Iron absorption from brown rice/brown rice-based meal and milled rice/milled rice-based meal

Abstract

Background Milled rice is the staple food among Filipinos and is mostly consumed three times a day. Rice as a source of iron could therefore have an important role in the existing 37% prevalence of iron-deficiency anemia in the country. Previous iron absorption studies in Filipinos from rice and rice-based meals were carried out on milled rice but no research was done on brown rice of the same variety. This leads to the hypothesis that brown rice may be better than milled rice in terms of iron content.

Objective To determine iron absorption from brown rice and brown rice-based meal, and from milled rice and milled rice-based meal of the same variety.

Methods The rice variety used in the study was F₂ seeds of PSB Rc72H. Iron absorption from brown/milled rice and brown/milled rice-based meals was determined in 12 healthy human subjects from the incorporation of radioisotopes of iron into erythrocytes 14 days after administration of the labeled rice/rice-based meals. The above samples were also analyzed for nutrient content, including dietary fiber, and iron.

Results The iron content of brown rice was significantly higher (1.1 ± 0.1 mg/100 g) than that of milled rice (0.6 ± 0.1 mg/100 g). Brown rice has significantly greater amounts of total dietary fiber (5.4 ± 0.4%) than milled rice (1.7 ± 0.2%; P < 0.05). Both tannic acid and phytic acid contents in brown rice (56.9 ± 3.2 mg/100 g and 290.1 ± 18.0 mg/100 g, respectively) were significantly higher than those of milled rice (21.3 ± 2.3 mg/100 g and 84.0 ± 12.4 mg/100 g, respectively; P<0.05). The amount of iron absorbed from brown rice (0.13 ± 0.02 mg) did not differ significantly from that from milled rice (0.14 ± 0.02 mg). However, the amount from brown rice-based meal (0.36 ± 0.04 mg) differed significantly from that from brown rice (P<0.05) as well as that from milled rice-based meal (0.35 ± 0.03 mg) from that from milled rice (P<0.05). Moreover, brown rice-based meal did not differ significantly from milled rice-based meal (P<0.05).

Conclusion Iron absorbed from milled rice and brown rice did not differ significantly, as well as that from brown rice-based meal and milled rice-based meal. Differences in iron absorbed from brown/milled rice and brown/milled rice-based meals may be due to the iron content of the test foods and the presence of iron enhancers in the meal (e.g. fish, vegetables and citrus fruit).

Keywords::

• Iron absorption
• brown rice
• milled rice

Acknowledgements

The study was partially funded by PhilRice through its Executive Director, Dr Leocadio S. Sebastian. The authors acknowledge the technical assistance of Maureen Ugat, Zoilo B. Villanueva and Paz S. Lara of the Food and Nutrition Research Institute, Department of Science and Technology.