Iodine - what is it and why do we need it?
Iodine is a trace mineral used by the body in small amounts to synthesize thyroid hormones that are necessary for regulating growth, development, metabolism and body temperature. Iodine loomed largely in my childhood as something so fundamentally important it needed to be added to our table salt to ensure everyone had access to it on a daily basis. I now know that this incremental iodine was to prevent goitre - a swelling of the thyroid gland (a butterfly shaped organ) which is located in the front of the neck just under the Adams apple. Suboptimal iodine levels can lead to goitre because the thyroid cannot produce those important hormones (such as thyroxine), so it overcompensates and enlarges, in an attempt to snatch more iodine from the blood.
A healthy thyroid gland correctly regulates our metabolism - the conversion of oxygen and kilojoules/calories to energy - in practically every cell in our body. Essentially, food fuels our body, and each person burns fuel at a different rate; this is why some people are described as having a fast metabolism (often slimmer people), while others have a slower metabolism (prone to weight gain). The history of iodine supplementation in New Zealand began in the late 1800s and early 1900s when goitre was very common, and eventually, in 1938, the effective recommended supplemental dose agreed upon to prevent iodine deficiency was 40-80 mg of iodine per kilo of salt. Marine foods like seafood, seaweed and fish, as well as dairy and eggs are the main natural dietary sources of iodine. The naturally occurring iodine content of food is also affected by certain fertilisers and cooking.
But people don't get goitre nowadays do they, so why do we still need to be concerned with our iodine levels?
Well, as reported on the New Zealand Nutrition Foundation’s website, NZ soils continue to be low in iodine (in fact iodine deficiency is still a major issue globally), and therefore adversely affects the iodine levels of locally grown foods and while salt and some breads are still fortified with iodine, often individual dietary choices or restrictions mean that these are unreliable daily sources for many people. The result of this is the re-emergence of wide-spread iodine deficiency across the New Zealand population. Some of the concerns this raises are that even a mild to moderate iodine deficiency can negatively affect hearing, intelligence and mental capability during childhood development, while a severe deficiency during pregnancy can lead to adverse consequences on foetal development such as cretinism and severe mental retardation, and a higher incidence of still births. A long-term deficiency in adults can eventually lead to hypothyroidism, a condition characterised by sensitivity to cold, constipation, depression, fatigue, heavier menstrual periods, joint or muscle pain, paleness, dry skin, brittle hair and fingernails, general weakness and unintentional weight gain.
As with many aspects of our health, advancing age also brings with it a reduction in iodine uptake and the production of thyroid hormones. This means our metabolism slows down and we may gain weight or feel tired. This does not have to happen to you though! By ensuring that we are getting the recommended daily intake of iodine - no matter what our age - the benefits to how we feel and how our bodies function are numerous. About Health’s multivitamin supplement - Multiva, is specifically formulated to addresses the deficiencies in New Zealand soils. This new and improved Multiva formula, has been made here in New Zealand and now has triple the Iodine content, providing the recommended daily intake (RDI) for Iodine of 150mcg, to ensure adequate supply of this important mineral in just one tablet daily.
Source: Nutrition Foundation NZ
Recent world events have highlighted the use of iodine for protection from radiation poisoning. While this is not relevant for us here in New Zealand, it is interesting and important that we understand the mechanism by which this protection is offered. The radiation from a nuclear event (such as the recent Japanese Nuclear Reactor Meltdown) releases radioactive iodine into the air, which can then enter the body, and be scooped up by the thyroid which cannot distinguish between radioactive or stable iodine. By taking stable iodine we block radioactive iodine from being absorbed into the thyroid gland and therefore help protect the thyroid gland from damage. The thyroid won’t absorb any more iodine for approximately 24 hours. It is important to remember that stable iodine can protect only the thyroid gland from radioactive damage, not any other parts of our body.
