Time was, bone health was seemingly achieved with simple daily servings of milk, sunshine, and a diet rich with natural calcium. But the lifelong struggle for bone health and terror of brittle bones also spawned an industry of calcium supplements and calcium-fortified foods. Alas, bones are losing the battle. Today, half of all American citizens older than 50 are at risk of osteoporosis and low bone mass.
Unfortunately, calcium deficiency is common. Many do not get enough calcium from their daily diets. For those with chronic dietary deficiencies, the use of both calcium supplements and vitamin D has been the standard recommendation for meeting requirements. And for a while, the commerce of calcium supplementation enjoyed the boost of incidental benefits – calcium supplementation, besides reducing fractures and osteoporosis, also showed benefits in lowering blood pressure and reducing colon cancer risks.
The past few years, alas, studies have raised doubts on the benefits of calcium supplementation, and further, raised concerns on increased cardiovascular events, myocardial infarction and strokes, including the adverse effect of "abrupt increases" of calcium within hours of supplementation.
Calcium is in the YesNoYesNo category.
Many are not aware of the on-going debates and concerns, and physicians, still mired in debate and disagreement, are unable to provide a consensus advice to patients. Many patients continue cobwebbed advice on vitamins and supplements, religious in their doses of calcium for the bones, and vitamins and supplements for what they can replenish and for the maladies they can prevent.
As the debate goes on.
• Calcium is the most abundant mineral in the human body, accounting for about 1.5% of body weight, more than 99% of it is stored in the bones and teeth where it provides support and structure; and the other 1% is in the blood, muscle, and intercellular fluids involved in the intricate systems of enzymes, hormones, neurologic functions, cardiac rhythm and muscle contraction.
• Calcium is found in some foods, added to some (calcium-fortified), present in some medicines (antacids) and available as dietary supplements.
• Unfortunately, calcium deficiency is common. Many do not get enough from the food they eat. When intake is low or ingested calcium is poorly absorbed, the body makes up by bone breakdown, mobilizing stored calcium for essential biological functions. For chronic deficiency of intake, meeting requirements require the use of supplements.
• The 99% stored in bones and teeth is in a dynamic state of remodeling, with constant resorption (loss, reabsorption, removal) and deposition (addition, formation) into new bone. This balance changes with age: In children and adolescents, bone formation exceeds resorption; in early and middle adulthood, the processes are relatively equal; and in aging adults, especially postmenopausal women, bone breakdown and loss exceeds formation, an imbalance that increase the risk for osteopenia (low bone mass) and osteoporosis (bone porosity and fragility) over time.
• In the U.S., there is an estimated 1.5 million fractures a year attributed to osteoporosis. calcium is critical in the prevention and treatment of osteoporosis and in lowering the risk of fractures over the age of 65.
• Excess of calcium: Hypercalcemia (elevated calcium) rarely results from dietary or supplemental intake; it is most often associated with primary hyperparathyroidism or malignancy. However, excessive intake or supplementation may influence the absorption of other minerals such as iron and magnesium; cause flatulence and habitual constipation; and long term, it may cause renal stones.
• Calcium supplements constitute the largest component of U.S. dietary supplements, with a 2001 value of $846.1 million, an increase of 4.4% from the previous year. In 2002, calcium supplements were about $875 M in the U.S., accounting for about 60% of mineral sales.
• Vitamin D is a fat-soluble vitamin naturally present in very few foods, added to others, and available as a dietary supplement. Sun exposure is essential for maintenance of vitamin D requirements. It is produced endogenously when sunlight's ultraviolet rays strike the skin and trigger vitamin D synthesis. Vitamin D from food, sun exposure, and supplements is biologically inert and must undergo two hydroxylations in the body for activation–first, in the liver, converting to calcidiol (25-hydroxyvitamin D[25(OH)2D]; and second, in the kidney, forming calcitriol,1,25-dihydroxyvitamin D[1,25(OH)2D].
• It promotes calcium absorption in the gut and helps maintain adequate calcium and phosphate balance required for normal mineralization of the bone and to prevent hypocalcemic tetany. It is also essential for bone growth and bone remodeling by osteoblasts and osteoclasts. It is essential in the prevention of rickets in children and osteomalacia in adults. With calcium, it helps protect from osteoporosis.
• Vitamin D is also essential in modulation of cell growth, neuromuscular and immune function, and reduction of inflammation.
• Vitamin D deficiency is an unrecognized epidemic among both children and adults in the U.S. Besides causing rickets in children and osteomalacia in adults, it also precipitates and worsens osteoporosis in adults. Deficiency also increases risks for cancers, cardiovascular diseases, multiple sclerosis, rheumatoid arthritis and type 1 DM.
• Excessive sun exposure does not result in vitamin D toxicity. Sustained heat on the skin is thought to photodegrade provitamin D3 and vitamin D3 as it is formed. Vitamin D from food is an unlikely cause of toxicity. Toxicity is more likely to occur from high intakes of dietary supplements containing vitamin D.
• Most reports suggest a toxicity threshold for vitamin D of 10,000 to 40,000 IU/day and a serum 25(OH)D levels if 500-600 nmol/L (200-240 ng/mL). Symptoms are unlikely at intakes of 10,000 IU/day.
Calcium / Osteoporosis / Cardiovascular Events
• Yes / Blood Pressure: (1) Research indicates calcium intake at 1,000 to 1,200 mg a day may be helpful in preventing or treating moderate hypertension. (2) A pooled estimate shows a statistically significant decrease of systolic blood pressure with calcium supplementation, both for hypertensive persons and for the overall sample. However, the effect is too small to support the use of calcium supplementation for preventing or treating hypertension.
• Yes / Osteoporosis: The porous frailty of bones threaten both men and women, but postmenopausal women are more susceptible to this condition. Although a lot has been brought to the preventive medicines - estrogen, biphosphonates, calcium supplementation has long been a mainstay of preventive therapy In women with low intake of dietary calcium, increasing calcium intake is associated with a decrease in risk of fractures and osteoporosis. In women with high and adequate dietary calcium intakes, increasing calcium intake does not further reduce the risks for fracture, hip fracture, and osteoporosis.
• Calcium and vitamin D are taken in combination, as supplements, by millions of people in the hopes of reducing the risk of fractures, but this strategy should be reconsidered in the face of evidence pointing to a roughly 20% increased risk of both MI and stroke in people taking both calcium and vitamin D, according to Dr Mark Bolland (University of Auckland, New Zealand) and colleagues.
• Yes / Calcium & Vitamin D3 / Reduction of Hip Fractures: A 1992 landmark study of 3270 healthy ambulatory elderly women supplemented with calcium and vitamin D3 showed a reduction of risk of hip fractures and other nonvertebral fractures.
• Yes / Calcium & Colon Cancer Protective Effect: Observational and experimental studies, though somewhat inconsistent, are highly suggestive of a protective effect. Several studies have found that higher calcium intake from foods (low-fat dairy sources) and/or supplements are associated with a decreased risk of colon cancer. A study showed supplementation with calcium carbonate led to reductions in the risk of adenoma (a nonmalignant tumor) in the colon, a precursor to cancer. In two large prospective epidemiological trials, men and women who consumed 700–800 mg per day of calcium had a 40%–50% lower risk of developing left-side colon cancer. However, other observational studies have found the associations to be inconclusive.
• Yes / Calcium & Vit D for Osteoporosis: A 2007 meta-analysis supported the use of calcium (1,200 mg) and vitamin D (800 IU) supplementation in the prevention of osteoporosis people aged 50 years or older.
• No / Calcium Supplements and Increased Risk of Kidney Stones: Some, but not all, studies suggest a positive association between supplemental calcium intake and the risk of kidney stones.
• No / Increased Prostate Cancer Risk: Several epidemiological studies have found an association between high intakes of calcium, dairy foods or both and an increased risk of developing prostate cancer. Others have found only a weak relationship, no relationship, or a negative association between calcium intake and prostate cancer risk. A meta-analysis of prospective studies concluded that high intakes of dairy products and calcium might slightly increase prostate cancer risk. Interpretation of the available evidence is complicated by the difficulty in separating the effects of dairy products from that of calcium. But overall, results suggest that total calcium intakes >1,500 mg/day or >2,000 mg/day may be associated with increased prostate cancer risk (particularly advanced and metastatic cancer) compared with lower amounts of calcium (500–1,000 mg/day. Additional research is needed to clarify the effects of calcium and/or dairy products on prostate cancer risk and elucidate potential biological mechanisms.
• No / No Benefit of Bone Mineral Density and Hip Fractures: (1) Several pivotal studies have shown little substantial benefit on BMD (bone mineral density) or fracture risk from calcium supplementation. (2) In the RECORD randomized, controlled trial of 5292 older women and men with a low trauma fracture evaluated supplementation with vitamin D, calcium, vitamin D and calcium, or double placebo and showed no reduction in fractures in the supplementation groups over placebo after 60 months.
• No / No Reduction in Fracture Risk: In the Women's Health Initiative Study, with 36,000 postmenopausal women aged 50 to 79 randomly assigned to receive calcium (1000 mg) and vitamin D (400 IU) or placebo daily, results showed small improvement in BMD in the calcium and vitamin D group, but no overall reduction in fracture risk.
• No / Calcium Monotherapy: Data from 5,500 women involved in calcium monotherapy show consistent adverse trends in the numbers of hip fractures. Observational data from the Study of Osteoporotic Fractures show a similar increase in the risk of hip fracture associated with calcium use. Data suggests the reliance on high calcium intake to reduce the risk of hip fractures in older women is not appropriate. Those at risks should should be considered for other therapies with proven capacity to prevent hi fractures, such as biphosphonates.
• No / Calcium and Vitamin D and increase risk of MI and Stroke: Results suggest the strategy of taking calcium and vitamin D in combination, as supplements, in the hopes of reducing the risk of fractures, should be reconsidered in the face of evidence pointing to a roughly 20% increased risk of both MI and stroke in people taking both calcium and vitamin D, according to Dr Mark Bolland (University of Auckland, New Zealand) and colleagues.
• No / Calcium Supplementation and Cardiovascular Events / MI and Stroke: (1) A recent meta-analysis showed an association between calcium supplementation and myocardial infarction and cardiovascular events. (Counterpoint: Study was criticized for poor study design, statistical interpretation, self-reporting and non-verification.) (2) A reanalysis if WHI CaD Study and incorporation in meta-analysis with eight other studies concluded calcium supplements with or without vitamin D modestly increase the risk of cardiovascular evens, especially myocardial infarction. The finding was obscured in the WHI CaD Study by widespread use of personal calcium supplement. (3) Calculations on cardiovascular effects of calcium supplementation ranged from 25% to 30% for myocardial infarction and 15% to 20% for a stroke.
• No / Abrupt Increases in Blood Calcium Levels: It is suggested that even small levels of supplemental calcium create "abrupt" increases in blood calcium levels within hours. Although strokes may be due to longer-term process of calcium accumulation in vessel walls, MI spikes might reflect an acute response to blood calcium levels, together with changes in platelet function, blood coagulability, and/or endothelial cell activity.
• Yes / Vitamin D3 Better than D2: Vitamin D3 was 56% to 87% more potent than vitamin D2 in raising serum 25(OH)D. Given its potency and lower cost, D3 should be the preferred treatment for correcting vitamin D deficiency or as D supplement.
|Recommended Daily Requirements for Calcium
|Up to 1 year old
||210 to 270 mg
|Age 1 to 3 years
|Age 4 to 8 years
|Age 9 to 18 years
|Age 19 to 50 years
|Age 51 or older
So, what to do?
The debate within the scientific community is ongoing. Physicians are divided and continuing to advise patients according to their chosen viewpoint. While alternative gurus and naturopaths espouse their natural methods of supplementation, the nutritional supplement industry, with its more than $20 billion sales, of which calcium is a major component, would love to continue to fortify your bones through the commerce of vitamins and minerals. Trying to decide what to do is not an easy task.
. . until the cloud settles and a consensus if formed:
No, for supplemental calcium.
Yes, for dietary sources of calcium.
• Alas, easier said than done. Despite the wars waged against osteoporosis – dietary and nutritional education, calcium and
vitamin D awareness, the calcium fortification of the food industry, osteoporosis is still winning the war. Calcium deficiency continues to be common.
• In his report, Surgeon General Richard Carmona warned that half of all American citizens older than 50 will be at risk for fractures from osteoporosis and low bone mass if no immediate action is taken. About 10 million Americans over age 50 already have osteoporosis, with an additional 34 million more at risk.
• With the views shifting against calcium supplementation, the list of options for achieving adequate calcium balance has become shorter.
• Unfortunately, in the U.S. as many as 50% to 75% of people do not get enough calcium in their diets, nor enough of vitamin D. Many are unaware of the varied choices of calcium rich foods; many are drawn to "high calcium, fortified" foodstuffs, alas, some too high in calories. But there is easy sources of natural calcium out there.
• Calcium is high in tofu, low fat milk, cheese, milkshakes, eggnog, sardines with bones, salmon with bones, sesame seeds. Figs are a good low-calorie source of calcium: 4 figs giving 506 mg of calcium in 130 calories.
• Some vegetables are higher in calcium than others: soybeans, okra, almonds, collard greens, oranges, spinach, kelp, broccoli, blackstrap molasses, sesame seeds, Brazil nut and celery.
• Another list of10 vegetables highest in calcium: collard greens, raw kale, turnip greens, garlic, arugula, rabe broccoli, mustard greens, sun-dried tomatoes, rach spinach, and okra.
Philippine Medicinal Plants / Calcium Sources
• The poor in rural Philippines might not always have affordable access to the usual sources of calcium (milk and calcium fortified foodstuff), but certain kinds of fish, especially sardines, are common food fare; and for some, there is the serendipity of calcium rich sources in their surrounding flora.
• Plants listed as excellent sources of calcium: Alambangbang (leaves); alugbati (shoots and stems); ampalaya (twice the calcium content of spinach), apoi-apoian (tender shoots and young leaves); endiba, gulasiman (leaves), katurai (flowers); kintsay; lubi-lubi (large fruit variety), malunggay (96 mg/100 g/ 1 cup cooked), mustasa, pasaw-na-haba (young shoots), pili (119 mg/ 100g), siling labuyo, spinach.
• Plants considered good sources of calcium are: bignay, bubo (young leaves), calabash (shoots, flowers, roots), kamote (leaves and roots), labanos (young leaves), okra, pasau (young shoots), patola, sigarilyas, sinkamas, tiesa (100g fruit/ 26.5 mg), upo, utong (fruit), watercress.
VITAMIN D and SUNLIGHT
And of course, bone health is more than just trying to maintain adequate calcium intake. Vitamin D, regular exercise, and regular doses of sunlight are essential components of bone health.
• Vitamin D
• Most people get their vitamin D from sunlight, an easy source in high latitudes. However, if you're housebound, sun-screened, sun-averse or avoiding the sun because of skin cancer risks, food and supplements are the other options for vitamin D. However, food is not an easy source of vitamin D. Although present in oil fish (tuna and sardines) and eggs yolks, these are not usual daily food items. Vitamin D supplements remain the good alternative.
• The optimal daily dose is uncertain, but it is safe for anyone older than 1 year to take up to 2,000 IU a day. Recommendations for adults are from 400 to 1,000 IUs a day. And all vitamin D are not the same. Studies have shown vitamin D3 to be better than D2. Vitamin D3 was 56% to 87% more potent than vitamin D2 in raising serum 25(OH)D. Given its potency and lower cost, D3 should be the preferred treatment for correcting vitamin D deficiency or as D supplement.
•Sun exposure is essential for maintaining the balance of vitamin D and calcium. One regimen of sensible sun exposure consists of 5 to 10 minutes of exposure of the arms and legs or the hands, arms, and face, 2 to 3 times a week. Regular doses of good sunlight will benefit in the maintenance and balance of vitamin D and calcium.
Sources and Suggested Readings
Dietary Sources of Calcium / StuartXchange
Higher Calcium Intake May Not Lower Risk for Fractures and Osteoporosis / Laurie Barclay, MD / Medscape Education Clinical Briefs
Calcium Supplements and CV Events: New Data, More Debate / Shellyd Wood / Heartwire
Dietary Supplement Fact Sheet: Calcium / Office of Dietary Supplements / National Institutes of Health
Dietary Supplement Fact Sheet: Vitamin D / Office of Dietary Supplements / National Institutes of Health
Finding consensus in the dietary calcium-blood pressure debate. / McCarron DA, Reusser ME. / J Am Coll Nutr. 1999 Oct;18(5 Suppl):398S-405S.
Dietary calcium and blood pressure: a meta-analysis of randomized clinical trials / Allender PS, Cutler JA, Follmann D, Cappuccio FP, Pryer J, Elliott P. / Ann Intern Med. 1996 May 1;124(9):825-31.
Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis / Bolland MJ, Avenell A, Baron JA, Grey A, MacLennan GS, Gamble GD, Reid IR. / BMJ. 2010 Jul 29;341:c3691. doi: 10.1136/bmj.c3691.
Use of calcium or calcium in combination with vitamin D supplementation to prevent fractures and bone loss in people aged 50 years and older: a meta-analysis / Dr Benjamin MP Tang, Guy D Estick PhD et al / The Lancet, Vol 370, No 9588, Pages 657 - 666, 25 August 2007 /doi:10.1016/S0140-6736(07)61342-7
Support for Calcium Supplementation Eroding / Nancy A. Melville / Medscape
Effect of calcium supplementation on hip fractures / Reid IR, Bolland MJ, Grey A./ Osteoporos Int. 2008 Aug;19(8):1119-23. Epub 2008 Feb 20.
Vitamin D3 and calcium to prevent hip fractures in the elderly women / Chapuy MC, Arlot ME, Duboeuf F, Brun J, Crouzet B et al / N Engl J Med. 1992 Dec 3;327(23):1637-42.
Calcium Supplements With or Without Vitamin D and Risk of Cardiovascular Events / Mark J Bolland; Andrew Grey; Alison Avenell; Greg D Gamble; Ian R Reid / Medscape Internal Medicine
Calcium Supplements and CV Events: New Data, More Debate / News Author: Shelley Wood / Medscape Internal Medicine
Vitamin D3 Considerably More Potent Than D2 / David Douglas / From Reuters Health Information / Medscape
12 Vegetables High in Calcium / FitDay
Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease. / Holick MF / Am J Clin Nutr. 2004 Dec;80(6 Suppl):1678S-88S.