Selenium characterization in the global rice supply chain.
Paul N Williams1, Enzo Lombi, Guo-Xin Sun
1Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Environmental Science & Technology
|September 8, 2009
Summary
Global rice selenium (Se) levels vary significantly, with many varieties failing to meet daily Se intake recommendations. Most Se in rice endosperm is organically bound, impacting bioavailability.
Area of Science:
- Agricultural Science
- Human Nutrition
- Geochemistry
Background:
- Selenium (Se) deficiency affects up to 1 billion people globally, with cereals being a primary source for malnourished populations.
- Soil selenium content, influenced by geology, dictates crop Se levels, but rice Se concentrations and speciation are poorly understood.
- Rice is a dietary staple for a significant portion of the global population, making its Se content critical for public health.
Purpose of the Study:
- To characterize the total selenium (Se) content and speciation in market-sourced polished rice from major global producers and exporters.
- To assess the contribution of rice consumption to daily Se intake recommendations worldwide.
- To investigate the localization and chemical forms of Se within rice grains.
Main Methods:
- Analysis of 1092 market-sourced polished rice samples from dominant rice-producing and exporting countries.
- Calculation of weighted average Se concentrations based on global production and export data.
- Utilized X-ray fluorescence (micro-XRF) and X-ray absorption near edge structure (micro-XANES) for Se localization and speciation.
Main Results:
- Significant variations in Se concentrations were observed, with U.S. and Indian rice being most enriched and Egyptian rice having the lowest levels (32-fold difference).
- Modeled baseline values indicated that approximately 75% of rice from production and export pools would not meet 70% of daily Se recommendations at a consumption rate of 300 g/day.
- Se speciation analysis in a Se-rich sample revealed that the majority of Se in the endosperm exists in organic forms.
Conclusions:
- Rice consumption alone may be insufficient to meet daily selenium requirements for a large percentage of the global population.
- Geographical variations in soil selenium significantly impact rice Se content, necessitating targeted dietary strategies.
- Understanding Se speciation in rice is crucial for assessing its nutritional value and bioavailability.
Related Concept Videos
02:35Key Elements for Plant Nutrition
Like all living organisms, plants require organic and inorganic nutrients to survive, reproduce, grow and maintain homeostasis. To identify nutrients that are essential for plant functioning, researchers have leveraged a technique called hydroponics. In hydroponic culture systems, plants are grown—without soil—in water-based solutions containing nutrients. At least 17 nutrients have been identified as essential elements required by plants. Plants acquire these elements from the atmosphere, the...
01:29Sources of Food Contamination
Contamination of food by microbial agents and natural toxins poses significant risks to public health. These hazards can be introduced at various points across the food supply chain, ranging from environmental sources to processing and storage stages. Understanding these contamination pathways is critical for developing strategies to ensure food safety.Seafood is particularly vulnerable to contamination through both environmental exposure and microbial colonization. Toxins from harmful algal...