Some days ago we talked about salt and sodium. We will now talk about another phytochemical component: dietary fibre.
Why did we decide to talk about fibre? Because recently the study findings showed that often the GF diet and gluten-free products are usually low in fibre and vitamin B, calcium, vitamin D, zinc and magnesium, too.
Let’s take a closer look at component!
First of all we will try to answer some frequently asked questions: what is fibre exactly? What are the best sources of it? And what are its health benefits? What is the recommendation of dietary fibre for people?
And then I will give you some healthly tips to increase the amount of fibre in your diet.
What is fibre? Most experts agree that a key defining characteristic of dietary fibre is that it’s derived from the edible parts of plants that are not broken down by human digestive enzymes. Infact it is broken down in the colon by anaerobic bacteria (the process is called fermentation).
The most recent fibre definition is a balance between nutrition knowledge and analytical method capabilities. Whereas the physiologically-based definitions are already widely accepted and are the result of several adjustments in response to advances in scientific research.
Historically, there has been a consensus since the late 1970s that “Dietary Fibre consists of the remnants of edible plant cells, polysaccharides, lignin and associated substances which are not broken down by human digestive enzymes. It has traditionally been considered to be plant sourced.”
Since 1980 the dietary fibre definition was broadened to include all undigestible polysaccharides in the human small intestine such as cellulose, hemicellulose, lignin, pectins, gum and mucilages and associated minor substances such as waxes, cutin and suberin.
Since 1990 the scope has been extended and now includes undigestable oligosaccharides and aminosaccharides. They are usually found in food. Moreover the scientific community argues that may also be included syntetic oligo-carbohydrates and resistant starch.
Furthermore the definition of dietary fibre should be based on chemical and physiological perspectives. The fermentability and solubility of these components are two attributes of fibre. They allow the fibre to be classified into fermentable and unfermentable; soluble and insoluble.
Finally in 2001 the American Association of Cereal Chemists (AACC) and l’American Academy of Sciences produced a report to update the definition and more clearly to delineate the makeup of dietary fiber and its physiological functionality.
What are the best sources of fibre? The most natural sources of fibre are vegetables, fresh fruit (including peel or skin), wholemeal cereals, pulses (peas, beans), grains, nuts, potatoes. Moreover there are whole-grain bread, pasta, pizza, crackers, rusks, biscuits, breakfast cereals.
Now food industries have developed new food products (fibre-enriched foods) not of vegetal origin, but animal origin such as cheese, yogurt and meat. All of them carry healthy sounding food labels indicating that they contain fibre: “with fibre” or “high level fibre”
What does this mean exactly?
In Europe the directive 2008/100/CE of the European Commission, has anended the Directive 90/496/CEE. It clarifies the issue and helps us to understand the claims. The law about the nutritional information of these products reiterates the updated definition of dietary fibre……
“The charboidrates polymers of vegetal origin which correspond to the definition of dietary fibre can be strictly associated with lignin or other non charboidrate components such as phenolic components, wax, saponins, phytate, cutin and phytosterol. These substances, if strictly associated with charboidrates polymers of vegetal origin and extracted with charboidrates polymers for the analyses of dietary fibre can be considered dietary fibre too. If however they are separated from charboidrates polymers and added to food, these substances cannot be considered dietary fibre.”
When shopping, look for the terms “good source of” and “high in” and use them to identify foods that have significant amounts of dietary fibre.
In Europe you can find the health claim “good source of fibre” if the products have at least 3g/100g or 1.5g/100 kcal.
Whereas you can find the health claim “high levels of fibre” or similar, if the products have at least 6g/100g or 3g/100kcal.
The same directive emphasizes the healthy benefits of fibre…..
Traditionally fibre is considered an important nutritional and healthy component of the diet for people of all ages. Research over the past several decades has shown that increased consumption of dietary fibre produces a positive effect on levels of serum cholesterol, particularly LDL-cholesterol a biomarker related to the risk of coronary heart disease (CHD). Scientific consensus on the evidence for the role of dietary fibre in reducing the risk of CHD has long been acknowledged. Moreover an increased consumption of dietary fibre and high fibre products also produce a measurable reduction in the peak level of serum glucose after eating. Fibre also helps to regulate blood sugar (is why it plays a very important role in the diet of diabetics).
Since the fibre passes through the digestive tract it is helpful in preventing constipation. A diet rich in fibre improves body function and reduces your risk of gastrointestinal problems, like Irritable Bowel Syndrome (IBS), colon-rectal cancer and other intestinal inflammation. The effect results in an increase in faecal bulk, reduces transit time of faecal material through the intestine and improved the regularity of defecation.
Dietary fibre also plays an important role in the prevention of certain types cancer (oral cavity and pharynx, larynx, lung, esophagus, stomach and colon-rectum).
It has demonstrated that the same results are obtained from undigestible polymers and/or synthetic dietary fiber analogues, which are not naturally in food that we eat daily.
for those who like counting the calories, we must dispel the following myth: fibre does not contribute any calories! This is false ……
It’s very difficult to determine the calories for fibre because we must consider: the uncertainty of analytical methodology, the amount of fibre fermented by bacteria in the large intestine and the individual capacity of its absorption in the small intestine. At least we must consider the negative effect of dietary fibre i.e the reduction of absorption of some nutrients such as vitamins and its capacity to bind to certain minerals such as calcium, iron…..
The energetic value of dietary fiber is 8 kJ/g or 4 kcal/g.
Increasing the amount you eat each day isn’t difficult.
– increase your consumption of fresh fruit and vegetables (5-6 portions/day)
– increase your consumption of peas, beans and other pulses (1-2 /week)
– chose gluten-free wholemeal cereal-based products.
So it isn’t necessary buy commercial products enriched in fibre.These types of fibre are derived from industrial chemical processes which are patented by companies.
Lastly if this is true for the celiac consumers (it’s the same for all people) we must also say something to the gluten-free food manufactures.
It would be very useful to correctly indicate the amounts of fibre in the nutritional information on food labels. This information helps us to choose the product with the highest fibre levels and such awareness will enable us to make the right purchase.