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Dietary Reference Intakes The Essential Guide to Nutrient Requirements (2006) / Chapter Skim
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Pages 402-413

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From page 402...
... TABLE 1 Dietary Reference Intakes for Zinc by Life Stage Group DRI values (mg/day) EARa RDAb AIc ULd males females males females Life stage group 0 through 6 mo 2 4 7 through 12 mo 2.5 2.5 3 3 5 1 through 3 y 2.5 2.5 3 3 7 4 through 8 y 4.0 4.0 5 5 12 9 through 13 y 7.0 7.0 8 8 23 14 through 18 y 8.5 7.3 11 9 34 19 through 50 y 9.4 6.8 11 8 40 ≥ 51 y 9.4 6.8 11 8 40 Pregnancy 14 through 18 y 10.5 12 34 19 through 50 y 9.5 11 40 Lactation 14 through 18 y 10.9 13 34 19 through 50 y 10.4 12 40 a EAR = Estimated Average Requirement.
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From page 403...
... PART III: ZINC 403 ZINC Z inc is crucial for growth and development. It facilitates several enzy matic processes related to the metabolism of protein, carbohydrates, and fats.
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From page 404...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 404 Absorption, Metabolism, Storage, and Excretion During digestion, zinc is absorbed by the small intestine through a transcellular process, with the jejunum being the site with the greatest transport rate. The mechanism of absorption appears to be saturable and there is an increase in transport velocity with zinc depletion.
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From page 405...
... PART III: ZINC 405 and the concentration declines even further by 12 months. It is apparent, therefore, that human milk alone is an inadequate source of zinc after the first 6 months.
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From page 406...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 406 Lactation 14 through 18 y Adolescent female EAR plus average amount of zinc secreted in human milk 19 through 50 y Adult female EAR plus average amount of zinc secreted in human milk The UL The Tolerable Upper Intake Level (UL) is the highest level of daily nutrient intake that is likely to pose no risk of adverse effects for almost all healthy people.
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From page 407...
... PART III: ZINC 407 TABLE 2 Qualitative Bioavailability of Zinc According to Diet Characteristicsa Bioavailability Dietary Characteristics High Refined diets low in cereal fiber and phytic acid, with adequate protein primarily from meats and fish Phytate/zinc molar ratio < 5 Medium Mixed diets containing animal or fish protein Vegetarian diets not based primarily on unrefined, unfermented cereal grains Phytate/zinc molar ratio 5–15 Low Diets high in unrefined, unfermented, and ungerminated cereal grains, especially when animal protein intake is negligible High-phytate soy protein products are the primary protein source Diets in which ≥ 50 percent of energy is provided by high-phytate foods (high extraction rate [90 percent] flours and grains, legumes)
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From page 408...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 408 TABLE 3 Potential Interactions with Other Dietary Substances Substance Potential Interaction Notes NUTRIENTS THAT AFFECT ZINC Iron Iron may decrease In general, data indicate that high intakes of zinc absorption. supplemental iron inhibit zinc absorption if both are taken without food, but do not inhibit zinc absorption if they are consumed with food.
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From page 409...
... PART III: ZINC 409 TABLE 3 Continued Substance Potential Interaction Notes Picolinic Picolinic acid may promote Picolinic acid has a high metal binding affinity. People acid negative zinc balance.
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From page 410...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 410 INADEQUATE INTAKE AND DEFICIENCY Overt human zinc deficiency is rare. Because zinc is involved in so many core areas of metabolism, the signs and symptoms of mild deficiency are diverse and inconsistent.
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From page 411...
... PART III: ZINC 411 cause vomiting. Gastrointestinal distress has been reported at doses of 50–150 mg/day of zinc • Impaired immune function: Intake of 300 mg/day of supplemental zinc for 6 weeks has been shown to cause impaired immune function SPECIAL CONSIDERATIONS Individuals susceptible to adverse effects: People with Menke's disease may be distinctly susceptible to the adverse effects of excess zinc intake.
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From page 412...
... DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 412 KEY POINTS FOR ZINC Zinc functions as a component of various enzymes in the 3 maintenance of the structural integrity of proteins and in the regulation of gene expression. Factors such as stress, acute trauma, and infection can cause plasma zinc levels to drop.
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From page 413...
... PART III: ZINC 413 It is noteworthy that zinc homeostasis within the body is such 3 that zinc deficiency can occur with only modest degrees of dietary zinc restriction, while circulating zinc concentrations are indistinguishable from normal. People with malabsorption syndromes, including sprue, 3 Crohn's disease, and short bowel syndrome are at risk of zinc deficiency due to malabsorption of zinc and increased urinary zinc losses.
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