Livro DRI 2006 (Micronutrientes)

Livro DRI 2006 (Micronutrientes)


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cereals
and other grains.
3 Most carbohydrates occur as starches in food. Grains and
certain vegetables are major contributors. Grain sources
include corn, tapioca, flour, cereals, popcorn, pasta, rice,
potatoes, and crackers.
3 The amount of dietary carbohydrate that confers optimal health
in humans is unknown.
3 Of particular concern is the long-term effect of a diet so low in
carbohydrate that it induces a chronically increased production
of keto acids. Such a diet may lead to bone mineral loss,
hypercholesterolemia, increased risk of urolithiasis, and
impaired development and function of the central nervous
system.
3 Data are mixed on potential adverse effects of overconsuming
carbohydrate.
Copyright © National Academy of Sciences. All rights reserved.
Dietary Reference Intakes: The Essential Guide to Nutrient Requirements
http://www.nap.edu/catalog/11537.html
TABLE 1 Dietary Reference Intakes for Total Fibera by Life
Stage Group
DRI values (g/1,000 kcal) [g/day]b
AIc
males females
Life stage group
0 through 6 mo NDd ND
7 through 12 mo ND ND
1 through 3 y 14 [19] 14 [19]
4 through 8 y 14 [25] 14 [25]
9 through 13 y 14 [31] 14 [26]
14 through 18 y 14 [38] 14 [26]
19 through 30 y 14 [38] 14 [25]
31 through 50 y 14 [38] 14 [25]
51 through 70 y 14 [30] 14 [21]
> 70 y 14 [30] 14 [21]
Pregnancy
< 18 y 14 [28]
19 through 50 y 14 [28]
Lactation
< 18 y 14 [29]
19 through 50 y 14 [29]
aTotal Fiber is the combination of Dietary Fiber, the edible, nondigestible
carbohydrate and lignin components as they exist naturally in plant foods, and
Functional Fiber, which refers to isolated, extracted, or synthetic fiber that has proven
health benefits.
b Values in parentheses are example of the total g/day of total fiber calculated from
g/1,000 kcal multiplied by the median energy intake (kcal/1,000 kcal/day) from the
Continuing Survey of Food Intakes by Individuals (CSFII 1994\u20131996, 1998).
c AI = Adequate Intake. If sufficient scientific evidence is not available to establish
an Estimated Average Requirement (EAR), and thus calculate a Recommended Dietary
Allowance (RDA), an AI is usually developed. For healthy breast-fed infants, the AI is
the mean intake. The AI for other life stage and gender groups is believed to cover the
needs of all healthy individuals in the group, but a lack of data or uncertainty in the
data prevents being able to specify with confidence the percentage of individuals
covered by this intake.
d ND = Not determined.
Copyright © National Academy of Sciences. All rights reserved.
Dietary Reference Intakes: The Essential Guide to Nutrient Requirements
http://www.nap.edu/catalog/11537.html
PART II: FIBER 111
FIBER
The term Dietary Fiber describes the carbohydrates and lignin that areintrinsic and intact in plants and that are not digested and absorbed inthe small intestine. Functional Fiber consists of isolated or purified car-
bohydrates that are not digested and absorbed in the small intestine and that
confer beneficial physiological effects in humans. Total Fiber is the sum of Di-
etary Fiber and Functional Fiber. Fibers have different properties that result in
different physiological effects, including laxation, attenuation of blood glucose
levels, and normalization of serum cholesterol levels.
Since data were inadequate to determine an Estimated Average Require-
ment (EAR) and thus calculate a Recommended Dietary Allowance (RDA) for
Total Fiber, an Adequate Intake (AI) was instead developed. The AIs for Total
Fiber are based on the intake levels that have been observed to protect against
coronary heart disease (CHD). The relationship of fiber intake to colon cancer
is the subject of ongoing investigation and is currently unresolved. A Tolerable
Upper Intake Level (UL) was not set for fiber. DRI values are listed by life stage
group in Table 1.
Dietary Fiber is found in most fruits, vegetables, legumes, and grains. Di-
etary and Functional Fibers are not essential nutrients; therefore, inadequate in-
takes do not result in biochemical or clinical symptoms of a deficiency. As part
of an overall healthy diet, a high intake of Dietary Fiber will not cause adverse
effects in healthy people.
DEFINITIONS OF FIBER
Dietary Fiber, Functional Fiber, and Total Fiber
This publication defines Total Fiber as the combination of Dietary Fiber, the
edible, nondigestible carbohydrate and lignin components as they exist natu-
rally in plant foods, and Functional Fiber, which refers to isolated, extracted, or
synthetic fiber that has proven health benefits. Nondigestible means that the
material is not digested and absorbed in the human small intestine (see Box 1
for definitions). Fiber includes viscous forms that may lower serum cholesterol
concentrations (e.g., oat bran, beans) and the bulking agents that improve lax-
ation (e.g., wheat bran).
Dietary Fiber in foods is usually a mixture of the polysaccharides that are
integral components of plant cell walls or intracellular structures. Dietary Fiber
Copyright © National Academy of Sciences. All rights reserved.
Dietary Reference Intakes: The Essential Guide to Nutrient Requirements
http://www.nap.edu/catalog/11537.html
112 DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS
sources contain other macronutrients (e.g., digestible carbohydrate and pro-
tein) normally found in foods. For example, cereal brans, which are obtained
by grinding, are anatomical layers of the grain consisting of intact cells and
substantial amounts of starch and protein. Other examples include plant
nonstarch polysaccharides (e.g., cellulose, pectin, gums, and fibers in oat and
wheat bran), plant carbohydrates (e.g., inulin, fructans), lignin, and some resis-
tant starch.
Functional Fiber may be isolated or extracted using chemical, enzymatic, or
aqueous steps, such as synthetically manufactured or naturally occurring iso-
lated oligosaccharides and manufactured resistant starch. In order to be classi-
fied as a Functional Fiber, a substance must demonstrate a beneficial physiologi-
cal effect. Potential Functional Fibers include isolated nondigestible plant (e.g.,
pectin and gums), animal (e.g., chitin and chitosan), or commercially produced
(e.g., resistant starch, polydextrose) carbohydrates.
FIBER AND THE BODY
Function
Different fibers have different properties and thus varying functions. They aid
in laxation and promote satiety, which may help reduce energy intake and there-
fore the risk of obesity. They can also attenuate blood glucose levels, normalize
serum cholesterol levels, and reduce the risk of CHD. For example, viscous
BOX 1 Definitions of Fibera
\u2022 Dietary Fiber consists of nondigestible carbohydrates and lignin
that are intrinsic and intact in plants.
\u2022 Functional Fiber consists of isolated nondigestible carbohydrates
that have beneficial physiological effects in humans.
\u2022 Total Fiber is the sum of Dietary Fiber and Functional Fiber.
a In the United States, dietary fiber is defined for regulatory purposes by a
number of analytical methods that are accepted by the Association of Official Ana-
lytical Chemists International (AOAC). In Canada, a distinction is made between
dietary fiber (defined as the endogenous components of plant material in the diet
that are resistant to digestion by enzymes produced by man) and novel fibers,
whose definition is similar to functional fiber. Novel fibers must be demonstrated to
have beneficial effects to be considered as fiber for the purposes of labeling and
claims.
Copyright © National Academy of Sciences. All rights reserved.
Dietary Reference Intakes: The Essential Guide to Nutrient Requirements
http://www.nap.edu/catalog/11537.html
PART II: FIBER 113
fibers can interfere with the absorption of dietary fat and cholesterol, as well as
the enterohepatic recirculation