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Calcium in a nutshell:
Calcium is the mineral that we all know is essential for bones and teeth.  Most calcium in the body is used for that but small amounts of calcium is also essential for muscle contractions, regulation of blood pressure and hormonal regulation.

Best source of Calcium for Juicers
Juicers have a good selection of produce to use to get calcium.  These include kale, parsley, dandelion greens, watercress, beet greens, broccoli, spinach, orange, celery and carrots

Alternative names: Calcium. Supplements include calcium carbonate, calcium citrate, calcium citrate malate, bisglycinocalcium, and calcium-D-gluconate, among others.

Table of Contents

What Is Calcium?
What Does Calcium Do in the Human Body?
The Relationship Between Calcium and Vitamin D
What Happens When We Don’t Have Enough Bloodstream Calcium?
What are the symptoms of low bloodstream calcium levels?
Are You At Risk for Low Bloodstream Calcium Levels?
What Happens When There Is Too Much Calcium in Our Bloodstreams?
Are You at Risk of High Bloodstream Calcium Levels?
How Much Calcium Do We Need for Good Health?
What About Calcium Supplements?
So how on earth do you get the right amount of calcium?
Calcium-D-Glucarate as a Detoxifier

What Is Calcium?

Calcium is the mineral we all know is necessary for healthy bones. Our bodies can only absorb small amounts of calcium at one time, however, and too much calcium can cause as many problems as too little.

Calcium is one of the most abundant elements on earth. It is the fifth most abundant mineral in the earth's crust and the fifth most abundant element in sea water. In its pure form, calcium is a soft, silvery metal that can be cut with a knife. Calcium does not stay in its pure form very long, however, because it quickly combines with both the oxygen and nitrogen in the atmosphere and it slowly reacts with water.

On a global level, calcium helps regulate the amount of carbon dioxide in the atmosphere. Rocks containing calcium are worn down by wind and rain and release calcium into surface water. The calcium-enriched water flows into the oceans where it combines with bubbles of carbon dioxide (more precisely, ions of carbonate formed when carbon dioxide is dissolved in acidic sea water) to form calcium carbonate, the predominant mineral compound in limestone. Eventually, over millions of years, limestone reaches the surface where it can again be broken down by wind and rain to release calcium and carbon dioxide once again, in equal quantities. Granite rocks, however, break down to release much more calcium than carbon dioxide, dissolving to take more carbon dioxide out of the atmosphere than they release as they break down.

Plants use calcium to regulate electrical charges inside and outside their cells. Calcium compounds dissolve in the watery sap of plants to release positively charged ions. Plant cells can pump these positively charged ions inside to make themselves more attractive to negatively charged nutrients or less attractive to positively charged nutrients. Plants also can use calcium to create free radicals of oxygen that activate their immune processes when they are attacked by infections.

Animals and humans, of course, use calcium to make bones and teeth. A small amount of the calcium in our bodies, however, performs other important functions.

What Does Calcium Do in the Human Body?

Most of the calcium in the human body, about 99% of the calcium in the human body, is in the form of calcium hydroxyapatite, which strengthens bones and teeth. Tiny amounts of calcium, however, have to be released from bone into the bloodstream to stimulate the secretion of hormones, especially insulin, to stimulate the contraction of muscles, and to regulate the flexibility of blood vessels and the pressure of the blood flowing through them. The 1% of calcium that isn't in bones or teeth is vital for day to day life.

Calcium flows through the bloodstream in the form of calcium ions, which are the result of dissolving calcium compounds in water. Some calcium is bound to a protein called albumin, and small amounts of calcium circulate through the bloodstream as calcium phosphate, calcium bicarbonate, calcium citrate, and calcium sulfate.

There is 100 times more calcium in the bones than in the bloodstream, but there is also roughly 12,000 times more calcium in the bloodstream than there is in the soft tissues it serves. The reason there is so much more calcium in the bloodstream than inside cells is that calcium is used as a “second messenger” for hormones.

Instead of having to move a bulky and delicate hormone from the bloodstream into a cell to activate or deactivate a cellular process, many hormones just act like a key for a lock opening a calcium channel. From 10 to 100 times the normal amount of calcium may flow into a cell that is “docked” by a hormone. The calcium changes the way the cell works, and the effects on many cells change the way a tissue works.

An example of calcium's work as a second messenger is the release of insulin from the beta-cells of the pancreas. The beta-cells make small amounts of insulin all the time, but the body doesn't need the same amount of insulin all the time. From 10 to 100 times more insulin is needed for just a few minutes as the sugars digested from food begin to enter the bloodstream about an hour after a meal.

When blood sugar glucose levels begin to rise, the membranes lining beta-cells become more sensitive to calcium. Calcium flows into the cell and binds to a “vesicle” or storage unit for the pre-formed insulin, causing it to burst. The insulin is released into the bloodstream and helps store the extra glucose sugar in the liver and muscles and other tissues that need it. A deficiency of calcium prevents the pancreas from releasing insulin. Too much calcium can, in people who don't have diabetes, cause a sudden release of insulin that can cause blood sugar levels to fall.

Calcium is also involved in the activation of B and T cells in the immune system, in the creation of the intercellular “glue” that binds cells into the tissues of which they are a part, as an activator of apoptosis (“cellular suicide” of cells with genetic damage and cells that are pre-cancerous), in stabilizing active and depressed states of nerve function, and in the contraction of muscle fibers that make muscle motion possible. Calcium also activates cells in ways that make it possible for them to use phosphorus compounds as antioxidants and detoxifiers.

The amount of calcium in the bloodstream is very tightly regulated. Too much or too little calcium in the bloodstream can cause very serious health problems.

The Relationship Between Calcium and Vitamin D

Vitamin D is critical for the regulation of calcium in the bloodstream. When the parathryoid glands (tiny glands on either side of the thyroid gland) sense low levels of calcium in the bloodstream, they release a hormone called parathyroid hormone. In turn, the kidneys respond to parathyroid hormone by releasing an enzyme called 1-alpha-hydroxylase. This enzyme converts vitamin D into its active form, vitamin D3, and vitamin D3 stimulates greater absorption of calcium from food across the membrane lining the small intestine.

Without enough active vitamin D, the intestines don't absorb enough calcium. Of course, there also has to be sufficient calcium from food or supplements or the whole process does not work.

What Happens When We Don't Have Enough Bloodstream Calcium?

A typical adult as 1.2 kilos (1200 grams) of calcium in their bones. That same typical adult has just 5 to 6 grams of calcium in various forms in the bloodstream at any one time. Between 500 and 600 milligrams (about half a gram) of calcium, however, are exchanged between the bones and the bloodstream every day as various tissues need to be activated or need to release calcium as they respond to hormones and as the muscles use calcium to power contractions. The kidneys usually excrete almost exactly as much calcium as the intestines absorb from food.

Sometimes, however, the calcium in the bloodstream may not be circulating in an available form. If the blood becomes slightly acidic, more calcium binds to albumin proteins circulating in the blood and becomes unavailable. While nutrition pundits write a great deal about the “acid danger,” this problem is actually rare.

A more likely problem is that the kidneys remove calcium from the bloodstream faster than the intestines absorb new calcium. This can happen when there isn't enough vitamin D or when the parathyroid glands don't sense low calcium levels, can't make parathyroid hormone, or the kidneys are resistant to parathyroid hormone. It can happen when the parathyroid glands are damaged by radiation, physical injury, or iron overload in a condition called hemochromatosis.

Low bloodstream calcium problems can be a problem when a sick liver cannot absorb vitamin D sent to it from the intestines, or when pancreatitis causes the release of fats that form sticky compounds with calcium in the colon. Low bloodstream calcium can occur when bone tumors use large amounts of calcium, when an overactive thyroid triggers a condition known as hungry bone syndrome. Some of the medications used to treat osteoporosis can cause low levels of calcium in the bloodstream.

The most common causes of mildly to moderately low levels of bloodstream calcium, however, are:

• Getting too much phosphorus in the diet along with
• Not getting enough magnesium in the diet.

The kidneys regulate calcium and phosphorus together. The general rule is “phosphorus in, calcium out.” Eating too many high-protein foods, seeds, whole grains, and nuts can raise phosphorus levels.

Not getting enough magnesium, on the other hand, can make it impossible for the body to absorb calcium even when the diet provides enough calcium and vitamin D. The parathyroid glands can't release parathyroid hormone without magnesium. And without this hormone, calcium is not absorbed. However, making up for magnesium deficiency quickly restores the release of parathyroid hormone.

What are the symptoms of low bloodstream calcium levels?

• Numbness around the mouth and in the fingers and toes.
• Muscle cramps, especially in the lower back and in the calves of the legs.
• Wheezing and laryngitis even without infection or allergy.
• Difficulty swallowing.
• Fatigue.
• Personality changes, irritability, and mood swings.
• Brittle nails, coarse hair, dry skin, itchy skin, and easily broken fingernails.
• Cataracts.

Fortunately, most of these symptoms will go away for most people who have low bloodstream calcium levels with appropriate nutrition: enough calcium, vitamin D, and magnesium, and not too much phosphorus.

Are You At Risk for Low Bloodstream Calcium Levels?

Getting enough calcium isn't enough to prevent low bloodstream calcium levels. Certain categories of people are at risk of the disease even when they get plenty of calcium in their daily diets:

• People who don't get enough sun.
• People who have chronic kidney failure.
• People who have acute pancreatitis.
• People who have poor function of the parathyroid glands.

When low bloodstream levels of calcium occur in children, the problem usually is poor nutrition. But when low bloodstream levels occur in adults, the problem usually is chronic kidney failure.

What Happens When There Is Too Much Calcium in Our Bloodstreams?

Too much calcium in the bloodstream is just as detrimental as too little. This condition known as hypercalcemia affects every organ in the body, but it its effects are especially evident in the kidneys and in the central nervous system.

The kidneys attempt to lower calcium levels in the bloodstream by releasing calcium into the urine. This can result in the formation of kidney stones.

Calcium power muscle contraction. Too much calcium in the electrical conduction system of the heart makes contractions of the heart more powerful. This raises blood pressure and can cause irregular heart rhythms.

In the gastrointestinal tract, hypercalcemia can cause constipation, nausea, pancreatitis (which tends to lower calcium levels), stomach ulcers, and loss of appetite.

One of the first neurological manifestations of high calcium levels is fatigue. As calcium levels continue to rise, there may also be confusion, anxiety, depression, and other personality changes. Severely elevated calcium levels can result in coma and death.

What causes the accumulation of too much calcium in the bloodstream? Usually the problem is overactivity of the parathyroid glands. When overactive parathyroids are the cause of the condition, the symptoms are usually mild. High bloodstream calcium levels caused by the destruction of bone by cancer, however, often result in death.

Are You at Risk of High Bloodstream Calcium Levels?

Hypercalcemia can be caused by hyperparathyroidism or metastatic cancer, or both. It can also be caused by a condition known as sarcoidosis. Mildly elevated calcium levels can be caused by:

• Excessive consumption of calcium-rich foods. Since the body can absorb limited amounts of calcium from any given meal, this requires eating calcium-rich foods nearly 24 hours a day. If you don't get up in the middle of the night to eat cheese or drink milk, it is unlikely that you will develop hypercalcemia due to overindulgence in calcium-rich foods.
• Excessive consumption of vitamin D.
• Rarely, failure to consume enough phosphorus-rich foods.
• Immobility (the bones absorb more calcium when weight is put on them).
• Excessive consumption of sodium, or, conversely, insufficient consumption of sodium, affecting the rate of urination.
• Dehydration, which concentrates calcium in the bloodstream.

Correcting these problems may or may not correct mild symptoms of hypercalcemia, depending on whether there is also parathyroid disease or cancer of the bone.

How Much Calcium Do We Need for Good Health?

While everyone needs a minimum amount of calcium in the diet, more is not always better with calcium. In the United States, the Institute of Medicine announced new recommended daily intakes (RDIs) for calcium in November of 2011:

• The Institute of Medicine was not able to determine an RDI of calcium for infants, but noted that 200 mg of calcium per day was likely to be adequate.
• For toddlers aged 1 to 3, the RDI of calcium is 700 mg per day.
• For children aged 4 to 8, the RDI of calcium is 1000 mg per day.
• For children and teens aged 9 to 18, the RDI of calcium is 1300 mg per day.
• For most adults, the RDI of calcium is 1000 mg per day. However, women past the age of 50 and men past the age of 70 have an RDI of 1300 mg per day. Women who are pregnant or breastfeeding should take the RDI for their age group.

There is also an upper tolerable limit, a maximum daily consumption of calcium, set by the Institute of Medicine:

• Infants up to six months of age should not receive more than 1,000 mg of calcium per day.
• Infants between 6 and 12 months of age should not receive more than 1,500 mg of calcium per day.
• Children aged 1 to 8 should not receive more than 2,500 mg of calcium per day.
• Children aged 9 to 13 should not receive more than 3,000 mg of calcium per day.
• Teens aged 14 to 18 should not receive more than 3,000 mg of calcium per day.
• Adults aged 19 to 50 should not receive more than 2,500 mg of calcium per day.
• Adults 51 and older should not receive more than 2,000 mg of calcium per day.

In the United States, most people aged 50 and younger get enough calcium from their diets, but most people over the age of 50 do not. In the USA, men in their 50's and 60's usually have a deficit of 200 to 300 mg of calcium per day. Women in their 50's and 60's and men who are 70 or older usually have a deficit of 600 to 800 mg per day. Canadians tend to get a little more calcium from their diets, but most people who are over 50 do not get enough.

Getting enough calcium from your daily diet isn't just matter of eating the right foods. The body can only absorb about 400 mg of calcium from any single meal. This means that there needs to be a calcium-rich food at every meal, and that trying to get all your calcium from a single meal or snack just won't work. The are also other nutrients that are required for absorption of or that interfere with absorption of vitamin D.

• Absorbing calcium from your food requires getting enough vitamin D. About 15% of Australians and New Zealanders and 20 to 25% of people in other English-speaking countries are deficient in vitamin D. The group most prone to vitamin D deficiency is Muslims who live in regions that require air conditioning because of heat. African-Americans of any religious preference also have high rates of vitamin D deficiency, up to 50% in the United States.
• Getting too much protein is not the problem it is often said to be—it's phosphorus that's the problem, not protein. Low-protein levels are actually risk factor for osteoporosis.
• Consuming more than 400 mg of caffeine (3 cups of coffee, or a tumbler of iced tea or soft drink) with your meal can accelerate the rate at which your kidneys excrete calcium, but only very slightly, about 10 mg of calcium for every 400 mg of caffeine.
• Consuming too much salt can also accelerate the rate at which the kidneys release calcium, but for reasons of genetics this is primarily a problem for people who are of African heritage.
• Phytates in high-fiber grains and vegetables trap calcium in forms that cannot be absorbed. Having healthy bacteria in your lower digestive tract, however, helps break down phytate so it does not inhibit calcium absorption. Some calcium supplements contain an ingredient called phytase, which is an enzyme that breaks down phytates. They increase calcium absorption.

So how can you get enough calcium without consuming more than your body can absorb? Here are the amounts of some common foods that give contain 400 mg of calcium.

• Just 1/3 of an ounce (approximately 10 grams) of Kellogg's TOTAL breakfast cereal.
• Just 1/2 of an ounce (approximately 14 grams) of dried tofu.
• Just 3/4 of an ounce (approximately 20 grams) of dried milk powder.
• Just 1 ounce (28 grams) of queso fresco.
• 1-1/4 ounces (35 grams) of romano cheese.
• 1-1/3 ounces (37 grams) of gruyere cheese.
• 1-1/2 ounces (42 grams) of crispy fried tofu.
• 1-1/2 ounces (42 grams) of Swiss, mozarella, provolone, or Monterrey jack cheese.
• 2 ounces (56 grams) of cheddar, colby, Munster, queso anejo, or KRAFT singles cheese.
• 3-1/2 ounces (100 grams) of cooked agave, winged beans, shrimp, most infant formulas, sardines, polenta, or grits.
• 4 ounces (112 grams) of almonds, pizza, cheese curd, low-fat ricotta cheese, ice cream, or salmon.
• 4 fluid ounces (120 ml) of evaporated milk.
• 5-1/2 ounces (154 grams) of natto, whole milk ricotta, or rhubarb.
• 6 ounces (168 grams) of dandelion greens, low-fat yogurt, nopal (cactus), or tortilla chips.
• 7-1/2 ounces (210 grams) of uncooked figs, arugula, black beans, quinoa, pizza, soft-serve ice cream, boiled spinach, boiled turnip greens, boiled collard greens, boiled kale, or
• 1 cup (240 ml) of cow's milk.
• 6 cups (1440 ml) of homemade soy milk.
• 72 cups (17,280 ml, more than you could ever drink) of homemade almond or rice milk. Many commercial brands of soy, almond, and rice milk, however, are fortified with artificial calcium.

Dr. Joel Furhman, a physician who was a partner of American TV's Dr. Oz and who wrote the bestselling diet book Eat to Live, argues that calcium in plant foods is easier to absorb than calcium in dairy foods. He's right, but most other vegetables (green beans, tomatoes, salad greens, and so on) contain only about 50 mg of calcium per 3-1/2 oz (100 gram) serving. About 18% more of the calcium in leafy greens is actually absorbed into the human body than the calcium in cow's milk, but it takes 4 times the weight and 20 times the volume of raw plant foods to get the same amount of calcium. And since fiber interferes with the absorption of calcium, if you are a strict vegan you probably need to consider taking a calcium supplement.

What About Calcium Supplements?

The first thing to know about calcium supplements is that different forms of calcium in foods and supplements are absorbed at very different rates.

• Most of the calcium in plant foods is in the form of calcium oxalate. About 10% of the calcium oxalate in plant foods is absorbed.
• The least expensive form of calcium in calcium supplements is calcium carbonate. About 26% of the calcium in calcium carbonate supplements is absorbed if they are taken on an empty stomach and about 29% of the calcium carbonate supplements is absorbed if they are taken with food.
• Calcium citrate is advertised as a better absorbed form of calcium, but only about 25% of the calcium in calcium citrate is absorbed when calcium citrate supplements are taken on an empty stomach.
• About 36% of calcium citrate malate is absorbed when the supplement is taken with a meal.
• The best absorbed form of calcium for supplements is bisglycinocalcium. About 44% of the calcium in bisglycinocalcium supplements is absorbed if they are taken on an empty stomach.

There are no foods from which even 50% of the calcium in the food reaches the bloodstream. There are no calcium supplements from which even 50% of the calcium in the supplement ever reaches the bloodstream. And the forms of calcium that are more completely absorbed are found in bulkier, heavier compounds.

Just 20% of calcium citrate, for example, is actually calcium. The rest is citrate. And of the 20% of the supplement that is calcium, just one-quarter is actually absorbed. And if that sounds complicated, consider this. Scientists have discovered that:

• Taking 1000 mg of calcium or more in a single dose can actually lower bloodstream concentrations of calcium (by activating the parathyroid glands).
• Taking 200 mg of calcium raises concentrations of calcium in the bloodstream more than taking 500 mg of calcium.
• Taking calcium supplements in the morning raises bloodstream levels of calcium more than taking them at night, due to the fact that the parathyroid glands release pulses of hormones in the evening.

So how on earth do you get the right amount of calcium?

Keep in mind that most people only need 200 to 400 mg of calcium more than they are getting in their diets. That means they need to take 400 to 1200 mg of calcium supplements, depending on the form of calcium in the supplement.

Ideally, one should take 200 or 250 mg of calcium on an empty stomach three times per day, starting before breakfast. Taking 500 mg of calcium once day may also work if the diet contains calcium-rich foods. Taking 1000 mg of calcium in a single pill, however, may actually make calcium deficiencies worse.

Calcium-D-Glucarate as a Detoxifier

One form of calcium, calcium-D-glucarate, is an important detoxifier. Many plants, especially vegetables in the cabbage family and citrus, produce a compound called D-glucaric acid. When this compound is digested by humans or other mammals, it becomes a salt called calcium-D-glucarate.

Calcium-D-glucarate inhibits an enzyme called beta-glucuronidase. This enzyme is released by pathogenic bacteria in the small intestine and it is also made in the liver. The function of beta-glucuronidase outside of the liver is to break down mucopolysaccharides, the complex carbohydrates that make mucus “slimy.” The function of beta-glucuronidase in the liver is to recycle hemoglobin from old red blood cells. Overactivity of beta-glucuronidase can cause inflammation of mucous membranes all over the body and anemia.

Beta-glucuronidase can also reverse a process in the liver known as glucuronidation. What this complex chemical process does is to bind sex hormones, steroids, chemical carcinogens, and fat-soluble toxins so they “stick” to bile salts and are carried out of the liver and into the small intestine to be expelled with stool. Certain kinds of pathogenic E. coli bacteria in the small intestine can undo this process and release sex hormones, steroids, carcinogens, and fat-soluble carcinogens so they go right back into the bloodstream. Failure of the glucuronidation process in the liver is associated with greater risk of breast, uterine, cervical, and ovarian cancer in women, prostate cancer in men, and lung, skin, colon, and liver cancer in both sexes. Taking calcium-D-glucarate may lower the risk of these cancers in susceptible individuals.

Calcium-D-glucarate may also help women who suffer excesses of estrogen. By stimulating circulation in the liver, it may also help lower LDL cholesterol.

There is a great deal of D-glucaric acid in apples and grapefruit and also in Brussels sprouts, cabbage, and broccoli. If you never eat these foods, consider taking a calcium-D-glucarate supplement, especially if you smoke.

Where to get Calcium?