Iodine deficiency in New Zealand re-emerged in the 1990s, so in 2009 the government introduced mandatory fortification of bread with iodised salt. The Iodine Global Network, an international body assessing iodine status throughout the world, now defines New Zealand as free of iodine deficiency.
However, Dr Louise Brough of the School of Food and Nutrition at Massey’s College of Health and other New Zealand researchers recently argued in the British Journal of Nutrition that some population groups here are still at risk of deficiency. A Massey University study published last year found pregnant and breastfeeding women in Manawatū were still not getting enough iodine.
Dr Jasmine Thomson, who specialises in human nutrition, says very active men who sweat a lot, such as cyclists exercising for hours at a time, might be at risk of iodine deficiency. “Sweat is one of the ways iodine is excreted from the body therefore men who exercise a lot will be losing a high amount of iodine. Also active men are often health conscious and may be cutting down on salt or reducing their bread intake and hence their iodine intake could be low.”
Dr Louise Brough, says iodine is only required in very small amounts by the body yet plays an essential role as part of the thyroid hormones, regulating metabolism, reproduction, growth and muscle function. “The iodine status of men has not been thoroughly investigated, as the concern traditionally has been about the requirements of women and children,” says Dr Brough.
Dr Thomson investigates sports nutrition, while Dr Brough studies nutrition in women and babies. Dr Thomson says they united “to research iodine, as we feel this is a very important and under-researched area of nutrition in active men that may affect their health and sport performance.”
The study requires male participants, who are either very active, or conversely, not active at all, aged 19-45 and living in Manawatū. Highly active men should have cycling as one aspect of their normal training e.g. triathletes, cyclists or mountain bikers. Non-active men need to be physically active for less than 30 minutes a day, either in their daily job or as exercise.
Participants will visit Massey University’s Human Nutrition Laboratory twice, with most of the data collection carried out over three days as participants go about their normal daily life.