The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject.(December 2010) |
Fibre supplements (also spelled fiber supplements) are considered to be a form of a subgroup of functional dietary fibre, and in the United States are defined by the Institute of Medicine (IOM). According to the IOM, functional fibre "consists of isolated, non-digestible carbohydrates that have beneficial physiological effects in humans". [1]
Fibre supplements are widely available, and can be found in forms such as powders, tablets, and capsules. Consumption of fibre supplements may be for improving dietary intake, lowering blood cholesterol, alleviating irritable bowel syndrome, reducing the risk of colon cancer, and increasing feelings of satiety.
Excessive fibre intake can lead to fluid imbalance, dehydration, mineral deficiencies, nutrient and drug interactions, and other medical problems.
The American Dietetic Association recommends that the average adult consume 25 to 38 grams of dietary fibre per day. [2] However, research has shown that the average American only consumes 14 to 15 grams per day. [2] To reach the recommended amount of fibre, consumption of dietary fibre from foods (e.g. plants, vegetables, legumes, and grains) instead of supplements is preferred because they contain additional beneficial nutrients and non-nutritive components (e.g. antioxidants and phytoestrogens). Nevertheless, a fibre supplement may be needed to prevent constipation when fibre intake via food is low, which is the case among many inactive elderly people. A cereal bran such as psyllium seed husk, or a synthetic fiber such as methylcellulose is often used in this case. [3]
Foods that are high in viscous fibres have been found to lower blood cholesterol by binding with bile acids. In order to compensate for this, cholesterol from the liver may be used to make more bile acids. The products of bacterial fermentation in the colon may also decrease the rate of cholesterol synthesis in the liver. [4]
However, research has produced mixed results with respect to whether fibre supplements are as effective as dietary fibre in reducing blood cholesterol. Two recent studies show nearly opposing results, using fibre-supplemented apple juice containing both the soluble pectin from apples and gum arabic. In the first study, the supplement-enriched juice had no discernible effect on the blood cholesterol levels of 110 hypercholesterolaemic men and women. [5] In the second study, the total and LDL-cholesterol levels of mildly hypercholesterolaemic men were lowered. [6]
In another study, a dietary supplement consisting of both soluble fibre (guar gum, pectin) and insoluble fibre (soy fibre, pea fibre, corn bran) was found to reduce LDL-cholesterol for individuals that have mild to moderate hypercholesterolaemia without reducing HDL-cholesterol or increasing triglycerides. [7]
Supplements containing extracted insoluble fibre may have an effect on blood lipids that most resembles the effects of dietary fibre. In a more recent randomized, double blind clinical study of 58 hypercholesterolaemic volunteers, an extruded carob pulp preparation added to daily diet reduced total and LDL-cholesterol and improved the ratio of HDL:LDL cholesterol in all participants, and also showed a marked reduction in serum cholesterol in the women of the study. [8]
The protective properties of dietary fibre against colorectal cancer are undisputed. However, not all fibre supplements seem to provide the same defensive effect. A study of 1429 men and women over six months showed that a high-fibre cereal (wheat bran) supplement had no protective effect on recurring colorectal adenomas. In addition, no significant improvement in the proportion or features of existing colorectal adenomas was observed. [9]
Diverticulitis is mainly attributed to the low fibre intake commonly found in the Western diet for which a gradual increase in dietary fibre over several weeks is a commonly prescribed clinical solution. Fibre supplementation has been found to be less effective than dietary fibre in this regard. One study of 58 men and women with uncomplicated diverticulitis in a double-blind controlled trial concluded that common doses of wheat bran and a psyllium-derived supplement provided relief of constipation only, with no other observable effects. [10]
Irritable bowel syndrome (IBS) is a common gastrointestinal ailment for which dietary soluble fibre is often prescribed as part of a therapeutic solution. As a supplement, partially hydrolysed guar gum (PHGG - completely soluble, fully fermentable [11] ) has been shown to be quite effective in clinical trials for decreasing IBS symptoms such as abdominal pain and generally improving quality of life for sufferers well beyond treatment. In addition, PHGG has been shown to have prebiotic properties by acidifying bowel contents and increasing gut microflora. [12]
Acacia senegal fiber (gum arabic - completely soluble, fully fermentable) has also been shown to have a prebiotic effect in the gut, significantly increasing Bifidobacteria and Lactobacilli after 4 weeks of consumption. [13] Acacia ferments very slowly in the gut, and due to its polymeric nature does not disturb osmotic pressure, so it has a good gastrointestinal tolerance (it has no sudden and painful release of gas, and the total gas production is much lower than with FOS, for instance) and does not present any side effects at dosages up to 50 grams per day. [14] Particularly helpful for IBS is that Acacia senegal behaves as a regulator; it is able to reduce diarrhea [15] and reduce constipation. [14]
Dietary insoluble fiber has long been shown to exacerbate Irritable Bowel Syndrome symptoms. [16]
It has been suggested that the refining of fibre-rich grains has contributed to the obesity epidemic of Western countries. Whole, dietary forms of fibre are more difficult to ingest and absorb than milled and refined food products. [17] This is because dietary fibre may be able to displace available calories and nutrients, requires more time for chewing (thereby slowing intake rate and inducing satiety), and reduces the efficiency of absorption in the small intestine. [17] [18]
Supplemental forms of fibre have been shown to potentially assist weight management by increasing satiety, [19] [20] [21] decreasing the absorption rate of starches and sugars, and binding to lipids in the small intestine thereby reducing serum triglycerides and chylomicron. [22]
Powdered guar gum, a soluble fibre, was shown to be associated with a significantly lower energy intake in obese subjects who ingested a non-restricted diet over one week, when the same participants did not consume the fibre supplement. [19]
A similar reduction of energy intake through fibre supplementation was observed in another study. A dose of guar gum was administered to normal-weight and obese participants. A 10% reduction of energy was observed in the normal subjects, and a 30% reduction of energy for obese subjects. [23] Fibre supplementation has also been indicated to assist compliance to low-calorie diets, as indicated through decreased feelings of hunger and increased ratings of satiety. [19] Other soluble fiber forms such as glucomannan have also been studied in relationship to blood sugar and fat digestion in obese patients. [24]
Abruptly adding elevated amounts of fibre to the diet too quickly can lead to intestinal gas, diarrhea, abdominal bloating, cramping, and constipation. [25] It is therefore better to regulate and moderate daily fibre intake. If increased fibre intake is desired, gradually increasing the amount over a few days allows the natural bacteria in the gastrointestinal tract to adjust to the change. Drinking 1- 2 L of water every day can prevent some uncomfortable symptoms by making the stool soft and bulky.
The risk of intestinal obstruction from insoluble fiber in susceptible individuals, [26] fluid imbalance leading to dehydration and mineral deficiencies may increase if more than 50 g of fibre is ingested per day. For this reason, individuals who decide to suddenly double or triple their fibre intake are often advised to double or triple their water intake. In addition, excessive intake of non-fermentable fibre (typically in supplemental form) may lead to mineral deficiencies by reducing the absorption or increasing the excretion of minerals, especially when mineral intake is too low or when mineral needs are increased such as during pregnancy, lactation, or adolescence.
Excessive fibre intake can also contribute to nutrient and drug interactions. For example, antidepressant medications, diabetes medications, carbamazepine, [27] cholesterol-lowering medications and penicillin. According to figures from Public Health England (PHE), most Britons are not getting enough fiber from their diets. Findings from the latest National Diet and Nutrition Survey reveal that the average Briton consumes 18g of fiber each day; however, this is significantly below the recommended intake of 30g.[ citation needed ]
Product Name | Soluble / Insoluble | Ingredients | Capsule / Powder |
---|---|---|---|
Benefiber | S | natural, manufacturing by-product - wheat dextrin (USA), inulin (Canada) | C/P |
Citrucel | S | synthetic - methylcellulose | C/P |
FenFiber | S | natural, whole food - fenugreek | C |
FibreSmart | S/I | natural, whole food - flax | C/P |
FiberCon | I | synthetic - calcium polycarbophil | C |
Fiber Choice | S | natural, manufacturing by-product - inulin | C |
Heather's Tummy Fiber | S | natural, whole food - organic acacia senegal | P |
Metamucil | S/I | natural, whole food - psyllium | C/P |
Fiberlyze | S/I | natural, whole food - psyllium, corn fiber | P |
Natural Brand Psyllium seed husk | S/I | natural, whole food - psyllium | C |
PGX | S | natural, manufacturing by-product - glucomannan | C |
ReCleanse Fibre Powder | S/I | natural, manufacturing by-product and whole food - inulin/flax | P |
ReguFIT | S/I | flax-seed, wheat bran, pineapple, oat bran, senna leaves, psyllium husks, stevia, omega 3-6 | P |
S=Soluble, I=Insoluble C=Capsule/Tablet, P=Powder
In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.
Guar gum, also called guaran, is a galactomannan polysaccharide extracted from guar beans that has thickening and stabilizing properties useful in food, feed, and industrial applications. The guar seeds are mechanically dehusked, hydrated, milled and screened according to application. It is typically produced as a free-flowing, off-white powder.
Dietary fiber or roughage is the portion of plant-derived food that cannot be completely broken down by human digestive enzymes. Dietary fibers are diverse in chemical composition and can be grouped generally by their solubility, viscosity and fermentability which affect how fibers are processed in the body. Dietary fiber has two main subtypes: soluble fiber and insoluble fiber which are components of plant-based foods such as legumes, whole grains, cereals, vegetables, fruits, and nuts or seeds. A diet high in regular fiber consumption is generally associated with supporting health and lowering the risk of several diseases. Dietary fiber consists of non-starch polysaccharides and other plant components such as cellulose, resistant starch, resistant dextrins, inulin, lignins, chitins, pectins, beta-glucans, and oligosaccharides.
Constipation is a bowel dysfunction that makes bowel movements infrequent or hard to pass. The stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the bowel movement. Complications from constipation may include hemorrhoids, anal fissure or fecal impaction. The normal frequency of bowel movements in adults is between three per day and three per week. Babies often have three to four bowel movements per day while young children typically have two to three per day.
Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder characterized by a group of symptoms that commonly include abdominal pain, abdominal bloating and changes in the consistency of bowel movements. These symptoms may occur over a long time, sometimes for years. IBS can negatively affect quality of life and may result in missed school or work or reduced productivity at work. Disorders such as anxiety, major depression, and chronic fatigue syndrome are common among people with IBS.
Psyllium, or ispaghula, is the common name used for several members of the plant genus Plantago whose seeds are used commercially for the production of mucilage. Psyllium is mainly used as a dietary fiber to relieve symptoms of both constipation and mild diarrhea, and occasionally as a food thickener. Allergy to psyllium is common in workers frequently exposed to the substance.
Inulins are a group of naturally occurring polysaccharides produced by many types of plants, industrially most often extracted from chicory. The inulins belong to a class of dietary fibers known as fructans. Inulin is used by some plants as a means of storing energy and is typically found in roots or rhizomes. Most plants that synthesize and store inulin do not store other forms of carbohydrate such as starch. In the United States in 2018, the Food and Drug Administration approved inulin as a dietary fiber ingredient used to improve the nutritional value of manufactured food products. Using inulin to measure kidney function is the "gold standard" for comparison with other means of estimating glomerular filtration rate.
Hypercholesterolemia, also called high cholesterol, is the presence of high levels of cholesterol in the blood. It is a form of hyperlipidemia, hyperlipoproteinemia, and dyslipidemia.
Diverticulosis is the condition of having multiple pouches (diverticula) in the colon that are not inflamed. These are outpockets of the colonic mucosa and submucosa through weaknesses of muscle layers in the colon wall. Diverticula do not cause symptoms in most people. Diverticular disease occurs when diverticula become clinically inflamed, a condition known as diverticulitis.
Stanol esters is a heterogeneous group of chemical compounds known to reduce the level of low-density lipoprotein (LDL) cholesterol in blood when ingested, though to a much lesser degree than prescription drugs such as statins. The starting material is phytosterols from plants. These are first hydrogenated to give a plant stanol which is then esterified with a mixture of fatty acids also derived from plants. Plant stanol esters are found naturally occurring in small quantities in fruits, vegetables, nuts, seeds, cereals, legumes, and vegetable oils.
Glucomannan is a water-soluble polysaccharide that is considered a dietary fiber. It is a hemicellulose component in the cell walls of some plant species. Glucomannan is a food additive used as an emulsifier and thickener. It is a major source of mannan oligosaccharide (MOS) found in nature, the other being galactomannan, which is insoluble.
Abdominal bloating is a short-term disease that affects the gastrointestinal tract. Bloating is generally characterized by an excess buildup of gas, air or fluids in the stomach. A person may have feelings of tightness, pressure or fullness in the stomach; it may or may not be accompanied by a visibly distended abdomen. Bloating can affect anyone of any age range and is usually self-diagnosed, in most cases does not require serious medical attention or treatment. Although this term is usually used interchangeably with abdominal distension, these symptoms probably have different pathophysiological processes, which are not fully understood.
Resistant starch (RS) is starch, including its degradation products, that escapes from digestion in the small intestine of healthy individuals. Resistant starch occurs naturally in foods, but it can also be added as part of dried raw foods, or used as an additive in manufactured foods.
Cholesterol absorption inhibitors are a class of compounds that prevent the uptake of cholesterol from the small intestine into the circulatory system. Most of these molecules are monobactams but show no antibiotic activity. An example is ezetimibe Another example is Sch-48461. The "Sch" is for Schering-Plough, where these compounds were developed. Phytosterols are also cholesterol absorption inhibitors.
Beta-glucans, β-glucans comprise a group of β-D-glucose polysaccharides (glucans) naturally occurring in the cell walls of cereals, bacteria, and fungi, with significantly differing physicochemical properties dependent on source. Typically, β-glucans form a linear backbone with 1–3 β-glycosidic bonds but vary with respect to molecular mass, solubility, viscosity, branching structure, and gelation properties, causing diverse physiological effects in animals.
A low-fat diet is one that restricts fat, and often saturated fat and cholesterol as well. Low-fat diets are intended to reduce the occurrence of conditions such as heart disease and obesity. For weight loss, they perform similarly to a low-carbohydrate diet, since macronutrient composition does not determine weight loss success. Fat provides nine calories per gram while carbohydrates and protein each provide four calories per gram. The Institute of Medicine recommends limiting fat intake to 35% of total calories to control saturated fat intake.
Weight management refers to behaviors, techniques, and physiological processes that contribute to a person's ability to attain and maintain a healthy weight. Most weight management techniques encompass long-term lifestyle strategies that promote healthy eating and daily physical activity. Moreover, weight management involves developing meaningful ways to track weight over time and to identify the ideal body weights for different individuals.
Satiety value is the degree at which food gives a human the sense of food gratification, the exact contrast feeling of hunger. The concept of the Satiety Value and Satiety Index was developed by Australian researcher and doctor, Susanna Holt. Highest satiety value is expected when the food that remains in the stomach for a longer period produces greatest functional activity of the organ. Limiting the food intake after reaching the satiety value helps reduce obesity problems.
The Portfolio Diet is a therapeutic plant-based diet created by British researcher David J. Jenkins in 2003 to lower blood cholesterol. The diet emphasizes using a portfolio of foods or food components that have been found to associate with cholesterol lowering to enhance this effect. Soluble fiber, soy protein, plant sterols, and nuts are the four essential components of Portfolio diet. The diet is low in saturated fat, high in fibre. Researchers have suggested that the Portfolio diet may be a useful addition to statin therapy to help people achieve their lipid targets.
Oat β-glucans are water-soluble β-glucans derived from the endosperm of oat kernels known for their dietary contribution as components of soluble fiber. Due to their property to lower serum total cholesterol and low-density lipoprotein cholesterol, and potentially reduce the risk of cardiovascular diseases, oat β-glucans have been assigned a qualified health claim by the European Food Safety Authority and the US Food and Drug Administration.