The findings were presented in a paper titled “Food and nutrient intake in dietary supplement users: a nationwide school-based study in Japan” published in the Journal of Nutritional Science.
The team investigated the conundrum using a cross-sectional school survey supported by the Ministry of Education, Culture, Sports, Science and Technology of Japan and local educational boards at the prefectural and municipal levels.
The survey periodically documented the dietary intakes of 910 children from 14 elementary and 13 junior high schools aged eight to nine years old, 10 to 11 years old and 13 to 14 years old. The subjects were recruited from across Japan from November to December 2014. Dietary supplements were defined as containing at least one vitamin and one mineral.
Some measurements include estimation using the Standard Tables of Food Composition in Japan, categorisation of food types and calculation of nutrients.
Of the 910 children, 80 or 8.8% used dietary supplements, and 20 (2.3%) used dietary supplements every day.
The study participants were grouped as users and non-users of dietary supplements. The dietary supplement users were significantly older and participated less frequently in sports than non-users. The income per capita was also significantly higher for dietary supplement users than for non-users.
Most guardians then reported that they intended to provide fruits and vegetables to their children. Accessibility to fruits and vegetables was significantly lower for dietary supplement users than for non-users. Additionally, dietary supplement users had a significantly lower intake of fruits and vegetables than non-users.
In school lunches, the dietary supplement users had a significantly higher intake of energy and oils and a significantly lower protein intake than non-users. In meals consumed outside school, dietary supplement users had a significantly higher intake of confectioneries and a significantly lower intake of fruits and vegetables, folate, vitamin C and dietary fibre.
Inconsistent with previous studies, fruit and vegetable intake was significantly lower, whereas confectionary intake was significantly higher in dietary supplement users than in non-users. This difference suggests that dietary supplement users were less likely to consume healthy diets than non-users in the present study for Japanese children.
A plausible explanation could be understood through the “compensation hypothesis”, which suggests that individuals use dietary supplements to compensate for an unhealthy diet. The use of dietary supplements among the subjects may reflect their guardians’ belief that dietary supplements, such as multivitamins, are good substitutes for fruits and vegetables.
In conclusion, this study demonstrated that dietary supplement use in children was associated with a lower mean intake of fruits and vegetables.
“Further studies are warranted to confirm these results and investigate whether appropriate dietary supplements are used to compensate for unhealthy diets in children,” concluded the researchers.
The study was funded by the Ministry of Health, Labour and Welfare of Japan.
Source: Journal of Nutritional Science
“Food and nutrient intake in dietary supplement users: a nationwide school-based study in Japan”
Authors: Kazue Ishitsuka et al