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Dietary Reference Intakes (DRI) of Vitamin C
Introduction to Vitamin C DRI
Vitamin C, also known as ascorbic acid, is a crucial nutrient for maintaining overall health. The Dietary Reference Intakes (DRIs) for vitamin C are established to ensure adequate intake levels for various population groups, including men, women, children, pregnant women, and the elderly. These guidelines are formulated by the Food and Nutrition Board of the Institute of Medicine (IOM) and are periodically updated based on the latest scientific evidence.
Recommended Dietary Allowance (RDA) for Vitamin C
The Recommended Dietary Allowance (RDA) for vitamin C is designed to meet the nutritional needs of nearly all (97-98%) healthy individuals in specific life stages and gender groups. For adults aged 19 years and older, the RDA is set at 90 mg/day for men and 75 mg/day for women4. These values are slightly higher than the previous RDA of 60 mg/day for both men and women, reflecting updated research and understanding of vitamin C's role in health.
Vitamin C Intake During Pregnancy
Pregnant women have increased nutritional needs, including for vitamin C. Research indicates that a daily intake of 100 mg of vitamin C during the second half of pregnancy is sufficient to maintain adequate leukocyte vitamin C concentrations, which are crucial for both maternal and fetal health3. This intake level helps ensure that pregnant women maintain optimal vitamin C status without excessive urinary excretion.
Tolerable Upper Intake Level (UL) for Vitamin C
The Tolerable Upper Intake Level (UL) is the maximum daily intake unlikely to cause adverse health effects in the general population. For vitamin C, the UL is set at 2 grams (2000 mg) per day for adults4. This level is based on evidence that very high intakes of vitamin C (2-4 g/day) are generally well tolerated in healthy individuals, although there is insufficient data to define a precise UL1.
Vitamin C Requirements for Different Population Groups
Children and Adolescents
The vitamin C requirements for children and adolescents vary by age and gender. The RDA values are adjusted to ensure adequate growth and development. For example, children aged 1-3 years require 15 mg/day, while those aged 4-8 years need 25 mg/day. Adolescents aged 14-18 years require 75 mg/day for boys and 65 mg/day for girls2.
Elderly Population
Elderly individuals may have different vitamin C needs due to changes in metabolism and absorption efficiency. The RDA for older adults remains the same as for younger adults, but ensuring adequate intake is crucial for maintaining immune function and overall health2.
Biomarkers and Vitamin C Intake
Plasma vitamin C levels are often used as biomarkers to assess dietary vitamin C intake. Studies show a moderate correlation between dietary intake methods (such as Food Frequency Questionnaires and Dietary Recalls) and plasma vitamin C levels, indicating that these methods can reasonably predict vitamin C status5. However, factors such as bioavailability, absorption conditions, and external influences like stress and food processing can affect this relationship.
Conclusion
The DRIs for vitamin C are essential guidelines to ensure adequate intake and prevent deficiency in various population groups. The RDA values are based on the latest scientific evidence and are designed to meet the needs of nearly all healthy individuals. Pregnant women, children, and the elderly have specific requirements that must be met to maintain optimal health. Understanding and adhering to these guidelines can help individuals achieve and maintain adequate vitamin C status.
Sources and full results
Most relevant research papers on this topic
Biomarkers for establishing a tolerable upper intake level for vitamin C.
Very high intakes of vitamin C (2-4 g/day) are well tolerated in healthy mammalian systems, but strong scientific evidence is needed to define a Tolerable Upper Intake Level for vitamin C.
Highly CitedRecommended dietary intakes (RDI) of vitamin C in humans.
Maintaining a suitable vitamin C intake of 900 mg for an adult male is sufficient, with no known health advantages at higher levels.
Highly Cited[Bases to determine the dose of vitamin C in pregnancy].
A 100 mg/day dose of vitamin C during the second half of pregnancy maintains leukocyte storage and could help establish the daily recommended intake during pregnancy.
RCTThe new US Dietary Reference Intakes for vitamins C and E
The new US Dietary Reference Intakes for vitamins C and E are 90 mg/day for men and 75 mg/day for women, with no recommendations for -carotene or other carotenoids.
Is plasma vitamin C an appropriate biomarker of vitamin C intake? A systematic review and meta-analysis
Food Frequency Questionnaire and Dietary Recall methods show a moderate relationship with plasma vitamin C levels, but this correlation may be affected by factors such as vitamin bioavailability, absorption condition, stress, food processing, and storage time.
Meta-Analysis
Rigorous JournalHighly CitedCirculating vitamin C concentration and risk of cancers: a Mendelian randomization study
Circulating vitamin C has no strong evidence of a causal association with the five most common cancers in European populations, but higher dietary intake may reduce lung cancer risk.
Meta-AnalysisRigorous JournalGenetically predicted vitamin C levels significantly affect patient survival and immunotypes in multiple cancer types
Vitamin C levels are significantly correlated with overall survival and immune characteristics in multiple cancer types, with potential therapeutic potential in colon cancer.
Meta-AnalysisThe effects of surgery on plasma/serum vitamin C concentrations: a systematic review and meta-analysis
Postoperative plasma vitamin C concentrations show a mean depletion of 39.9% during the first week and 21.1% 2-3 months postoperatively.
Meta-Analysis
Very Rigorous JournalQuantitation of vitamin C content in herbal juice using direct titration.
Direct titration with iodine effectively quantifies vitamin C content in herbal juices, with excellent linearity and precision.
Highly CitedMatrix-specific method validation for quantitative analysis of vitamin C in diverse foods
The method for analyzing vitamin C in diverse foods is reliable and accurate, but requires adjustments for specific matrices to avoid over- or underestimation.
Highly Cited