Just for historical reference:
WHO (2004)
Recommended calcium allowanced based on North American and western European data
WHO (2004): Vitamin and mineral requirements in human nutrition, 2nd edition (Table 4.2, page 71):
In this report (page 77), they also state:
"[...] Until fairly recently, it was widely assumed that low calcium intakes had no injurious consequences. This view of the global situation underpinned the very conservative adequate calcium intakes recommended by FAO/WHO in 1962 (2). At that time, osteoporosis was still regarded as a bone matrix disorder and the possibility that it could be caused by calcium deficiency was barely considered.
As previously stated, the paradigm has since changed. Calcium deficiency is taken more seriously now and the apparent discrepancy between calcium intake and bone status worldwide has attracted considerable attention. However, with the exception of calcium deficiency rickets reported from Nigeria (102), no satisfactory explanation has been found for the apparently low prevalence of osteoporosis in developing countries on low calcium intakes; on international comparisons on a larger scale, it is very difficult to separate genetic from environmental factors. [...]"
FAO/WHO (2001)
Recommended calcium allowances based on Western European, American and Canadian data
FAO/WHO (2001): Human Vitamin and Mineral Requirements. Report of a joint FAO/WHO expert consultation Bangkok, Thailand (Table 31, page 161):
