Fiber-Rich Oranges For Digestion

Introduction

Many studies have demonstrated the numerous benefits of dietary fibres across both human and animal species. Soluble fibres have been found to improve intestinal transit time, delay gastric emptying and absorption of glucose and increase pancreatic secretions. Insoluble fibres have been found to aid the faecal bulking and water-holding capacity, reducing the transit times in the intestine.

These in turn have been known for their many beneficial effects ranging from reducing blood cholesterol to improving glycaemic control. They are also known to prevent intestinal diseases, especially cancer.¹ Individuals who consume a fibre-rich diet tend to have minimal risk of coronary heart diseases, some cancers, as well as obesity.

They have also been proven to prevent constipation and provide a high degree of satiety. Due to its bulking capacity, Fiber is capable of reducing the energy density of foods. Some fibre-containing foods also provide additional benefits by providing micronutrients, some proteins and even some essential fatty acids.² 

Dietary fibers

In the United Kingdom,  the recommended dietary fibre required daily is stated to be 18 g.³ The recommended fibre intake varies across the regions of the world and it is safe to say the UK recommendation is among the lowest in the world because other region values range between 25-35 g per day. The dietary fibre is obtained from foods like fruits, vegetables, and grains and their fibre contents vary based on the content of each as well as the extent of milling and processing.² 

Some carbohydrates that get to the large intestine of humans are resistant starch, non-digestible oligosaccharides and modified starch. The Fiber is usually completely or partly fermented and used as a source of energy by the microflora of the colon and the carbohydrate is converted into gases such as methane, hydrogen and carbon dioxide. The carbohydrate substrate made available in the colon leads to a rise in the bacteria population.

The human body plays host to a diverse community of health-impacting bacteria and this varies with individuals and dietary carbohydrates. In the Gastrointestinal tract alone, there are 10¹⁴ times more bacterial cells than the human cells, the colon contains the most dense populations.

These bacteria cells are mostly obligate anaerobes and they mostly rely on undigested components of human diets (loosely referred to as dietary fibre- although this definition is still quite controversial. More recently, a more accepted term proposed is resistant carbohydrate) for energy and growth such as Non-starch polysaccharides (NSP), resistant starch, and oligosaccharides (including pre-biotics).

The resistant carbohydrates which are not digested in the upper gastrointestinal tract are thereafter fermented to short-chain fatty acids (SCFA) by colonic bacteria. The increase in microbial biomass and the absorption of fluid by some fibre components therefore increases the faecal mass. SCFAs such as Butyrate, Acetate, and Propionate are produced from fibre fermentation and this is essential in the health of colon cells.

These also confer some degree of protection against colon cancer and cardiovascular diseases. SCFA also reduces the pH in the colon and thereby prevents the formation of toxic by-products as well as the growth of pathogenic organisms. Additionally, studies suggest that they trigger some beneficial effects on the metabolism of lipids, and lower the secretion of insulin because they reduce the rate of absorption after a meal.^2,4 

There is a recent rise in the development of food products containing dietary fibres in the food industry globally. As the world evolves into an industrialized, fast-paced one, the need for a healthy digestive system for a good quality of life. It is worthy of note that most fractions of dietary fibre is the main component of the cell walls of plants.

Such include cellulose, hemicellulose, lignin, pectins, mucilages and gums. Some rich sources of fibre are tropical fruits, vegetables, nuts, cereal grains, seeds, and legumes. Citrus is one of these sources with between 25-70 % fiber.

Orange contains 50 % juice, and the other 50 % is made up of seeds, sacs, rind, and albedo with different ranges of fibre components. These components and by-products are sometimes further dried for preservation and may be utilized exclusively for their fibre benefits. The residue from the orange juice industry provides a high concentration of fibre. Fibre from oranges can absorb and bind to larger quantities of water- as much as twelve times its weight.⁵ 

The are many species of citrus and many other hybrids all over the world. Citrus has been ranked to be one of the topmost and most important fruit crops in the world with more than 108 million tonnes. One of the most widespread genera and most popular cash crops is Citrus. Citrus is generally grouped into sweet oranges, mandarins (Satsuma, tangerines), clementines, limes, lemons, grapefruits, and sour or bitter oranges among many others.

These are well known for their huge mutagenic and antioxidant benefits stemming from their fibre, phytochemicals, vitamins, mineral compositions. Orange, a member of the citrus family, is a major source of health-beneficial vitamins including vitamin C, niacin, calcium, folacin, potassium, thiamine, and magnesium. Although they seem to have originated from Southeast Asia, Brazil and the United States of America are two of the biggest producers of oranges.

However, it is cultivated all over the world for human consumption and it is popular for its nutritional value and other uses. The increased consumption of fruits and vegetables provides essential phytochemicals which have been found to enhance human health and even provide beneficial antioxidants, thereby improving immunity and preventing many degenerative diseases. Sweet Oranges are low in calories and lack cholesterol or saturated fats.

However, they have high fibre-pectin content which is beneficial for individuals with obesity due to the bulk laxative effect of pectin. Pectin protects the mucous membrane from carcinogenic substances and other toxic substances in the colon. Pectin also lowers cholesterol levels and it does this by reducing colon re-absorption by binding it to bile acids present in the colon.

Carbohydrates and lignin obtained from plants and remain undigested or absorbed from the small intestine make up dietary fibre.^6-7 The pectin in citrus fibre contains galacturonic acid and it is responsible for the fibre’s gel-forming capability which is further increased by the heat stability of citrus fibre. The insoluble components and cellulose aid the viscosity.

These characteristics are favourable for its water-absorbing ability which not only occurs at the surface but deep in the fibre structure, thereby causing it to swell in the presence of water and form a gel-like material after hydration. This has been considered for use in processed meat and poultry industries as a natural and healthier alternative to phosphates which are used to increase yield, fat-binding ability, and water-holding capacity.⁸ 

Hindrances to orange consumption

An average adult in the United States consumes approximately 57 % of the required daily needed fibre. Thereby, missing out on the many astounding health benefits of fibre. In some areas in the US, the production and ingestion of citrus fruits are on a decline as well as in many European countries. This has been attributed to lower production due to diseases of the plants, increased competition from other fruits, price and accessibility factors, inadequate knowledge of its numerous benefits for human health and potential use as an additive in industrial manufacturing.

More research needs to be funded and executed to explore and maximize available opportunities. Increased domestic production should be encouraged and subsidized by governments as well as investments in transportation, and promotion of marketing, thereby improving accessibility which will in turn positively affect the price and affordability.⁶ 

Summary

Fibre is an essential component of the human diet. It is made up of indigestible carbohydrates that are undigested and remain unabsorbed from the intestine. They have the ability to increase satiety, improve glycemic control, control blood-lipid concentration as well as provide some antioxidant and anti-cancer benefits.

They have also been shown to reduce the risk of coronary heart disease and obesity. The UK has one of the world’s minimum stated daily dietary requirements for fibre- 18 g per day. Some other countries have as high as 35 g per day set to obtain the maximum benefits of fibre.

Fibre is able to retain water many times its size and improve faecal mass and digestive functioning and also improve the healthy microflora in the intestine thereby protecting humans against pathogenic organisms. Orange is one of the most popularly traded fruits in the world and it is a fibre-rich fruit containing pectin which has been shown to provide all the benefits of fibre in the diet when consumed. The benefits of orange consumption have been found to improve the overall quality of human digestive health when consumed in sufficient quantities as a consistent part of the human diet. 

Conclusion

Oranges contain a high composition of dietary fibre that is beneficial for digestion and overall improved quality of life of humans.