Those looking to make the move to a Paleo Diet often question the nutritional value of “this way of eating.” One of the assumptions is that, without dairy foods included, the overall diet will be very low in calcium.
I recently created a comparison of a day's worth of meals on the USDA recommended diet versus a Paleo diet for children so that we can have real numbers to view first-hand. [1,2] I designed the example based on recommendations for children as many people who are concerned about calcium are most concerned about it for growing kids, but you'll note that the foods eaten are pretty standard and an average adult could conceivably be eating as it adds up to roughly 2,000 calories for each example. You can enter a day's worth of your own meals and see how it stacks up. Perhaps if you're not eating many calcium rich foods (dark leafy greens, sardines and properly prepared sesame seeds or tahini to name a few), now's the time to evaluate and update your intake.
Note: To view the USDA worksheet for recommended Kids’ nutrition, click here.  A Paleo diet has no set rules for consumption other than to eliminate grains, legumes and dairy and to focus on quality meats, seafood, eggs, vegetables, fruits, nuts and seeds.
How does the Paleo diet stack up in calcium?
We can see in a day’s worth if USDA meals that the RDA is slightly exceeded at 123%, while the Paleo diet (PD) comes a lot closer than parents might assume at 90%. Now, I wasn’t specifically searching for calcium-rich foods when I calculated this day, but you can see how a child can easily come close to the RDA for calcium without a DROP of dairy in his or her daily diet. That said, even at 90% of the RDA, the amount of calcium that’ll be absorbed by the child’s body is likely going to be much higher since the cofactors for calcium absorption are higher across the board in the PD day. Vitamin and mineral cofactors required for calcium absorption include Vitamin D (56% in Paleo vs 12% in USDA) and Magnesium (103% in Paleo vs 87% in USDA). So, by allowing a child to eat a diet that is not only fairly high in calcium from non-dairy sources but also providing balanced nutrition to allow for the absorption of calcium, it’s clear that the need for dairy in the diet as a calcium source is overstated and inaccurate.  Furthermore, studies show that the phytic acid in grains (specifically whole wheat products in one study) reduces the absorption of dietary calcium from milk products, which would likely then leave the USDA diet at a much lower level of bio-available calcium than the PD. 
If you are lactose intolerant, wish to follow a strict Paleo diet, or find that dairy just isn't an ideal food choice for you for a myriad of reasons (from allergies to proper handling of the animals providing the milk) obtaining calcium from other sources may be a good idea. If you tolerate dairy well, meaning you experience no digestive discomfort (gas, bloating, diarrhea, constipation, etc.), no histamine response (mucous build-up, sniffling, coughing, etc.) then choosing raw/unpasteurized grass-fed sources are ideal. Click here for more info on food quality choices.
SELECTED NON-DAIRY SOURCES OF DIETARY CALCIUM: [6,7]
|Item||Calcium mg per 100g serving||% DV||Portion Size Notes||Other notable nutrients…|
|sardines||382||38%||1c= 149g||Vitamin D, Niacin, B12, Phosphorous, Selenium|
|nopales (cooked)||165||16%||1c= 149g||Magnesium, Manganese|
|collard greens (cooked)||140||14%||1c= 190g||Vitamin A, Vitamin K, Vitamin C, Folate, Manganese|
|turnip greens (cooked)||137||14%||1c= 144g||Vitamin A, Vitamin C, Vitamin K, Folate|
|spinach (cooked)||136||14%||1c= 180g||Vitamin A, Vitamin K, Folate, Iron, Magnesium, Manganese|
|sesame seeds||975||98% (see serving size)||1Tbsp= 9g (87.8mg of calcium)||Iron (non-heme), Magnesium, Phosphorus, Copper, Manganese, Zinc, Thiamin, Niacin, B6, Folate|
 USDA day: http://nutritiondata.self.com/facts/recipe/2202570/2?nc=1&autosave=form.info.autosave
 Paleo Diet day: http://nutritiondata.self.com/facts/recipe/2205032/2?nc=1&autosave=form.info.autosave
 My Pyramid Worksheet: http://www.fns.usda.gov/tn/Resources/mpk_worksheet.pdf
 Abrams, et al. Calcium and magnesium balance in 9-14 year-old children American Journal of Clinical Nutrition (1997), vol. 66 no. 5 1172-1177.
 Weaver, et al. Human calcium absorption from whole-wheat products. The Journal of Nutrition (1991), 0022-3166/91.
 NutritionData.com – http://nutritiondata.self.com/tools/nutrient-search
 WH Foods – http://www.whfoods.com/genpage.php?tname=nutrient&dbid=45