Drink pastuerized fresh milk which good source of calcium. Black sesame is also high in calcium but we can't eat in large quantity.

Another tip is try to take iron tablets with calcium supplement at different time.

Personally tried Calcium supplement called isotonix calcium. It is powder form which need to be dissolved in 60ml of water before consumption to become isotonic condition making it readily absorbed.

The isotonic state ensure 95% of the calcium absorbed within 5 minute which can be very cost effective. Rather than spending on calcium tablets where absorption is probably just 40-50% and takes longer time to absorbed by the stomach.

I purchase Isotonix Calcium from my friend. Drop me a message if interested to get best price.