Rda of vitamins
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Recommended Dietary Allowances (RDA) of Vitamins: A Comprehensive Overview
Vitamin C RDA: Discrepancies and New Recommendations
Global Variations in Vitamin C RDA
The recommended dietary allowance (RDA) for vitamin C varies significantly across different countries, with discrepancies arising from differing interpretations of scientific data. Some recommendations are based on outdated assumptions from the 1960s and 1970s, which have been proven to underestimate the actual needs1. Factors such as gender, age, pregnancy, lactation, and smoking are considered by some authorities but not all, leading to further inconsistencies1.
Updated RDA Based on Chronic Disease Prevention
Recent evidence suggests that the current RDA of 60 mg/day for vitamin C, aimed at preventing scurvy, is insufficient for optimal health. Studies indicate that an intake of 90-100 mg/day is more effective in reducing the risk of chronic diseases like cancer and cardiovascular disease, suggesting a new RDA of 120 mg/day3. Another study supports increasing the RDA to 200 mg/day based on pharmacokinetic data showing that this amount achieves optimal plasma and tissue saturation without adverse effects5.
Vitamin D RDA: Ethnic and Weight Considerations
RDA for Different Ethnic Groups
The Institute of Medicine (IOM) set the RDA for vitamin D at 600 IU/day for individuals up to 70 years old and 800 IU/day for those older. However, recent studies indicate that these values may not be adequate for African American adults, who may require up to 1640 IU/day to maintain optimal serum 25-hydroxyvitamin D levels2. This discrepancy highlights the need for ethnic-specific RDA values to address varying risks of vitamin D deficiency2.
Weight-Specific Recommendations
Research has shown that body weight significantly affects vitamin D requirements. For normal weight individuals, 1885 IU/day is recommended, while overweight and obese individuals may need 2802 IU/day and 6235 IU/day, respectively, to achieve optimal serum levels4. This approach aims to minimize the risk of both low and high vitamin D concentrations, which can have adverse health effects4.
Vitamin A RDA: Adjustments for Different Populations
General Population and Special Groups
The RDA for vitamin A is set at 700 micrograms for men and 600 micrograms for women, based on maintaining adequate body stores to meet physiological needs and provide a reserve7. However, these values may need adjustment for specific groups such as infants, children, the elderly, and pregnant or lactating women, who have different requirements7.
Elderly Population
For older women, current RDAs for vitamin A and vitamin C may need to be increased. A study found that the calculated RDA for vitamin C should be 115 mg/day, higher than the current recommendations, to meet the needs of this demographic10.
Conclusion
The RDA values for vitamins are crucial for public health but require periodic reevaluation to reflect new scientific evidence and address the needs of different population groups. For vitamin C, an increase to 120-200 mg/day is suggested to optimize health benefits. For vitamin D, ethnic-specific and weight-specific recommendations are necessary to ensure adequate intake. Finally, the RDA for vitamin A and other vitamins may need adjustments for special populations, particularly the elderly, to ensure optimal health outcomes.
Sources and full results
Most relevant research papers on this topic
Discrepancies in global vitamin C recommendations: a review of RDA criteria and underlying health perspectives
Global vitamin C recommendations vary by more than five fold, with discrepancies in criteria and underlying health perspectives, and body weight not being considered in current recommendations.
Literature Review
Highly CitedThe vitamin D RDA for African American adults: higher than that for white persons?
The recommended daily allowance for vitamin D for African American adults is 1640 IU/d, significantly higher than the age-specific 600 and 800 IU/d established by the IOM.
RCT
Very Rigorous JournalToward a new recommended dietary allowance for vitamin C based on antioxidant and health effects in humans.
A new recommended dietary allowance for vitamin C should be 120 mg/d for optimal reduction of chronic disease risk in nonsmoking men and women, based on antioxidant and health effects in humans.
Literature ReviewHighly CitedOptimal Vitamin D Supplementation Doses that Minimize the Risk for Both Low and High Serum 25-Hydroxyvitamin D Concentrations in the General Population
Optimal vitamin D supplementation doses should be individualized to minimize the risk of both low and high serum 25-hydroxyvitamin D concentrations, rather than a single recommended daily allowance.
Very Rigorous JournalVitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance.
The current recommended daily allowance for vitamin C should be increased to 200 mg from fruits and vegetables, with safe doses below 1000 mg and no evident value above 400 mg.
Non-RCTHighly CitedFat-soluble vitamins in food supplements: do the labels follow the recommended doses?
Most food supplement labels recommend daily doses of fat-soluble vitamins above the recommended daily allowance, potentially causing adverse health effects.
Observational StudyRecommended dietary intakes (RDI) of vitamin A in humans.
Lower recommended dietary intakes of vitamin A (RDI) are preferable to the 1980 RDA values, as they provide adequate levels for all physiological needs and a reserve for 4 months on low intakes or during stress.
Highly CitedVitamin D in liquid food supplements: are labels in line with RDA?
Most liquid food supplement labels in Portugal exceed the recommended daily allowance for vitamin D, with some exceeding the tolerable upper intake level defined by EFSA.
The 2011 Report on Dietary Reference Intakes for Calcium and Vitamin D from the Institute of Medicine: What Clinicians Need to Know
The 2011 IOM report on dietary reference intakes for calcium and vitamin D supports their key role in skeletal health, but the evidence for extraskeletal outcomes is inconsistent and insufficient to inform nutritional requirements.
Literature Review
Rigorous JournalHighly CitedAre the Recommended Dietary Allowances for Vitamins Appropriate for Elderly People?
Current RDAs are adequate for older women's intake of riboflavin, vitamin B-6, and folic acid, but should be raised for vitamin B-12 and vitamin C.
Observational Study