Dietary Reference Intakes The Essential Guide to Nutrient Requirements (2006) / Chapter Skim
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Pages 202-210
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From page 202... ...
TABLE 1 Dietary Reference Intakes for Vitamin C by Life Stage Group DRI values (mg/day) EARa RDAb AIc ULd males females males females Life stage group NDe 0 through 6 mo 40 7 through 12 mo 50 ND 1 through 3 y 13 13 15 15 400 4 through 8 y 22 22 25 25 650 9 through 13 y 39 39 45 45 1,200 14 through 18 y 63 56 75 65 1,800 19 through 30 y 75 60 90 75 2,000 31 through 50 y 75 60 90 75 2,000 51 through 70 y 75 60 90 75 2,000 ≥ 70 y 75 60 90 75 2,000 Pregnancy £ 18 y 66 80 1,800 19 through 50 y 70 85 2,000 Lactation £ 18 y 96 115 1,800 19 through 50 y 100 120 2,000 a EAR = Estimated Average Requirement.
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From page 203... ...
PART III: VITAMIN C 203 VITAMIN C V itamin C (ascorbic acid) is a water-soluble nutrient that acts as an anti oxidant and a cofactor in enzymatic and hormonal processes.
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From page 204... ...
DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 204 Besides dose-dependent absorption, body vitamin C content is also regu lated by the kidneys, which conserve or excrete unmetabolized vitamin C Re nal excretion of vitamin C increases proportionately with higher intakes of the vitamin.
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From page 205... ...
PART III: VITAMIN C 205 Smoking: Studies have shown that smokers have decreased plasma and leukocyte levels of vitamin C compared to nonsmokers, even after adjusting for vitamin C intake from foods. Metabolic turnover of the vitamins has been shown to be about 35 mg/day greater in smokers.
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From page 206... ...
DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 206 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 people.
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From page 207... ...
PART III: VITAMIN C 207 TABLE 2 Potential Interactions with Other Dietary Substances Substance Potential Interaction Notes VITAMIN C AFFECTING OTHER SUBSTANCES Iron Vitamin C may enhance Vitamin C added to meals facilitates the intestinal the absorption of absorption of nonheme iron, possibly due to nonheme iron. lowering of gastrointestinal iron to the more absorbable ferrous state or to countering the effect of substances that inhibit iron absorption.
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From page 208... ...
DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 208 • Ecchymoses • Coiled hairs • Inflamed and bleeding gums • Perifollicular hemorrhages • Joint effusions • Arthralgia • Impaired wound healing Other signs and symptoms include dyspnea, edema, Sjögren's syndrome (dry eyes and mouth) , weakness, fatigue, and depression.
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From page 209... ...
PART III: VITAMIN C 209 KEY POINTS FOR VITAMIN C Vitamin C (ascorbic acid) is a water-soluble nutrient that acts 3 as an antioxidant and a cofactor in enzymatic and hormonal processes.
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From page 210... ...
DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 210 Severe vitamin C deficiency is rare in industrialized countries, 3 but it is occasionally seen in people whose diets lack fruits and vegetables or in those who abuse alcohol or drugs. Adverse effects have been associated primarily with large 3 doses (> 3,000 mg/day)
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