13 October, 2011
Heart Arrhythmia: Iodine or Magnesium?
A group of specialized cells in the upper right chamber of your heart, known as the sinus node, produce tiny electrical impulses that stimulate heart muscles to contract. Many factors affect your heart’s ability to maintain a rhythmic heartbeat, including a balance of minerals, including potassium, sodium, calcium and magnesium. Iodine, another essential mineral, is vital for the production of hormones that regulate heart rate. Too much or too little of the essential minerals magnesium and iodine can induce heart arrhythmia, an abnormal or irregular heartbeat.
Normally, heart muscle cells work together to simultaneously contract and relax. The cells in the upper chambers of the heart, known as the atria, receive the electrical impulse first and contract in response. As the impulse moves across the AV node that separates the upper and lower chambers, known as the ventricles, the atria relax while the ventricles contract. The rhythmic contractions and relaxations pump the blood through the heart and blood vessels. Arrhythmia can occur when the heart beats too fast or too slow, and it might originate in the atria or the ventricles. Shock, fright, stress, certain medications, alcohol, caffeine and nicotine can all cause temporary arrhythmia. Recurrent arrhythmia can be a sign of an underlying medical condition, so see your doctor if you experience problems, so she can test your mineral and hormone levels.
Your body needs magnesium to support more than 300 biochemical reactions necessary for life. Magnesium, like calcium, sodium and potassium, also functions as an electrolyte, which means that it transmits electrical impulses within cells and influences the cells' ability to contract and relax. While your cells store calcium inside a specialized internal structure, magnesium remains in the fluid portion of the cell. In response to the electrical impulses, the internal structure releases calcium ions into the fluid portion of the cell, which triggers the cell to contract. The magnesium ions generate a tiny electrical impulse that propels the calcium ions back into the internal structure, allowing the cell to relax. An imbalance between calcium and magnesium can interrupt the rhythm of contraction and relaxation, causing heart arrhythmia.
Your thyroid gland traps iodine and uses it to produce the two thyroid hormones: thyroxine and triiodothyronine. Thyroid hormones act on nearly every cell in your body to regulate metabolism, which is all of the physical and chemical processes involved with the conversion of oxygen and calories into energy. Thyroid hormones regulate the breakdown and absorption of nutrients, body temperature, breathing, blood circulation and heart rate. Low levels of thyroid hormones, a condition known as hypothyroidism, can slow your heart rate to 30 beats per minute and cause arrhythmia. Iodine deficiency can cause hypothyroidism. In contrast, hyperthyroidism, a condition of high levels of thyroid hormones, can cause your resting heart rate to increase with spikes up to 300 beats per minute, resulting in arrhythmia or heart attack.
The treatment for arrhythmia depends upon the underlying cause. If you experience the symptoms of heart arrhythmia, including dizziness, pounding in the chest, palpitations, chest discomfort, weakness and fatigue, see your doctor. Arrhythmia caused by a magnesium or iodine deficiency can be corrected by increasing your consumption of foods that provide these minerals or by taking supplements. Foods rich in magnesium include dark green, leafy vegetables; beans; whole grains; nuts and fish, such as halibut. Although many fruits and vegetables contain small amounts of iodine, depending on the soil in which they grew, the best sources include fish, shellfish and iodized salt.
- Cleveland Clinic: Management of Arrhythmia
- Colorado State University; Mechanism of Action and Physiologic Effects of Thyroid Hormones; R. Bowen; July 2010
- Endocrineweb; How Your Thyroid Works; October 2010
- Cambridge Information Group; Thyroid Hormone Disorders; Jennifer Phillips; May 2001
- National Institutes of Health Office of Dietary Supplements; Magnesium; July 2009
- Comstock/Stockbyte/Getty Images