Calcium supplements are coming under scrutiny due to concerns that they might increase heart attacks. A new study shows that patients over 40 who take 500 mg/day or more of calcium have an increased risk of heart attack.
And, the theory is plausible as too much calcium might lead to vascular calcification and atherosclerosis.
But it is WAY, WAY, WAY  too soon to jump to any conclusions for at least a couple of reasons:

• The analysis only looked at people taking calcium supplements alone.
• It doesn’t address the role of dietary calcium or taking vitamin D along with calcium. Especially since some research suggests that taking calcium plus vitamin D does not significantly affect coronary artery calcification.

The Doctors of Pharmacology at the Natural Medicines Comprehensive Database tell prescribers this:

Continue to advise people to use calcium supplements if needed, but not to exceed recommended amounts.

Advise patients to consider their TOTAL calcium intake from supplements PLUS foods. Recommend aiming for calcium 1000 mg/day for adults under 50 and 1200 mg/day for adults over 50. Many people get about half this amount in their diet.

To this I add, if you’re going to take a calcium supplement (and, I do), then be sure to take it with vitamin D (and consider having your doctor test your vitamin D level).
To figure out dietary calcium intake, I have my patients count 300 mg/day from NON-dairy foods plus 300 mg/cup of milk, fortified orange juice, etc.
I also recommend vitamin D (based upon the new guidelines from Osteoporosis Canada) 1000 IU/day for adults under age of 50 and up to 2000 IU/day for adults over 50, to maintain adequate levels and help prevent fractures. I recommend using vitamin D3 (cholecalciferol) because it’s more active, but vitamin D2 (ergocalciferol) is also fine for increasing vitamin D levels. And, I do not recommend sunlight exposure for increasing vitamin D levels. You can read my reasons here.
Keep in mind, as I’ve told you before, the Institute of Medicine will come out with new calcium and vitamin D recommendations later this fall.