Selenium content and speciation differences in selenium enriched soups made from selenium biofortified plants

Authors: Banuelos, Gary; FREEMAN, JOHN - National Aeronautics And Space Administration (NASA); Arroyo, Irvin

Submitted to: Journal of Food Composition and Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/2021
Publication Date: 11/2/2021
Citation: Banuelos, G.S., Freeman, J., Arroyo, I.S. 2021. Selenium content and speciation differences in selenium enriched soups made from selenium biofortified plants. Journal of Food Composition and Analysis. 105. Article 104255. https://doi.org/10.1016/j.jfca.2021.104255.
DOI: https://doi.org/10.1016/j.jfca.2021.104255

Interpretive Summary: Food crops are major sources of selenium (Se) in many countries of the world, however, little information is available on the identification of selenium and its different forms in soups made from selenium-enriched crops. Consumption of Se-enriched food products like soup can conveniently increase Se intake in regions that are Se-deficient. In this study, we produced soups from Se-enriched vegetables grown in soils with naturally high levels of Se, and from commercially produced Se-enriched maize and wheat. In each respective soup powder, we first determined Se content and the inorganic and organic forms of Se, and then determined Se and its forms in the soup and residual soup solids. In all soup powders, almost 80% and 20% of total Se was present in the inorganic and organic forms, respectively. In the soups, more than 80% Se was present as inorganic Se in the vegetable blend and 55% in both maize and wheat. In the residual soup solids, 50% was present as organic Se in the vegetable blend, and >85% in both maize and wheat. These results demonstrated that Se-enriched soups contain both inorganic and organic Se, while residual soup solids are a major source of organic Se. These findings are important because organic Se species are generally more efficiently absorbed by humans than inorganic forms of Se. Thus, the Se nutritional value of a Se-enriched soup will depend on the plant species used to make the soup. Irrespective of plant species, the results indicate that the residual soup solids should be consumed in addition to soup because of the higher organic Se content. Consumption of Se-enriched soups can be a practical and safe strategy for increasing Se intake in low Se regions.

Technical Abstract: Food crops are the major dietary sources of selenium (Se) in many countries of the world. Consumption of Se-enriched food products can increase Se intake, however, it is important to determine the total Se and speciation content, i.e., inorganic Se (selenate) and organic Se (selenomethionine [SeMet], methyl selenocysteine [MeSeCys], selenocystine [SeCys2]). Organic forms of Se are reported to be utilized more effectively by human enzymes and participate in antioxidant carcinogenic defense activities. In this study, three different Se-enriched plant-based soups were made from Se-enriched vegetables (Cruciferous) and commonly consumed cereals (maize and wheat). We determined total Se and Se speciation in plant material, soups, and in residual soup solids. Our results showed the extractable selenate (80%) and SeCys2 (<20%) were the predominate inorganic and organic Se species, respectively, in all plant materials. In the soups, most of the Se was detected as selenate>selenite>SeCySe2. More than 80% of the Se was present as selenate in the vegetable soup, while an average of 55% was found in the maize and wheat soups. In the residual soup solids, most of the Se was detected as SeMet because it was protein bound and was not extractable; 50% was present as SeMet in the vegetable blend and more than 85% found in both maize and wheat. Our results demonstrated that Se-enriched soups containing both inorganic and organic Se can be made from Se-biofortified plants. We observed that inorganic Se is the major form of Se in the soup and organic Se was greatest in residual soup solids, especially for maize and wheat. Hence, it is important to consume both soup and residual soup solids to most effectively increase both Se intake and Se bioaccessibility for human absorption.