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.

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.

Glutamine, MSG & excitotoxins, and protective nutrients

Clinicians giving several grams a day of pure L-Glutamine do not report excitotoxic reactions. The main one is for the synthetic chemical MSG. Sometimes people react to fermented foods, which indicates a problem in containment and nutritional status. Vitamin C removes glutamate from the neurons, which are additionally protected by antioxidants (tocotrienols, tocopherols, et al) and by magnesium. Branched-chain amino acids help to compartmentalize glutamates. Glutamine is fine with other aminos; the main competition is between the arginine pathway aminos (arginine, ornithine, and lysine); with another noted competition to get through the Blood Brain Barrier between the Large Neutral Amino Acids: aromatic aminos (tyrosine, phenylalanine, and tryptophan) and the BCAAs (leucine, isoleucine, and valine).

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.

Neil on TV 12/27/06 (Asthma)

the piece can be viewed for the next several weeks on CBN's Previous Broadcasts page -- http://www.cbn.com/700club/showinfo/schedule/previousbroadcasts.aspx?WT.svl=menu -- go to the "Play Now" button for Wednesday, Dec. 27 -- in the window that comes up, click on "Player Only" so that you can fast forward to 2:27 on your Windows Media Player -- the piece runs to 5:20. The print version is at http://www.cbn.com/cbnnews/78309.aspx as well as a low resolution viewing option.