Iodine is an electronegative element of the halogen family, and is an essential nutrient that must be obtained through dietary sources. Iodide is the anionic or negatively-charged form of iodine. The iodine content of foods is largely dependent upon the iodine content of the soil in which they are grown. Most foods are naturally quite low in iodine, save for most saltwater fish and various sea vegetables or seaweed [1] [2]. Undoubtedly, iodine deficiency continues to stand as a significant health issue throughout the world, affecting both industrialized and developing nations [3]. The propagandization of iodized salt is objectionable though, as conventional table salt is crap, and iodized salt can lose much of its added iodine during storage [4] [5].
Because of the need for iodine in the making of thyroid hormones, iodine is necessary for the normal development of the early brain and for general growth and maturation (in addition to the maintenance of a healthy basal metabolic rate) [6]. Iodine deficiency is one of the most common causes of preventable cognitive impairment, with a moderate-to-severe lack of iodine being associated with a reduction in mean IQ scores of 13.5 points [7] [8]. And the classical marker of iodine deficiency is enlargement of the thyroid gland or goiter [9]. Sufficient iodine intake during pregnancy is crucial, for the requirement of this nutrient rises by about 50% during the gestation period [10]. Appropriate supplementation with or adequate intake of iodine can prevent cretinism, increase birth weight, and decrease infant mortality [11]. The recommended level for iodine intake during pregnancy is at least 250 micrograms per day [12]. Ingested iodide is efficiently absorbed in the stomach and small intestine [13]. Most ingested iodine is converted into iodide in the gut before being absorbed into the bloodstream, but not all [14] [15]. So supplementing with a combination of iodide and iodine can be more effective or beneficial than supplementing with iodide (usually in the form of potassium iodide) alone. Also, selenium and iron concentrations need to be adequate in order for iodine to be properly utilized in the thyroid gland [16]. Iodide absorbed into the bloodstream quickly mixes with iodine obtained from the breakdown of iodothyronines (T3 and T4) to form the extrathyroidal pool of ‘plasma inorganic iodine,’ regulated by the thyroid and kidneys [17]. Evidently, a normal adult employs roughly 80 micrograms of iodine per day in the manufacturing of the thyroid hormones, but much more than 80 micrograms of iodine is required by the body each day [18]. For adults, the recommended daily allowance (RDA) for iodine is 150 micrograms per day, but because of our exposure to iodine-blocking pollutants, it could be argued that such a level is too low for modern needs [19]. Furthermore, we should consider that many Japanese citizens consume far more than 150 micrograms of iodine per day, and that breast cancer incidence and mortality rates have historically been much lower in Japan compared to the United States [20] [21]. A 24-hour urinary iodine test can be used to assess iodine status, but because most ingested iodine is excreted through the urine within 24 hours, results from this test can vary quite a bit [22]. Hence, iodine sufficiency is tough to measure accurately without collecting multiple urine samples [23]. And it’s worth noting that athletes or anyone who participates in vigorous exercise can lose a notable amount of iodine through sweat, so iodine supplementation could be warranted in these individuals [24]. Iodide uptake in the thyroid gland and elsewhere is accomplished via sodium-iodide symporters (membrane proteins that traffic iodide into cells), which are located mostly in the thyroid, but can also be found in the stomach, small intestine, breasts, and salivary glands [25]. Normal sodium-iodide symporter (abbreviated as NIS) function can be disturbed as a result of inflammation, a genetic defect, or exposure to environmental toxins like perchlorates and phthalates [26] [27] [28] [29] [30]. Evidence suggests that vitamin C supplementation works well for helping to repair dysfunctional sodium-iodide symporters [31]. Despite claims to the contrary, the presence of excessive iodide in the body can suppress thyroid function by inhibiting the NIS-mediated uptake of iodide in the thyroid [32] [33]. This suppression of thyroid hormone synthesis should be temporary, but there can be a failure to “escape” from the Wolff-Chaikoff effect in which the suppression is prolonged or sustained (those with autoimmune thyroiditis are more susceptible to this failure) [34]. Too much iodine can stifle autophagy in the thyroid and promote apoptosis of thyroid follicular cells as well [35]. Iodide excess can also downregulate the NIS-mediated uptake of iodide in the small intestine [36]. With all of that said, a molecular iodine dosage of 6,000 micrograms per day for five months has been administered to healthy, euthyroid women without indication of toxicity [37]. Wagner et al. observed that the maximum accumulation of iodide by the thyroid gland was achieved at a dosage of 600 micrograms per day [38]. And it has been concluded by Koutras et al. that “as the plasma inorganic iodine level rises, iodide utilization by the thyroid becomes less complete” [39]. A relatively recent estimate of total body iodine content averaged 14.6 milligrams (not to be confused with micrograms, 1 milligram equals 1,000 micrograms), the majority of iodine being concentrated in the thyroid gland [40]. Now let’s turn our attention to the known roles of iodine in the body and potential benefits that might be derived from its supplementation. Firstly, it’s important to know that bromide can weaken the impact of consumed iodide by decreasing the accumulation of iodide in the thyroid gland and increasing the excretion of iodide through the kidneys (bromine can be found in some cosmetics as well as some plastics and flame retardants) [41]. And the potency of fluoride as an antagonist to iodine is well known, with fluoride’s deleterious effects on the thyroid gland and brain being strong enough to masquerade as serious iodine deficiency [42] [43]. Chlorine and organochlorine pesticides may antagonize iodine in the body similar to fluoride too [44] [45]. Fortunately, iodine supplementation can greatly assist in the displacement and flushing out of the halides bromide and fluoride [46]. Abraham has reported that the giving of an iodide and iodine combination supplement can also promote the excretion of the toxic metals lead, mercury, cadmium, and aluminum [47]. Secondly, acute damage to the mucosa of the esophagus and stomach has been documented with the application of Lugol’s iodine, but this occurrence is uncommon [48] [49]. Placing drops of a liquid iodine solution into an enteric-coated capsule might bypass this potential issue. Moving on, iodide can serve as an antioxidant by scavenging hydroxyl radicals and defending against lipid peroxidation in cell membranes [50] [51]. The thymus gland concentrates inorganic (nonradioactive) iodine, and iodine supplementation appears to strengthen the adaptive immune system [52] [53]. Iodine can also reduce the virulence of H. pylori bacteria in the stomach as well as help normalize corticosterone secretion throughout the day [54] [55]. Stable iodine can thwart the thyroid’s uptake of radioactive iodine-131 present in nuclear fallout, but it won’t protect the body against other radionuclides like cesium-137, strontium-90, and plutonium-241 [56]. Iodine supplementation may be capable of improving the receptivity of T3 receptors, possibly via a bolstering of transmembrane iodothyronine transporters [57] [58]. Vitamin A, zinc, and fish oil may also help improve T3 receptor function [59] [60] [61]. Sufficient iodine intake might assist with the normalization of the menstrual cycle, at least in PCOS patients, in addition to possibly bettering restless legs syndrome [62]. And iodine supplementation may lower the amount of exogenous insulin needed by both type 1 and type 2 diabetics [63]. Iodine has exhibited antifungal action against the fungal species Candida albicans and antibacterial action against the bacterial species Porphyromonas gingivalis, Escherichia coli, Staphylococcus aureus, and Enterococcus faecalis [64] [65] [66]. Iodine has also shown notable antiviral activity against adenovirus, influenza A virus, Ebola virus, and HIV [67] [68] [69]. And nascent or monatomic iodine has demonstrated efficacy against Plasmodium protozoa (responsible for malaria) [70]. A low intake of iodine has been associated with a high incidence of breast cancer, and vice versa [71]. Indeed, molecular iodine has been shown to induce apoptosis in breast cancer cells, as well as outperform potassium iodide in preventing the onset of breast cancer in rats administered the carcinogen N-methyl-N-nitrosourea [72] [73]. Iodine administration has blocked breast tumor growth in rats too [74]. In a way, iodine is apparently more nourishing for the breasts, while iodide is apparently more nourishing for the thyroid [75]. A study conducted by Eskin et al. showed that abnormal mammary glands respond better to molecular iodine than they do to iodide [76]. A paper by Ghent et al. corroborated that observation, finding that molecular iodine was more beneficial for fibrocystic breast disease than iodide [77]. Iodine deficiency appears to drive the onset of fibrocystic breast disease [78]. In conclusion, there is no doubt that iodine is a critical nutrient because of its direct and indirect offices. And supplementing with iodine can surely have a positive impact on multiple physiological fronts. However, I do not agree with the recent, narrow-minded approach of administering massive amounts of iodine to the body in order to effect changes that iodine is not designed to effect. The body is an interconnected web, and when we colossally magnify one variable, we inadvertently impact the others and make it more difficult for the body to achieve and maintain a state of dynamic homeostasis. A holistic and comprehensive approach to medicine is the safe and appropriate approach to medicine. References:
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AuthorDenton Coleman is an Exercise Physiologist and Medical Researcher. Archives
October 2023
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