High-selenium wheat: biofortification for better health

Abstract

The metalloid Se is ubiquitous in soils, but exists mainly in insoluble forms in high-Fe, low-pH and certain leached soils, and hence is often of limited availability to plants. Consequently, it is often supplied by plants to animals and human consumers at levels too low for optimum health. Se deficiency and suboptimality are manifested in populations as increased rates of thyroid dysfunction, cancer, severe viral diseases, cardiovascular disease and various inflammatory conditions. Se deficiency probably affects at least a billion individuals. Optimal cancer protection appears to require a supra-nutritional Se intake, and involves several mechanisms, which include promotion of apoptosis and inhibition of neo-angiogenesis. Evidence suggests that in some regions Se is declining in the food chain, and new strategies to increase its intake are required. These could include education to increase consumption of higher-Se foods, individual supplementation, food fortification, supplementation of livestock, Se fertilisation of crops and plant breeding for enhanced Se accumulation. Se levels in Australian residents and wheat appear to be above the global estimated mean. Wheat is estimated to supply nearly half the Se utilised by most Australians. Increasing the Se content of wheat represents a food systems approach that would increase population intake, with consequent probable improvement in public health and large health cost savings. The strategies that show most promise to achieve this are biofortification by Se fertilisation and breeding wheat varieties that are more efficient at increasing grain Se density. Research is needed in Australia to determine the most cost-effective fertilisation methods, and to determine the extent of genetic variability for grain Se accumulation. Before recommending large-scale fortification of the food supply with Se, it will be necessary to await the results of current intervention studies with Se on cancer, HIV and AIDS, and asthma.

Agronomic selenium biofortification of two-rowed barley under Mediterranean conditions

“…Higher Se concentration in grains was related to emmer (59-68 μg/kg DM) and einkorn (50-55 μg/kg DM) varieties, in spring varieties Se concentration ranged from 30 to 40 μg/kg DM. The highly significant linear relationship between the total Se concentration in grain and the Se doses regardless of the Se application form (Table 2) is consistent with many previous studies performed since the 1970s (reviewed by Lyons et al 2003). The Se accumulated in tworowed barley grain increased by 55-33 μg/kg DW and 10-6 μg/kg DW for each g/ha of Se applied as sodium selenate and sodium selenite in 2010/2011 and 2011/2012, respectively (Table 2).…”

Selenium in reproductive health

“…Other foods make a substantial contribution to selenium intake in northern Europe, 161 particularly meat, poultry, and fish (a total of about 36% in the UK) ( contour, the use of high-sulphur fertilisers and microbial activity; some bacteria can 169 convert insoluble forms of selenium to soluble forms, which can then be taken up by 170 plants (Diplock, 1993, Lyons et al, 2003. Selenium tends to be more concentrated in the 171 soils of the drier regions of the world, where soil tends to be more alkaline; in acidic 172 poorly aerated soils, selenium is relatively unavailable to plants as it is present mainly as 173 insoluble selenite complexes (Lyons et al, 2003, Reilly, 2006.…”

“…Selenium tends to be more concentrated in the 171 soils of the drier regions of the world, where soil tends to be more alkaline; in acidic 172 poorly aerated soils, selenium is relatively unavailable to plants as it is present mainly as 173 insoluble selenite complexes (Lyons et al, 2003, Reilly, 2006. 174…”

“…Soil selenium concentrations range from 0.1 to more 180 than 100 mg/Kg. However, most soils contain between 1.0 to 1.5 mg/Kg (0.1-0.6 mg/Kg 181 is considered deficient) (Lyons et al, 2003, Combs, 2001. 182…”

Increased consumption of wheat biofortified with selenium does not modify biomarkers of cancer risk, oxidative stress, or immune function in healthy Australian males

“…The Se content of wheat can be increased by agronomic biofortification. This involves fertilizing the growing crop with an appropriate inorganic form of the micronutrient, which the plant converts to several organic Se forms, notably Se-met, which are more suitable for human consumption [Lyons et al, 2003[Lyons et al, , 2005b. The effect of increased consumption of Se via Se-biofortified wheat on genome damage and immune function has not been tested previously.…”