• Nutrition Research and Practice
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• v.16 no.sup1
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• pp.126-133
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• 2022

Choline is a water-soluble organic compound that is important for the normal functioning of the body. It is an essential dietary component as de novo synthesis by the human body is insufficient. Since the United States set the Adequate Intakes (AIs) for total choline as dietary reference values in 1998, Australia, China, and the European Union have also established the choline AIs. Although choline is clearly essential to life, the 2020 Dietary Reference Intakes for Koreans (KDRIs) has not established the values because very few studies have been done on choline intake in Koreans. Since choline intake levels differ by race and country, human studies on Koreans are essential to set KDRIs. Therefore, the present study was undertaken to provide basic data for developing choline KDRIs in the future by analyzing data on choline intake in Koreans to date and reference values of choline intake and dietary choline intake status by country and race.

• Nutrition Research and Practice
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• v.16 no.sup1
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• pp.57-69
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• 2022

BACKGROUND/OBJECTIVES: Vitamin D is produced in the skin during sun exposure and is also ingested from foods. The role of vitamin D needs to be considered in the prevention and management of various diseases. Moreover, since the majority of Koreans spend their days indoors, becoming susceptible to the risk of vitamin D deficiency. The current study aims to prepare a basis for determining dietary reference intake of vitamin D in Korea, by reviewing the evidence against various diseases and risks. MATERIALS/METHODS: Literature published in Korea and other countries between 2014 and 2018 was prioritized based on their study design and other criteria, and evaluated using the RoB 2.0 assessment form and United States Department of Agriculture Nutrition Evidence Library Conclusion Statement Evaluation Criteria. RESULTS: Of the 1,709 studies, 128 studies were included in the final systematic analysis after screening. To set the dietary reference intakes of vitamin D based on the selected articles, blood 25(OH)D levels and indicators of bone health were used collectively. Blood vitamin D levels and ultraviolet (UV) exposure time derived from the Korean National Health and Nutrition Examination Survey were analyzed to establish the dietary reference intakes of vitamin D for each stage of the life cycle. The adequate intake levels of vitamin D, according to age and gender, were determined to be in the range of 5-15 ㎍/day, and the tolerable upper intake level was established at 25-100 ㎍/day. CONCLUSIONS: The most important variable for vitamin D nutrition is lifestyle. A balanced diet comprising foods with high contents of vitamin D is important, as is vitamin D synthesis after UV exposure. The adequate intake level of vitamin D mentioned in the 2015 Dietary Reference Intakes for Korean (KDRI) remained unchanged in the 2020 KDRI for the management of vitamin D nutrition in Koreans.

• Journal of Nutrition and Health
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• v.55 no.4
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• pp.441-449
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• 2022

This review is focused on analyzing the limits and shortage of zinc (Zn) for the 2020 Dietary Reference Intakes for Koreans (KDRIs), and provides suggestions for the future establishment of the 2025 KDRIs for Zn. The 2020 KDRIs for Zn have been established to estimate the adequate requirement (EAR), recommended nutrient intakes (RNI), adequate intake (for only 0-5 mon) and tolerable upper intake level (UL). EAR was estimated in 2-stages: the first stage was to construct of the frame of analysis for Zn requirement and the second stage involved a factorial approach by considering the various factors which affect Zn requirement, such as intestinal and urine Zn loss, Zn requirement for growth and development, and Zn absorption rate. For a more precise and accurate establishment of the Zn requirement, we suggest for the following to be considered: 1) considering that Zn is present in minuscule amounts as a trace element in our body, the present values for Zn EAR (as 6-9 mg/d) should be expressed as a decimal point for more accurate DRIs; 2) the frame of analysis for Zn requirement has to be more specifically and should includes the factors which affect Zn requirement; 3) both, the factorial approach and extrapolation method need to be well reviewed and thoroughly understood for establishing precise Zn requirement; 4) currently, human clinical study and balance study (Zn intake, excretion and absorption rate) are limited and more human Zn subject studies are required. All these suggestions are provided to better establish the Zn requirement in the 2025 KDRIs.

• Nutrition Research and Practice
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• v.16 no.sup1
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• pp.89-112
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• 2022

An accurate assessment of the recommended calcium (Ca) intake may contribute to reducing the risk of fractures and chronic diseases, ultimately improving quality of life. This review was performed to summarize key findings of Ca studies, investigate the effect of Ca intake on health outcomes, and determine the adequacy of evidence to revise the 2015 Dietary Reference Intakes for Koreans (KDRIs) for Ca in 2020. Databases were searched for intervention studies that assessed health outcomes by providing Ca in diets or as supplements. The framework of the systematic review comprised conducting literature searches, data extraction, quality assessment of the literature, and summarizing key findings relevant to set the Estimated Average Requirement (EAR) and Tolerable Upper Intake Level (UL) for Ca for the 2020 KDRI. The final search was performed in June 2019. A total of 13,309 studies were identified through databases and manual search. Sixtyfive studies were included in the final quality assessment and were summarized according to health indicators. As bone health was used as an indicator of the EAR for Ca, literature reports on bone health were further categorized by the life-cycle stage of the participants. This systematic review did not find new evidence that could be applied to the general Korean adult population, including postmenopausal women, for defining a new EAR for Ca in the 2020 KDRIs. Evidence in most of the reviewed literature was considered weak; however, some evidence was found that could improve the criteria on how the EAR for Ca was determined in children and adolescents. A review of the literature for the 2020 KDRIs for Ca did not find strong evidence in order to change the recommended values of the 2015 KDRIs. More clinical interventions are required among Koreans to strengthen the body of evidence to warrant the revision of the KDRIs.

• Nutrition Research and Practice
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• v.16 no.sup1
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• pp.113-125
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• 2022

In the current years, it has now become necessary to establish standards for micronutrient intake based on scientific evidence. This review discusses issues related to the development of the 2020 Dietary Reference Intakes for Koreans (KDRI) for magnesium (Mg), zinc (Zn), and copper (Cu), and future research directions. Following issues were encountered when establishing the KDRI for these minerals. First, characteristics of Korean subjects need to be applied to estimate nutrient requirements. When calculating the estimated average requirement (EAR), the KDRI used the results of balance studies for Mg absorption and factorial analysis for Zn, which is defined as the minimum amount to offset endogenous losses for Zn and Mg. For Cu, a combination of indicators, such as depletion/repletion studies, were applied, wherein all reference values were based on data obtained from other countries. Second, there was a limitation in that it was difficult to determine whether reference values of Mg, Zn, and Cu intakes in the 2020 KDRI were achievable. This might be due to the lack of representative previous studies on intakes of these nutrients, and an insufficient database for Mg, Zn, and Cu contents in foods. This lack of database for mineral content in food poses a problem when evaluating the appropriateness of intake. Third, data was insufficient to assess the adequacy of Mg, Zn, and Cu intakes from supplements when calculating reference values, considering the rise in both demand and intake of mineral supplements. Mg is more likely to be consumed as a multi-nutrient supplement in combination with other minerals than as a single supplement. Moreover, Zn-Cu interactions in the body need to be considered when determining the reference intake values of Zn and Cu. It is recommended to discuss these issues present in the 2020 KDRI development for Mg, Zn, and Cu intakes in a systematic way, and to find relevant solutions.

• Journal of Nutrition and Health
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• v.57 no.4
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• pp.365-375
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• 2024

Purpose: Zinc is involved in regulating homeostasis and metabolism in the body, and understanding these processes is important for estimating intake requirements. This review aimed to assist in setting the standards for Dietary Reference Intakes for Koreans (KDRIs, 2025) for zinc by examining specific factors associated with role of zinc in the body and using the factorial analysis method. Methods: We reviewed the zinc-specific factors that should be considered when setting the required zinc intake to maintain zinc homeostasis in the body and used the factorial analysis method for estimating zinc requirements for different population groups. Results: Factorial analysis involves estimating the required intake based on various factors that affect zinc metabolism and requirements. The key components and steps involved in determining the zinc dietary reference intake (DRI), particularly the estimated average requirement (EAR), include: 1) Estimating basal requirements, which involves calculating the amount of zinc needed to replace natural losses through the intestinal (feces) and non-intestinal (urine, skin and other body secretions) routes, 2) Accounting for the various biomarkers related to metabolic functions of zinc, 3) Considering physiological requirements for zinc, such as those for growth, development, pregnancy, and lactation since zinc is essential for DNA and protein synthesis, and 4) Estimating the dietary absorption rate of zinc. Conclusion: The factorial analysis for zinc requirement is based on scientific evidence and is tailored to meet the requirements of different population groups, ensuring optimal health and preventing deficiency. It includes considerations of physiological needs, dietary absorption, and population-specific characteristics.

• Nutrition Research and Practice
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• v.12 no.6
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• pp.459-468
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• 2018

BACKGROUND/OBJECTIVES: The Dietary Reference Intakes for Koreans (KDRIs), a set of reference intake values, have served as a basis for guiding a balanced diet that promotes health and prevents disease in the general Korean population. In the process of developing DRIs, a systematic review has played an important role in helping the DRI committees make evidence-based and transparent decisions for updating the next DRIs. Thus, the 2015 KDRI steering committee applied the systematic review framework to the revision process of the KDRIs. The purpose of this article is to summarize the revision process for the 2015 KDRIs by focusing on the systematic review framework. MATERIALS/METHODS: The methods used to develop the systematic review framework for 2015 KDRIs followed the Agency for Healthcare Research and Quality and the Tufts Evidence-based Practice Center. The framework for systematic review of the 2015 KDRIs comprised of the 3 following steps: (1) development of an analytic framework and refinement of key questions and search terms; (2) literature search and data extraction; and, (3) appraisal of the literature and summarizing the results. RESULTS: A total of 203,237 studies were retrieved through the above procedure, with 2,324 of these studies included in the analysis. General information, main results, comments of reviewers, and results of quality assessment were extracted and organized by study design. The average points of quality appraisals were 3.0 (range, 0-5) points for intervention, 6.1 (0-9) points for cohort, 6.0 (3-9) points for nested case-control, 5.4 (1-8) points for case-control, 14.6 (0-22) points for cross-sectional studies, and 7.0 (0-11) points for reviews. CONCLUSIONS: Systematic review helped to establish the 2015 KDRIs as a useful tool for evidence-based approach. Collaborative efforts to improve the framework for systematic review should be continued for future KDRIs.

• Journal of Nutrition and Health
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• v.54 no.6
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• pp.573-583
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• 2021

Energy requirement is defined as energy expenditure in an energy equilibrium state. The doubly labeled water (DLW) method is considered the gold standard for measuring total energy expenditure (TEE). In 2002, the Institute of Medicine (IOM) of the National Academies established dietary reference intakes (DRIs) for Americans and Canadians, and the equations for estimated energy requirement (EER) were developed by using pooled data from studies that had applied the DLW method. Since 2005, these equations have been used for establishing EER in the DRI for Koreans. These equations based on age group include the physical activity (PA) coefficient determined by the PA level (PAL; sedentary, low active, active and very active) as well as body weight and height. The PAL values of Koreans calculated using the DLW method and PA diaries were determined to fall in the low active category (1.40~1.59). Therefore, the PA coefficient corresponding to 'low active' was applied to the EER equations. In recent years, with increasing number of people regularly engaging in various physical activities in Korea, EER is now separately presented for people with 'active' and 'very active' PALs. In the future, like the United States and Japan, Korea needs to expand the DLW research for developing EER predictive equations for Koreans. In addition, standardized guidelines should be prepared to accurately evaluate the PAL using the physical activity diary and the new PA classification table for Koreans.

• Korean Journal of Community Nutrition
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• v.21 no.4
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• pp.344-353
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• 2016

Objectives: New retinol activity equivalent (RAE) was introduced as vitamin A unit in Dietary Reference Intake (DRI) for Koreans 2015. The purpose of this study was to evaluate the adequacy of 2015 reference intake (RI) of vitamin A in RAE unit by the comparison with RI and dietary intake of vitamin A. Methods: Analyses on RI of vitamin A were based on the Recommended Dietary Allowances (RDA) for Koreans (1962~2000) and DRIs for Koreans (2005~2015). Analyses on Koreans dietary intake of vitamin A were based on the Korea National Health and Nutrition Examination Survey (KNHNES) reports (1969-2014). For recalculation of RI and dietary intake of vitamin A in RE to RAE, 2013 Koreans intake of retinol: carotenoids ratio of 13: 87 was applied. Results: RI of vitamin A was 600~750 RE for Korean adult, and 339~425 RAE when calculated by applying the retinol and carotenoids intake ratio. Vitamin A intakes of Koreans were <100% RI, 267~668 RE from 1969 to 2001. From 2005, vitamin A intake had increased to >700 RE, >100% RI. When vitamin A intake was converted from RE to RAE (2005~2014), 718~864 RE became 405.8~488.1 RAE, decreased to 56.5% level. The recent 2015 RI of vitamin A is 850 RAE, two times of 2005 & 2010 RI of 425 RAE for adult male. Conclusions: When nutritional status of vitamin A was assessed for Koreans using the estimated average requirement (EAR) of 2015 (570, 460 RAE for male, female adults, respectively), ratio of deficient people increased significantly when judged based on the previous intake of Koreans, <490 RAE. We needs to examine the 2015 RI (EAR) of vitamin A, find a way to measure the accurate intake of dietary vitamin A, and to increase the dietary intake of this vitamin.

• Journal of the East Asian Society of Dietary Life
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• v.17 no.4
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• pp.483-489
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• 2007

This study was performed to investigate dietary habits, and to evaluate the relationship between nutritional status and certain blood parameters in premenopausal and postmenopausal women living in Daejeon. Adult Korean females(n=110) that had visited the Health Promotion Center of Eulji University Hospital were analyzed. We examined blood parameters, body composition, and life style factors such as food habits and physical activity in pre- and post-menopausal women. The collected data were then analyzed to evaluate the various items. Overall, there were no differences between the pre- and post-menopausal women for food habit score, or for intakes of energy, protein, Int, iron, vitamin A, vitamin $B_1$, vitamin $B_2$, niacin, vitamin C, and calcium. However, carbohydrate intake was significantly higher in the postmenopausal women than in the premenopausal women. The Dietary Reference Intakes for Koreans(KDRIs), in terms of energy, fat, calcium, vitamin A and vitamin $B_1$, were less than 100% in both the premenopausal women and postmenopausal women. All intakes of protein, iron, vitamin $B_2$, niacin, and vitamin C satisfied the KDRIs in both groups. Finally, the postmenopausal women had higher serum fasting blood glucose, total cholesterol, LDL-cholesterol and alkaline phosphatase levels than the premenopausal women.