Best food groups: Dairy, green vegetables, soybeans, nuts and seeds, fish
Also consider: Soybeans, tofu, dark green vegetable sprouts, cauliflower, sesame seeds, red beans, Brazil nuts, herring, herbs
What is calcium and why is it so important? Calcium is the fifth-most-abundant element found in nature. It is what makes up limestone and marble, coral, seashells and eggshells, antlers and bones. Our very structure depends on it, as 99 percent of all calcium stored in the body can be found in the bones (including teeth). It is also responsible for cardiovascular, nervous, and muscular cell conduction.
Lifestyle choices are the biggest contributor to calcium deficiencies: poor intake, lack of exercise, and tobacco or excessive alcohol use. Being underweight might cause more loss of calcium than being overweight; and hormonal imbalances, such as menopause, have also been found to disrupt calcium balance. Besides inadequate intake, calcium deficiencies can also be caused by certain diseases such as Crohn's, liver, and celiac disease. Health conditions associated with immobility or bed rest for more than six months, such as stroke, Parkinson's disease, or multiple sclerosis (MS), can waste calcium. Even certain medications, such as steroids, can deplete calcium.
When calcium is not adequate in your bloodstream, your body pulls it from its storage depots—a.k.a. your bones and teeth—which can lead to osteoporosis and dental problems. In addition, disorders of calcium deficiency can include congestive heart disorder, heart arrhythmias, hypotension, and muscle stiffness and cramps.
Did you know? Adequate calcium intake has been found to lower the risk of developing obesity, hypertension, hyperinsulinemia, and insulin resistance. Adequate vitamin D levels also help ensure appropriate calcium absorption . Watch that sodium! It can compete with calcium for absorption in the body, meaning that too much sodium could contribute to the development of osteoporosis!
How much is enough?
The DV for calcium is 1,000 mg, based on a 2,000-calorie diet.
Consuming excess calcium can lead to a buildup of calcium (hypercalcemia). Symptoms of hypercalcemia include fatigue, weakness, loss of appetite, nausea, excessive urination, dehydration, lethargy, stupor, and coma. Long-term calcium overload can lead to such health conditions as hyperparathyroidism, certain cancers, hyperthyroidism, hypervitaminosis D, immobilization, and sarcoidosis.
Supplements: Considering that dairy products supply 78 percent of the calcium in the U.S. diet, it may be hard to maintain adequate calcium levels without consuming dairy or fortified foods. (Blood tests are not the best way to determine whether you have adequate stores of calcium in your body. Your body will leach calcium from your bones to keep blood levels normal if there are not adequate amounts of calcium in your diet. Ask your doctor if a bone density study may be in order.) Calcium can be found in multivitamins, bone formulations, by itself or in combinations with other nutrients.
1. Hard Cheese
Hard cheeses in general contain the most calcium of all the cheeses. Parmesan is made from partially skimmed cow's milk and typically aged anywhere from ten months to several years. The long aging process is what produces the crumbliness of Parmesan cheese. It is an excellent source of calcium and protein and a good source of phosphorous. In fact, cheeses are among the most concentrated protein sources found on Earth, with Parmesan cheese containing more than 38 g of protein per 3.5 ounces of grated cheese. That is more than all meats and other protein sources.
Parmesan cheese dates back in the literature as early as the fourteenth century. Its namesake is Parma, one of five provinces in Italy that boast over 1,600 cheese factories.
2. Yogurt
Three servings of yogurt per day given to women who had very poor calcium intake significantly slowed down the excretion of a chemical in the body that signals bone loss.
3. Collard Greens
Got Collards? True—you don't see green mustache campaigns promoting collard greens for their calcium. However, get this: Cup for cup, collards have more calcium than milk! But when it comes to nutrient supremacy, it's what get's absorbed that matters. Unfortunately, green leafies, such as collards, are also high in oxalates, which can block some of the calcium from being absorbed. Serving dark greens with a vitamin C source such as a citrus glaze, or adorned with slices of citrus, can help.
Calcium-starved rats were attracted to the taste of collards over three other not-as-calcium-rich sources presented to them in a study. Calcium may contribute to the bitterness in greens and can be a turn-off to some humans. But if prepared the right way, the bitter flavor can be masked and acceptable to humans and rats alike!
4. Rhubarb
The most popular use of rhubarb is in rhubarb pie or to make tarts and sauces. It is not naturally sweet, so sugar must be added. It is also a great source of fiber and a fair source of many other nutrients. Rhubarb is rich in calcium but also in oxalates, which can impede much of its calcium from being absorbed. It must also be prepared carefully (the rest of the plant, aside from the stalks, is poisonous). Bottom line? Enjoy it but don't count on it as a preferable source of calcium.
The use of rhubarb as a medicinal plant dates back as far as 2700 BC in China, and supposedly it was given to the Wu emperor of the Liang dynasty to break a fever. In America, it is thought that a gardener from the state of Maine first planted rhubarb in the late 1700s after obtaining the seeds from Europe.
5. Sardines
Sardines contain a boatload of soft bones (but you'd be hard pressed to feel them when you eat them because they are soft), which makes this food one of the best sources of calcium, provided you eat them with their bones. Sharing that vessel are many other nutrients. Along with dairy products, sardines are the main dietary source of calcium among the elderly. Unfortunately, they don't consume enough of these inexpensive little fishies to meet their needs and offset osteopenia and osteoporosis.
6. Milk
No other naturally occurring drink contains as many nutrients as milk, which is the largest contributor of calcium, potassium, and vitamin D to the American diet.
Switching from whole milk to skim milk can help you lose almost 7 pounds a year. According to the National Academy of Sciences, milk has ten times the bioavailability for calcium as spinach does!
7. Spinach
Although spinach does contain oxalates that can bind calcium, a study in Japan found that young women who didn't get in daily intake of yellow and green vegetables, such spinach, had almost a fivefold risk of developing low bone mass, compared to those women who did.
Source: USDA National Nutrient Database for Standard Reference, Release 24