Essential Trace Elements in Commonly Consumed Varieties of Sri Lankan Cooked Rice and Its Dietary Significance: A Focus on Recommended Daily Allowances

Essential trace elements (ETEs) are indispensable micronutrients required in trace amounts for maintaining metal homeostasis and supporting critical physiological functions. Dietary intake is the principal source, with deficiencies linked to numerous chronic conditions. In Sri Lanka, rice ( Oryza sativa L.) is the staple food and a primary source of ETEs. However, post-harvest and culinary processes significantly influence ETE bioavailability. This study assessed Zn, Se, Mn, and Cu concentrations in raw and cooked grains from 25 rice-composites representing widely consumed Sri Lankan rice, including Traditional ( Suwandel, Kaluheenati, Pachchaperumal ), Improved (White/Red Nadu, Samba, Kekulu ), and Imported (Indian Basmati) varieties. Samples were stratified by pericarp color (red/white) and parboiling treatment. Standardized domestic cooking methods were applied, and lyophilized samples were digested and profiled using ICP-MS. Mean ± SD concentrations in raw grains (mg/kg dry weight) were: Zn 32.02 ± 6.82, Se 0.049 ± 0.016, Mn 13.71 ± 3.86, Cu 0.47 ± 0.83. Red pericarp and parboiled varieties exhibited significantly higher ETE levels ( p  < 0.05), with Traditional cultivars enriched in Se and Mn ( p  < 0.05). Cooking led to significant reductions ( p  < 0.001): Zn (17.42–60.26%), Se (20.98–59.35%), Mn (20.92–53.73%), Cu (4.53–65.36%). Based on average rice intake (682.5 g/day), cooked rice contributed: Zn 73.50–101.06%, Se 19.63–21.42%, Mn 123.44–157.73%, Cu 44.51% of RDA. Notably, the Se insufficiency was consistently low across all varieties. While Sri Lankan rice provides meaningful ETE contributions, dietary diversification remains essential to meet micronutrient adequacy, particularly for elements with inherently low gut-absorption efficiencies.