Nutrient Profiles and Bioavailability in Industrial Hemp (Cannabis sativa L.) Seeds from Diverse Provenances

Hemp (Cannabis sativa L.) seeds have been essential for human nutrition for millennia. The products and by-products of hemp seeds are gaining popularity nowadays as food, feed and medicine for their high nutritional and nutraceutical properties. In parallel, concerns about phytate, an antinutritional compound limiting nutrient bioavailability in hemp seeds and seed meal are rising. Hemp seeds contain an array of nutrients, but their bioavailability is mostly unknown. Here, we report nutrient and phytate concentrations and phytate contents in source seeds and multiplied seeds of seven industrial hemp varieties. We estimated the bioavailability of specific nutrients based on calculated molar ratios of phytate to minerals. Seed multiplication was carried out in a phytotron using a compost-based growth medium. Five macronutrients (P, K, Mg, S, Ca), four micronutrients (Fe, Mn, Zn, Cu) and Cr were measured in seeds using ICP-OES. Seed phytate was determined using a UV-visible spectrophotometer rapid colourimetric assay. The results revealed significant differences between seven industrial hemp varieties for most macro- and micronutrient concentrations (not Fe), phytate concentration and content and phytate-to-mineral molar ratios in both source and multiplied seeds. Multiplied hemp seeds had higher K, Mn and Zn and, lower Cr and phytate concentrations and lower phytate content than source seeds. Considering nutrient bioavailability, Ca and Fe are non-bioavailable, and Zn is bioavailable in hemp seeds. Ferimon has increased Zn bioavailability in source and multiplied seeds, indicating the variety’s potential for seed production in Western Australia.