Does zinc supplementation reduce absorption of calcium or magnesium?

In general, no.  While it’s true that zinc can reduce absorption of calcium it would have to be a high level to do so; studies showing such a relationship have primarily been on zinc sulfate supplements containing about 140 mg of elemental zinc.  This is far above the RDA/DV level of 15 mg. typically found in dietary supplements, or even the 30-50 mg. found in some immune or prostate formulas.  One typical study used 142 mg/day of zinc to achieve this; far higher than the amount in supplement formulas.  The study noted that the decrease in calcium absorption occurred when low calcium and high zinc intake was noted, but not with adequate calcium intake, and specifically tested lower doses of zinc along with low calcium intake and did not find a reduced absorption of calcium at commonly supplemented levels:  https://www.ncbi.nlm.nih.gov/pubmed/1452955

 

So the issue is limited to a very high zinc intake combined with a very low calcium intake, not the levels found in common supplements.  One will find zinc and calcium together in multiple vitamins or some mineral formulas, but at typically available levels they are not shown to cause the reduced absorption of calcium found in those studies cited above. 

 

The issue has also been studied for magnesium versus zinc intake.  Likewise, very high zinc intake interfered with low calcium intake (500 mg.) but less likely at higher levels of calcium intake.  Again, the levels of zinc in question (around 140 mg.) are not typically found in over-the-counter zinc supplements or multivitamins. https://www.ncbi.nlm.nih.gov/pubmed/7836627/ 

 

 It is more convenient for people to supplement with combination formulations instead of taking several single ingredient supplements, typically increasing compliance with label instructions and dosing.  Knowing that it's okay to take minerals in combinations that are commonly found in the marketplace is reassuring when some pundits claim that it is inappropriate based on the unusual circumstances of low mineral intake combined with abnormally high zinc intake.  For physicians prescribing the high strength zinc products, this is something to consider, but not something for consumers of dietary supplement formulas to be concerned about.

Calcium and Vitamin D are Safe for Heart Health

Huge study of ½ million adults age 40-69: calcium & D supplements pose no cardiovascular risk (heart attack, etc.) in the UK Biobank study:

fb.me/IOHg07RL

Functional Doses of Vitamins and Minerals for Bones

• Protein: 0.8 grams per kilogram of body weight

• Calcium: Over 1 gram per day

• Magnesium: 310 – 420 mg per day

• Zinc: 15 mg per day

• Copper: 2.5 to 3 mg per day

• Boron: 3 mg per day

• Manganese: 5 mg per day

• Potassium: 3,500 to 4,000 mg per day

• Vitamin D: over 500 IU daily

• Vitamin K: Levels are not well understood; at least 90 mcg/d for women and 120 mcg/d for men

• Vitamin C: over 500 mg daily

• Vitamin A: 2333 IU in women and 3000 IU in men; avoid low and excessive amounts

Palacios C. The role of nutrients in bone health, from A to Z. Crit Rev Food Sci Nutr. 2006;46(8):621-8. Review. PubMed PMID: 17092827.

Nutrients for Bone and Joint Health Interview

This interview was given to Whole Foods Magazine, excerpts were published in the February 2011 issue:

Despite evidence in recent medical journals, including several review studies calling for a far higher RDA and UL (upper limit) that would be five times the previous levels, the IOM held true to its conservative bent and raised the RDA and the UL; but only by 50% by only 100%, respectively . Observers are somewhat disappointed, but not really surprised. The most controversial part of the IOM committee’s report is that the only proven role for vitamin D is in bone and calcium metabolism, combined with its finding that most Americans already get enough for those benefits. That should come as news to researchers from Mayo Clinic operating under an NIH grant who recently reported that “Vitamin D insufficiency is common globally and in the United States. Approximately 25-50% of patients seen in routine clinical practice have vitamin D levels below the optimal range…” It also should be news to European regulators that recognize vitamin D’s beneficial effects on muscles, immunity, inflammation, cellular health, and reproduction. We recognize the new increased recommendations for vitamin D and the new higher safety recommendation, but believe that these numbers are insufficient to support vitamin D’s roles that go beyond calcium and bone health.

The need for joint and bone health nutrients in general increases with age. Aging also tends to reduce absorption of nutrients, forcing us to take higher amounts and better forms in order to assure adequate nutrition. The tendency of many seniors to cut back on meals, for reasons such as loss of taste or smell or interest in cooking, may also increase the need for supplementation of essential nutrients. The major joint and bone problems increase with age, and studies have shown the ability of relevant nutrients to maintain healthy bone and joint structures during these vulnerable times of life. Older customers that are more likely to take calcium supplements also tend to have diminished stomach acid available for digesting calcium from food and non-chelated (predigested) forms, so tend to do better with the predigested forms. These include calcium as citrate, malate, ascorbate, or bonded to specific amino acids; all are weak acidic sources that form a stable bond with the alkaline calcium and the resulting compound simulates the calcium complexes formed naturally during proper digestion.

While calcium and vitamin D are known for their role in bone and calcium metabolism, there are other nutrients necessary for bone health. These include silica, boron, magnesium, vitamins C and K, etc. protein. Comprehensive bone formulas include over a dozen nutrients, which are also available singly.

Children need to get sunshine, exercise, and a variety of calcium from food sources to ensure the body’s needs for bone health. If the child does not eat ample amounts milk and dark green leafy vegetables, they may need to complement the diet with appropriate dietary supplements.

Adults need to take care of their bodies and not impact the joints too much with hard exercises or excess weight. Support the joints nutritionally with glucosamine, vitamin C, a good multivitamin, and natural substances that modulate inflammation.

One should not neglect the long-term benefits of glucosamine to maintain joint distances that may otherwise erode, for example, while seeking fast-term temporary relief of aches and pains. By providing those products in both categories as well as overlapping combination products, we can supply a more holistic and sustainable nutritional joint support program.

Many of the Joint Structural Support Products contain varying amounts of glucosamine and/or chondroitin, as well as MSM, Hyaluronic Acid, and other well-known ingredients.

Increased US Vitamin D Recommendations

Chicago Tribune’s report “Don’t overdo vitamin D, calcium, experts warn” focused only on the risks of taking very high doses of these essential nutrients but missed the most important part of the new NIH Institute of Medicine (IOM) report by omitting that there are now higher daily recommended allowances (RDA) for vitamin D intake. It’s uncommon to take toxic amounts of vitamin D but far more common for some to be deficient, with resultant health deficits and increased healthcare costs.

Trib readers didn’t learn that the IOM panel raised vitamin D’s RDA by 50% to 600 IU (800 IU if over age 70), while doubling the tolerable Upper Limit (UL) to 4,000 IU.

In Chicago, it’s already been months since we could make any of the “sunshine vitamin” from sunlight, since the sun must be high enough in the sky so one’s shadow is shorter than his/her height. Darker skin allows less vitamin D production even with adequate sunlight; sunscreen blocks it. Chicagoland residents must rely on fortified foods and dietary supplements as primary sources of vitamin D for over half the year.

The IOM statement that people get enough vitamin D refers only to its conclusion that bone health is the only as yet proven role for this nutrient. Yet the IOM’s European counterpart, the European Food Safety Agency, recognizes an established cause and effect relationship between vitamin D and normal muscle health, immunity, inflammation, reproduction, and cellular health. Researchers have estimated that these additional benefits occur when people take 1,000-2,000 IU daily. Scientific toxicity reviews show safety up to intakes of 10,000 - 20,000 IU daily; multiples of the recently doubled UL.

By ignoring vitamin D’s increased RDAs and other benefits, and publishing broad statements that focus primarily on the unlikely “risks” of vitamin D and calcium supplementation, Tribune readers missed important parts of the IOM report.

Calcium & Cardiovascular Health: My review of the latest meta-analysis

At the end of July (2010) there was another nasty swipe at dietary supplements (Natural Health Products, for our Canadian friends). Again, the negative report came not from a single study, but from a particularly troubling type of report called a meta-analysis. Rising like a spider on a lethal web, this type of report keeps popping out of nowhere, attempting to make connections between studies where none may have been found before. In fact, we rarely see a competently designed meta-analysis on nutrients because there are many variables that come into play that simply don’t exist for isolated pharmaceutical drugs that aren’t (or at least aren’t supposed to be) present in our normal food supply. The interplay of nutrients affects each others’ metabolism, serum levels, and activities in a live human body. So when I see yet another meta-analysis getting major press coverage based on fairly flimsy evidence, I cringe and wonder why researchers and journalists fail to see the obvious flaws in their big story. Perhaps drug researchers are trying to branch out into nutrient research and just get in over their heads because they fail to see the complexity of nutrient research design.

The alleged danger this time: supplemental calcium was associated with a 30% increased risk of myocardial infarction, so the risks now outweigh the benefits. But was this proven? NO! Absolutely not. Nada. Zilch. Even the authors of this analysis know better than to claim that their report was definitive proof of these alleged dangers.

First of all, there was no increase in deaths in the groups given supplemental calcium. There was an increase in non-fatal heart attacks; but only in people who had already high calcium intake from their diets and also took high doses of supplemental calcium that they apparently didn’t need. And there was no problem demonstrated when calcium was given along with supplemental vitamin D, so maybe the problem was really that some folks had inadequate levels of that essential vitamin to deal with a high calcium intake.

But since vitamin D is both in the diet (as is calcium) and made from sunshine under the right conditions, these meta-analysis authors don’t really know how much vitamin D these people actually had, confounding their data. They don’t know because it would have required a rigorous study design that looked at all three intakes: food, supplements, and sunlight exposure at the times of day and year where vitamin D could be internally produced. Or at least measuring the serum before treatment to detect vitamin D levels and eliminate that as a variable. But that wasn’t done, perhaps because these researchers only looked at other people’s studies rather than running a human clinical trial themselves.

This points out perhaps the major problem with this type of study: since a meta-analysis is only a statistical model that cannibalizes previously published work to “mine” data in ways that were not planned by the original study designers, it has many built-in limitations. For example, cardiovascular outcomes were admittedly not intended as the primary endpoints in any of the 15 studies ‘Mixmastered’ together to make up this meta-analysis, so data on cardiovascular events were not gathered in the usual standardized manner. In plain English: the few cherry-picked studies included in this report had not done the type of standardization and control of variables needed to properly design a robust cardiovascular study because the original studies actually were looking at calcium’s effects on bone health, not heart health. This was, in fact, an admitted limitation of the current meta-analysis.

A good meta-analysis tries to pick the largest possible number of studies with similar designs to pool their results and in effect try to get a larger, hopefully more significant number of virtual test subjects. The farther from that model the meta-analysis gets, the more variables get introduced to confound the researchers. And since control of variables is the essential competence of the scientific method, we unfortunately find that an inexpertly executed meta-analysis is a misleading and erroneous scientific tool; like a ruler that has not been calibrated correctly and implies that our measurements are accurate when they may be way off the mark.

Researchers utilizing the imprecise tool of meta-analysis should not delude themselves that their work is definitive, because it almost never is. Nor should they become media darlings because they have espoused new theories - based on an unproven brew of mathematical models - that usually are already contradicted by a lot of better designed primary science. Nor should their attempts to re-examine previously published studies for results which were never intended to be measured scare us away from taking essential nutrients, which are commonly more healthful than harmful. As the current meta-analysis reported, the problem was that people who ate a lot of calcium who also took a lot of supplemental calcium without the benefits of taking vitamin D or other bone-forming cofactors had more non-fatal heart attacks. No one died. This implies that, at the most, one should not take a single nutrient in excess as if it were a magic drug, especially when they probably already get plenty in the diet. Don’t most of us know that already?

Nutrients are synergistic; therefore an imbalanced diet, including unneeded supplements that may tilt one even more into imbalance, may not properly support good health. Heck, I could have told you that before all this media fuss. But, with enough vitamin D the problem magically disappeared!. Supplementation of vitamin D apparently re-established good calcium metabolism, even at high levels of intake. The true issue then isn’t so much related to variations in calcium and vitamin D supplies, not to mention the unknown availability of other essential bone nutrients. It’s the misapplication of a drug model to a nutrient while ignoring known variables that affect the body’s proper use of that nutrient. One shouldn’t give a lot of calcium to those with adequate dietary intake, nor to those with insufficient vitamin D (and K, magnesium, et al) intake. This type of thought process is elementary to a nutritionist, of course, but apparently not to the well credentialed authors of many flawed drug model meta-analyses and their often overreaching conclusions.

You may be interested to know that a world-class researcher who has been working on calcium metabolism and osteoporosis for more than 50 years, the respected scientist who drafted the World Health Organization’s dietary calcium recommendations, strongly opposed the conclusions of the current calcium meta-analysis. Professor Chris Nordin from the Royal Adelaide Hospital in Australia was interviewed by ABC News. This news report cited Professor Nordin as saying that the meta-analysis was misleading because it improperly included studies involving a mixture of men and women, and the findings were not statistically significant. "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 was quoted. Professor Nordin noted the fact that 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 well to calcium supplementation (and vitamin D, if necessary). But he reports that calcium is seldom recommended for elderly men because their bone loss has a different cause, which is seldom caused by a need for more of that mineral. "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.

According to ABC News, Osteoporosis Australia has also questioned the findings of the meta-analysis because many long-term studies have shown calcium supplements are safe and effective. In a statement posted on its website, Osteoporosis Australia says the weight of evidence to date indicates no increased risk of heart attacks from taking calcium supplements, which it says are an effective way of reducing fracture risk and bone loss in older men and women who have diets low in calcium.

This should point out the folly of well-meaning researchers who design studies to investigate topics that they don’t properly understand. In those cases, they simply don’t realize that there are other essential factors that can change everything and require a completely different and more comprehensive study design. That’s par for the course when meta-analyses are used to sort through previously published nutrient studies. Basic design flaws often make meta-analyses fatally flawed, despite the apparently sophisticated mathematical models and methods that researchers incorrectly try to apply to the data. Is it any wonder that we’re so confused about nutrition when researchers gain worldwide prominence for issuing highly questionable sensational reports that contradict the scientific consensus - but never have to say they’re sorry?

Calcium does not cause more heart attacks in well-designed primary human clinical studies. Healthy people should not be concerned about taking essential nutrients just because certain studies were flawed or performed on sick or at-risk populations and may have had negative results. Many of those negative reports have been challenged and may not have been verified and replicated in well designed clinical trails. The conclusions of such reports are sensational and well publicized precisely because they seem to negate our previous scientific consensus; which should make them more, not less, suspect. But the modern news cycle seems to thrive on such controversy, without caring how confused we get about what’s healthy and what’s not. But don’t worry; you have Honest Nutrition to help you sort it all out!

REFERENCES:

Bolland MJ, Avenell A, Baron JA, Grey A, Maclennan GS, Gamble GD, Reid IR. Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. BMJ. 2010 Jul 29;341:c3691. doi: 10.1136/bmj.c3691. PubMed PMID: 20671013.

http://www.bmj.com/cgi/content/full/341/jul29_1/c3691?view=long&pmid=20671013

http://www.abc.net.au/news/stories/2010/08/03/2972399.htm?section=justin

Nocturnal leg cramps: quinine vs nutrients

Quinine is kind of dangerous (real risk of multiple organ failure). It's basically an old folk remedy lacking validity. In fact, the FDA banned the marketing of quinine in 1994 due to its toxicity and lack of evidence that it even helps with nocturnal leg cramps. (Procedings of Baylor University Medical Center, 2003 January; 16(1): 21–26. PMCID: PMC1200805) Since 2007, the Food and Drug Administration has recommended that quinine be prescribed only for the prevention and treatment of malaria. For nocturnal leg cramps, "better to rely instead on stretching exercises to flex the legs before bedtime," according to the Mayo Clinic, which also recommends drinking plenty of fluids and eating foods high in potassium. (NY Times 8/5/08) There are certainly much safer and more convincingly effective things to take for leg cramps. Giving elderly patients a vitamin B supplement providing 250 micrograms of B-12, 30 mg of B-6, 5 mg of riboflavin (B-2), and 50 mg of thiamine (B-1) for three months, doctors found that 86 per cent of their patients who took vitamin B complex vitamins enjoyed complete remission for noctural leg cramping. The researchers reported that, in their view, safe and effective vitamin B should be the treatment of choice for nighttime leg pain in older people. (Chan P, Huang TY, Chen YJ, Huang WP, Liu YC. Randomized, double-blind, placebo-controlled study of the safety and efficacy of vitamin B complex in the treatment of nocturnal leg cramps in elderly patients with hypertension. J Clin Pharmacol. 1998 Dec;38(12):1151-4.) [The B vitamins will be found in multiple vitamins and B-Complex vitamins, but some are far weaker than these amounts.] Vitamin E may also be helpful (about 400 IU minimum). (Robert F. Cathcart, III, M.D. The Journal of the American Medical Association, Vol. 219, No. 2.) http://naturalsolutionsradio.com/articles/article.html?id=6614 And another study showed that calcium, magnesium, and B Vitamins were all effective at dramatically reducing or eliminating noctornal leg cramps. (Int J Gynecol Obstet 2006 Aug 17 [e-pub ahead of print]) http://bastyrcenter.org/content/view/1131/ Some people may simply require more than normal of some specific nutrients...probably due to recent medical history, such as GI problems. Muscle cramps can be aggravated by some drugs, but rarely remedied by any drug. After all, all drugs are "controlled substances" precisely because of their known toxicities and side effects.

BMJ finding on calcium and D "failure" questionable

A 25% reduction in the number of fractures was not considered significant in this study, calling into question the statistical model and study design. They did not find "no evidence" of the supplements' effectiveness, as cited, but rather found no significant evidence. Why? Thus creating the "failure" of the supplements. (Click on title to read the journal article.)