Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (2005) / Chapter Skim
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7. Dietary, Functional, and Total Fiber
7. Dietary, Functional, and Total Fiber
Pages 339-421
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From page 339... ...
Viscous fibers can interfere with the absorption of dietary fat and cholesterol, as well as with the enterohepatic recirculation of cholesterol and bile acids, which may result in reduced blood cholesterol concentrations. Consumption of Dietary and certain Functional Fibers, particularly those that are poorly fermented, is known to improve fecal bulk and laxation and ameliorate constipation.
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From page 340... ...
Functional Fiber consists of isolated, nondigestible carbohydrates that have beneficial physiological effects in humans. Total Fiber is the sum of Dietary Fiber and Functional Fiber.
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From page 341... ...
Although sugars and sugar alcohols could potentially be categorized as Functional Fibers, for labeling purposes they are not considered to be Functional Fibers because they fall under "sugars" and "sugar alcohols" on the food label. Distinguishing Features of Dietary Fiber Compared with Functional Fiber Dietary Fiber consists of nondigestible food plant carbohydrates and lignin in which the plant matrix is largely intact.
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From page 342... ...
Functional Fiber consists of isolated or extracted nondigestible carbohydrates that have beneficial physiological effects in humans. Functional Fibers may be isolated or extracted using chemical, enzymatic, or aqueous steps.
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From page 343... ...
How the Definitions Affect the Interpretation of This Report The reason that a definition of fiber is so important is that what is or is not considered to be dietary fiber in, for example, a major epidemiological study on fiber and heart disease or fiber and colon cancer, could determine the results and interpretation of that study. In turn, that would affect recommendations regarding fiber intake.
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From page 344... ...
. Intervention studies often use specific fiber supplements such as pectin, psyllium, and guar gum, which would, by the above definition, be considered Functional Fibers if their role in human health is documented.
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From page 345... ...
. Naturally occurring -glucans can be classified as Dietary Fibers, whereas added or isolated -glucans are potential Functional Fibers.
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From page 346... ...
With respect to the definitions outlined in this chapter, the naturally occurring fructans that are found in plants, such as chicory, onions, and Jerusalem artichoke, would be classified as Dietary Fibers; the synthesized or extracted fructans could be classified as Functional Fibers when there are sufficient data to show positive physiological effects in humans. Lignin.
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From page 347... ...
Resistant dextrins can potentially be classified as Functional Fibers when sufficient data on physiological benefits in humans are documented. Resistant Starch.
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From page 348... ...
. There appears to be no relationship between the level of Dietary Fiber intake and fermentability up to very high levels (Livesey, 1990)
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From page 349... ...
. Physiological Effects of Isolated and Synthetic Fibers This section summarizes the fibers for which there is a sufficient database that documents their beneficial physiological human effects, which is the rationale for categorizing them as Functional Fibers.
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normalization of blood lipid concentrations, and (3) attenuation of blood glucose responses.
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From page 351... ...
Similar to the relationship between cellulose and serum cholesterol concentrations, cellulose is also often used as a placebo in studies that evaluate the effect of fiber on blood glucose and insulin concentrations. Cellulose is ineffective in decreasing the postprandial glucose response (Librenti et al., 1992; Niemi et al., 1988)
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From page 352... ...
. Furthermore, hypercholesterolemic men who received 15 g/d of guar gum had significantly lower serum total cholesterol and LDL cholesterol concentrations compared to the placebo controls after 6 weeks (Aro et al., 1984)
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The addition of 10 g/d of guar gum to a test meal generated an overall decrease in blood glucose concentrations in both normal (n = 5) and diabetic (n = 6)
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. The ingestion of 9 g/d of inulin significantly reduced plasma total cholesterol and triacylglycerol concentrations in young men (Brighenti et al., 1999)
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From page 355... ...
. Total plasma and LDL cholesterol concentrations were lower in the oat bran concentrate period (9 g/d of viscous fiber)
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From page 356... ...
did not observe reductions in serum cholesterol concentrations following the consumption of 10 g of pectin with 100 g of glucose. The consumption of 7.2 g/d of psyllium that had been added to foods did not result in a significant decrease in LDL cholesterol concentration.
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From page 357... ...
Sixty-one healthy volunteers received 15 g/d of polydextrose for 2 months. Serum concentrations of total cholesterol, triacylglycerols, and LDL cholesterol did not change during this period; however, concentrations of HDL cholesterol decreased (Saku et al., 1991)
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From page 358... ...
Several of these studies provided 10.2 g/d of psyllium for up to 26 weeks and all showed marked reductions in serum total and LDL cholesterol concentrations compared to cellulose (Anderson et al., 1988, 1999, 2000b; Levin et al., 1990)
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From page 359... ...
During the cereal-plus-diet phase of the study, total and LDL cholesterol concentrations in the psyllium-enriched cereal group decreased by 5.9 and 5.7 percent, respectively. A meta-analysis was conducted to determine the effect of consumption of psyllium-enriched cereal products on blood lipid concentrations in 404 adults with mild to moderate hypercholesterolemia consuming a low fat diet (Olson et al., 1997)
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From page 360... ...
The intake of 60 g/d of resistant maltodextrin was shown to reduce serum total cholesterol and triacylglycerol concentrations in type 2 diabetics as compared with type 2 diabetics or healthy adults who consumed 30 g/d of resistant maltodextrin (Ohkuma and Wakabayashi, 2001)
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From page 361... ...
. When healthy, normolipidemic individuals were given glucose or 30 g/d of RS3 supplements for 3 weeks, there were no significant differences in fasting serum total, LDL, and HDL cholesterol concentrations or triacylglycerol concentrations (Heijnen et al., 1996)
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From page 362... ...
A number of epidemiological studies have been conducted to evaluate the relationship between fiber intake and risk of chronic disease. While Functional Fibers, such as pectins and gums, are added to foods as ingredients, these levels are minimal and therefore fiber intakes that are estimated from food composition tables generally represent Dietary Fiber.
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From page 363... ...
followed 337 men in London, England for 10 to 20 years and found that men with a high intake of cereal fiber had a lower rate of CHD than men with a low cereal fiber intake. In the Health Professionals Follow-up Study, the relative risk for fatal coronary disease and total myocardial infarction were 0.45 and 0.59, respectively, for men in the highest quintile of Dietary Fiber intake (28.9 g/d)
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From page 364... ...
b Dietary Fiber intake is energy-adjusted to 1,600 kcals. increased intake of 6 g/d of Dietary Fiber was associated with a 33 percent risk reduction for CHD in women and 24 percent in men, and the reduction in CHD mortality was independent of other dietary variables.
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From page 365... ...
. In addition, viscous Functional Fibers such as guar, pectin, and psyllium, have been tested in intervention trials and found to decrease serum total and low density lipoprotein (LDL)
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From page 366... ...
. A meta-analysis testing the effects of pectin, oat bran, guar gum, and psyllium on blood lipid concentrations showed that 2 to 10 g/d of viscous fiber were associated with small but significant decreases in total and LDL cholesterol concentrations (Brown et al., 1999)
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From page 367... ...
The diets containing the viscous fibers led to significantly lower plasma cholesterol concentrations. Although these relatively small-scale intervention trials using viscous Functional Fibers have reported substantial cholesterol-lowering effects and therefore should be protective against CHD, no protective effect against CHD was seen in a large-scale clinical trial with individuals who had a previous myocardial infarction (Burr et al., 1989)
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It is of interest to compare the hypothetical risk reduction for CHD per gram of oat bran consumed (in the clinical intervention trials) to that for total dietary fiber intake in the epidemiological studies.
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Summary On the basis of the evidence provided on fiber intake and CHD, certain sources of Dietary Fiber (cereal foods) and certain Functional Fibers (viscous)
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. Also, Dietary Fiber intake is usually negatively correlated with transit time (Birkett et al., 1997)
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. Several types of studies have shown a relationship between fiber intake and diverticular disease.
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From page 372... ...
For duodenal ulcer and diverticular disease, the data are promising for a protective effect, but insufficient data exist at this time upon which to base a recommended intake level. It is clear that fiber fermentation products provide energy for colonocytes and other cells of the body, but again this is not sufficient to use as a basis for a recommendation for fiber intake.
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From page 373... ...
reviewed 48 epidemiological studies on the relationship between diets containing Total Fiber and colon cancer and found that 38 reported an inverse relationship, 7 reported no association, and 3 reported a direct association. In the Netherlands, Dietary Fiber intake was reported to be inversely related to total cancer deaths, as the 10-year cancer death rate was approximately threefold higher in individuals with low fiber intake compared with high fiber intake (Kromhout et al., 1982)
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do not support a protective effect of Dietary Fiber intake against colon cancer. This issue remains to be resolved.
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. Dietary Fiber Intake and Colonic Adenomas People with colonic adenomas are at elevated risk of developing colon cancer (Lev, 1990)
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. Possible Reasons for the Lack of a Protective Effect of Dietary Fiber in Some Trials There is considerable debate and speculation as to why clinical intervention trials on the relationship between fiber intake and colon cancer have not shown the expected beneficial effect of fiber.
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From page 377... ...
, but that the amounts or types of Dietary Fibers consumed did not result in these physiological effects. In addition, positive benefits of fiber with respect to colon cancer may not occur until Dietary Fiber intake is sufficiently high; for example, greater than the median 32 g/d for the highest quintile in The Health Professionals Follow-Up Study of men (Giovannucci et al., 1994; Platz et al., 1997)
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investigated the relationship between Dietary Fiber intake and breast cancer risk in The Netherlands Cohort Study. This prospective cohort study showed no evidence that a high intake of Dietary Fiber decreased the risk of breast cancer.
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. Summary There are no reports on the role of Functional Fibers in the risk of breast cancer.
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From page 380... ...
Dietary Fiber and Other Cancers Although the preponderance of the literature on fiber intake and cancer involves colon cancer and breast cancer, several studies have shown decreased risk for other types of cancer. Because Dietary Fiber has been shown to decrease serum estrogen concentrations, some researchers have hypothesized a protective effect against hormone-related cancers such as endometrial, ovarian, and prostate.
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From page 381... ...
This theory is supported by results from the Zutphen Elderly Study, where a negative relationship was observed between Dietary Fiber intake and insulin concentrations (Feskens et al., 1994)
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. Viscous Dietary and Functional Fibers, such as are found in oat products, beans, isolated pectin, and isolated guar gum, have been found to produce significant reductions in glycemic response in 33 of 50 studies (66 percent)
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From page 383... ...
. Consumption of viscous fibers delays gastric emptying (Roberfroid, 1993)
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From page 384... ...
. Summary The strongest data supporting a relationship between fiber and weight maintenance come from the few epidemiological studies showing that Dietary Fiber intake is lower for obese men and women than for lean men and women and that BMI is lower with higher fiber consumption for both men and women.
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From page 385... ...
Those with energy intakes significantly above or below the reference intakes for their age and gender may want to consider adjusting their total fiber intake accordingly. Infants Ages 0 Through 12 Months There are no functional criteria for fiber status that reflect response to dietary intake in infants.
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From page 386... ...
It should be kept in mind that recommendations for fiber intake are based on a certain amount of total fiber as a function of energy intake. This means that those who consume less than the median energy intake of a particular category need less fiber than the recommendation (which is based on the mean energy intake)
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From page 387... ...
are adequately powered, divide fiber intake into quintiles, and provide data on energy intake (Table 7-2) , it is possible to set a recommended intake level.
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From page 388... ...
The literature on Dietary Fiber intake and glucose tolerance, insulin response, and amelioration of diabetes alone is insufficient at this time to use as a basis for a recommendation (see "Evidence Considered for Estimating the Requirement for Dietary Fiber and Functional Fiber")
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From page 389... ...
. Total Fiber AI Summary, Pregnancy AI for Pregnant Women 1418 years 28 g/d of Total Fiber 1930 years 28 g/d of Total Fiber 3150 years 28 g/d of Total Fiber Lactation Method Used to Set the AI There is no evidence to suggest the beneficial effects of fiber in reducing the risk of CHD for lactating adolescent girls and women are different from nonpregnant adolescent girls and women.
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From page 390... ...
Oligofructose is most commonly added to cereals, fruit preparations for yogurt, cookies, dairy products, and frozen desserts. Depending on one's chosen diet, naturally occurring and manufactured resistant starch, as well as that produced during normal processing of foods for human consumption, could make a significant contribution to daily Total Fiber intake.
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From page 391... ...
food composition database to estimate the intake of various nutrients. This database primarily measures Dietary Fiber intake because isolated Functional Fibers, such as pectins and gums, that are used as ingredients represent a very minor amount of the fiber present in foods.
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153 0 Total for snack 606 5.2 Daily total 3,078 38.1 NOTE: Source of food composition data: NDS-R Food and Nutrient Data Base, Version 4.04_32, 2001, Nutrition Coordinating Center, University of Minnesota.
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From page 393... ...
108 0.9 Peanut butter sandwich 138 1.3 Cola (1 can) 153 0 Total for snack 480 5.9 Daily total 2,393 25.8 NOTE: Source of food composition data: NDS-R Food and Nutrient Data Base, Version 4.04_32, 2001, Nutrition Coordinating Center, University of Minnesota.
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From page 394... ...
. Most studies that assess the effect of fiber intake on mineral status have looked at calcium, magnesium, iron, or zinc.
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From page 395... ...
Since the potential adverse health effects of Functional Fiber are not completely known, they should be evaluated on a case-by-case basis. In addition, projections regarding the potential contribution of Functional Fiber to daily Total Fiber intake at anticipated patterns of food consumption would be informative.
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From page 396... ...
While the adverse gastrointestinal effects of gums are limited, incidences of moderate to severe degrees of flatulence were reported from a trial in which 4 to 12 g/d of a hydrolyzed guar gum were provided to 16 elderly patients (Patrick et al., 1998)
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From page 397... ...
Although both carbohydrates are fermented by colonic microflora, they differ in osmolarity. The osmotic force is twice as high for lactulose as for frutooligosaccharide.
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From page 398... ...
In the European Center Prevention Organization Study, psyllium (Functional Fiber) was provided at a level of 3.5 g/d (Bonithon-Kopp et al., 2000)
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From page 399... ...
and its relationship to these endpoints. · Conduct a doseresponse study to determine the amount of fiber that needs to be ingested to promote optimum laxation so that this could form the basis for a recommendation for fiber intake and provide a basis for determining functional fibers.
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From page 400... ...
and satiety and weight control to see if a higher fiber diet will help with weight maintenance or promote adherence to reduced calorie diets for weight reduction. · Examine the relation between Dietary Fiber intake, energy intake, and long-term body weight in existing prospective epidemiological studies in addition to intervention studies.
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From page 401... ...
Am J Clin Nutr 71:14331438.
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From page 402... ...
Am J Clin Nutr 39:911916. Ascherio A, Rimm EB, Giovannucci EL, Colditz GA, Rosner B, Willett WC, Sacks F, Stampfer MJ.
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From page 403... ...
Hum Nutr Clin Nutr 40:429440. Bosello O, Cominacini L, Zocca I, Garbin U, Ferrari F, Davoli A
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From page 404... ...
Am J Clin Nutr 36:873877. Burr ML, Fehily AM, Gilbert JF, Rogers S, Holliday RM, Sweetnam PM, Elwood PC, Deadman NM.
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From page 405... ...
2000. Beneficial effects of high dietary fiber intake in patients with type 2 diabetes mellitus.
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From page 406... ...
1993. Resistant starch decreases serum total cholesterol and triacylglycerol concentrations in rats.
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From page 407... ...
Eur J Clin Nutr 42:425435. Englyst HN, Cummings JH.
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From page 408... ...
Am J Clin Nutr 58:513518. Grossman SP.
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From page 409... ...
1988. Fiber intake, age, and other coronary risk factors in men of the Baltimore Longitudinal Study (19591975)
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From page 410... ...
Am J Clin Nutr 68:248257. Jacobs LR.
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From page 411... ...
1998. Physiological effects of resistant starches on fecal bulk, short chain fatty acids, blood lipids and glycemic index.
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From page 412... ...
Am J Clin Nutr 53:14801486. Kochen MM, Wegscheider K, Abholz HH.
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From page 413... ...
Am J Clin Nutr 51:617637. Loening-Baucke V
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From page 414... ...
1999. Measurement of low dietary fiber intake as a risk factor for chronic constipation in children.
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From page 415... ...
1993. Dietary fiber intake of Japanese younger generations and the recom mended daily allowance.
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From page 416... ...
Eur J Clin Nutr 53:379381. Platz EA, Giovannucci E, Rimm EB, Rockett HRH, Stampfer MJ, Colditz GA, Willett WC.
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From page 417... ...
1996. Vegetable, fruit, and cereal fiber intake and risk of coronary heart dis ease among men.
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From page 418... ...
Hum Nutr Clin Nutr 37:171183. Sandstead HH.
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From page 419... ...
Eur J Clin Nutr 46:S91S101. Tuohy KM, Kolida S, Lustenberger AM, Gibson GR.
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From page 420... ...
1990. Relation of meat, fat, and fiber intake to the risk of colon cancer in a prospective study among women.
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From page 421... ...
Am J Clin Nutr 49:11791183. Woods MN, Barnett JB, Spiegelman D, Trail N, Hertzmark E, Longcope C, Gorbach SL.
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