There has been alot of information in peer reviewed journals for sometime now regarding Calcium supplement intake and possible heart complications.  Quick background:  calcium supplementation has been linked to heart attacks.  Few abstracts:
1. “Calcium supplements are known to have several side effects, the most common being indigestion and minor constipation, and kidney stones are a rare complication. However, several recent studies have suggested that calcium supplements can also lead to an increase risk of heart attacks.”
2. “A 2010 British Medical Journal study, which pooled nearly a dozen randomized trials, concluded that calcium supplements “are associated with an increased risk of myocardial infarction [heart attacks]” and went on to say, ” As calcium supplements are widely used, these modest increases in risk of cardiovascular disease might translate into a large burden of disease in the population.”
3. “A 2013 JAMA Internal Medicine non-randomized study examined 11,778 cardiovascular-related deaths and found an increased risk with calcium supplement use. The authors concluded, “high intake of supplemental calcium is associated with an excess risk of CVD (cardiovascular disease) death in men but not in women.”
So why do we mention this in the Paleo section of this site?  Because according to the October 17th, 2013 article in the New England Journal of Medicine you are better off getting dietary calcium from whole foods instead of supplements.  Guess one nutritional style that is very high in dietary calcium….yep you guessed it a Paleo style.
Foods highest in calcium (other than dairy): sardines and green leafy veggies.  And if you actually follow our veggie recommendations (10 cups a day) AND you get rid of dairy and  cereals, your calcium intake will be in a positive balance.  Now what do I mean by that?
Well dairy sources of calcium are extremely acidic and actually leach more calcium then you get resulting in a negative calcium intake balance from that food.  Which overtime results in a greater change of osteoporosis.   On the other hand eat a green leafy veggie which is not only high in calcium but very basic (opposite of acidic) and not only to you get calcium but you also get to keep it!
Think of it this way; the U.S. has the highest intake of dairy, and the highest intake of osteoporosis.  See any connection?
So yes, your mother was right, eat your veggies!!
References:
Caren G. Solomon, Douglas C. Bauer. Calcium Supplements and Fracture Prevention. New England Journal of Medicine, 2013; 369 (16): 1537 DOI: 10.1056/NEJMcp1210380
Sophie A Jamal, Ben Vandermeer, Paolo Raggi, David C Mendelssohn, Trish Chatterley, Marlene Dorgan, Charmaine E Lok, David Fitchett, Ross T Tsuyuki. Effect of calcium-based versus non-calcium-based phosphate binders on mortality in patients with chronic kidney disease: an updated systematic review and meta-analysis. The Lancet, 2013; DOI: 10.1016/S0140-6736(13)60897-1
Xiao Q, Murphy RA, Houston DK, Harris TB, Chow W, Park Y. Dietary and Supplemental Calcium Intake and Cardiovascular Disease Mortality: The National Institutes of Health–AARP Diet and Health Study. JAMA Internal Medicine, 2013; DOI: 10.1001/jamainternmed.2013.3283