Fibre, Flatulence and Weight Loss Diet

“Eat your porridge – it is good for you”

“Eat your fruits and vegetables – they are good for you.”

This is a common mantra given to people who want to eat a well balanced healthy diet. But, how often do we ask, “What does this really mean? Is there any science behind it or is it all hot air at the end of the tunnel?” You know what I mean.

Dietary fibre is found in plants. Fibre is composed of cellulose (a complex carbohydrate that is composed of glucose units, forms the main constituent of the cell wall in most plants), lignin (chief non-carbohydrate constituent of wood), pentosans (group of polysaccharides found with cellulose in many woody plants), pectin (water-soluble carbohydrate found in ripe fruits) and gums (viscid exudation from plants).

Fibre is divided into soluble and insoluble fibre.

Soluble fibre dissolves in water to form a gel-like substance. It is readily fermented by bacteria in the colon into gases and physiologically active byproducts. Sources of soluble fibre are oats, legumes (beans, peas, and soybeans), apples, bananas, berries, barley, some vegetables, and psyllium. More fibre you eat, more gas you produce. There is not much you can do about it except look over your shoulder and let it out.

Soluble fibre has now been shown to lower LDL (bad cholesterol) levels through a series of processes that alter cholesterol and glucose metabolism – reduces the absorption of sugar, reduces sugar response after eating, normalizes blood lipid levels and, once fermented in the colon, produces byproducts with wide-ranging physiological activities.

Insoluble fibre increases the movement of material through the digestive tract and increases stool bulk by absorbing water and easing defaecation, reduces transit time, thus preventing constipation which decreases the opportunity for both nutrients and fecal mutagens to interact with the intestinal lining. There is no fermentation by bacteria. Sources of insoluble fibre are whole wheat foods, bran, nuts, seeds and the skin of some fruits and vegetables.

Constipation leads to hemorrhoids and anal fissures. Although insoluble fibre is associated with reduced diabetes risk, the mechanism by which this occurs is unknown. Although many researchers believe that dietary fibre intake reduces risk of colon cancer, one study conducted by researchers at the Harvard School of Medicine of over 88,000 women did not show a statistically significant relationship between higher fibre consumption and lower rates of colorectal cancer or adenomas.

The five most fibre-rich plant foods, according to the Micronutrient Center of the Linus Pauling Institute, are legumes (15–19 grams of fibre per US cup serving, including several types of beans, lentils, and peas), bran (17 grams per cup), prunes (12 grams), Asian pear (10 grams each, 3.6% by weight), and quinoa (9 grams).

On average, North Americans consume less than 50 per cent of the dietary fibre levels required for good health. Current recommendations from the United States National Academy of Sciences, Institute of Medicine, suggest that adults should consume 20–35 grams of dietary fibre per day.

Although fibre falls under the category of carbohydrates, it is low in calories. Regardless of the type of fibre, the body absorbs fewer than 4 Calories (16.7 kilojoules) per gram of fibre. In some countries, fibre is not listed on nutrition labels, and is considered 0 Calories/gram when the food’s total Calories are computed.

For weight loss, a diet rich in fibre from cereals, not from fruit and vegetables, is more likely to help limit weight gain, says Dr. Khursheed Jeejeebhoy, a well known gastroenterologist in Toronto, writing in the Medical Post (March 9, 2010). High-fibre breakfast reduces subsequent intake of energy, delays digestion and slows absorption. A Dutch study found that an intake of 10 g of total fibre per day was associated with a loss of 39 g of body weight per year and a reduction in waist circumference of 0.08 cm per year.

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Flatulence and Bloating

Dear Dr. B: I suffer from bloating and flatulence. Why do I have so much flatulence? How can I get rid of it?

Answer: Dictionary defines flatulence as the presence of excessive gas in the digestive tract. Sometime ago I had written a column on this subject. Next day, a friend sent me the following:

A question past through the ages
And pondered by many, including the sages
Is it better to hold the fart and feel the pain?
Or let the fart and feel the shame!

To fart or not to fart is a dilemma faced by everybody on a daily basis. A survey shows that 97 per cent of Canadians suffer from intestinal gas, and about 15 per cent say they have cancelled a date or a meeting because of it.

Releasing intestinal gas is a normal and important physiological function. From birth to death, the production of intestinal gas continues unhindered.

Fart is the word easily understood by all. Quite often though, we are afraid to use the word in public, fearing the mere mention of the word “fart” would make people smell something foul! Sorry, Dr. Pavlov!

Those who have had children will never forget the countless times we have had to wait for the baby to burp or pass flatus before he or she (I mean the baby) would finish the bottle. The release of gas had dual effect – some relief for the infant and great relief for the parent.

It does not matter whether you are a king or a queen, a prince or a princess, rich or poor – we all have to release intestinal gas. Unfortunately, and quite often, the desire to release gas is not always at a socially convenient place.

For example, if the Queen has to pass gas then what does she do? What about our politicians? They blow lot of gas verbally. What do they do when they have to release intestinal gas during the Question Period in the Parliament?

President Lyndon B. Johnson (1908-1973), a Democrat, said of his Republican rival Gerald Ford, “So dumb he can’t fart and chew gum at the same time.” Of course, Gerald Ford went on to become President of the United States.

What about the astronauts? Have you ever wondered why they go out for a space walk?

What about Saddam Hussein’s dilemma in that six by eight feet “spider hole”? For eight months he was hiding in that tiny place with little ventilation and a small fan. Once a very powerful man now stuck in a hole smelling his own body odor and release of intestinal gas. Did he have any gas masks with him?

A textbook of Gastroenterology says that gas and bloating embrace three unrelated phenomena. Farting is a physiologic phenomenon due to the production of gas by colonic bacteria. Excessive belching or burping is associated with aerophagia (air swallowing). And the mechanism of bloating is obscure.

Usually, intestinal gas consists of odorless gas – carbon dioxide and hydrogen – produced by bacterial action on carbohydrates and the proteins in the food we eat. There is methane and swallowed nitrogen as well. These four gases make up 99 percent of colonic gas.

The remaining component consists of trace gases that compensate for their small quantities by their strong odors. Smelly gases include hydrogen sulfide, ammonia, indole and volatile fatty acids.

The textbook says that an average person on normal diet emits about one liter of gas per day. On an average we pass gas 13.6 times per day – although there is great variation from person to person, from time to time, what you eat, and how much air you swallow.

You can reduce gas by eliminating certain foods (peas, beans, cauliflower, certain grain products, carbohydrates etc.) in your diet. Patients with irritable bowel syndrome and lactose intolerance may have excess gas.

There is only one way to get rid of gas – look over your shoulder and let it go!

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Abdominal Gas (Flatulence)

“Doc, your column on constipation was interesting. What about bloating and flatulence? Don’t you think it is a major problem for many individuals!”

Dave, you are absolutely right. Call it what you want – flatulence, burp, belch, gaseous distention, wind, flatus, fart – excess intestinal gas can be a nuisance.

There is a social taboo associated with this topic. Unlike Eddie Murphy’s family dinner explosions in The Nutty Professor, most of us find a socially convenient place to “cut the cheese”.

From birth to death, the production of gastrointestinal gas continues unhindered. We are all familiar with our child’s difficulty with gas and colic. What about that burp? I bet that gave more sense of relief to the parent than the child.

There are 3 phenomenon of gas production: 1) Flatus is mainly due to production of gas by colonic (large intestine) bacteria, 2) Belching or burping is due to swallowed air, and 3) Bloating – the mechanism of which is not very clear.

A normal diet emits about one liter of gas in the intestine. Some gas is absorbed by the body. The rest, about 50 to 500 ml, is passed as flatus in small quantities several times a day. At night, minimal gas is produced, but we continue to release wind in our sleep. So, first thing in the morning, our abdomen is as flat as can be.

It is normal to pass flatus. Usually, it consists of odorless gas – carbon dioxide and hydrogen – produced by bacterial action on carbohydrates and the proteins in the food we eat.

Hydrogen, carbon dioxide, methane and swallowed nitrogen comprise 90 percent of colon gas. The remaining one percent consists of trace gases that compensate for their small quantities by their strong odors. Smelly gases include hydrogen sulfide, ammonia, indole and volatile fatty acids.

Belching and burping occurs from the air ingested with breathing and swallowing. Anxiety, thumb sucking, gum chewing, drinking carbonated drinks, rapid eating and wearing poor dentures increase the amount of gas swallowed. Stomach gas has the same composition as the atmosphere.

Bloating occurs in 30 percent of adults. Individuals complaining of bloating and distention are convinced that they have excess gas. But this is not true.

In the morning the abdomen is nice and flat. As the day progresses, the abdominal girth increases by 3 to 4 cm. Plain x-rays and CT scan of the abdomen fail to show that this is due to gas. Passing flatus may temporarily relieve the symptom but the
phenomenon is not due to gas. By next morning the distention is gone.

“What influences the production of excess gas?” Dave asks.

Beans, broccoli, and cabbage have a high content of nondigestible polysaccharides. Other foods are cauliflower, corn, brussels sprouts, eggplant, nuts, onions, and prunes.

Most of the intestinal gas consists of swallowed air. Only about 10-30 percent of gas is produced in the intestine.

Furne and Levitt did a study looking at factors influencing frequency of flatus emission by healthy subjects. They concluded that some subjects consistently passed gas more often than did others. The individual differences depend on the ability of the bacteria to produce gas from the fermentable food residue.

Therefore, the management of “too much gas” should be directed toward reducing swallowed air and avoiding gas producing food. This is not always easy. But worth trying.

Finally, Dave, here is what Sir John Suckling (1609-1642) said about love and flatulence:
Love is the fart
Of every heart:
It pains a man when ‘tis kept close,
And others doth offend, when ‘tis let loose.

This series of articles explore the health problems of Dave and his family. They are composite characters of a typical family with health problems.

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