Impact of Dietary Supplement Usage on Nutrient Adequacy and the Risk of Nutrient Excess Among Korean Adults

OBJECTIVES: The growing popularity of frequent dietary supplements (DS) use raises concerns about DS overconsumption, posing challenges in achieving nutritional balance while avoiding excessive intake. Nonetheless, most studies have compared DS users with non-users without examining specific usage patterns. This study aimed to identify the varying DS usage patterns, frequencies, and associated nutrient adequacy and excess in 9889 Korean adults from the 2019-2020 KNHANES. METHODS: Dietary intake was assessed using a 24-h recall. DS use was assessed using structured questionnaires. Nutrient intakes from foods and DS were compared to reference levels, including estimated average requirements (EAR) and tolerable upper intake levels (UL), according to daily DS tablet consumption level. The mean adequacy ratio (MAR) was also calculated to assess overall nutritional adequacy. RESULTS: Fifty-six percent of Korean adults used DS, and 61% of DS users consumed two or more DS products. Among multiple DS users, multivitamins were the most commonly used types of DS, often taken with single vitamins, and mineral products. Compared to food alone, nutrient intake at any level of daily DS tablet consumption was mostly associated with a lower prevalence of intake below the EAR (p-trend < 0.001). However, the prevalence of exceeding UL increased with the use of a greater daily DS tablet consumption for vitamin C, iodine, iron, magnesium (all p-trend ≤ 0.022), while the MAR improvements plateaued. CONCLUSIONS: While frequent DS use reduces micronutrient inadequacy, it may increase the risk of excessive intake, yielding only diminished gains in overall nutritional adequacy.