The Health Benefits of Calcium
Calcium and Bone Health
Your bones remodel throughout life according the stresses placed on them much like a muscle responds to exercise. During childhood and adolescence, your bones increase in size and mass. They continue to add more mass until around age 30, when peak bone mass is reached. Because bone loss, like bone growth, is a gradual process, the stronger your bones are at age 30, the more your bone loss will be delayed as you age. Therefore, it is particularly important to consume adequate calcium, along with magnesium and vitamins D and K2 throughout your childhood and adolescence.
It is also important to do regular weight-bearing exercise to maximize bone strength and bone density to help prevent osteoporosis later in life. Weight bearing exercise is the type of exercise that causes your bones and muscles to work against gravity while they bear your weight. Resistance exercises such as weight training are also helpful because they help to improve your muscle mass and bone strength. Examples of weight bearing exercise are walking, running, dancing, aerobics, tennis, skiing, skating and rollerblading.
When your calcium intake is low or calcium is poorly absorbed, bone breakdown occurs because the body must use the calcium stored in bones to maintain more urgent biological functions such as generating a heart beat, nerve and muscle function. Bone loss also occurs in post-menopausal women because of decreased estrogen. Researchers have identified many factors that increase the risk for developing osteoporosis. These factors include being female, thin, inactive, of advanced age, cigarette smoking, excessive intake of alcohol, taking immune suppressing drugs such as prednisone, and having a family history of osteoporosis.26
Bone mineral density tests performed by DEXA scans can help determine bone mass. These tests provide a T-score which is a measure of bone mineral density that compares an individual's bone mineral density to an optimal 30 year old healthy adult's bone density. A "T-Score" of -1.0 and above indicates normal bone density. A T-score of -1.0 to -2.5 indicates that a person is considered to have low bone mass - a condition called osteopenia. A score below -2.5 indicates osteoporosis.28
Although osteoporosis affects people of different races, genders and ethnicities, women are at highest risk because their skeletons are smaller to start with and because of the accelerated bone loss that accompanies menopause. Adequate calcium, vitamin D, vitamin K2, magnesium and trace mineral intakes, as well as weight bearing exercise are critical to the development and maintenance of healthy bone throughout the lifecycle.
Calcium and High Blood Pressure
Some studies indicate if you eat a vegetarian diet high in plant minerals including calcium, magnesium and potassium, and fiber, you tend to have reduced blood pressure.29-31
Other studies indicate that an increased calcium intake lowers blood pressure and the risk of hypertension (high blood pressure) .32,33 However, the results of some studies produced small and inconsistent reductions in blood pressure. One reason for these mixed results is because these research studies tended to test the effect of single nutrients rather than foods with several minerals on blood pressure.
To help test the combined effect of nutrients including calcium from food on blood pressure, a study was conducted to investigate the impact of various eating patterns on blood pressure. This study titled "Dietary Approaches to Stop Hypertension (DASH)" was reported by the National Institutes of Health. It examined the effects of three different diets on high blood pressure: a control, "typical American" diet and two modified diets (high fruits-and-vegetables and a combination "DASH" diet - high in fruits, vegetables, and calcium). The combination "DASH" diet, with increased calcium, decreased blood pressure.35 A number of further studies have been done, all showing a similar relationship between increasing calcium intakes and decreased blood pressure.36
Overall it appears that consuming an adequate intake of fruits and vegetables as well as calcium plays a significant role in controlling blood pressure.
Calcium and Colorectal Cancer
The relationship between calcium and colon cancer has not been determined conclusively, there is, however, some evidence of a link between adequate calcium intake and this common disease. Some studies suggest that increased intakes of dietary and supplemental calcium are associated with a decreased risk of colon cancer.38-41 Calcium supplementation is reported to lead to reduced risk of adenomas (nonmalignant tumors) in the colon, a precursor to colon cancer, but it is not known if this will ultimately translate into reduced cancer risk.42 Another study reported on the association between diet and colon cancer history in 135,000 men and women participating in two large health surveys, the Nurses' Health Study and the Physicians' Health Study. The authors found that those who consumed 700 to 800 mg calcium per day had a 40 to 50% lower risk of developing left side colon cancer.43 In balance, you should note that a few other studies found inconclusive evidence regarding any association of calcium intake with colon cancer.44-46 Some encouraging research indicates a protective effect of calcium against colon cancer, but further studies are necessary to understand it better.
Calcium and Kidney Stones
Kidney Stones are crystallized deposits of calcium and other minerals in the urinary tract. Calcium oxalate stones are the most common form of kidney stones. High calcium intakes or high calcium absorption were previously thought to contribute to the development of kidney stones, but more recent studies show that high dietary calcium intakes actually decrease the risk for kidney stones.55-57 Other factors such as high oxalate intake from leafy vegetables like spinach and kale, and reduced fluid consumption appear to be a risk factor in the formation of kidney stones, but calcium is not.58
Calcium and Weight Management
Can you lose weight from taking calcium? Several studies have linked higher calcium intakes to lower body weights or less weight gain over time,59-62 while other studies have found little or no effect of calcium on fat loss. Two explanations have been proposed for how calcium may help to regulate body weight. First, high-calcium intakes may reduce calcium concentrations in fat cells by lowering the production of two hormones (parathyroid hormone and an active form of vitamin D), which in turn increases fat breakdown in these cells.61 In addition, calcium from food or supplements may bind to small amounts of dietary fat in the digestive tract and prevent its absorption, carrying the fat out in the feces.61,63 It seems calcium plays a contributing role, but more studies are needed to determine calcium's exact activity in weight management.
Calcium Supplements
Because of our food choices, and because of decreased calcium in plants due to modern agricultural practice, it is probably necessary for you to take supplements in order to meet the recommended intakes for calcium.
Calcium never exists naturally by itself. It is always attached to another molecule such as carbonate. The two main forms of calcium found in supplements are carbonate and citrate. Calcium carbonate, usually from limestone, is the most common because it is inexpensive. Contrary to marketing claims, the absorption of calcium citrate is similar to calcium carbonate for most people. Calcium carbonate supplement contains 40% calcium while a calcium citrate supplement only contains 21% calcium, so you need to take twice as many pills to get the same amount of elemental (pure) calcium. Other forms of calcium in supplements or fortified foods include calcium gluconate, calcium lactate, and calcium phosphate.
The amount of calcium your body obtains from various supplements depends on the amount of elemental calcium in the tablet. Elemental calcium is the amount of actual calcium. The Supplements Facts box on your supplement label may just say "calcium" but it always means elemental calcium.
