the form of fruits, vegetables, beans and whole grains. It's not clear why fiber reduces inflammation, but it may lower cholesterol and blood sugar, both of which can contribute to inflammation. Both of the main forms of fiber, soluble and insoluble, were related to lower CRP levels. Soluble fiber is found in foods like oatmeal, beans, berries and apples, while whole grains and many vegetables are good sources of insoluble fiber. American Journal of Clinical Nutrition, April 2006.

Low fiber diet
A low fiber diet is composed of foods that are low in residue content. This diet reduces fecal mass. A low fiber diet is sometimes used in the treatment of chronic diarrhea, colitis and other gastrointestinal disorders, although more recently, higher fiber diets have been employed for these purposes.

Side effects, safety
Consuming too many high fiber foods that have not been cooked can cause side effects of abdominal bloating and gas. Taking too many fiber supplements without adequate water intake can lead hard stools. Make sure to take psyllium and other fibers with quite a few ounces of water.

Additional plants with a lot of fiber include:
Int J Biol Macromol. 2014 Feb 15. Locust Bean Gum: Processing, Properties and Food Applications -A Review. Locust bean gum or carob gum is a galactomannan obtained from seed endosperm of carob tree i.e. Ceratonia siliqua. It is widely utilized as an additive in various industries such as food, pharmaceuticals, paper, textile, oil well drilling and cosmetics. Industrial applications of locust bean gum are due to its ability to form hydrogen bonding with water molecule. It is also beneficial in the control of many health problems like diabetes, bowel movements, heart disease and colon cancer due to its dietary fiber action.
Barley fiber
2008 - The Food and Drug Administration (FDA) has issued an interim final rule to amend the existing health claim regarding soluble fiber and reduced risk of heart disease, to include barley betafiber as an authorized source of soluble fiber. The FDA's revision of the health claim is a result of Cargill's health claim petition, based in large part on Cargill's proprietary clinical research with Barlív™ barley betafiber. Cargill is the only producer of barley betafiber; therefore, Barlív barley betafiber is the only barley beta-glucan concentrate that qualifies for the FDA health claim as defined.
Yucca root

Herb used for constipation
Cascara Sagrada bark is helpful. You can purchase Cascara Sagrada without a prescription.