Calcium deficiency is widespread globally, especially in diets with minimal consumption of dairy. It is therefore important to identify plant-based sources of calcium that can make a meaningful contribution to calcium intakes for populations following diets with a minimum supply of dairy products. The best sources of calcium have a high calcium content and bioavailability. Therefore, we evaluated the gross and bioaccessible calcium supplies of 25 plant-based products from 5 food groups considered to be good and important sources of calcium. Bioaccessible calcium was examined using the INFOGEST static digestion model in which isotopically labelled ⁴³Ca was used as a tracer of reagent calcium to improve accuracy of bioaccessibility measurements. The gross calcium content varied widely amongst all the food products, ranging between 7.48 and 959 mg/100 g fresh weight (fw), with approximately 50 % of the products being equivalent to or surpassing the calcium content of skimmed milk. Bioaccessibility of calcium was equally variable, ranging from about 0.1 - 50 %. The lowest bioaccessibility (<10 %) was found in spinach, plant-based beverages, tofu, dried figs and tahini and was attributed to: 1. the high content of oxalate and phytate in some of the products, and 2. the low solubility of tricalcium phosphate which was used for fortification in the plant-based beverages. The remaining products generally had a high bioaccessibility that was similar to, or higher than that of skimmed milk (∼30 %). When both bioaccessibility and recommended serving portions were considered, only 3 products were identified as good sources of calcium, requiring 0.2 - 1.4 servings to equal the bioaccessible supply from skimmed milk. The top three sources of plant-based calcium identified were kale, finger millet and fortified white bread in that order, with kale providing 5 times more bioaccessible calcium than 1 serving of skimmed milk. Moderate sources of calcium where 1.5 - 3 servings was equivalent to 1 serving of skimmed milk included wholemeal bread, some bean varieties (black chickpeas, chickpeas, kidney beans, peas), broccoli, cabbage and almond drink. The rest of the products were either of low calcium content, poor bioaccessibility, and/or not consumed in sufficient quantities to make a significant contribution to daily requirements. White bread was a good source of calcium as it was fortified with calcium carbonate and this suggests that mandatory widescale fortification of staple cereals with this form of calcium should be considered a viable approach to augment dietary calcium intakes in vulnerable populations. Low bioaccessibility of fortified calcium in plant-based beverages, often marketed as good sources of calcium, suggests the need for regulation and for further in vivo studies to validate bioavailability of calcium in these products.

Many weaning and complementary foods in Africa are plant based and thus are not good sources of bioavailable iron and zinc owing to the presence of anti-nutritional factors, in particular phytic acid, phenolic compounds, and, to some extent, dietary fiber. Several strategies are being developed to increase the levels of bioavailable iron and zinc in plant-based diets. These strategies range from fortification, biofortification, dietary diversification, and use of household processing methods such as soaking, cooking, germination, and fermentation. Fermentation poses a great potential as a significant amount of these foods in Africa involve a natural fermentation step. Exploration of this process could offer a more economical and sustainable way to reduce iron and zinc binders and consequently increase the bioavailability of the minerals in diets consisting of fermented cereals.