|Mineral Nutrient :: Calcium|
|Content Below:||What is Calcium · Benefits · Deficiency Signs · Foods · Supplements · RDA · Toxicity|
What is Calcium ?
Calcium is the most abundant mineral in the body. The human body has between 750g to 1300g of calcium, which accounts for roughly 1.5% of body weight.
99% of the calcium in the body is used in combination with phosphorus to form calcium phosphate, the dense hard material that makes up bones and teeth. The remaining 1% is found in tissues, muscles, blood, extracellular fluid, and cells, and is needed for other vital body processes.
Because of this, calcium is most well known for its role in maintaining the density and strength of bones, and for preventing osteoporosis, a disease where bones become porous and brittle. This is quite a common disease, and one cause is calcium deficiency.
For this reason, people are encouraged to consume foods high in calcium or take calcium supplements to prevent osteoporosis and consequent risk of bone fractures.
Calcium in foods is not easily depleted by cooking or storage.
Calcium is essential for many functions in the body.
Most of it is used for building and maintaining strong bones and teeth, and healthy gums. Calcium in bones needs to be continually replaced, which is why proper levels of calcium are needed throughout life. In fact the need for this mineral increases with age, as the body becomes less efficient at absorbing it from food.
Bone mass – the amount of mineral in bones – increases through childhood and early adulthood till it reaches peak bone mass at some point between the ages of 25 to 40, after which it declines. The higher this peak, the longer it takes for severe bone loss to set in. It is therefore important to consume enough calcium and vitamin D in childhood and early adulthood, to achieve greater peak bone mass.
Calcium is also needed for other vital processes. It has a role in regulating various body functions, including the cardiovascular and nervous systems, muscle contraction, enzyme activity, and cell membrane function.
Since these functions are critical to life, the body tries to make calcium always available by regulating blood calcium levels. It does so by drawing calcium from bones into blood whenever dietary intake of it is insufficient to maintain enough calcium in the blood. However such continual leaching of calcium from bones, over time, can lead to osteoporosis.
The main benefits of calcium are summarized in this table.
|::||Calcium Benefits & Functions|
|1.||major component of, and vital for strong bones, cartilage, muscle, and teeth|
|2.||slows rate of bone loss linked to osteoporosis|
|3.||slows down tooth loss in older people from the jaw bone becoming too weak to hold teeth firmly in place; helps prevent gingivitis in children|
|4.||protects bones and teeth from lead by inhibiting absorption of the toxic metal|
|5.||needed for muscle contraction and relaxation; prevents muscle cramps|
|6.||plays a vital role in transmission of nerve impulses|
|7.||important for blood clotting|
|8.||helps regulate passage of nutrients across cell walls|
|9.||needed for normal heartbeat|
|10.||needed for blood vessel expansion and contraction, and helps regulate blood pressure|
|11.||some research shows that calcium supplements can help reduce blood cholesterol levels|
|12.||there is some evidence that calcium supplements can reduce the risk of colon cancer|
|13.||activates several enzyme systems needed for biochemical processes in the body|
|14.||supplementing with calcium appears to help relieve symptoms linked with Premenstrual Syndrome (PMS)|
|15.||anecdotal evidence that calcium alleviates insomnia|
Calcium Deficiency Symptoms and Causes
Calcium deficiency can be due to many reasons. Many people just don’t take enough calcium in their diets. American adults typically consume less than 600 mg daily, below the RDA of 1,000 to 1,200 mg.
Others suffer from poor absorption of calcium in foods or poor utilization of it, or too much of it being excreted. Too much phosphorus or magnesium in the diet, or insufficient secretion of stomach acid (which happens in many people especially the elderly) can also inhibit the uptake of calcium.
Vitamin D facilitates the absorption and utilization of calcium. If vitamin D is lacking or not converted into its active form (perhaps due to problems in the liver or kidneys where this should take place), then calcium levels are impaired.
Heavy exercise also hinders the uptake of calcium while moderate exercise enhances it. Physical inactivity, especially during periods of complete bed rest, increases calcium loss. Exercise plays an important role in preventing osteoporosis.
A diet that is high in fat, protein, or sugar decreases calcium uptake. Tea, coffee, carbonated drinks, tobacco, alcohol, refined sugar, and excess salt all contribute to loss of calcium from bone and urinary excretion.
The average modern diet of soft drinks high in phosphorus, refined grains, and meat tends to lead to calcium deficiency. To counter this, take foods high in calcium such as fruits, whole grains and vegetables.
Female athletes and menopausal women need higher calcium intake due to lower estrogen levels. (Estrogen protects the skeletal system by promoting deposition of calcium in bones.)
Inadequate calcium intake produces little or no obvious symptoms in the short term, as the body regulates blood calcium levels tightly by drawing calcium from bones. However in the long term, low calcium levels can lead to serious consequences.
|::||Calcium Deficiency Symptoms|
|1.||osteoporosis, characterized by brittle, porous bones and frequent bone fractures, as deficiency in blood calcium may result in skeletal calcium being pulled out to meet the body’s calcium needs
|2.||impaired bone mineralization which, in children, can cause rickets (where bones soften and become so pliable that they bend, resulting in skeletal problems such as knock-knees, bowed legs, spinal curvature, enlarged ankles and wrists, narrowed chest, contracted pelvis, bulging forehead, soft skull bones and increased joint space)
|3.||osteomalacia (adult rickets) due to inadequate calcium in bones, that causes bones to be soft and prone to fractures, and symptomized by deformities in the spine and limbs, and rheumatic or arthritic-like pain
|4.||osteonecrosis (loss of bone mineralization in the jaw)
|5.||tooth decay or periodontal disease
|6.||lead is absorbed by the body and deposited in bones and teeth, which may explain why children with more teeth cavities have higher levels of lead
|7.||brittle or misshapened nails
|8.||rheumatoid arthritis (autoimmune disease that causes tissue damage and chronic inflammation of joints, leading to joint swelling and pain)
|9.||heart palpitations or abnormal heart rhythms
|10.||risk of hypertension (high blood pressure)
|11.||higher cholesterol levels
|13.||lethargy or chronic fatigue
|15.||very low blood levels of calcium can lead to tetany, a condition in which nerve activity becomes excessive and causes spasmodic contractions of skeletal muscles; symptoms range from tingling of fingers, toes or lips, to numbness in the arms or legs, to muscle pain, to severe muscular cramps or spasms, and in extreme cases, even death
Foods high in calcium include dairy foods and some plants. Many of these plants also contain oxalic acid (almonds, cashews, chard, celery, spinach, kale, tea) and phytic acid (nuts, whole grains, legumes) that bind with the calcium in the food and lower its absorbability. But fears over this tend to be overblown, as the decrease in available calcium is relatively small.
For example, a study of the calcium bio-availability of kale vs that of milk, found its absorbability higher in more cases than for milk calcium.
Foods high in calcium · dairy foods such as buttermilk, mozzarella cheese, raw (non-pasteurized) milk, whey, yoghurt · goat’s milk · fresh dark green vegetables like collard greens, dandelion greens, mustard greens, spinach, turnip greens, wing beans.
Other foods containing calcium include · blackstrap molasses · brewer’s yeast · dried apricots, figs, prunes · dried beans · fruits like oranges and papaya · herbs such as basil, cinnamon, dill, fennel, garlic, oregano, parsley, peppermint leaves, rosemary, thyme · oats · sesame seeds and almonds · sea vegetables such as arame, dulse (a red seaweed), kelp, kombu, and wakame · seafood · soft bones of wild salmon, sardines, tuna, and anchovies are good sources of calcium that is easily absorbed by the body · tofu · vegetables like asparagus, bok choy (chinese cabbage), broccoli, Brussel sprouts, cabbage, carrots, celery, green beans, kale, okra, romaine lettuce, swiss chard.
Taking vitamins and minerals in their correct balance is vital to the proper functioning of all vitamins. They work synergistically, which means that the effectiveness of any one nutrient requires, or is enhanced, sometimes dramatically, by the presence of certain other nutrients.
For this reason, if you are looking to take supplements for maintenance of optimal health, the recommended approach is to take a multi-vitamin that has the proper balance of all the necessary nutrients your body needs.
For a list of reputable top ranked vitamin and mineral supplements chosen in an independent supplement review, see Best Multivitamin Supplements. Many of these are manufactured to pharmaceutical or nutraceutical GMP compliance, which is the highest multivitamin standard possible.
Keep in mind, however, that while mineral supplements are useful to plug nutritional gaps that are almost inevitable in modern diets, and to ensure we get optimal doses of nutrients, they are no substitute for a good diet. Instead, use them to complement a healthy diet and lifestyle.
Calcium RDA (Recommended Dietary Allowance)
The Food & Nutrition Board of the Institute of Medicine, National Academy of Sciences, in their 1997-2001 collaboration between the US and Canada, set the daily Adequate Intake (AI) of Calcium as follows.
|Life Stage | Gender||Calcium Dosage | Day|
|Infants 0-6 mths||210* mg|
|Infants 7-12 mths||270* mg|
|Children 1-3 yrs||500* mg|
|Children 4-8 yrs||800* mg|
|Girls 9-13 Yrs||1300* mg|
|Boys 9-13 Yrs||1300* mg|
|Females 14-18 Yrs||1300* mg|
|Males 14-18 Yrs||1300* mg|
|Females 19-50 Yrs||1000* mg|
|Males 19-50 Yrs||1000* mg|
|Females older than 50 Yrs||1200* mg|
|Males older than 50 Yrs||1200* mg|
|Pregnant Women 14-18 Yrs||1300* mg|
|Pregnant Women 19-50 Yrs||1000* mg|
|Lactating Mothers 14-18 Yrs||1300* mg|
|Lactating Mothers 19-50 Yrs||1000* mg|
These dosages are the minimum required per day to ward off deficiency. In therapeutic use of this nutrient, dosage is increased as necessary for the ailment, keeping in mind Calcium toxicity levels.
1 µg = 1 mcg = 1 microgram = 1/1,000,000 of a gram
1 mg = 1 milligram = 1/1,000 of a gram
* Indicates AI figures based on Dietary Reference Intake (DRI) figures
Calcium Overdose Symptoms, Toxicity Level & Side Effects
The most common side effects of calcium overdose are constipation and stomach upset. Excessive dosages over 3000 milligrams a day may cause loss of appetite, nausea, vomiting, kidney stones, frequent urination, and irregular heartbeat, and hinder the absorption of essential minerals like iron and zinc.
Calcium overdose can also lead to abnormally high blood levels of calcium, known as hypercalcemia. In cases where the body’s phosphorus levels are low as well, this can cause calcium to accumulate in soft tissue.
The Food and Nutrition Board of the Institute of Medicine has set Tolerable Upper Intake Levels (ULs) for calcium, listed in the table below. These are levels above which there is risk of calcium overdose, especially when taken over a long time.
Tolerable Upper Intake Levels (UL) for Calcium per Day
|0 to 12 months||*ND||*ND|
|1 to 13 years||2,500 mg||2,500 mg|
|14 years & above||2,500 mg||2,500 mg||2,500 mg||2,500 mg|
*ND : Not determinable. Intake should be from food/milk only.
The ULs do not apply to therapeutic use of calcium for treatment.
Individuals suffering from kidney stones or kidney disease should not take calcium supplements, as they are more vulnerable to calcium side effects.
« Back to Health Supplements Nutritional Guide Home page
|1.||Institute of Medicine, Food and Nutrition Board. Dietary reference intakes for calcium, phosphorous, magnesium, vitamin D, and fluoride. Washington DC: National Academy Press; 1997.|
|2.||U.S. National Libary of Medicine [NLM] & National Institutes of Health [NIH]: MedlinePlus. NLM-NIH home page. <http://www.nlm.nih.gov/medlineplus>. Use the built-in search function to find specific data. Accessed 2009 March – June.|
|3.||National Institutes of Health, NIH Clinical Center: Office of Dietary Supplements [ODS]. ODS home page. <http://ods.od.nih.gov>. Use the built-in search function to find specific data. Accessed 2009 Mar – Jun.|
|4.||The George Mateljan Foundation: The world’s healthiest foods [WHFoods]. WHFoods home page. <http://www.whfoods.com>. Accessed 2009 March – June.|
|5.||Mayo Foundation for Medical Education and Research. Mayo Clinic book of alternative medicine: The new approach to using the best of natural therapies and conventional medicine. New York, NY: Time Inc; 2007. p 67-75.|
|6.||Balch JF, Balch PA. Prescription for nutritional healing: A practical A-Z reference to drug-free remedies using vitamins, minerals, herbs & food supplements. Garden City Park, New York: Avery Publishing; 1990.|
|7.||Ulene A. Dr. Art Ulene’s complete guide to vitamins, minerals and herbs. New York, NY: Avery Publishing; 2000.|
|8.||Denke MA, Fox MM, Schulte MC. Short-Term Dietary Calcium Fortification Increases Fecal Saturated Fat Content and Reduces Serum Lipids in Men. Journal of Nutrition, 1993 Jun; 123(6): 1047-1053.|
|9.||Ditscheid B, Keller S, Jahreis G. Cholesterol Metabolism Is Affected by Calcium Phosphate Supplementation in Humans. Journal of Nutrition, 2005 Jul; 135(7):1678-1682.|