Ms Lim Su Lin, Chief Dietitian and manager at the dietetics department at National University Hospital of Singapore said

Anchovies with bones intact are a good source of calcium. They have 2 to 3 times more calcium that those with the bones removed. However, the entrails ad head o f anchovies contribute to a higher cholesterol content so it is better to have them removed but leave the bone intact.

Three tablespoons would give us about 180 mg of calcium which is one-fifth of an adult’s daily calcium consumption. Other source of calcium are milk, cheese, beancurd and dihal (a dish prepared with lentils or other pulses)

Source: Mind Your Body, The Straits Times, 9 April

Additional Reading
Healthy Urban Kitchen Cookbook by Antonia Valladores and Jamie Larose