Comparison Between Milk, Yogurt And Non-Dairy Milk Consumed in Portugal

Iodine is an essential trace element and its nutritional importance is well established. It is required for the synthesis of the thyroid hormones thyroxine and its active form T3, as well as the precursor iodotyrosines. The major role of thyroid hormones is related to the growth and development of the body. Iodine deficiency is the most common cause of preventable mental impairment. Chronic iodine deficiency can lead to disorders which include mental impairment and retardation, and formation of goiter (thyroid dysfunction), an enlargement of the thyroid gland which implies inadequate thyroid hormones production (Rohner et al., 2014). Recently EFSA and WHO established 150 µg per day as the adequate iodine daily intake (EFSA Panel on Dietetic Products, 2014; World Health Organisation and Food and Agriculture Organization of the United Nations, 2004). Food is the largest natural source of iodine. Dairy products are one of the major iodine suppliers, because of dairy-farming practices that contribute to its high iodine content (Leufroy et al., 2015). In literature the contribution of dairy products has been estimated between 25 % and 70 % of the daily iodine intake (van der Reijden et al., 2017). Nowadays, several people are substituting dairy products for non-dairy milks. For example, people with allergy or lactose intolerance. This work aims to determine the iodine content in dairy products and compare them with non-dairy milks. Samples of milk, yogurt and non-dairy milk consumed in Portugal were selected. In total, 41 samples were analyzed in triplicate. Iodine contents were determined using inductively coupled plasma-mass spectrometry (ICP-MS) after alkaline extraction assisted by a heating block. The preliminary results show a high variation between brands, ranging from 91.2 to 367 μg/L. Similar results (17 - 365 μg/L) were reported by other authors (Dahl et al., 2003). Comparing between dairy products and non-dairy milks revealed a large variation. Non-dairy milks present about 60 times less iodine than dairy products. These results are in agreement with the literature (Bath et al., 2017). For people with lactose intolerance, allergic to milk, or under voluntary restrictive diets as vegans the alternative to dairy products may be non-dairy milks, with iodine fortification. This fortification is necessary so that the recommended nutrient intake of iodine can be supplied. In conclusion these results combined with consumption data are a contribution to estimate a real intake of dietary iodine of Portuguese population.

Este trabalho foi desenvolvido com o apoio da FCT.

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