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Chapter 1. Fiber Carnage

“Many patients starting [out on] fiber complain of flatulence, distention, bloating, poor taste, and are unwilling to continue.”
Rome II: The Functional Gastrointestinal Disorders; Ch. 7, Constipation [1]

Fiber‘s Role in Disease:
A Lifelong Demolition Derby

If you consume minor quantities of fiber from natural, unprocessed food, there isn‘t anything wrong with it, because (a) small amounts of natural fiber (which is mostly soluble) will not obstruct your intestines or cause diarrhea, (b) most of it will get fermented in the large intestine, and (c) the remainder will not bulk up the volume of stool high enough to cause any damage from “roughage.” But that‘s not what most Americans do or are urged to do:

 Average recommended fiber intake  (grams per day)[2]

Age Children Boys Girls Men Women Pregnant
1-3 19 g          
4-8 25 g          
9-13   31 g 26 g      
14-18   38 g 26 g      
19-30       38 g 25 g 28 g
31-50       38 g 25 g 28 g
51-70       30 g 21 g  
Over 70       21 g 21 g  

These are the standing recommendations from the Food and Nutrition Board, a division of the Institute of Medicine of the National Academies, which is the body that establishes the nutritional policy guidelines of the U.S. Government. Let‘s analyze these recommendations:

As the dynamics of a “broken telephone” transform already bad advice, it gets worse, much worse. Here are the “enhanced” recommendations from what is considered one of the best medical and research institutions in the nation, The Mayo Clinic. The article is entitled “Fiber—A Good Carb”:

Fiber—A Good Carb

The June issue of Mayo Clinic Women's HealthSource suggests ways to increase fiber in your diet:

— Eat a high-fiber cereal or add a few spoonfuls of unprocessed wheat bran to your cereal.

— Add bran cereal or unprocessed bran when making foods such as meatloaf, breads, muffins, cakes, and cookies.

— Choose whole-grain bread instead of white bread. Look for breads made with 100 percent whole-wheat flour.

— Substitute whole-wheat flour for half or all of the white flour when baking.

— Experiment with whole grains and whole-grain products such as brown rice, barley, whole-wheat pasta, and bulgur.

— Try adding canned kidney beans, garbanzos and other beans to canned soups or salads.

— Eat snacks that are high in fiber, such as fresh and dried fruits, raw vegetables, low-fat popcorn, and whole-grain crackers.

— Add barley to soups and stews.

— Eat generous quantities of vegetables and fruits.[4]

Mayo Clinic Women‘s HealthSource

If you follow this advice, just one cup (60 g/2 oz) of Kellogg‘s® All-Bran® With Extra Fiber[5] cereal gives you 30 g of fiber, already the daily amount recommended for adults, and many more times for children. And that‘s just for breakfast, before adding in the recommended breads, salads, soups, stews, and “generous quantities of vegetables and fruits” throughout the rest of the day.

Think about it—just one cup of fiber-fortified cereal contains three times more fiber than the maximum recommended daily dose for fiber laxatives, such as Metamucil® (3.0 g up to three times daily[6]). Even that little, just under 12 g of fiber in Metamucil, may cause severe side effects:

Metamucil Side Effects

To all intents and purposes, the indigestible fiber in cereals isn‘t any different from the fiber in Metamucil‘s psyllium—fiber is fiber regardless of the source. People who aren‘t accustomed to a high-fiber diet may have identical side effects whether it is Metamucil or high-fiber cereals.

Shocked? Puzzled? Surprised? Bewildered? Here is a brief Q&A which explains why the side effects of various kinds of fiber consumption are identical:

Q. Why does fiber cause bloating?

Because (a) fiber fermentation inside the intestines produces gases, and (b) because the acidity from fermentation causes intestinal inflammation. Since the absorption of gases is the primary function of the intestine, the combined impact of (a) and (b) blocks their absorption, and causes the intestines to expand just like an air balloon.

Q. Why does fiber cause gas?

The intestines are colonized with symbiotic bacteria (normal intestinal flora), which are essential for many health-sustaining functions. Normally, mucin—a component of mucus—provides bacteria with the nutrients they need. But when fiber—soluble as well as insoluble—reaches the lower intestine, the bacteria go wild, ferment everything in sight, and multiply prodigiously. The fermentation is accompanied by lots of gases, just as with yeast-rising dough or aging champagne. If you don‘t experience gas after ingesting fiber, it means that your intestines lack normal bacteria, and you are affected by dysbacteriosis, a serious pathology which is explained in Chapter 4, Dysbacteriosis.

Q. Why does fiber cause “stomach cramps”?

Actually, not stomach cramps, but abdominal cramps. The cramping is a pain sensation in the abdominal region that results from gases, inflammation, acidity, intestinal obstruction, and large stools, or that stems from regular contractions of affected sections of the small and large intestines.

Q. Why does fiber cause nausea  and vomiting?

Once inside the stomach, fiber lumps together and may cause mechanical stimulation of the receptors that activate the vomiting center in the brain. The lumped fiber may also temporarily obstruct the path between the stomach and duodenum, and cause vomiting related to the stomach‘s overload or delayed emptying. If you have gastritis (inflammatory stomach disease) or ulcers, the likelihood of fiber-related nausea and vomiting is even higher because of the fiber‘s contact with extra-sensitive impaired tissues.

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Q. Why does fiber cause “rectal bleeding?

Doctors, nutritionists, and dietitians refer to fiber as “bulk” or “roughage,” because it makes stools rough and bulky. When large stools pass through the narrow anal canal, they may lacerate its delicate lining, and cause bleeding. Large stools and the straining needed to expel them are also behind hemorrhoidal disease and anal fissures—lacerations inside the anal canal that won‘t heal. Far more dangerous bleeding may result from ulcerative colitis, caused by the prolonged contact of undigested fiber and large stools with the colorectal mucosal membrane. Ulcerative colitis raises the risk of colorectal cancer by 3,200%. The mechanical and chemical properties of fiber and large stools are also the most likely causes of precancerous polyps.

Q. Why does fiber cause “unrelieved constipation”?

For the same reason it causes anorectal bleeding. When stools become large from excess fiber, many people, particularly children, seniors, and those affected by hemorrhoidal disease or anal fissures, simply can‘t pass them. If this condition isn‘t quickly resolved, it may lead to fecal impaction. The continuous accumulation of impacted stools may cause diverticular disease (the bulging of the colorectal wall), megacolon (permanent stretching of the colorectal walls), and colorectal perforation (the spilling of intestinal content into the abdominal cavity), which is usually lethal.

Q. Why are there no fiber warnings printed on the boxes of fiber-fortified cereals?

Cigarettes didn‘t have any warnings either for a long, long time. It takes a while to change a belief system.

Q. I am young, fit, and healthy, and I consume lots of fiber. And it causes me no harm. Why?

Fiber is very much like a bomb with a time-delay fuse. For a while, it will not visibly affect you, because young people are still active enough to burn off all excess carbs, their intestines are still supple enough to process fiber, and young anorectal organs are still strong enough to handle large stools. Alas, if you keep consuming lots of fiber, your youthful bliss may soon be over. Just ask your parents and grandparents.

Avoiding dietary fiber in food isn‘t an easy task. It is often hidden behind obscure names such as cellulose, β-glucans, pectin, guar gum, cellulose gum, carrageen, agar-agar, hemicellulose, inulin, lignin, oligofructose, fructooligosaccharides, polydextrose, polylos, psyllium, resistant dextrin, resistant starch, and others.

These ingredients are factory-made from wood pulp, cotton, seaweed, husks, skins, seeds, tubers, and selected high-yield plants that aren‘t suitable for human consumption without extra processing. They are widely used to add texture and volume to ersatz food. For example, guar gum or cellulose gum are added to water and dry milk in order to fake yogurt or sour cream consistency, carrageen gives texture to cheap ice cream, and pectin thickens fruit preserves.

The only reliable way of avoiding hidden sources of fiber is this: read the labels! if you didn‘t learn the name of the ingredient on the product‘s label by the first grade, it doesn‘t belong on your plate or inside your gut.

So let‘s stroll along the mouth-to-anus pathway and check out the damage from this fiber orgy.

Reader's testimonial

Since I am a bit of a chatterbox, it has to be really something to render me speechless and that is because there are no words to convey my deep thanks and amazement about how the low/no fiber diet has impacted my very life..

The diarrhea is a thing of the past. How can this be with something so simple to do? Me, who was afraid to leave my house in fear of an "attack."

I have told everyone I know to read your book. As soon as I started reading I just knew you were right. My MD looked at me as if I had lost my mind, but I will be seeing her again in a month and I will encourage her to tell her IBS/UC patients to go low fiber. A.C. (via e-mail)

Fiber‘s effect on the oral cavity: As sticky as glue

The human mouth is primarily intended to cut and chop flesh, not grind indigestible fibers. Unlike humans, cows have so-called hypsodont teeth, which extend very far above the gum line and grow continuously to accommodate a lifetime of wear-and-tear from grinding fibrous grasses.

We aren‘t as lucky—our teeth are brachydont, and aren‘t intended for chewing fiber, otherwise, after a decade or so, you simply wouldn‘t have any teeth left to argue this point with clarity.[8] That‘s why the fiber for human consumption is crushed, milled, or ground first, and requires little or no chewing. But even after processing, it affects the oral cavity with a menacing vengeance:

  • Obstruction of the salivary glands. Fiber, especially in dry-roasted cereals, has a tendency to obstruct the salivary glands. When that happens, the tongue senses a polyp-like protrusion. Though unpleasant, this benign problem may, in some instances, cause acute inflammation and require treatment with antibiotics.
  • Dental caries (cavities). Powdered (well-milled) fiber of any kind has a natural tendency to lodge itself inside the abrasions both on the chewing surfaces and between the teeth. Once there, it provides perfect feed for normal oral flora. The bacterial fermentation in the mouth produces lactic acids that bind with the minerals that form the enamel mineral matrix. In turn, the weakening of the matrix causes dental caries. That‘s why all kinds of fiber-rich products, especially cereals, are exceptionally destructive for dental health. Not surprisingly, tooth decay is the second most common disease in the United States. The common cold is the first. Weak immunity related to dysbacteriosis happens to be one of the leading causes of most colds as well.
  • Periodontal disease (gingivitis, necrotizing ulcerative gingivitis, periodontitis). Pulverized fiber lodges easily inside the gingival sulcus, a pocket that exists between the teeth and the gums (gingiva). The bacterial fermentation inside the sulcus causes inflammation of gingiva, the periodontal ligament, and alveolar bone, and eventual tooth loss. Gingivitis—the initial stage of periodontal disease—is easily recognized by bleeding gums. A receding gum line, even without bleeding, indicates the progression of periodontal disease.

Fiber‘s effect on the esophagus: If not plugged, then burned

The esophagus is the narrow muscular tube that transports chewed food and water from the mouth to the stomach. A chewed mass is called a bolus. The bolus travels the entire length of the esophagus in just a few seconds. This unassuming organ is quite vulnerable to the vagaries of indigestible fiber. The impact is indirect, through the digestive disorders of the stomach, such as heartburn, but the suffering is real—millions of people suffer from dysphagia, the difficulty or inability to swallow food. The other prominent fiber-related complications are:

  • Esophageal obstruction. Supplemental fiber may rapidly expand and cause an obstruction when not accompanied by a lot of liquid. It isn‘t likely to happen in healthy adults, but is probable in small children, people with a narrowed esophagus or affected by dysphagia (difficulty swallowing), as well as the mentally disabled, old, and infirm.
  • Heartburn is the most common symptom of gastroesophageal reflux disease (GERD)—a spilling over (reflux) of the stomach‘s content back into the esophagus. The burning sensation emanates from the esophageal mucosa, unprotected from digestive juices and enzymes.
  • Barrett‘s esophagus (change of mucosa, precursor to cancer), dysphagia (difficulty swallowing), ulceration, bleeding, and esophageal cancer. Indirectly through the GERD, indigestible fiber is a primary causative factor behind these conditions.

Fiber‘s effect on the stomach: The luck stops here

The digestion of protein is the exclusive provenance of the stomach. When gastric digestion commences, the contents of the stomach are churned[9] inside, until it‘s completed (i.e. solid particles of food larger than 2 millimeters, or 0.08,” are no longer detected).

Fiber‘s specific properties—water absorbency, expansion, stickiness (congregation)—interfere with digestion and may cause an array of gastric disorders. Fiber-related problems become more pronounced with age because of the inevitable wear-and-tear on the internal organs. Insoluble fiber affects the stomach particularly hard because it tends to congregate and form lumps, and its rapid expansion fills the stomach with idle bulk.

You don‘t even need to consume that much fiber to feel its punch. For example, TV commercials for antacids are commonly shot inside Mexican restaurants because beans—a main staple of Mexican cuisine—commonly cause heartburn, even though a 100 g (0.22 lb) serving of beans contains a paltry 4 to 5 g of fiber. Just imagine the cumulative impact on the aging stomach of 30 to 40 grams of fiber consumed daily. Here are the most prominent problems:

  • Nausea and vomiting. The congregated lumps of fiber may cause mechanical stimulation of the receptors that activate the vomiting center in the brain. That much, as you recall, is stated in the side effect section of common fiber supplements.
  • Obstruction (Gastric outlet obstruction, Duodenal obstruction). The lumps of expanded fiber, primarily from supplements, may temporarily obstruct the path between the stomach and duodenum. If there are no other pathologies, the situation resolves itself with nausea and vomiting.
  • Gastroparesis (delayed stomach emptying). The stomach‘s peristalsis and digestion are completed when specialized receptors no longer detect undigested components over 2 mm. The undigested lumps of fiber may considerably extend the duration of the gastric phase of digestion because the stomach can‘t distinguish between an undigested chunk of meat and a lump of fiber. This problem is particularly acute among older individuals, who may have weak peristaltic contractions of the stomach. The digestion can extend from the customary 4–6 hours to 10, 12, and beyond. The extended exposure of the stomach lining to digestive juices and enzymes, particularly while laying down, may cause inflammation and ulceration of the esophagus and upper stomach regions (cardia and fundus), that aren‘t as well-protected as its lower regions (antrum and pylorus). [The original meaning of gastroparesis is the paralysis (paresis) of the stomach‘s peristalsis related to nerve damage from trauma, diabetes, surgery, medication, and other causes. Today this term is broadly used as delayed stomach emptying irrespective of nerve damage – ed.]
  • Gastroesophageal Reflux Disease (GERD). Simply speaking, GERD results from two primary factors: overloading the stomach with food and liquids, and delayed digestion (indigestion). Because indigestible fiber expands four to five times its size, it is the largest contributor to the stomach‘s overload. Absence of indigestion, heartburn, and reflux is one of the most immediate and pronounced benefits of low- or fiber-free diets.
  • Dyspepsia. A general term that describes non-specific pain and discomfort that emanates from the stomach (upper middle abdominal region). The sensation of pain may result from conditions described above and below. The pain may become more pronounced after a meal. Meals heavy in all kinds of fiber cause more pain because of the volume and the extended duration of digestion. Some medical writers refer to dyspepsia as “indigestion.” Well, guess what substance doesn‘t digest in the stomach?
  • Gastritis. All of the above conditions, related to fiber interfering with or extending gastric digestion, are the primary causes of gastritis—an inflammation of the stomach‘s mucosa, caused by the inability of the stomach‘s lining to withstand its own aggressive environment. The risk of gastritis goes up exponentially if you‘re under a great deal of stress (it inhibits digestion); consume alcohol (in small amounts it stimulates digestion, but inhibits in large); drink coffee, chew gum, or smoke (all three stimulate digestion); regularly take aspirin and other NSAIDs drugs; or are infected with H.pylori bacteria. The fiber adds to this mix far more than the proverbial two cents. Please note that there is nothing wrong with stimulating digestion when appropriate. The problems develop when the digestion is stimulated inappropriately—between meals, before going to bed, while experiencing reflux, dyspepsia, and similar circumstances.
  • Gastric Ulcer (Peptic ulcer disease). A perforation of the stomach‘s mucosa causes ulcers. Gastritis commonly precedes ulceration and bleeding. All of the causative factors behind gastritis apply to ulcers as well. Fiber extends digestion. The longer the digestion lasts, the more difficult, if not outright impossible, for the ulcers to heal. That‘s why people who are admitted to a hospital with a bleeding ulcer are placed on a liquids-only diet. If a zero-fiber diet helps ulcers to heal, a low-fiber one isn‘t as likely to cause them.
  • Hiatal (Hiatus) Hernia. The diaphragm (midriff) is a muscular membrane that separates the heart and lungs (thoracic cavity) from the digestive organs (abdominal cavity). The esophagus connects with the stomach through the esophageal hiatus—an opening in the diaphragm. A pathological protrusion (herniation) of the stomach‘s upper wall above the diaphragm through that opening is called hiatal hernia. This condition affects over 40% of the population[10] in the United States. When the stomach capacity is exceeded by food and fluids, the upward pressure created by peristalsis (at the bottom of the stomach) causes its upper walls to prolapse into the opening. Fiber is the only food that expands four to five times its original size once inside the stomach. This expansion creates strong volumetric pressure long after the meal has already been consumed. Neither proteins, nor fats, nor soluble carbohydrates can expand beyond their initial volume. A horizontal position (i.e. while lying down) is likely to contribute to herniation. You may have heard that herniation contributes to heartburn, dyspepsia, gastritis, and peptic ulcers. It isn‘t so—the hiatal hernia simply mirrors the state of the affected stomach, and these conditions are already present there, regardless of the hernia. Unless patients stop recklessly stuffing their stomachs with fiber, the majority of surgeries to remove hiatal hernias are also useless.

As you can see, the relationship between the stomach and the fiber is awkward at best, ruinous at worse. Well, what else would you expect when matching a primary digestive organ with an indigestible substance?

Fiber‘s effect on the small intestine: Not welcome at any price

The journey of food from the plate to the large intestine—that is, through the mouth, esophagus, stomach, and small intestine—normally takes about 24 hours, depending on what was on that plate.

The small intestine is long and thin—about 7 meters (23‘) of coiled tubing laid out in a tight serpentine shape (3.5 to 4 cm wide in adults), which is about the width of a half-a-dollar coin.

The more insoluble fiber there is in the meal, the longer the trip, because of the bottlenecks in the small intestine, which is an organ nature intended for moving along liquid chyme, not lumps of heavy fiber. If you doubt this, just visualize the following experiment:

  • To replicate the chewing action, use a fork to crush a serving of high-fiber cereal in a bowl;
  • To reproduce the stomach‘s churning, add water or milk to the bowl, mix thoroughly, and let the crushed cereal soak in the liquid;
  • To imitate the small intestine, cut a piece of garden hose, about 7 meters long, and lay it down into a serpentine shape—a good approximation of the small intestine‘s architecture;
  • To simulate the propulsion of food through the small intestine, keep adding the “digested” cereals through a funnel on top until it appears at the other end of the hose. Or will it appear?

It‘s highly unlikely. The more fiber in the cereal, the faster this dense, thick, semi-liquid mass will clog the hose (intestine) at the bottom of its very first bend, and there are quite a few more bends left to go. To propel the cereal to the end of the hose, you‘d need to keep adding more of the mixture from the top, in order to push out the jam in the middle—a process strikingly similar to pressure-stuffing homemade sausages with ground meat.

Unlike the clumps of cereal, any liquid poured through the funnel, no matter how thick, will soon reach the end thanks to the inscape-able laws of gravitation. As long as the exit is located below the en-trance, no clogging occurs, even if the hose is old and worn out.

If you chew your food thoroughly, and your stomach digests it well, it‘s transformed to chyme—a thick liquid without any solids. And the first organ to greet chyme is the duodenum.

Duodenum. Literally twelve fingers‘ breadths, the duodenum is the first and the shortest (18–25 cm) section of the small intestine. The pyloric valve (sphincter) separates the stomach from the duodenum. When the gastric phase of digestion is completed, this valve controls the transfer of chyme into the duodenum. Once inside, the chyme is neutralized with bicarbonate, mixed with bile and pancreatic juices, and the intestinal phase of digestion begins.

Fiber is particularly hard on the duodenum, because, unlike the stomach, the duodenum isn‘t expandable, but a small, narrow, and easy-to-clog circular tube shaped like the letter C. That‘s why duodenitis (a condition identical to gastritis) and duodenal ulcer (a condition identical to gastric ulcer) strike their victims in their early twenties, twenty to thirty years ahead of the peak occurrences of gastritis and gastric ulcer.

It‘s a well-known fact among military doctors that duodenitis and duodenal ulcers are quite common among recent recruits. No surprise there—beans, legumes, whole grain cereals, whole wheat pasta, and bread make up the largest share of military rations, and young soldiers are particularly prodigious eaters after the daily grind of military life.

The duodenum possesses a few specifics that make it particularly vulnerable to obstruction with fiber. The ducts from the liver, gallbladder, and pancreas congregate into the common bile duct and terminate inside the duodenum. They supply a prodigious amount of bile (400 to 800 ml daily) and pancreatic juice (up to 1500 to 3000 ml daily). It doesn‘t take long to cause considerable damage to the liver, gallbladder, and pancreas by blocking, even partially, a considerable outflow of these fluids.

The blockage of biliary and pancreatic ducts can be purely mechanical or caused by duodenitis, an inflammation that affects the lining of the duodenum and the common duct itself. Again, the prolonged contact of a fibrous, acidified mass with the duodenal mucosa is the most likely cause of both inflammation and blockage. The conditions that follow are quite common:

  • Pancreatitis (inflammation of the pancreas). Besides fiber there isn‘t any other substance in human nutrition that enters the duodenum not only as is, but also expanded many times its original size. Lo and behold, the recent (17th edition) of The Merck Manual of Diagnosis and Therapy confirms this fact: “recent data indicate that obstruction of the pancreatic duct in the absence of biliary reflux can produce pancreatitis.”[11] Acute pancreatitis is quite common in toddlers, who are placed on solid food, which means loads of fiber from cereals, bread, pasta, fruits, and vegetables. The condition itself often remains undiagnosed, while its most prominent symptom—the onset of juvenile diabetes (type I), a failure to produce insulin because of acute inflammation—manifests itself almost immediately. Here is yet another ruinous aspect of fiber that strikes so early in life.
  • Cholecystitis (Inflammation of the gallbladder). Gallstones are the primary (90%) cause of acute (sudden, severe) and chronic cholecystitis. Gallstones are formed from concentrated bile salts when the outflow of bile from the gallbladder is blocked. The gallstones cause inflammation either by irritating the gallbladder mucosa or by obstructing the duct that connects it to the duodenum. The gallstones are the secondary factor, because before they can form, something else must first obstruct the biliary ducts. Just like with pancreatitis, that “something” is either inflammatory disease or obstruction caused by fiber.

Women are affected by gallstones far more than men, because they are more likely to maintain a “healthy” diet, which nowadays means a diet that is low in fat and high in fiber. Since the gallbladder concentrates bile pending a fatty meal, no fat in the meal means no release of bile. The longer concentrated bile remains in the gallbladder, the higher the chance for gallstones to form.

Upper (jejunum) and lower (ileum) small intestine. The duodenum transitions into the jejunum, which comprises the upper two-fifths of the small intestine. It‘s distinguished from the ileum by its larger width and thickness, slightly more pronounced mucosa structure, and deeper color, because it embodies more blood vessels.

It‘s somewhat ironic that the name jejunum is derived from the Latin fasting, because during dissection this particular segment of the small intestine was always found empty. Apparently, the fathers of anatomy, who named the internal organs, hadn‘t yet been confronted with the scourge of indigestible fiber; otherwise this particular section of the small intestine would be called intestinum repletus (filled intestine).

The final three-fifths of the small intestine are called the ileum (from Latin‘s groin, meaning near groin). The ileum is narrower (3.5–3.75 cm), has thinner walls, and is not as vascular. At the very end, the ileocal valve terminates the small intestine and prevents the content of cecum (the first section of large intestine) from spilling back into the small intestine.

One look at the small intestine, laid out inside the abdominal cavity like a tangled, convoluted garden hose, makes it apparent that this organ was designed to move fluids only, and that it‘s remarkably easy to jam with solid, undigested stuff. There is only one substance that can get down there undigested and expanded many times its size—indigestible fiber. And when that happens, here are the possible outcomes (a partial list):

  • Mechanical obstruction. The medical term for an undigested mass that forms inside the stomach or intestines and gets stuck there is bezoar (pronounced bee-zawr). Indigestible fiber is the only consumable substance that doesn‘t digest, and has the potential to form bezoars, which cause mechanical obstruction of the small intestine. When bezoars are lodged beyond the reach of the endoscope, abdominal surgery is the only option available to remove the obstruction. Bezoars are rare among healthy adults, but more common among children (whose intestines are comparatively tiny and underdeveloped). Old and infirm individuals, whose intestines lack the muscular tone needed to propel anything but fluids, are also vulnerable. That‘s why indigestible fiber should be taboo for children, or very old, infirm, and bed-ridden patients.
  • Enteritis (inflammation of the small intestine). The insides of the small intestine are covered with a pinkish mucosal membrane, superficially similar to the insides of one‘s mouth or vagina. The assimilation of digested nutrients into the bloodstream is the sole function of the intestinal mucosa. It can only assimilate nutrients dissolved in liquid chyme. It isn‘t intended to transport anything other than mildly acidic chyme (pH 6.0 to 6.5). Once inside the stomach, undigested fiber soaks up acid and enzymes like a sponge. When expanded fiber enters the small intestine, the permanent contact with the delicate mucosa causes mechanical and chemical damage, which in turn causes mucosal inflammation (enteritis). Once inflamed, the mucosa can no longer absorb the nutrients and gases formed during digestion, and the intestines expand, causing bloating and cramping, which is often accompanied by severe pain.
  • Crohn‘s disease. If left unchecked long enough, enteritis progresses into Crohn‘s disease. The mucosal inflammation gets so severe that it may cause intestinal obstruction—a condition similar to a stuffy nose during a cold, flu, or allergy attack, all of which cause acute inflammation of the nasal mucosa. The inflammation may happen at any point along the length of the small and large intestines, but it‘s most commonly localized in the bottom section of the ileum—the place where clogging with undigested fiber, bacterial fermentation, and fecal reflux is likeliest to occur. According to The Merck Manual of Diagnosis and Therapy: “Over the past few decades, the incidence of Crohn‘s disease has increased in the Western populations of Northern European and Anglo-Saxon ethnic derivation, third-world populations, blacks, and Latin Americans.”[12] What else happened during “the past few decades?” A substantial increase in the consumption of indigestible fiber, of course.
  • Hernia. When intestines protrude through the abdominal wall or inside the scrotum, they cause hernias. About 5 million Americans suffer from this unpleasant, potentially lethal condition. Coughing, straining, or lifting weights isn‘t generally enough to push the intestines so hard that they pierce the abdominal muscles or squeeze down into the scrotum (inguinal hernia). Intestinal bloating from inflammatory diseases caused by indigestible fiber is the primary force capable of expanding the intestines so much that they don‘t have enough room inside the abdominal cavity, and may ripple through the abdominal wall. The physical exertion that causes the actual herniation is a secondary force. Straining to move large stools (caused by fiber) is one of the major causes of hernia as well.
  • Malnutrition, and vitamin and mineral deficiencies. All the hard work that the body did breaking food down into basic nutrients—simple sugars, amino acids, fatty acids, vitamins, and minerals—is wasted unless they get assimilated into the blood-stream to become energy, electrolytes, hormones, enzymes, neurotransmitters, tissues, and other substances that keep our bodies functional and healthy. This final act of digestion takes place throughout the entire length of the small intestine, unless it‘s affected by inflammation. In this case, the essential nutrients will not digest, even if your diet contains plenty of them. Since indigestible fiber is the major source of intestinal inflammation, it is also a major cause of malnutrition and mineral and vitamin deficiencies. Pernicious anemia, which is a chronic shortage of dietary iron, folic acid, and vitamin B12, related to gastric and intestinal inflammation, is one of the most common forms of such a deficiency. It‘s also the most difficult to overcome, because regular oral supplements won‘t digest, no matter what the dose, unless the fiber is completely withdrawn and the stomach and intestines permitted to heal.

Fiber‘s effect on the large intestine: Demolition completed

The large intestine (a.k.a. gut, colon, bowel, entrails, and viscera) is a bona fide digestive organ. Its time is primarily taken up with the fermentation of undigested carbohydrates and assimilation of nutrients, water, and electrolytes. In the process, the large intestine converts the remnants of liquid chyme into stools and expels them. The more undigested fiber there is in the chyme, the larger and harder the stools become.

The adjective “large” next to the word “intestine” is misleading—the large intestine isn‘t that large vis-à-vis the small intestine, but wide. In Russian, for example, the intestines aren‘t small or large, but, respectively (and correctly), thin for small and thick for large. Length-wise, the large intestine is under 1.5 meters (5‘); width-wise, it‘s 6 to 9 cm (2.3–3.5”) at the base, narrowing down at the end.

The large intestine is made up of four functional sections that encircle the small intestine. It starts with a sac at the bottom that metamorphoses into a tube that looks like the letter “U” upside down. At the opposite end of the tube, another sac, terminated by a tight sphincter, completes the U-turn. Respectively, these are the cecum, colon, rectum, and anal canal.

Cecum. The cecum is a large pouch at the bottom of the ascending colon, also known as the blind gut. It is called blind because it only has one exit, just like a blind alley. The cecum is located at the lower-right-hand side of the abdomen. It collects chyme from the ileum, which is the final segment of the small intestine.

The cecum can hold up to 1.5 liters (1.58 quarts) of chyme. A sphincter (ileocecal valve) prevents chyme from spilling back into the small intestine whenever you lie down, bend down, or stand on your head.

As water, electrolytes, and micronutrients get absorbed into the bloodstream, the chyme is slowly propelled up the ascending colon. By this stage, it begins transformation into what we call stools or feces.

The cecum‘s most famous sibling—the appendix—is attached to the cecum‘s inside wall, further to the left, just under the intersection with the small intestine. Despite what you may have seen in pictures, the appendix is pointed upwards, not downwards, and its orifice faces sideways, not down.

Colon. The terms colon and large intestine are often used interchangeably, although technically this isn‘t correct. Actually, the colon is the tubing between the cecum and rectum, and it is divided into four parts: the first three are named for their direction: ascending, transverse, descending, and the fourth—sigmoid—for its sigma-like shape.

This is why medical professionals use the term colorectal in connection with such words as cancer, exam, surgery, x-ray, etc., because saying “an exam of the large intestine” is cumbersome, while “colon exam” is incorrect: doctors must pass and examine the rectum before reaching the colon, hence the term “colorectal exam.”

The word colon gave birth to numerous related terms, none of them particularly pleasant, such as colic (abdominal pain emanating from the colon), colitis (inflammation of the large intestine), colonoscopy (examination with an optical scope), colonics (a type of generous two-way enema), and colonic (specific to the large intestine, as in colonic bacteria).

The fecal mass goes up through the ascending colon, makes a sharp left, passes the transverse colon, turns down into the descending colon, and then makes a slight right into the sigmoid colon—the ramp leading into the rectum, and the last stop before being dumped. The mucus secretion (binding factor), water removal (drying factor), and bacterial action (volumetric factor) solidify the remnants of liquid chyme into solid stools before they reach the descending colon. The descending and sigmoid colon essentially perform a storage function for ready-to-be eliminated stools.

Rectum. The rectum is a stretchable, muscular sac, 10 to 15 cm (4”–6”) long, situated at the end of the sigmoid colon. It‘s right above the anus, and it shares a central space inside one‘s pelvis with the reproductive organs. Not romantic, but it works. The term rectal ampoule is often applied to the rectum‘s shape, because it‘s narrow at the bottom and dilates further up to form an ampoule-like appearance.

Anal Canal. This is the least appreciated organ, and usually the first to get into trouble because it‘s so tiny. The anal canal‘s maximum aperture is tight and narrow—3.5 cm (1.37”). The anal canal itself is about 3 cm (1.18”) long, and is encircled with two taut muscular sphincters—internal and external. Both sphincters perform in concert to keep the stools safely inside the rectum. We can consciously control only the external sphincter, while the internal is controlled autonomously, by the body itself.

The elimination of stools is the final act of digestion. Technically, it should be as easy as eating—the first act of digestion. When everything works just right, it is, but when it doesn‘t, it becomes a long and awful ordeal, first because of large stools caused by undigested fiber, second because of all the damage caused by large stools.

As with everything else in life, timing is everything with digestion: the mouth is busy chewing an average meal for 15–20 minutes; the healthy stomach digests an average mixed meal in 5 to 7 hours; the small intestine takes about 24 hours to transport chyme down to the large intestine; and the large intestine processes stools in about 72 hours.

In young, healthy people, indigestible fiber slows down stomach digestion and the transport time in the small intestine, but considerably speeds up the transport time (motility) in the large intestine, sometimes down to 24 hours. When this happens, the person may experiences diarrhea and cramping, which are usually “diagnosed” as irritable bowel syndrome. The word “diagnosed” is in quotes, because what‘s happening isn‘t a disease, but the natural reaction of a healthy colon to an unhealthy content. If caught early, the “syndrome” disappears a few days after the fiber is removed from the diet.

When a person is no longer young, or the digestive organs aren‘t in perfect shape, everything takes longer—the digestion in the stomach, the transport of chyme through the small intestine, and colonic motility. And when fiber is added, it takes even longer:

Functional Constipation

Those with defecation disorders or slow transit respond [to fiber] much less favorably. Those with severe colonic inertia may not be helped by fiber, since there is decreased smooth muscle contractile activity.[13]

Rome II: The Functional Gastrointestinal Disorders, C3: p. 389;
by Douglas A. Drossman (editor); [link]

That‘s why fiber affects the large intestine the most, earlier than any other organ, why its impact becomes much greater and more obvious, and why the list of associated diseases is so much longer. Here are the conditions that one may get, or have already, from consuming too much fiber:

Appendicitis. Appendicitis is the sudden swelling and inflammation of the appendix. It generally follows the obstruction of the appendix by undigested food or a large accumulation of hardened stools (fecal impaction). There is only one type of food that reaches the cecum undigested, and that‘s plant fiber, including seeds and husks. The swelling occurs because the bacteria trapped inside the appendix continues to divide, grow in volume, and generate refuse that has nowhere to go. Inflammation follows the swelling, and then sharp pain and other symptoms ensue. Without prompt surgical removal, the swollen appendix may burst and spill the cecum‘s “dirty” contents into the sterile peritoneal cavity, and cause peritonitis—an infectious inflammation of the membrane (peritoneum) that lines the insides of the abdomen. Without rapid and competent surgical treatment, the chances of recovering from acute peritonitis are slim.

Appendicitis is more prevalent among children precisely because their tiny ceca (plural of cecum) and appendixes are so much easier to clog with undigested fiber and large stools. When infected appendixes are removed in children, in many cases the source of obstruction and infection are undigested seeds, nuts, and grains.

Think twice before force-feeding your child fiber-rich food or supplements. Most children dislike raw, cooked, or pureed fibrous vegetables, such as broccoli, cauliflower, carrots, cabbage, and spinach, because their reaction to fiber, literally and figuratively, is visceral (by the gut): discomfort, flatulence, cramps, and sharp pain. And these “veggies” aren‘t even that fiber-rich (just one or two grams per serving) until you recognize that just five grams of fiber for a three-year old is about the same as thirty to forty grams for an adult, which is almost twice the amount of the average daily fiber intake for people in the U.S.[14]

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The combination of fecal impaction and fiber laxatives may also cause appendicitis in adults. It just takes longer to “stuff” a much larger adult‘s bowel with fibrous stool, until the cecum is completely clogged with undigested fiber. It takes about two to four weeks to fill the large intestine to capacity, depending on the amount of fiber in the diet and the degree of distention.

(The overviews that follow are shorter than those above because these conditions are discussed in greater depth in Part II of this book.)

Anal abscess. An injury of the anal canal mucosal lining may cause small ulcerations. The spontaneous healing of the ulcer may leave encapsulated pus inside the wound. This condition is extremely painful, because of the continuous pressure of the pus on the upper skin layer. This condition may require treatment with antibiotics and/or surgery.

- Anal fissures—a tear in the skin lining the anus. Fissures are particularly hard to heal, because each consecutive hard stool damages newly grown tissues and breaks the wound apart.

Anal fistulas (non-congenital)—permanent ducts (passages) from the anal canal into the perianal (around anus) region or vagina. Fistulas form as a result of ulcerations, fissures, or abscesses inside the anal canal. The fistulas cause the continuous spillage of stools, which is particularly unsafe when the fistula terminates inside the vagina. In almost all cases, the elimination of fistulas requires surgery.

- Rectal prolapse. This condition is likely to affect older people, and is characterized by the protrusion of the rectal wall or just the rectal mucosa through the anus (to the outside). Rectal prolapse requires urgent medical intervention.

Withdrawal of stools. This problem is particularly acute among children, and it happens in response to pain and discomfort related to the above complications. The withdrawal of stools causes fecal impaction, which usually requires manual disimpaction, because laxatives are no longer effective. The most dangerous thing one can do (and often does) in this case is to give a child more fiber. In this case, there is a high probability of stools spilling into the small intestine, and fiber causing obstructions.

There is just one solution to straining-related complications—elimination of fiber from the diet, resulting in the semisoft or even watery stools that will allow healing, and soft, small stools thereafter. (See Chapter 11, Avoiding the Perils of Transition.)

Fiber‘s effect on the genitourinary organs: Unlucky neighbors

The bladder and reproductive organs (collectively, genitourinary organs) share common space at the bottom of the abdominal cavity with the small and large intestines. The sigmoid colon bend is situated right next to the bladder; a thin wall separates the female rectum from the vagina; the uterus and ovaries are enveloped by intestines; the male prostate gland is located in the immediate proximity of the rectum. You get the picture.

This layout may offend your sense of sexual aesthetics, but it has been working quite well for millennia, except when the intestines are expanded by large stools and gases “courtesy” of fiber. The resulting outward pressure of the distended intestines on the reproductive organs, even slight pressure, causes symptoms identical to genitourinary disorders, such as prostatitis, endometritis, cystitis, and urethritis—respectively, an inflammation of the prostate gland, endometrium, bladder, and urinary canal.

Unfortunately, modern day gynecologists and urologists aren‘t trained to recognize the impact of intestinal disorders and large stools on the genitourinary organs, and may prescribe potent pain relievers, antibiotics, diuretics, or antidepressants to treat these phantom conditions instead of advising patients to eliminate fiber, large stools, or treat constipation. Here are some of the results:

Premenstrual Syndrome (PMS). The impact of fiber‘s side effects is particularly profound prior to menstruation. The physical metamorphosis that precedes menstruation—water and sodium retention, enlargement of the endometrium and ovaries, egg movement through the fallopian tube(s)—predisposes women to premenstrual syndrome. The ensuing symptoms, such as Mittelschmerz (middle pain, a condition related to the enlargement of ovaries during ovulation), cramping (primary dysmenorrhea, a condition not related to physical anomaly), abdominal pain, and backache, are often related to undue pressure by the distended intestines on the uterus, fallopian tubes, and ovaries, which become hypersensitive during ovulation.

Correspondingly, the emotional aspect of PMS isn‘t related to hormonal changes so much, but to the constant presence of pain and discomfort, which trigger the continuous release of stress hormones. In turn, stress hormones cause migraine headaches and patterns of social interaction typical for PMS sufferers.

PMS is often accompanied by intermittent constipation and diarrhea. Evidently, both conditions are usually already present before menstruation. They simply become more pronounced and noticeable during this period.

Nausea and Vomiting during Pregnancy (NVP). If fiber causes so many problems during menstruation, imagine its impact during pregnancy, especially the last two trimesters, when NVP can no longer be written off to hormonal changes. That‘s why many pregnant women unconsciously switch to liquid-only diets, in most cases with deleterious effects for both themselves and the fetus, as these diets may lack essential proteins, fats, and micronutrients.

NVP is easy to understand: the metamorphosis that is taking place in the abdominal cavity to accommodate the expanding uterus affects the stomach‘s ability to expand and accommodate fiber; the outward pressure on the small intestines increases the chances for intestinal obstructions by fiber. A pattern of diarrhea and vomiting caused by all of the above causes a predisposition to constipation.

If you‘re planning to become pregnant, study this book and wean yourself off fiber in advance of your pregnancy. If you‘re already pregnant, and suffer from NVP, just follow the guidelines in later chapters to restore the normal physiological functioning of the large intestine, so you can get off fiber without incurring the wrath of constipation, that comes with sudden fiber withdrawal. It will not only reduce or eliminate NVP altogether, but will also prevent you from developing numerous gastric disorders, related to persistent vomiting, diarrhea, and constipation.

Restoring normal intestinal flora in advance of pregnancy and maintaining adequate nutrition will improve the quality of your breast milk and enhance your ability to breastfeed. And, of course, all of the above will have a positive impact on fetal development, and the health, growth, intellect, and future life of your child.

Rectocele. The prolapse (herniation) of the rectal wall into the vagina is another common affliction related to fiber consumption (around an 18.4% prevalence[16] in the general population). Rectocele is most likely related to large stools and severe straining. Most, if not all, medical texts on this topic don‘t mention the rectal connection, and write off rectocele to abnormal childbirth, weakness of the pelvic support system, and unspecified congenital conditions. These are doubtful assertions, because rectocele affects women who have never been pregnant, the incidence of rectocele increases with age—which means the condition wasn‘t congenital, and the rectum wall can‘t simply prolapse into the vagina unless some external force pushes it down there. For most women, fiber-laden stools and straining are most likely these forces. To avoid corrective surgery and enjoy sex into the wee years, cutting out fiber, and avoiding constipation and straining, is the best prescription to preventing rectocele.

Vaginitis. An inflammation of the vagina‘s mucosal lining related to vaginal yeast infection (vulvovaginal candidiasis), which is characterized by an enlargement of the labia, inflammation of the external opening of the urethra, itching, vaginal discharge, odor, and pain during intercourse and urination. Candidiasis is directly related to dysbacteriosis, that may be caused, contributed to, or sustained by excess fiber. The absence of normal flora causes an overgrowth of yeast bacteria (Candida albicans) and a reduction of non-specific immunity.

Candidiasis affects up to 75%[17] of American women during their lifetimes—a number which accurately mirrors societal dietary dogma. Fiber reduction by itself isn‘t sufficient to eliminate candidiasis. An affected person and her sexual partner must restore normal intestinal flora as described in Chapter 11, Avoiding the Perils of Transition (see page  211 or here).

Candidiasis infects men via sexual intercourse with an infected partner or from contamination of the urethral opening with his own fecal matter. In this case, the condition is likely to be diagnosed as urinary tract infection (UTI) or prostatitis, and a harsh treatment with antibiotics may follow, which will only exacerbate dysbacteriosis and its side effects.

Urinary obstruction. The male urethra, the canal that discharges urine from the bladder, passes through the prostate gland. An accumulation of large stools in the rectum (typical for organic constipation and fecal impaction) causes strong pressure on the prostate gland which in turn squeezes the urethra and blocks urine flow. This blockage of the urethra interferes with normal urination, may stimulate frequent urination, and cause pain typical of prostatitis and benign prostate enlargement.

Sexual dysfunction. Finally, keep in mind that just a thin wall separates the rectum from the vagina, and an equally thin wall separates the rectum from the prostate gland. That‘s why even the mildest intercourse is capable of stimulating the defecation urge or the release of gas in the least desirable moment. The fear of such an occurrence tenses the anal muscles in both men and women, inhibits erection and arousal, and precludes orgasms, particularly among affected women. Good sex 'ain‘t' a laxative, though it often works that way. If you wish to enjoy relaxing, worry-free sex, cut out the fiber and finish reading this book.

Fiber‘s effect on heart disease: A bargain with the devil

Dietary fiber represents from 5 to 10% of the total content of consumed carbohydrates. For example, to get just the 30 grams of recommended daily fiber in natural form, you need to consume 300 to 600 grams of carbohydrates. But excessive carbohydrate consumption is the primary cause of diabetes, obesity, hypertension, elevated triglycerides, and hyperinsulinemia—the best researched and most obvious precursors of heart disease.

In this context, the idea of protecting yourself from heart disease with a high-carb, high-fiber diet is as preposterous as the suggestion to treat high blood pressure with bloodletting (less blood being equated with less blood pressure). That the patient would soon die from anemia or cardiac arrest caused by acute hypotension (extremely low blood pressure)—well, that‘s a problem for the undertaker. Nonetheless, the idea of using dietary fiber against heart disease received some traction, because certain types of fiber in combination with a low-fat diet slightly reduce LDL (“bad”) cholesterol.

To avoid the onslaught of natural carbs, you may try to fool the system, and replace these carbs with just fiber supplements. Well here, courtesy of the American Heart Association‘s research, is a description of the probable outcome:

 Fiber, Lipids, and Coronary Heart Disease
A Statement for Healthcare Professionals

...a fiber supplement containing a mixture of guar gum, pectin, soy fiber, pea fiber, and corn bran lowered LDL cholesterol by 7% to 8% in hypercholesterolemic participants after 15 weeks compared with those taking a placebo. These reductions persisted throughout the 51-week follow-up period with continued use of supplements. Potential risks of excessive use of fiber supplements include reduced mineral absorption and a myriad of gastrointestinal disturbances.[18]

Linda Van Horn, PhD, RD;
From the Nutrition Committee; American Heart Association

“Impressive,” isn‘t it? “Reduced mineral absorption,” meaning more hypertension, more arthritis, more osteoporosis, and a “myriad of gastrointestinal disturbances.” Well, “myriad” is an understatement, a euphemism for gastritis, gastric and duodenal ulcers, enteritis, Crohn‘s disease, irritable bowel syndrome, colitis, diarrhea, bloating, flatulence, and, of course, constipation and its side effects. Besides, according to the same research by the American Heart Association, the fiber-heart disease theory is a fluke anyway. It appears to work on paper, but not in real life:

“The rate of CHD [cardio-vascular disease] mortality was reported to be inversely associated with fiber intake across 20 industrialized nations, but adjustment for fat intake removed the association. Similarly, a 20-year cohort study of 1,001 middle-aged men in Ireland and Boston reported significant inverse association between fiber intake and risk of CHD, but the association diminished when other risk factors were controlled."[19]

(Same as above)

Well, well, well. Since heart disease isn‘t a topic covered in this book, it‘s up to you to decide who‘s the devil‘s advocate, and who‘s not.

Chapter summary

This entire chapter in itself is a summary of the most prominent problems caused by fiber. Hence, the list of key points is brief:


1Functional Constipation; Ch. 7: Rome II: The Functional Gastrointestinal Disorders by Douglas A. Drossman (editor);

2 Dietary, Functional and Total Fiber, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients) (2002), Food and Nutrition Board (FNB), Institute of Medicine (IOM); [link]

3 The American Dietetic Association recommends fiber for children only after two years of age, and no more than 5 grams + the child’s age. That amounts to 7 to 13 grams of fiber for the two to eight-year-old age group. Health implications of dietary fiber, J Am Diet Assoc 2002;102:993–1000; [link]

4 Mayo Clinic; Fiber–A Good Carb; Consumer Health Tips and Products; June 11, 2004; [link]

5 KELLOGG’S ALL-BRAN WITH EXTRA FIBER; NDB No: 08253; USDA National Nutrient Database for Standard Reference; [link]

6 Metamucil Psyllium Fiber for Regularity, Smooth Texture, Orange; Package Detail; [link]

7Metamucil Powder; RiteAid Patient Counseling; © First Databank; The Hearst Corporation;  [link]

8 Weston A. Price, D.D.S. Nutrition and Physical Degeneration; 6th Edition. (Examples of tooth decay related to fiber consumption are provided through out the book.)

9There is still considerable controversy as to whether the pyloric valve is completely closed during gastric digestion or not, hence “locked” is written in parenthesis. Still, whatever the mechanisms, the stomach has a remarkable ability to retain its content until it is almost completely liquefied. For more information, see The Pyloric Sphincteric Cylinder in Health and Disease by A.D. Kleet; Internet edition: [link]

10 Hiatus Hernia; The Merck Manual of Diagnosis and Therapy; 3:20; [link]

11 Pancreatitis: Inflammation of the pancreas; The Merck Manual of Diagnosis and Therapy; 3:26; [link]

12 Crohn's Disease; The Merck Manual of Diagnosis and Therapy; 3:31; [link]

13 Functional Constipation; C3: p. 389;  Rome II: The Functional Gastrointestinal Disorders by Douglas A. Drossman (editor);

14 Dietary, Functional and Total Fiber—Summary; Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients); Food and Nutrition Board; Institute of Medicine;  2002; 7:265; [link]

15 What are polyps; Colon Polyps & Colon Cancer; D. E. Mansell, MD; [link]

16 Pelvic Organ Prolapse in the Women’s Health Initiative: Gravity and Gravidity; Hendrix SL., Clark A., Nygaard I., Aragaki A., Barnabei V., McTiernan A.; Am J Obstet Gynecol 2002;186:1160–1166.

17 Vaginitis Due to Vaginal Infections; National Institute of Allergy and Infectious Diseases (division of National Institutes of Health); [link]

18 Linda Van Horn, PhD, RD; Fiber, Lipids, and Coronary Heart Disease; A Statement for Healthcare Professionals From the Nutrition Committee; American Heart Association; [link]

19 Ibid (same as above).