Bran

Synonyms: Crusca; Farelo; Kleie; Salvado; Son

Read code: y01RE

Description. Bran consists of the fibrous outer layers of cereal grains. It contains celluloses, polysaccharides or hemicelluloses, protein, fat, minerals, and moisture and may contain part of the germ or embryo. Bran provides water-insoluble fibre and, depending on the source, may also provide water-soluble fibre (see also Dietary Role, below). It comprises about 12% of the weight of the grain and is a byproduct of flour milling. It is available in various grades.

Pharmacopoeias. US includes wheat bran.

The United States Pharmacopeia 31, 2008 (Wheat Bran). The outer fraction of the cereal grain (comprising the pericarp, seed coat (testa), nucellar tissue, and aleurone layer) derived from Triticum aestivum, Triticum compactum, Triticum durum, or other common einkorn and emmer wheat cultivars. It is obtained by milling and processing the whole wheat grain, and is available in a variety of particle sizes depending on the degree of milling. It contains not less than 36% of dietary fibre. It is a light tan powder having a characteristic aroma. Practically insoluble in cold water and in alcohol.

 

Adverse Effects

Large quantities of bran may temporarily increase flatulence and abdominal distension, and intestinal obstruction may occur rarely.

Colonic atony.

Colonic atony has been reported in patients who had increased their intake of dietary fibre to relieve constipation associated with systemic sclerosis.

Diarrhoea.

A report of diarrhoea induced by a dramatic increase in fibre intake. Reduction of dietary fibre led to a return to normal bowel habit in 2 to 3 days.

Intestinal obstruction.

Intestinal obstruction associated with excessive bran intake has been reported.

Precautions

Bran is contra-indicated in patients with intestinal obstruction or with undiagnosed abdominal symptoms. There is a particular risk of intestinal or oesophageal obstruction if bulk laxatives are swallowed dry they should be taken with sufficient fluid and should not be taken immediately before going to bed. Wheat bran should be avoided in gluten enteropathies and coeliac disease.

Interactions

Bran may reduce the absorption of some drugs when given together by mouth. Interference with iron, zinc, and calcium absorption has been reported calcium phosphate may be added to bran to neutralise fytic acid, which can contribute to such interference.

Uses and Administration

The main use of bran is as a bulk laxative and source of dietary fibre in the management of disorders of the gastrointestinal tract such as constipation, especially in diverticular disease it is also widely used in irritable bowel syndrome, although its value has been questioned. It should always be taken with plenty of fluid. Bran is used as the basis for some breakfast cereals.

Dietary role.

There is no precise definition for the complex mixture of substances known as dietary fibre. It has been defined as plant polysaccharides and lignin resistant to hydrolysis by the digestive enzymes of humans but this covers many substances other than cell-wall and related poly sac char ides. Non-starch polysaccharides are the major component of the plant cell wall and are used as an index of dietary fibre. They comprise water-soluble fibres such as pectins, gums, and mucilages and water-insoluble fibres such as cellulose.

Wheat, maize, and rice contain mainly insoluble non-starch polysaccharides whereas oats, barley, and rye have a significant proportion of soluble fibres. Because the USA originally included nondigestible animal carbohydrates in the definition of fibre, the Food and Nutrition Board in the USA proposed a new definition of fibre, whereby dietary fibre consists of nondigestible carbohydrates and lignin that are intrinsic and intact in plants, and functional fibre consists of isolated, nondigestible plant or animal carbohydrates that have beneficial physiological effects in humans. Total fibre is the sum of dietary and functional fibre.

In the UK, dietary reference values (DRV) have been published for non-starch polysaccharides. It has been proposed that adult diets should contain an average for the population of 18 g daily (individual range 12 to 24 g daily) non-starch polysaccharide from a variety of foods whose constituents contain it as a naturally integrated component. Children should receive proportionately less non-starch polysaccharide according to body size. No evidence exists for benefit of intakes of non-starch polysaccharide in excess of 32 g daily, and therefore there is no advantage in exceeding this amount.

In the USA, an adult dietary fibre intake of 20 to 35 g daily has been suggested children should consume an amount equivalent to their age plus 5 g daily.

Disease prevention.

Diseases such as colorectal cancer, is-chaemic heart disease, diabetes mellitus, and obesity are common in affluent developed countries but occur rarely in rural Africa. This difference in disease patterns has been linked to the low fibre intake in developed countries compared with rural Africans. However, there are many other differences in diet and lifestyle, such as a lower intake of fat, protein, and sugar in rural Africans and less exposure to toxins and pollutants, any of which could contribute to the difference. The excessive consumption of energy-rich foods may be more to blame for diseases of affluence than is deficiency of dietary fibre.

Results from large prospective cohort studies have been conflicting as to whether there is any reduction in risk of colorectal cancer associated with a high intake of dietary fibre, and have mostly failed to show a reduction in the recurrence rate of colorectal adenomas (although most adenomas do not develop into cancer, and so the relevance of these results is unclear). A pooled analysis of 13 prospective cohort studies found a significant inverse association between dietary fibre intake and colorectal cancer. However, after adjusting for other risk factors, this association was attenuated and no longer statistically significant.

There was some suggestion that intake of dietary fibre from cereals and from whole-grain foods were both associated with a weak reduction in the risk of rectal cancer. Some have commented that fibre is a broad term encompassing a wide range of organic material, which may have a large number of actions on digestive physiology. Furthermore, there is some concern that the use of fibre supplements is not entirely without harmful effects: it has been pointed out that fermentable fibre substrates can stimulate cell proliferation in the colon. However, the role of cell proliferation as a marker for the development of colonic cancer is questioned by some authors. A small randomised crossover study in patients with type 2 diabetes mellitus suggested that an increased intake of dietary fibre was associated with improved glycaemic control, decreased hyperinsulinaemia, and lower plasma lipid concentrations. In prospective cohort studies, inverse associations were found between whole-grain intake and the risk of type 2 diabetes mellitus in some studies, this inverse association persisted for cereal fibre intake, but in one the protective effect of whole grain could not entirely be explained by fibre content.

Fibre may act as an obstacle to energy intake by displacing available calories and nutrients from the diet, by increasing satiety, and by decreasing the absorption efficiency of the small intestine. Epidemiological studies support the hypothesis that a higher dietary fibre intake prevents obesity populations that report higher fibre consumption also demonstrate lower obesity rates. Weight gain was inversely associated with increases in the intake of whole grains but positively associated with increases in the intake of refined grains, emphasising the importance of distinguishing whole-grain from refined-grain products. A large prospective cohort study in men found an inverse association between whole-grain intake and the incidence of coronary heart disease the finding was even stronger for bran intake. These associations were attenuated, but not eliminated, by adjustment for other risk factors for coronary heart disease. There is some suggestion that diets high in fibre may have a moderate effect on blood pressure reduction.

Preparations

Proprietary Preparations

Brazil: Fibracap † Trifibra Mix

Canada: Novo-Fibre

France: Doses-O-Son

Ireland: Trifyba †

Italy: Crusken

Malaysia: Fibrosinef

Mexico: Fisiolaxf

Portugal: Infibran

Singapore: Fibrosine

Sweden: Fiberform Fiberform Mix

Switzerland: Fibion †

Multi-ingredient

Argentina: Centella Queen Reductora Gelax Gurfi Fibras † Salutaris

Australia: Neo-Trim Fibre † Prochol † Proslender †

Austria: Herbelax

France: Maxi-Flore Stimulance

Italy: Bio Fibralax Bi-Attivo Ecofibra Levoplus Plurilac Resource Benefiber Sedastip Stimulance

Mexico: Psilumax

New Zealand: Stimulance

Poland: Magnezytki Otrebuski

Portugal: Stimulance †

Venezuela: Senokot con Fibra †