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Article History

Received: 6 February 2024

Revised: 31 March 2025

Accepted: 4 April 2025

First Online: 17 April 2025

Competing interests

: PYT, RL and KRS are employees of the Malaysian Palm Oil Board, who received and managed funding from the RMK-11 (Eleventh Malaysia Plan) Grant-PD219/16 (public funding), and conducted the study. KTT was formerly employed by the Malaysian Palm Oil Board when the study was conducted. The funder was not involved in the study design, collection, analysis and interpretation of data, the writing of the article, or the decision to submit it for publication. Other authors declare no conflicts of interest.

: The study adhered to the principles outlined in the Declaration of Helsinki and was registered at ClinicalTrials.gov under the identifier NCT03256123. Ethical approval was received from the Medical Research Ethics Committee, Ministry of Health (MOH) Malaysia (NMRR No: NMRR-16-1905-32547). The study was also approved with the participation of the respective health and education authorities. Before the study began, all literate parents provided written informed consents, while illiterate parents gave verbal consents and marked their thumbprints on the consent form, which were witnessed and formally documented. The parents were fully informed about the voluntary nature of their child’s participation, and their right to withdraw at any time. No child was withheld from receiving necessary medical care as part of the study protocol. Furthermore, the participants themselves signed an assent form.