Calcium is a nutrient necessary for the growth and maintenance of strong teeth and bones, nerve signaling, muscle contraction, and secretion of certain hormones and enzymes. A deficiency in calcium can lead to numbness in fingers and toes, muscle cramps, convulsions, lethargy, loss of appetite, and abnormal heart rhythms. Conversely, excess calcium (particularly from supplements) can lead to kidney stones, calcification of soft tissue, and increased risk of vascular diseases like stroke and heart attack.
Calcium is mostly found in dark leafy greens and dairy foods. While there is some evidence that oxalates in greens can hinder calcium absorption, green vegetables are still a good source of calcium, and the calculated daily value (DV) already takes into account absorption and bio-availability. For more info, see the section on calcium absorption.
High calcium foods include dark leafy greens, cheese, low-fat milk and yogurt, bok choy, fortified tofu, okra, broccoli, green beans, almonds, and fish canned with their bones. The daily value (DV) for calcium is 1000mg. Below is a list of high calcium foods by common serving size, for more, see the extended lists of high calcium foods by nutrient density, and calcium rich foods.
#1: Dark Leafy Greens (Watercress)
|Calcium in 100g (Raw)||1 Cup Chopped (34g)||10 Sprigs (25g)|
|120mg (12% DV)||41mg (8% DV)||30mg (3% DV)|
Other Greens High in Calcium (%DV per cup, chopped, raw): Curly Kale (14%), Dandelion Greens (10%), Turnip Greens (10%), Arugula (6%), and Collards (5%). Click to see complete nutrition facts.
#2: Low Fat Cheese (Mozzarella Nonfat)
|Calcium in 100g||1 Cup Shredded (113g)||1 Ounce (28g)|
|961mg (95% DV)||1086mg (109% DV)||269mg (27% DV)|
Other Cheeses High in Calcium (%DV per ounce): Reduced Fat Parmesan (31%), Low Fat Swiss (27%), Fat Free Cheddar (25%), Fat free American (22%), Full Fat (Regular) Swiss (22%), Full Fat (Regular) Cheddar (19%), Whole Milk (Regular) Mozzarella (14%). Click to see complete nutrition facts.
#3: Low Fat Milk & Yogurt (Low-Fat Yogurt)
|Calcium in 100g||1 Cup (245g)||1/2 Cup (123g)|
|183mg (18% DV)||448mg (45% DV)||224mg (23% DV)|
Other Dairy High in Calcium (%DV per cup): Non-fat yogurt (49%), Whole (Full-Fat) Yogurt (30%), Non-Fat Milk (31%), Low-Fat Milk (30%), Whole (Full-Fat) Milk (28%). Click to see complete nutrition facts.
#4: Chinese Cabbage (Pak Choi, Bok Choy)
|Calcium in 100g (Raw)||1 Cup Shredded (70g)||1 Head (840g)|
|105mg (11% DV)||74mg (7% DV)||882mg (88% DV)|
Other Cabbage (%DV per cup cooked): Green Cabbage Cooked (4% DV), Red Leaf Cabbage Cooked (3% DV). Click to see complete nutrition facts.
#5: Fortified Soy Products (Tofu)
|Calcium in 100g||1 Cup (248g)||1/2 Cup (124g)|
|350mg (35% DV)||868mg (86% DV)||434mg (43% DV)|
Other Fortified Soy Products High in Calcium (%DV per cup): Nonfat Soy Milk with added Calcium (25%), Unsweetened Soy Milk with added Calcium (25%). Click to see complete nutrition facts.
#6: Okra (Cooked)
|Calcium in 100g||1 Cup Sliced (160g)||8 Pods (85g)|
|77mg (8% DV)||124mg (12% DV)||65mg (7% DV)|
|Calcium in 100g||1 Cup Chopped (91g)||1 Cup Cooked (156g)|
|47mg (5% DV)||43mg (4% DV)||62mg (6% DV)|
One cup of cooked broccoli, boiled in water contains just 54 calories.Click to see complete nutrition facts.
#8: Green Snap Beans
|Calcium in 100g (Raw)||1 Cup Raw (110g)||Per Cup Cooked (125g)|
|37mg (4% DV)||41mg (4% DV)||55mg (6% DV)|
One cup of cooked green snap beans, boiled in water contains just 44 calories. Click to see complete nutrition facts.
|Calcium in 100g||1 Cup Whole (143g)||1 Ounce (28g)|
|264mg (26% DV)||378mg (38% DV)||74mg (7% DV)|
A one ounce (28g) serving of almonds, which is about 23 kernels, contains 161 calories. Click to see complete nutrition facts.
#10: Fish Canned (Sardines, in Oil, with Bones)
|Calcium in 100g||1 Cup Drained (149g)||1 Ounce (28g)|
|383mg (38% DV)||569mg (57% DV)||107mg (11% DV)|
Other Canned Fish High in Calcium (%DV per ounce serving): Pink Salmon (8%), Anchovies (6%) and Shrimp (4%). Click to see complete nutrition facts.
Factors which Affect Calcium Absorption
- Amount of Calcium Consumed – The more calcium you consume, the less you absorb. Though consuming more calcium will increase your total level.2
- Age – Children absorb about 60% of the calcium from foods, while adults absorb only 20%. Calcium absorption decreases with age and people over 50 should eat more calcium.2
- Pregnancy – Pregnant women absorb more calcium.2
- Vitamin D Intake – Vitamin D enhances calcium absorption. It can be found in foods or created by exposing skin to sunshine.2
- Phytic and Oxalic Acid – Even though some studies suggest phytic and oxalic acid affect calcium absorption, people eating a balanced diet will not be affected, further, the percent daily value already accounts for this absorption factor. High amounts of oxalic acid is found in plant foods like spinach, collard greens, sweet potatoes, rhubarb, and beans. Phytic acid is found in whole bread, and wheat bran.2
- Sodium, Protein, Alcohol, Caffeine (Coffee and Tea) – A diet high in sodium, protein, alcohol, and caffeine (coffee and tea) can harm absorption and retention of calcium by causing more calcium to be excreted. Alcohol also interferes with the metabolism of vitamin D.2
Health Benefits of Calcium
- Bone Health and Osteoporosis (*Controversial) – Adequate intake of calcium during childhood, adolescence, and early adulthood up to age 30 is essential to increase bone mass. The higher the bone mass at this age, the lower the risk of osteoporosis.2 Many factors lead to osteoporosis and affect its severity.3 There is mixed evidence if a diet higher in calcium benefits those with osteoporosis, however, the U.S. Food and Drug Administration still suggests that a diet high in calcium in addition with vitamin D and regular exercise may reduce risk of osteoporosis.4
- Lower Blood Pressure (*Controversial) – There is mixed evidence if increased intake of calcium will lower or raise blood pressure.5-7Several studies report that those who obtain calcium from plant sources are likely to have lower blood pressure and reduced risk of heart disease.8-12 Conversely, those who predominantly consume their calcium from salty cheeses are more likely to have higher blood pressure and increased risk of heart disease.
- Reduced Risk of Colon Cancer (*Controversial) – Several observational studies link a higher intake of calcium with reduced colon cancer risk.13-16 However, various other studies report the results to be inconclusive when compared to a placebo group.16-18
Health Risks of Excessive Calcium Intake
- Kidney Stones (*Controversial) – At least one clinical trial has shown that 7 years of vitamin D and calcium supplementation is associated with increased risk of kidney stones.30 However, several other studies report lower risk of kidney stones with increased calcium intake,31-33which suggests that consumption of oxalates and lower intake of fluids are more likely to play a role in increasing kidney stone risk.34
- Impairment of the Kidneys – Extremely high levels of calcium, often associated with hyperparathyroidism, as opposed to food or supplement intake, can impair functioning of the kidneys, and lead to reduced absorption of other essential minerals, such as iron, zinc,magnesium, and phosphorus.
- Increased Risk of Cardiovascular Disease (*Controversial) – Some studies show that taking calcium supplements in excess of 500mg daily can increase risk of cardiovascular diseases.44,45
- Increased Risk of Prostate Cancer (*Controversial) – Several studies have found a link between increased calcium intake, or 2.5 servings of dairy foods, and increased risk of prostate cancer. It is inconclusive whether the dairy products or the calcium increases the risk.19-25 However, several other studies have found no association between prostate cancer and calcium,26-29 suggesting that calcium from plant foods is better than from dairy products.
- Decreased Absorption of Certain Medications – Excessive intake of calcium can decrease the absorption of the following:35-37
- Biphosphonates (for osteoporosis)
- Antibiotics (fluoroquinolone and tetracycline)
- Levothyroxine (for hypothyroidism)
- Phenytoin (an anticonvulsant)
- Tiludronate disodium (for Paget’s disease)
People at Risk of a Calcium Deficiency
- Postmenopausal women – Due to a reduced level of the hormone estrogen, calcium absorption decreases in menopausal women.38Unfortunately, an increased intake of calcium during this time may not help.39,40
- Women who miss their menstrual period (Amenorrhea) – Amenorrhea is a condition that typically occurs in anorexic women, or women who are athletes. This is again due to a reduced level of estrogren. Increased intake of calcium foods is recommended.41
- Individuals with lactose intolerance – People with lactose intolerance consume fewer dairy products, which in turn, can reduce the amount of calcium consumed.
- Vegetarians and Vegans (*Controversial) – Oxalic and phytic acids found primarily in plant products are thought to reduce absorption of calcium.42 However, consumption of meats has also been shown to increase the excretion of calcium.43 As such vegetarians and vegans might not be any worse off than omnivores, but should still be sure to eat plenty of plant foods high in calcium.
- People taking Certain Medications
- Aluminum and magnesium containing antacids.
- Mineral oil and stimulant laxatives.
- Glucocorticoids, such as prednisone.