Calcium is commonly known for its important role in bone health, but it is also needed for proper nerve and muscle function. This essential mineral also plays a role in blood clotting, enzyme function and maintaining a normal heart rhythm. Our body stores calcium in bones and teeth, and normal blood levels are tightly regulated mainly by fluctuations in parathyroid hormone. When intake is inadequate this hormone signals our body to extract calcium from our bones.
Many people don’t get enough.
Almost 30 percent of men and 60 percent of women over the age of 19 do not consume enough calcium, and more than 90 percent do not get enough vitamin D. Vitamin D aids in calcium absorption. Long-term exposure to inadequate calcium intake or absorption can result in osteoporosis, which affects about 17 percent of women and 5 percent of men.
Who is at highest risk?
People who follow a vegan diet or those with lactose intolerance may struggle to get enough calcium in their diet. Long-term use of corticosteroid medications and inflammatory bowel diseases both decrease calcium absorption. In addition, chronic use of proton pump inhibitors, a common treatment for reflux or GERD, and bariatric surgery procedures that bypass part of the small intestine result in decreased calcium absorption. Postmenopausal women are also at risk because decreased estrogen production reduces calcium absorption and increases urinary calcium loss.
How much do we need?
The Recommended Daily Allowance (RDA) for calcium intake is 1000mg/day for adults or 1200mg/day for women over 50 and men over 70. (The RDA for vitamin D is 600 IU daily for both men and women.)
Where can we get it?
Dairy foods are considered the best source of calcium, with milk and yogurt being the most nutrient dense. The recommended daily intake for adults is three-cup equivalents. About 90 percent of the U.S. population does not consume recommended amounts of dairy. Dark leafy greens may be considered a good alternative source for calcium, but absorption is limited by the oxalic and phytic acids they also contain.
Calcium content in foods:
Serving size Food Calcium (grams)
1 cup nonfat yogurt 488
1 cup calcium fortified almond milk 442
1 cup low fat yogurt 415
½ cup firm tofu 253 (if prepared with calcium sulfate)
1 cup calcium fortified orange juice 349
1.5 oz part skim mozzarella 333
3 oz. canned sardines 325
1 cup low fat milk 305
1 cup fat free milk 299
1 cup calcium fortified soymilk 299
1 cup low fat Greek yogurt 260
1 cup nonfat Greek yogurt 250
1 cup cooked mustard greens 284
1 cup cooked collard greens 268
1 cup cooked spinach 245
1 cup cooked bok choy 185
1 cup cooked kale 177
3 oz. canned salmon with bones 181
1 Tbsp tahini (sesame paste) 154
1 cup low fat cottage cheese 138
¼ cup almonds 100
For those who are not able to consume enough dairy or calcium fortified foods a supplement is a good option. Aim to stay within the RDA from foods and supplements. The Tolerable Upper Limit from supplements is 2500mg/day for adults or 2000mg/day for women over 50 and men over 70 to avoid possible health risks associated with over-supplementation. Always consult a healthcare professional before taking dietary supplements.
Helaine Krasner, MS, RDN, CSOWM, CDN is a registered dietitian nutritionist who takes great pride in helping our Bariatric and Medical Weight Management patients achieve their health and weight loss goals.