This study is the first detailed investigation of the possible nutritional/medicinal value of termite mounds as eaten by Aboriginal people. Two communities of the Northern Territory (Nauiyu Narnbiyu, Daly River and Elliott) were chosen for detailed investigations on the choices, usages and modes of preparation of termitaria. The elements studied were AI, Ca, Co, Cu, Fe, K, Mg, Mn, Na and Zn together with the particle size analyses.
In Daly River, the Aboriginal women did not choose Amitermes vitiosus at all sites and preferred the mounds of Tumulitermes pastinator and Nasutitermes triodiae with the newly built material being the most favoured. In Elliott, Amitermes vitiosus mounds were used exclusively. In the two communities, the use of termitaria for gastric disorders or after eating certain foods like yams, turtle or goannas could be related to the clay content and in particular to the kaolin; while the consumption of termite mound material during pregnancy or lactation could be associated with their elemental content, in particular, iron and calcium.
The results of this study showed that at all sites and for all species, the mounds selected by the Aboriginal people had a higher percentage of clay than the adjacent top soil (0- 10cm) and the species most favoured by the Daly River people (Nasutitermes triodiae), had the highest mean clay content. The average clay content of soil was 12.9 ± 4.4% and for Amitermes vitiosus, Tumulitermes pastinator and Nasutitermes triodiae mounds was: 16.3 ± 4.6, 20.8 ± 6.2 and 22.8 ± 4.2% respectively. Differences in clay content occurred between mounds of the same species at most sites and between the same species at different sites for Nasutitermes triodiae and Tumulitermes pastinator. With respect to the Aboriginal preference for newly built as opposed to older material, no significant differences were found. The clay in the tennitaria appeared to be largely composed of kaolin. This is significant as kaolin has long been used for the treatment of gastric-disorders in both traditional and modern pharmacologies.
The concentrations of elements from the water "infusion" extract from Amitermes vitiosus mounds, which is drunk by the Aboriginal people, were minimal compared to the human needs but, nevertheless, they could contribute to the global intakes, especially calcium. On the other hand, the finer fraction which includes clay, preferentially selected in the infusion, could be beneficial against gastro-intestinal disorders.
In general, the termitaria had higher concentrations of elements than the adjacent top-soil and the differences between mounds and soils were more pronounced in the bioavailable tests. This could be a reflection of the termite by-products (of organic origin) added to the mounds.
In the bioavailable analyses, the differences in concentrations of elements cannot always explain the Aboriginal preference of one species at the exclusion of another at the same site or a particular species (Amitermes vitiosus) at one site but not at another. Between different age materials, with the exception of the soluble iron in Nasutitermes triodiae mounds, no significant differences in concentration were observed. The 44 % increase in soluble iron in the newly built parts of mounds in the pepsin-HCl extracts could be of importance in relation to the Aboriginal use of termitaria during pregnancy.
Undoubtedly one of the most remarkable aspects of termitaria are their high concentrations of elements. However, with the exception of calcium which had a high percentage recovery (82 %) between "total" and bioavailable analyses, only a fraction of the "total" concentrations of elements present in the termitaria was potentially available. In relation to human needs, the daily average quantity of termite mound consumption, estimated at 30-60 g per day, can only provide a small portion of the RDis for Ca, Cu, Fe, Mg and Mn. Fifty grams of termitaria would provide less than 5 % of the RDis for Ca, Cu and Mg. The relatively low concentrations of Na and K in termitaria would not provide a significant contribution towards salt replacement in the diet. The "total" aluminium concentrations were high (2676-7745 mg/100g) in the termitaria, however, only 0.37 to 13.9 mg/100g were present after the in vitro bioavailable analyses.
The bioavailability study showed that a maximum of 0.25 mg/100g of iron from termite mounds could be bioavailable to adult males. This represents less than 0.1 % of the “total” iron present in the termitaria studied. As the daily average loss for men is only 1 mg/day, 50g of termitaria could possibly contribute significantly to the daily requirements. Since the bioavailability of iron is influenced by a number of factors, including the diet, further study will be necessary to assess more precisely the iron bioavailability from termitaria for Aboriginal people.