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Magnesium is the third largest mineral constituent of bone (calcium and phosphorus and the first and second largest constituents, respectively). It is found in significant quantities throughout the body and used for numerous purposes, including muscle relaxation, blood clotting, and the manufacture of ATP (adenosine triphosphate, the body's main energy source). Magnesium is involved in the metabolism of carbohydrates and fats; it also acts as a catalyst for a number of enzymes.  

Magnesium has been called "nature's calcium-channel blocker," based on its ability to block calcium from entering muscle and heart cells. This may be the basis for magnesium's effects on migraine headaches and high blood pressure.  
Magnesium is available in many synthetic forms, including magnesium sulfate, magnesium gluconate, magnesium fumarate, magnesium citrate, magnesium malate, magnesium oxide, and magnesium chloride. Natural sources include kelp, wheat bran, wheat germ, nuts (almonds, cashews), blackstrap molasses, brewer's yeast (not to be confused with nutritional yeast), buckwheat, whole grains, collard greens, dandelion greens, avocado, sweet corn, cheddar cheese, sunflower seeds, shrimp, dried fruit (figs, apricots, and prunes), and many other fruits and vegetables.  

In pets, magnesium supplementation is often recommended for pets with heart disease, diabetes, and epilepsy. For pets with epilepsy, it is proposed that magnesium cools the liver down and relaxes the mind and heart electrical complexes.

In people, magnesium has been recommended as a therapy for migraine headaches, noise-related hearing loss, kidney stones, hypertension (high blood pressure), premenstrual syndrome, painful menstruation, diabetes, osteoporosis, low blood sugar, glaucoma, fibromyalgia, fatigue, stroke, autism, various forms of heart disease (such as mitral valve prolapse or congestive heart failure), and asthma.  

Low levels of magnesium can cause a variety of clinical signs including lack of appetite, muscle incoordination, slow growth, and seizures. Low levels of magnesium may occur with kidney disease/failure, high levels of blood calcium(hypercalcemia), hyperthyroidism (in cats), and the use of certain medications (diuretics, aminoglycoside antibiotics, cisplatin, cyclosporine, amphotericin, and methotrexate).

When combined with oral diabetes drugs in the sulfonylurea family (Tolinase, Micronase, Orinase, Glucotrol, Diabinese, DiaBeta), magnesium may cause blood sugar levels to fall more than expected. 

Excess levels of magnesium may contribute to the increased incidence of calcium oxalate stones. However, dietary magnesium does not contribute to the more commonly diagnosed struvite stones (high urine pH is more important in the development of these types of bladder stones).  

The recommended starting dosage for pets with heart disease and diabetes is 5mg/pound daily. Alternatively, magnesium supplementation for epileptic dogs is 100 mg twice daily. The AAFCO recommendation is 0.08 percent for growth and reproduction and 0.04 percent for adult maintenance for cats, and 0.04 percent for all life stages for dogs.  

Magnesium may interfere with the absorption of calcium and various other minerals. For this reason it's suggested that pets taking magnesium also take a multi-mineral supplement. In general, magnesium appears to be quiet safe when taken at recommended dosages. Pets with severe kidney or heart disease should not receive magnesium except under veterinary supervision.

Shawn Messonnier, DVM

As my thank you for reading my articles, enter code “drshawn” at my natural products web store,, to save 10% on all your future purchases!

Shawn Messonnier DVM Past Supporting Member, Oncology Association of Naturopathic Physicians Author, the award-winning The Natural Health Bible for Dogs & Cats, The Natural Vet’s Guide to Preventing and Treating Cancer in Dogs, and Breast Choices for the Best Chances: Your Breasts, Your Life, and How YOU Can Win The Battle!

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