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{{OR/15/070}}
Mineral micronutrient deficiencies (MNDs) are an important global health problem, affecting up to two billion people worldwide (WHO, 2009, 2015<ref name="WHO 2015">World Health Organization, Micronutrient deficiencies, http://www.who.int/nutrition/topics/ida/en/ (accessed Oct 2015).</ref>). The common mineral MNDs include; iodine (Andersson et al. 2012<ref name="Andersson 2012">Andersson M, Karumbunathan V, Zimmermann, M B. Global iodine status in (2011) and trends over the past decade. (2012). Journal of Nutrition, 142, 744–750.</ref>; Watts et al. 2015<ref name="Watts 2015">Watts, M J, Joy, E J M, Broadley, M R, Young, S D, Ander, E L, Chilimba, A D C, Gibson, R S, Siyame, E W P, Kalimbira, and Chilima, B. Iodine source apportionment in the Malawian diet. (2015). Scientific Reports, 5, 1521.</ref>; Zia et al. 2015<ref name="Zia 2015">Zia, M, Watts, M J, Gardner, A, Chenery, S R. Iodine content of agricultural soil and grain from Pakistan. (2015). Environmental Earth Sciences, 1–14.</ref>), iron (Siyame et al. 2014<ref name="Siyame 2014">Siyame, E, Hurst, R, Wawer, A W, Young, S D, Broadley, M R, Chilimba, A D C, Ander, E L, Watts, M J, Chilima, B, Gondwe, J, Kang’ombe, D, Kalimbira, A, Fairweather-Tait, S J, Bailey, K B, and Gibson, R S. A high prevalence of zinc but not iron deficiency among Women in Rural Malawi: a cross-sectional study. (2014). International Journal for Vitamin and Nutrition Research, 83, 3, 176–187.</ref>; Gibson et al. 2015<ref name="Gibson 2015">Gibson RS, Wawer AA, Fairweather-Tait SJ, Hurst R, Young SD, Broadley MR, Chilimba ADC, Ander EL, Watts MJ, Kalimbira A, Bailey KB, Siyame EWP. Dietary iron intakes based on food composition data may underestimate the contribution of potentially exchangeable contaminant iron from soil. (2015). Journal of Analytical Food Research, 40, 19–23.</ref>), selenium (Hurst et al. 2013<ref name="Hurst 2013">Hurst, R, Siyame, E, Young, S D, Chilimba, A D C, Joy, E J M, Black, C R, Ander, E L, Watts, M J, Chilima, B, Gondwe, J, Kang’ombe, D, Stein, A J, Fairweather-Tait, S J, Gibson, R, Kalimbira, A, and Broadley, M R. Soil type influences human selenium status and underlies widespread selenium deficiency risks in Malawi. (2013). Scientific Reports, 3, 1425.</ref>) and zinc (Ahmad et al. 2012<ref name="Ahmad 2012">Ahmad, W, Watts, M J, Imtiaz, M, Ahmed, I, and Zia, M H. Zinc deficiency in soils, crops and humans. (2012). Agrochimica, 2, 65–97.</ref>; Joy et al. 2015<ref name="Joy 2015">Joy, E J M, Black, C R, Young, S D, Broadley, M R, Ander, E L, Watts, M J, and Chilimba, A D C. Zinc enriched fertilisers as a potential public health intervention in Africa. (2015). Plant Soil, 389, 1–24.</ref>; Kumssa et al., 2015b<ref name="Kumssa 2015b">Kumssa, D B, Joy, E J M, Ander, E L, Watts, M J, Young, S D, Walker, S, and Broadley, M R. Dietary calcium and zinc deficiency risks are decreasing but remain prevalent. (2015b). Scientific Reports, 5, 10974.</ref>). Estimates of deficiency for some minerals (Fe, I, Se, Zn), are often based on direct measurement of mineral concentrations or indicators in blood, urine or other tissues (Ku et al. 2015; Fairweather-Tait et al. 2011<ref name="Fairweather-Tait 2011">Fairweather-Tait, S J, Bao, Y, Broadley, M R, Collings, R, Ford, D, and Hesketh, J E. (2011). Selenium in human health and disease, Antioxidant Redox Signal (2011). 14, 1337–1383.</ref>). Alternatively, for elements including Mg, food consumption or food supply data can be used to calculate dietary mineral intakes to estimate the risk of deficiency (Kumssa et al. 2015a<ref name="Kumssa 2015a">Kumssa, D B, Joy, E J M, Ander, E L, Watts, M J, Young, S D, Rosanoff, A, White, P J, Walker, S, and Broadley, M R. Global magnesium (Mg) supply in the food chain. (2015a). Crop and Pasture Science, 66, 1278–1289.</ref>; Ecker and Qaim, 2011<ref name="Ecker 2011">Ecker, O, and Qaim, M. Analysing nutritional impacts of policies: am empirical study for Malawi, World dev (2011). 39, 412–428.</ref>) and national Food Balance Sheets (FBSs) available from the United Nations Food and Agriculture Organisation (FAO, 2014<ref name="FAO 2014">FAO, Food Balance Sheets, http://faostat3.fao.org/browse/Q/*/E, (accessed 02/12/2015).</ref>; Broadley et al. 2012<ref name="Broadley 2012" >Broadley, M R, Brown, P, Cakmak, I, Rengel, Z, Zhao, F. Function of Nutrients: Micronutrients. In Marschner’s Mineral Nutrition of Higher Plants 3rd edition. (2012). ed. P. Marschner, pp.191–243. Boston, MA: Academic Press.</ref>; Joy et al. 2012<ref name="Joy 2012">Joy, E J M, Young, S D, Black, C R, Ander, E L, Watts, M J, and Broadley, M R. Risk of dietary magnesium deficiency is low in most African countries based on food supply data. (2012). Plant and Soil, 368. 129–137.</ref>; 2014<ref name="Joy 2014">

Joy, E J M, Ander, E L, Young, S D, Black, C R, Watts, M J, Chilimba, A D C, Chilima, B, Siyame, E W P, Kalimbira, A A, Hurst, R, Fairweather-Tait, S J, Stein, A J, Gibson, R S, White, P J, and Broadley, M R. Dietary mineral supplies in Africa. (2014). Physiologia Plantarum, 151, 208–229.</ref>). Local food composition data has improved estimates of mineral deficiencies, and for some MNs demonstrated a strong influence of soil type on dietary composition (Chilimba et al. 2011<ref name="Chilimba 2011">Chilimba, A D C, Young, S D, Black, C R, Rogerson, K B, Ander, E L, Watts, M J, Lammel, J, and Broadley, M R. Maize grain and soil surveys reveal suboptimal dietary selenium intake is widespread in Malawi. (2011). Scientific Reports, 1, 72.</ref>; Hurst et al. 2013<ref name="Hurst 2013">Hurst, R, Siyame, E, Young, S D, Chilimba, A D C, Joy, E J M, Black, C R, Ander, E L, Watts, M J, Chilima, B, Gondwe, J, Kang’ombe, D, Stein, A J, Fairweather-Tait, S J, Gibson, R, Kalimbira, A, and Broadley, M R. Soil type influences human selenium status and underlies widespread selenium deficiency risks in Malawi. (2013). Scientific Reports, 3, 1425.</ref>; Joy et al. 2015<ref name="Joy 2015">Joy, E J M, Black, C R, Young, S D, Broadley, M R, Ander, E L, Watts, M J, and Chilimba, A D C. Zinc enriched fertilisers as a potential public health intervention in Africa. (2015). Plant Soil, 389, 1–24.</ref>), resulting in significant spatial variation.

Mineral MNDs in developing countries, particularly in Sub-Saharan Africa are exacerbated by a lack of dietary diversity, with reliance on a limited range of staple foods for calorific intake (e.g. maize, rice). Developing countries most effected by MNDs often have a high reliance on a plant based diet, with the consumption of meat and dairy products limited in availability (Joy et al. 2012<ref name="Joy 2012"></ref>; Joy et al. 2014<ref name="Joy 2014"></ref>). This lack of dietary diversity can often lead to an insufficient intake of Fe and Zn, (Hunt et al. 2003<ref name="Hunt 2003"></ref>), whilst also increasing the intake of phytic acid (or phytate). Foods possessing large concentrations of phytic acid result in significant reductions to the bioavailability of Zn (Cakmak et al. 1998). Phytic acid is often present in seeds, serving as a storage for ''myo''-inositol and phosphorus, which is utilised during seed germination and seedling growth (Bentley et al. 2015). Phytic acid is a strong chelator of Fe2+ and Zn2+ ''in-vivo'' and poses a major risk of anti-nutrient deficiency throughout Africa and worldwide (Hunt et al. 2003<ref name="Hunt 2003">Hunt, J R. Bioavailability of iron, zinc, and other trace minerals from vegetation diets. (2003). The American Journal of Clinical Nutrition, 78, 633S–639S.</ref>; Kumssa et al., 2015b<ref name="Kumssa 2015b"></ref>), limiting the bioavailability of these essential minerals from an already deficient dietary intake. Measurement of phytic acid in foodstuffs is an important consideration to improve population estimates for mineral deficiency in combination with direct human biomonitoring, FBS, food composition data and better understanding of the spatial controls on their soil-to-crop transfer.

This report describes the analytical method used to quantify phytic acid in grain samples using simple and relatively low-cost UV/Vis spectroscopy, which could easily be applied in a developing world situation. Whilst measurement by Ion Chromatography provides very high sensitivity and specificity for phytate (Harlanda et al. 2004<ref name="Harlanda 2004">Harlanda, B F, Smikle-Williams, S, Oberleas, D. High Performance Liquid Chromatography analusis of phytate (IP6) in Selected Foods. (2004). Journal of Food Composition Analysis. 17, 227–233.</ref>), it requires expensive equipment and consumables, a high degree of technical competency and takes approximately 20–30 minutes per sample for analyses following a complex extraction process to measure phytic acid in solution. A commercially available kit (K-PHYT 12/12 Megazyme, Ireland) was reported by Xue et al. (2015)<ref name="Xue 2015">Xue, Y F, Xia, H Y, McGrath, S P, Shewry, P R, and Zhao, F J. Distribution of the stable isotopes 57Fe and 68Zn in grain tissues of various whear lines differing in their phytate content. (2015). Plant Soil, 396, 73–83.</ref> to determine the distribution of stable Fe57 and Zn68 isotopes in tissues of wheat lines with respect to phytic acid content, with sufficient sensitivity suitable for phytic acid in the majority of common grains (e.g. maize, rice). There is also the potential for high throughput with analyses taking only 6 minutes per sample, whilst using relatively low cost equipment that requires little maintenance and effort for calibration for each analytical batch. This methodology employed a commercially available assay kit from Megazyme® for measuring phytic acid by enzymatic and redox chemistry.

This report describes the validation and implementation of this method recently completed at BGS, with the aim of undertaking cost effective measurements of phytic acid in a range of food grains to improve estimations for dietary mineral intake.

==References==
<References/>

[[Category: OR/15/070 Quantification of phytic acid in grains | 04]]

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