Bulk-producing laxatives

When consumed with sufficient liquid, bulk-producing laxatives bind water in the colon, thereby softening the feces and expanding their bulk, which stimulates peristalsis and emptying of the bowel. They are probably the safest laxatives, functioning as they do in a fashion identical to high-residue foods rich in the dietary fiber found in plant cell walls. Dietary fiber is resistant to digestion and consists of varying quantities of cellulose, hemicellulose, pectin, lignin, cutin, waxes, and glycopro- teins. Foods differ widely in the type and content of fiber they contain. Grains, cereals, and bran (more than 40 percent dietary fiber) contain large amounts of insoluble, poorly digested fiber, and their ingestion will shorten intestinal transit time and increase stool bulk. Fruits and veg- etables contain more water-soluble fiber that results in a moister stool with less effect on transit time. 32

Chapter three: Digestive system problems

31 Psyllium seed

Probably the most popular of the bulk-producing laxatives is psyllium seed, also known as plantago seed. It is estimated that psyllium-contain- ing laxatives are used by four million Americans daily. Plantago seed is official in the United States Pharmacopoeia XXII, where it is described as the cleaned, dried, ripe seed of Plantago psyllium L. or of Plantago indica L.,

known in commerce as Spanish or French psyllium seed; or of Plantago ovata Forskal, known in commerce as blond psyllium or Indian plantago seed. All of these plants are members of the family Plantaginaceae. 33

The seed coats or husks of plantago seeds contain cells filled with mucilage that is neither absorbed nor digested in the intestinal tract. In contact with water, it swells to a large volume, thus providing both bulk and lubrication and causing either the whole seed or the husks to act as an effective bulk-producing laxative. Recent clinical studies have demonstrated the effectiveness of plantago seed therapy. In one study of twenty-two subjects with idiopathic constipation, it was found that stool frequency increased significantly after eight weeks of treatment, as did stool weight. Subjects also reported an improvement in stool consis-

tency and less pain on defecation. 34 In another study in older men and women with chronic constipation involving a single-blind, randomized, placebo-controlled fiber intervention with crossover, investigators found that psyllium fiber supplementation decreased total gut transit time from fifty-four hours to thirty hours. However, it did not rectify pelvic flow dysynergia, which was the principal cause of constipation in the group of patients studied. 35

The usual dose of the seed is 7.5 g (2 heaping teaspoonfuls); 1 tea- spoonful of the husks will provide the same effect. These doses are usually effective in twelve to twenty-four hours but may require as long as seventy-two hours in some individuals. Plantago seed husks, usually referred to as psyllium in the health-food industry, are readily available prepackaged and in bulk. For best results, stir the husks into a glass of water, juice, or milk and drink it quickly before the mixture has a chance to thicken.

In recent years, studies have shown that psyllium alone or mixed with other water-soluble dietary fibers in the diet of adult humans and children produces a modest but significant fall in total serum cholesterol and in low-density lipoprotein cholesterol. 36,37

A suggested mechanism is that psyllium increases fecal excretion of bile acids by binding bile acids in the intestine. Less is reabsorbed and less reenters the entero- hepatic circulation; therefore, in the liver more cholesterol is converted into bile acids to replace bile acids lost in fecal excretion. The net result is to decrease the amount of cholesterol available for incorporation into circulatory lipoproteins. 38

32 Tyler's herbs of choice: The therapeutic use of phytomedicinals An abundance of evidence suggests that dietary fiber may reduce

the risk of colon cancer. Dietary fiber can bind to carcinogens and tumor promoters, inhibiting carcinogenesis, and a preponderance of human epi- demiological studies has demonstrated an inverse association between high-fiber diets and colon cancer. A recent study has convincingly demonstrated the role of wheat bran and psyllium in the chemoprevention of colon carcinogenesis in the rat experimental model. 39

Bulk-producing laxatives