Research - Calcium
Dietary intake of calcium and magnesium and the metabolic syndrome in the National Health and Nutriion Examination (NHAMES) 2001-2010 data
Laura Moore-Schiltza1, Jeffrey M. Alberta1, Mendel E. Singera1, James Swaina2 and Nora L. Nocka1 c1
a1 Department of Epidemiology and Biostatistics, Case Western Reserve University, Cleveland, OH 44106, USA
a2 Department of Nutrition, Case Western Reserve University, Cleveland, OH 44106, USA
Higher dietary intakes of Mg and Ca, individually, have been associated with a decreased risk for the metabolic syndrome (MetSyn). Experimental studies suggest that a higher intra-cellular ratio of Ca:Mg, which may be induced by a diet high in Ca and low in Mg, may lead to hypertension and insulin resistance. However, no previous epidemiological studies have examined the effects of the combined intake of Mg and Ca on MetSyn. Thus, we evaluated the association between dietary intakes of Ca and Mg (using 24-h recalls), independently and in combination, and MetSyn in the National Health and Nutrition Examination Study 2001–2010 data, which included 9148 adults (4549 men and 4599 women), with complete information on relevant nutrient, demographic, anthropometric and biomarker variables. We found an inverse association between the highest (>355 mg/d) v. the lowest (<197 mg/d) quartile of Mg and MetSyn (OR 0·70; 95 % CI 0·57, 0·86). Women who met the RDA for both Mg (310–320 mg/d) and Ca (1000–1200 mg/d) had the greatest reduced odds of MetSyn (OR 0·59; 95 % CI 0·45, 0·76). In men, meeting the RDA for Mg (400–420 mg/d) and Ca (1000–1200 mg/d), individually or in combination, was not associated with MetSyn; however, men with intakes in the highest quartile for Mg (≥386 mg/d) and Ca (≥1224 mg/d) had a lower odds of MetSyn (OR 0·74; 95 % CI 0·59, 0·93). Our results suggest that women who meet the RDA for Mg and Ca have a reduced odds of MetSyn but men may require Ca levels higher than the RDA to be protected against MetSyn.
Source : British Journal of Nutrition
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Calcium intake and hypertension among obese adults in United States: associations and implications explored
Y Chen1, S Strasser2, Y Cao1, K-S Wang1 and S Zheng1
- 1Department of Biostatistics and Epidemiology, College of Public Health, East Tennessee State University, Johnson City, TN, USA
- 2Georgia State University, School of Public Health, Atlanta, GA, USA
The relationship between calcium intake and hypertension is receiving increased research attention. The prevalence of hypertension is high among the obese populations. Calcium is a mineral that influences blood pressure. The aim of the study was to examine the association between calcium intake and hypertension in a large nationally representative sample of obese American adults. A total of 14 408 obese adults aged 20 years or older were obtained from the 1999–2010 National Health and Nutrition Examination Survey. Analysis of variance and linear regression models were used to examine relationships between calcium intake and systolic blood pressure (SBP) as well as diastolic blood pressure (DBP). Multiple logistic regression models were used to examine the association between calcium intake and hypertension after adjusting for potential confounders and interactions, including: age, race, education level, alcohol use, smoking, diabetes status, sodium intake and potassium intake. Calcium intake was significantly lower for the hypertensive group compared with the normotensive group (P<0.0001), especially among those obese female young adults aged 20–44 years and among non-diabetic obese adults. Based on ordinary linear regression analysis, a significant inverse relationship was detected, SBP and DBP decreased if calcium intake increased (SBP: regression coefficient estimate=−0.015, P<0.0001; DBP: regression coefficient estimate=−0.028, P<0.0001). Multiple logistic regression showed that calcium intake was negatively associated with the probability of hypertension (odds ratio (OR)=0.81, 95% confidence interval (CI): 0.74–0.87, P<0.0001). In stratified analysis, calcium intake in youngest adults (age 20–44 years) had the lowest likelihood of hypertension (OR=0.77, 95% CI: 0.64–0.93, P<0.0001), the inverse relationship between calcium intake and probability of hypertension was stronger among females (OR: 0.68, 95% CI: 0.55–0.84, P<0.0001), when compared with the whole sample including all of 14 408 obese adults. The protective effect of calcium intake and hypertension was found significantly in obese non-diabetic adults (OR: OR=0.77, 95% CI: 0.67–0.89, P<0.0001) not in obese diabetic adults. SBP, DBP and calcium intake were log transformed for both ordinary linear regression analysis and logistic regression analysis. Our study findings underscore the need to explore the physiological mechanism between calcium intake and hypertension. In this study, increased calcium intake was associated with the lowest risk of hypertension. Future studies utilizing longitudinal research designs are needed to quantify therapeutic levels of calcium for control of hypertension among obese adults. Increasing calcium intake among American adults may offer promise as a cost-effective strategy to improve hypertension among obese adults; however, further scientific exploration is warranted.
Source : Journal of Human Hypertension
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No Heart Risk for Women From Calcium
The calcium supplements widely prescribed for bone health in women did not appear to be associated with increased cardiovascular risk, researchers found.With more than 2 decades of follow-up in a cohort of almost 75,000 women, the relative risk for cardiovascular disease was 0.86 (95% CI 0.65 to 0.88), Julie Paik, MD, of Harvard Medical School in Boston, reported here at the annual meeting of the American Society for Bone and Mineral Research.
Despite the popularity of calcium supplements -- one estimate says 60% of women older than 60 use them -- there has been a growing interest in a potential link with cardiovascular problems, with conflicting data having emerged.
In a secondary analysis of one study, calcium use was associated with an increased risk of myocardial infarction (MI) and for a composite endpoint of MI, stroke, and sudden death.
And in a meta-analysis of randomized trials, there was an increased risk of MI with or without additional vitamin D, while another meta-analysis found neutral effects for the supplements.
Because the prospective studies thus far have been of short duration, Paik and colleagues analyzed data from the Nurses' Health Study, which began enrolling women in 1976 at ages 30 to 55.
This analysis was based on outcomes for 74,272 women who completed a food questionnaire in 1984, in which participants detailed their routine intake of food, beverages, and dietary supplements.
Calcium was reported every 4 years.
All participants were free of cardiovascular disease and cancer at baseline.
The analyses were adjusted for dietary confounders such as fiber intake as well as nondietary factors such as smoking, family history, and aspirin use.
Outcomes were verified through review of clinical and imaging medical records.
During 24 years and 1,681,307 person-years of follow-up, there were 4,662 cardiovascular events.
A total of 2,855 related to coronary heart disease, with 748 being fatal, while 1,807 were strokes, 1,409 of which were ischemic.
"Of note, calcium supplement use increased dramatically over the study period, from 30% in 1984 to 72% in 2004," Paik said.
In an analysis looking at outcomes for women who took more than 1,000 mg of calcium each day -- the dose that has been used in many of the trials included in the meta-analyses -- no significant risks were identified:
- Coronary heart disease, RR 0.75 (95% CI 0.65 to 0.88)
- Nonfatal MI, RR 0.74 (95% CI 0.62 to 0.88)
- Fatal MI RR 0.81 (95% CI 0.60 to 1.09)
- Stroke, RR 1.01 (95% CI 0.85 to 1.21)
Limitations of the study included the possible lack of generalizability, because all participants were female and, because they were nurses, they were likely to be relatively healthy.
In addition, there may have been residual confounding because the study was observational.
However, strengths included detailed information on calcium use and cardiovascular risk factors, and the large population.
"We found no association between calcium supplementation and cardiovascular risk, including MI, and this was a very conservative conclusion," Paik said.
Source : Medpage Today via
Primary source: American Society for Bone and Mineral Research
Source reference: Paik J, et al "A prospective study of calcium supplement intake and risk of cardiovascular disease in women" ASBMR 2012; Abstract 1135.
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What you haven't heard about the latest calcium scare
By now you’ve probably heard about the latest piece of scientific evidence, published yesterday, saying that the No. 1 selling dietary supplement mineral, calcium, causes heart attacks. Is it true?
If you’ve been paying attention, you will recall that in the summer of 2010, a research group first published a study—a “meta-analysis” of researcher-selected studies (grain of salt alert!)—that sought to demonstrate their hypothesis that calcium supplements were linked with an increased risk of heart attacks.
This week, that same group of researchers from the same research center in Germany tried to replicate their findings from their cherry-picked meta-analysis. They reported that, after following 23,980 patients between the ages of 35 and 64 for 11 years as part of a European study into nutrition and cancer, there was an increased incidence of heart attack risk among those who took calcium supplements.
Two thoughts here. One, the primary end points of the study were on cancer, not cardiovascular events. Which counts for something. More notably, however, was their findings that greater dairy calcium intake—that’s dairy, as in milk or cheese or ice cream and not supplements—actually had a significantly lower risk of heart attacks.
A third finding also deserves mention: They found no link between either calcium supplements or food-based calcium intake and strokes or overall cardiovascular disease death (just not heart attacks).
I always say that one study does not a conclusion make, and even then I always hesitate to use the word “prove,” preferring the more modest “demonstrate.” Because what can truly be proved in this world anyway? Studies merely show that something at some time under some conditions were demonstrated. Has a different party replicated those results?
Turns out that just last week, these results were replicated. In a Swiss study, published last week and unheralded in the media, researchers followed 326 patients who were assessed for cardiac risk factors before undergoing surgery for something not related to a cardio condition. They found that calcium was implicated as being a strong predictor of bad news on the horizon. When researchers checked back in on patients 40 days after their surgery, the patients with the highest amount of calcium in their coronary arteries had the highest incidence of cardio events, defined as heart attacks, stroke and death. Similarly, those with the lowest amount of calcium deposits in their arteries had the lowest incidence of cardio events.
So, what does this mean for America’s favorite mineral? Three things, in inceasing levels of importance. (Can you feel the drama building?)
One, if calcium is implicated only in sudden-death heart attacks but not other types of cardiovascular insult like strokes, this makes me think of the greatest natural bioactive to counter this. Fish oil. Remember, heart attacks that kill you before you get a chance to get out of your chair are usually caused because a chunk of arterial plaque (comprised mostly of calcium, ahem) broke off and suddenly clogged your artery in full, and you drop like a fly. What fish oil does is decrease blood platelet stickiness—it makes your blood more slippery—so that the blood is more apt to slide around those plaque deposits without breaking them off.
Two, those researchers this week found calcium alone led to heart attack problems, but not calcium in a food.
Notably, researchers from the same research center found no correlation between blood levels of calcium and phosphate on coronary heart disease, but there was an association between calcium-only levels on death risk among 1,206 patients followed for eight years post-op.
Presence of trace minerals copper, selenium and zinc can positively enhance bone density. Other studies show no association between these minerals. However, research does show one mighty mineral does help: magnesium.
You likely know magnesium because of its traditional use with calcium in bone-health formulations at the 1:2 ratio of magnesium to calcium. That’s because calcium cannot get absorbed without its mineral mate magnesium. But we’re already consuming way too much calcium.
“Americans consume over 10 times the recommended allowance of calcium—highest consumption rate worldwide—and have the highest rate of osteoporosis,” said Rick Hand at supplements manufacturer Natural Vitality.
That’s why forward-operating supplements manufacturers are heeding the call and are beginning to dispense with formulations of the classic 2:1 ratio of calcium to magnesium, going more for a 1:1 ratio.
Combating overconsumption of calcium And three, when you take the studies and news from above, what you’ll see is that calcium alone kills, but calcium from dietary sources—meaning calcium linked with other nutrients—saves. That’s why truly cutting-edge supplements manufacturers and marketers are also including additional co-factors with calcium, including vitamin D, magnesium, phosphorus and vitamin K2.
That makes quite a bit of sense, because bones—despite being white like calcium—are comprised of a range of minerals. Just like dietary sources of calcium.
Vitamin D has been the clear winner the last few years, because it has benefits far beyond mere bone health. I’m seeing magnesium as following behind D’s footsteps, and it too has benefits far beyond bone health, including—that’s right—cardiovascular health, as well as cognitive health including sleep, memory and anxiety.
Everyone should also be formulating with vitamin K2, which has the unique ability to remove calcium from arteries (point for cardio health) and deposits it in bones (bonus for bones). K2, in particular the longer-chain menaquinone-7 form, had a study presented this very week showing it improves bone strength and prevents cardiovascular aging.
Taken as a whole, the clear recommendation is that calcium all by itself may well be bad for you. But that doesn’t mean you shouldn’t supplement. Just supplement with a quality-made product that includes calcium with a matrix of co-factors to both build bone and enhance cardiovascular health.
Calcium supplements may well be bad for you. But quality calcium-based supplements save lives.
Source : New Hope 360
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Calcium plus vitamin D shows bone boosting benefits for teenage girls
Supplements of calcium and vitamin D may boost the bone health of girls undergoing puberty, and potentially reduce the risk of osteoporosis later in life, suggests a new study from Down Under.
Australian researchers report that a supplement containing 800 mg of calcium and 400 IU of vitamin D3 produced significant increases in the bone density and strength of peripubertal female identical twins, compared with placebo.
The study is published in the journal Osteoporosis International.
Osteoporosis is characterized by low bone mass, which leads to an increase risk of fractures, especially the hips, spine and wrists. An estimated 75 million people suffer from osteoporosis in Europe, the USA and Japan.
Women are four times more likely to develop osteoporosis than men.
Potential reduction of osteoporosis has traditionally been a two-pronged approach by either attempting to boost bone density in high-risk post-menopausal women by improved diet or supplements, or by maximising the build up of bone during the highly important pubescent years.
About 35 per cent of a mature adult's peak bone mass is built-up during puberty.
Researchers from the Australian Catholic University recruited 20 pairs of identical twins and randomly assigned one from each set of twins to receive the vitamin D, calcium combination, and the other to receive a placebo for six months.
The study, reportedly the first to use peripheral quantitative computed tomography (pQCT) to measure bone responses to the combined supplement in peripubertal children, found that the vitamin D and calcium combination was associated with increased bone density and bone strength in the shinbone (tibia) and in the arm (radius).
Indeed, shin and arm bone strength was improved by between 4 and 66 percent, depending on the specific site of the bone tested.
Strong supporting science
The study supports previous findings, including results from an 18-month randomised trial from scientists at the University of Sheffield in the UK (American Journal of Clinical Nutrition, February 2008, Vol 87, Pages 455-462).
In the Sheffield study, a daily 792 mg calcium supplement was associated with increases in bone mineral content and density. However, the effects were then reversed once supplementation was discontinued.
Commenting on the mechanism, the Sheffield scientists proposed that the mineral most likely worked by suppressing bone turnover.
Calcium is reported to be the biggest seller in the US supplements industry. Annual sales were about $993m (€836m) in 2004, according to the Nutrition Business Journal.
Source: NutraIngredients.com via Osteoporosis International (February 2011, Volume 22, Issue 2, Pages 489-98 “Calcium and vitamin-D supplementation on bone structural properties in peripubertal female identical twins: a randomised controlled trial” Authors: D.A. Greene, G.A. Naughton
Link to NutraIngredients.com
Calcium and Heart Attack—What You Really Need to Know
You saw the sensational media headlines last week: calcium supplements cause heart attacks! We told you the truth about this several weeks ago, before the latest research came out. If you take calcium, be sure to read this.
The source of the media hype was a British Medical Journal article which reported on a survey of fifteen trials in which participants (all over age 40) were given at least 500 mg of elemental calcium per day. The researchers concluded that calcium supplements increasethe risk of myocardial infarction by about 30% over five years.
This was another example of bad research, poorly constructed from a scientific point of view. But it does contain an element of truth that we all need to understand.
First, the research itself: Daniel Fabricant, PhD, vice president of scientific regulatory affairs for the Natural Products Association, said the results of this study go against years of research showing the benefits of calcium supplementation, and suggested that the authors of the research “cherry picked” the fifteen studies from hundreds of available research studies in the area.
Andrew Shao, PhD, senior vice president of scientific and regulatory affairs for the Council for Responsible Nutrition (CRN), said that their conclusions are “dramatically overstated….Seven of the fifteen trials evaluated had no, or incomplete, data on cardiovascular outcomes…. Further, the researchers chose to exclude any trials administering calcium plus vitamin D—including the Women’s Health Initiative, which found calcium plus vitamin D had no effect on the risk of coronary heart disease or stroke.”
This last point—about taking calcium with vitamin D—is vital but still incomplete.
As we reported just last month, supplemental calcium should never be taken alone. It needs additional magnesium, vitamin D, omega–3 fatty acids, and vitamin K (in particular, vitamin K-2, which is especially important). Without these essential co-factors, the calcium may end up in our blood vessels or our heart, where it causes harm, rather than our bones, where it is needed. So long as these co-factors are taken as well, many studies have shown that added calcium plays an important role in building and maintaining bone mass—and also reduces the risk of colon cancer.
It is unarguably true that many people are taking calcium in the wrong way. The answer is not to stop taking it. There are enough cases of bone loss (osteoporosis) as it is. And the potential side effects of osteoporosis drugs are truly scary.
In the article we ran about calcium several weeks ago, the World Health Organization was urging world governments to put extra calcium in everyone’s water supply. We explained that this was a bad idea. Now the British Medical Journal is implying that any supplemental calcium is unsafe, which is untrue if the needed co-factors are taken too. So, in effect, one conventional medicine authority is saying one thing, and another conventional medicine authority is saying the opposite.
What this underscores is that the general public needs access to health advisors—including integrative MDs, and doctors of osteopathy (DOs)—who know about proper supplementation and can give the kind of expert advice that is needed. Conventional medicine’s attacks on the licenses of integrated doctors for practicing outside the conventional “standard of care,” which often means recommending particular supplements, doesn’t harm those physicians alone, but the entire American public.
People will take supplements whether conventional medicine (and especially the giant drug companies backing conventional medicine) like it or not. So it is particularly dangerous to try to shut down doctors who are skilled in the use of functional foods and supplements.
Source Alliance for Natural Health USA 3 Aug 2010
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Calcium supplement heart attack study absurd
By medical reporter Sophie Scott
Updated Tue Aug 3, 2010 4:33pm AEST
One of Australia's leading health experts has cast doubt on new research suggesting calcium supplements may increase the risk of heart attacks.
Professor Chris Nordin from the Royal Adelaide Hospital has been working on calcium metabolism and osteoporosis for more than 50 years. He drafted the World Health Organisation dietary calcium recommendations, which have been adopted in Australia.
He queries the findings of a recent review into calcium and heart attack risk published recently in the British Medical Journal.
Professor Ian Reid from the Department of Medicine at the University of Auckland reviewed 11 studies of almost 12,000 people.
His review found calcium supplements were associated with an increased risk of heart attack of about 30 per cent and smaller, non-significant increases in the risk of stroke and mortality. The findings were consistent across trials and were independent of age, sex and type of supplement.
But Professor Nordin says the review is misleading because it includes studies involving a mixture of men and women.
"Men are much more liable to heart attacks than women but women need calcium far more than men, so it is absurd to publish a study of the effect of calcium on the heart without separating men from women," he said.
Professor Nordin says calcium supplements are predominantly recommended for and used by postmenopausal women because their bone loss is due to an increase in bone breakdown, which responds to calcium (with vitamin D if necessary). But they are seldom recommended for elderly men because their bone loss has a different cause, which seldom needs calcium.
He says the findings were not statistically significant.
"Concluding that calcium supplements can lead to a 30 per cent increase in heart attack risk is quite premature and alarmist and can only set back the cause of osteoporosis prevention which should be our primary objective," he said.
Osteoporosis Australia has also queried the findings of the review, saying many long-term studies have shown calcium supplements are safe and effective.
In a statement on its website, Osteoporosis Australia says the weight of evidence to date indicates no increased risk of heart attacks from taking calcium supplements.
Osteoporosis Australia says calcium supplements are an effective way of reducing fracture risk and bone loss in older men and women who have a diet low in calcium.
Professor Nordin says he would like to see all women have their bone density measured at menopause so that women with low to normal bone density can take dietary and exercise measures to prevent osteoporosis developing.
As for calcium supplements, as the doctor responsible for setting current daily recommendations, he says 1,300mg for post-menopausal women is appropriate and could even be set a little higher.
See from ABC News Related Story: Calcium supplements linked to increased risk of heart attack
Source ABC News Australia
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