Dietary fatty acids play an essential role in energy provision in humans, in addition to regulating various physiological functions and supplying essential fatty acids [1, 2]. Alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and linoleic acid (LA) cannot be synthesized (or are synthesized in insufficient quantities) in the human body, and hence need to be obtained through food. These essential fatty acids are necessary for healthy development of the body as well as various physiological processes, and thus an adequate intake (AI) of essential fatty acids is particularly important for adolescents [1, 2].

A recent study analyzing trends in the intake of dietary fats among Korean adolescents aged 12–18 years reported an increase of about 7.5 g/day in the total fat intake from 2007 to 2017. The intake of saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA) markedly increased, while omega-3 fatty acid (n-3 FA) intake showed no significant change [3]. Accordingly, the same study noted an increase from 13.7% in 2007–2009 to 27.5% in 2016–2017 in the proportion of adolescents consuming total fat above the acceptable macronutrient distribution range (AMDR), with 49.7% of adolescents consuming SFA above the AMDR in 2016–2017 [3].

Due to the different effects on physiological function, health status, and metabolic diseases of dietary fatty acids, consuming a balanced and adequate amount of dietary fatty acids is crucial. Previous studies on adolescents have shown that a higher SFA intake can have adverse effects on serum triglycerides and HDL-cholesterol levels [4], whereas n-3 FA intake, particularly ALA, EPA, and DHA, have been found to exert favorable effects on waist circumference, insulin resistance, and HDL-cholesterol levels [5, 6]. Additionally, the intake of EPA and DHA have been reported to be closely related to improving cognitive function and learning capabilities, as well as preventing immune-related diseases [7, 8].

Previous studies of adolescents in other countries have consistently reported that the intake of essential fatty acids does not meet the recommended levels [9, 10, 11]. In addition, a study analyzing trends in essential fatty acids intake among Korean adults showed an increasing trend in the intake of ALA and LA, whereas the intake of EPA and DHA decreased, with a shift in major dietary sources of essential fatty acids from fish and plant-based foods to animal-based foods [12]. However, there is a lack of research evaluating the intake of essential fatty acids and their food sources among Korean adolescents. Therefore, this study aimed to evaluate the dietary intake of essential fatty acids and their food sources among Korean adolescents and assess them against the 2020 Dietary Reference Intakes for Koreans (KDRIs) using data from the 2016–2021 Korea National Health and Nutrition Examination Surveys (KNHANES). In this study, through detailed monitoring of the essential fatty acids intake among Korean adolescents, the findings can be used to identify related nutritional health issues and provide foundational information necessary for developing nutrition education and dietary guidelines for aimed at adolescents.

In this study, the dietary intake and food sources of essential fatty acids among Korean adolescents aged 9–18 years were evaluated using data collected from the 2016–2021 KNHANES. As a result, the intake of essential fatty acids among Korean adolescents was found to be 1.29 g/day for ALA, 69.6 mg/day for EPA, 166.0 mg/day for DHA, and 11.1 g/day for LA. Compared to the AI of the 2020 KDRIs, the proportion of subjects consuming above the AI for each of these essential fatty acids was 35.7% for ALA, 30.4% for EPA + DHA, and 41.5% for LA, indicating that the intake of EPA + DHA had the highest percentage of adolescents below the AI.

In recent years, the total fat intake among Korean adolescents has shown an increasing trend, with a significant increase in the intake of SFA and MUFA, while no significant change has been observed in the intake of n-3 FA [3]. In addition, the n-6 FA intake showed a slight increase in boys, and no significant change in girls [3]. Particularly, it was reported that the proportion of Korean adolescents and young adults consuming SFA above the AMDR was higher compared to the other age groups [3, 19]. In a previous study analyzing changes in essential fatty acids intake among Korean adults between 2007 and 2018, an increase in the intake of ALA by 0.3 g/day and LA by 1.4 g/day was observed, while the intake of EPA showed a tendency to decrease [12]. Among the Korean adolescents evaluated in the present study, the ALA and LA intake increased with age. Furthermore, boys showed higher intakes than girls in all of the age groups evaluated. However, no significant differences were observed in the intake of EPA and DHA depending on sex or age group, with the age group of 15–18 years showing the lowest intake of EPA and DHA. In a recent study that evaluated fatty acids intake in Koreans aged 1 year or older using data from the 2019–2021 KNHANES, usual daily intake of fatty acids was estimated based on dietary data obtained from one-day 24-hour dietary recall [20]. As a result, the usual dietary intake of ALA for Koreans was reported to be 1.399 g/day, EPA 0.099 mg/day, DHA 0.217 mg/day, and LA 9.88 g/day [20].

When comparing the intake levels of essential fatty acids among Korean adolescents with those in other countries, the ALA and LA intake among the US adolescents (12–19 years old) based on the one-day 24-hour dietary recall data from the 2017–2020 National Health and Nutrition Examination Surveys was higher than that of Korean adolescents, but EPA and DHA intake was lower [16]. Based on dietary data from 2 non-consecutive days of 24-hour dietary recall conducted in 2006–2007, 1,804 European adolescents (12.5–17.5 years old) showed a similar intake level of essential fatty acids as the subjects in the present study [21]. Australian and Brazilian adolescents also showed ALA and LA intake levels similar to those of Korean adolescents [5, 15]. The results of dietary assessment in Iranian adolescents using a food frequency questionnaire in 2011–2012 showed an intake level of EPA and DHA that was similar to Korean adolescents, but the ALA and LA intakes were 0.3 g/day and 17.54 g/day, respectively, which showed a significant difference [18]. The ALA intake of Costa Rican adolescents (13–18 years old) was reported to be as high as 2.55 g/day, while the EPA and LA intakes were also higher compared to adolescents in other countries [17]. Due to variations in sex and age composition among the study subjects, dietary assessment methods, and survey period across studies, a direct comparison of the results on the intake of essential fatty acids represented a challenge. Nonetheless, it was possible to identify a significant variation in the intake patterns of essential fatty acids in adolescents across different countries.

The current study found that the proportion of Korean adolescents consuming each essential fatty acid above AI did not exceed 50% in all sex and age groups. In particular, only 30% of Korean adolescents consumed EPA + DHA above AI. Previous studies in other countries have consistently reported that essential fatty acids intake in adolescents fail to meet the recommended levels [1, 9, 10, 11]. A systematic review on the intake of essential fatty acids in European countries revealed that the majority failed to meet the recommended levels for EPA + DHA intake, with only 2 out of 10 countries reaching the recommended intake levels [11]. When evaluating the intake of essential fatty acids among children and adolescents aged 4–12 years in Indonesia, the proportion of subjects with an intake below the reference level from Food and Agriculture Organization/World Health Organization criteria for ALA, EPA + DHA, and LA was reported as 84%, 80.9%, and 31%, respectively [1]. In a study of 822 Australian adolescents, the proportion of subjects who consumed above AI did not exceed 50% for each essential fatty acid, with less than 10% of the participants meeting the recommended intake criteria for EPA + DHA [10]. In French adolescents, it was reported that fewer than 10% achieved the recommended intake level for ALA and EPA + DHA, respectively [9]. Although essential fatty acids play an important role in the nutritional status and development of adolescents, the results showed that the intake levels of ALA and EPA + DHA did not meet the recommended levels in adolescents from various countries, including Korea. This highlights the need for the provision of dietary strategies for improving the intake of EPA + DHA, along with the periodic monitoring of essential fatty acids intake.

The main sources of essential fatty acids for Korean adolescents in this study were similar to those of Korean adults [12]. The main sources of ALA and LA were plant oils, mayonnaise, pork, and eggs, while fish contributed significantly to EPA and DHA. For Korean adults, beans and walnuts were among the top food sources of ALA. For Korean adolescents, snacks, biscuits and cookies were included in the list of main food sources of ALA, EPA, and DHA. In particular, the proportion of snacks, biscuits and cookies, from which adolescents derived their EPA and DHA intake was higher in girls compared to boys. Among Australian adolescents, the highest proportion of essential fatty acids were derived from the food sources as follows: 1) dairy products, margarine, potato and potato chips, and red meat for ALA; 2) fish and red meat for EPA and DHA; 3) margarine, bread, vegetable oils, cereals, potato chips, and poultry for LA [10, 22]. Similar reports found that Indonesian adolescents mainly derived their ALA intake from plant-based dishes, beans, nuts, and seeds, while the intakes of EPA and DHA were mainly derived from fish, which contributed to 91.2% of the intake of these essential fatty acids [1]. Among adolescents from European countries, the main dietary sources of ALA were meat, bread and cake, snacks, seasonings, and sauces. In addition, the main food sources of EPA and DHA were fish, meat, and eggs, while the main sources of LA were plant oils, meat, bread and snacks, seasonings, and sauces [9, 21].

The main food sources of essential fatty acids among adolescents in each country appear to differ due to differences in various factors, including the eating habits of adolescents, the food environment of households and communities, and the food culture of each country. However, a significant proportion of the intake of essential fatty acids has been attributed to animal-based food sources and processed foods across previous studies of adolescents, and these food sources also tend to be high in SFA and trans fatty acid. According to the KDRIs, foods rich in ALA include perilla oil, nuts, seeds, and beans, while EPA and DHA are predominantly found in oily fish [14]. This suggests that adolescents should be encouraged to choose healthy food sources that are rich in essential fatty acids while reducing their intake of animal-based and processed foods.

A limitation of this study is the challenge of reflecting the usual dietary intake of essential fatty acids in the study subjects based solely on an analysis of the dietary intake data obtained through a single 24-hour dietary recall. This method could underestimate the proportion of subjects meeting the KDRIs [20]. However, despite this limitation, given the lack of research on the evaluation of essential fatty acids intake in adolescents, it is worth highlighting the fact that this study analyzed essential fatty acids intake and food sources from a representative sample of Korean adolescents based on national-level nutritional survey data. The findings of this study can therefore be used as a basis from which to develop dietary guidelines and nutrition education for Korean adolescents, and are expected to contribute to improving the dietary practices and health status of adolescents across the world.

This study evaluated the dietary intake and food sources of essential fatty acids among Korean adolescents aged 9–18 years based on data obtained from the 2016–2021 KNHANES. We also evaluated essential fatty acids intake by comparing it with the AI levels of KDRIs. Our findings revealed that the proportion of Korean adolescents consuming essential fatty acids above the AI of KDRIs was relatively low, with 35.7% for ALA and 30.4% for EPA + DHA. As the nutritional status of adolescents has a significant impact on their growth and development, as well as their health and disease status in adulthood, detailed monitoring of nutrient intake during adolescence is necessary. In particular, this study is significant in that it is among the first to evaluate the intake patterns of essential fatty acids in Korean adolescents, which is lacking research. Based on the results of this study, an appropriate intake of essential fatty acids and a selection of healthy food sources should be emphasized through dietary guidelines and nutrition education aimed at adolescents. Future studies will need to examine trends in essential fatty acids intake among Korean adolescents, as well as determine the relationship between their essential fatty acids intake and health status.