Large Variability of Iodine Content in Retail Cow’s Milk in the U.S.

Abstract

Iodine intake is of contemporary public health interest. The recommended daily iodine intake is 150 µg for most adults, and milk is an important source of iodine in the U.S. diet. Iodine concentration in cow’s milk is affected by diet and iodine supplementation levels, milking sanitation practices, and other factors. Current analytical iodine data in U.S. retail milk are crucial for evaluating population-wide health outcomes related to diet. Samples of whole (3.25% fat), 2%, 1%, and skim (0–0.5% fat) milk were procured from 24 supermarkets across the U.S. using a census-based statistical plan. Iodine was analyzed by inductively coupled plasma mass spectrometry, including certified reference materials and control samples to validate results. No difference in iodine content was found between milkfat levels (F3,69 1.033, p = 0.4). Overall mean (SEM) was 85(5.5) µg/serving (240 mL). However, the 95% prediction interval of 39–185 µg/serving for individual samples indicated high variability among individual samples. Given the recommended 150 µg iodine per day for most adults along with the study mean, one milk serving can provide approximately 57% of daily intake. Researchers, health care professionals, and consumers should be aware of iodine variability in milk, while additional research is needed to investigate the impact of iodine variability factors.

Nutritional Quality of Plant-Based Drinks Sold in Italy: The Food Labelling of Italian Products (FLIP) Study

“…Being these values are far from the recommended values, it would be risky to consider plant-based beverages as substitutes for the daily portion of milk and, in turn, dairy products. More, milk is not only a good source of phosphorus, which bounds calcium to milk caseins, but also of iodine [31], an essential microelement for thyroid hormone synthesis, which is instead present in low amount in soy, rice, oat, and almond beverages unless added [32].…”

Iodine Content in Meal Replacements in the United States

“…24,33 Approximately, 49% of dietary iodine in the U.S. is obtained from dairy products. 21,32 Several of the meal replacement products we assessed likely contained iodine from dairy ingredients. The first listed ingredient in Carnations Breakfast Essentials powder is dry milk, which is likely the source of iodine in this meal replacement.…”

“…In nations such as Norway, Germany, Spain, Switzerland and the United Kingdom, dairy cows receive more supplementation in the winter resulting in milk iodine concentration varying seasonally. 21,37 This is unlikely to be the cause in the U.S. where cattle feed contains the same amount of iodine throughout the year. 22,36 Differences in iodine concentration can also occur due to the difference in strength and formulation of iodophor disinfectants.…”

“…There is some variation in iodine concentration in U.S cow's milk, but on average one serving of milk can provide 57% of daily intake of iodine (85 μg of iodine per cup of milk). 21 Varying levels of iodine can be found in plant foods, dependent on the levels of iodine in soil, crop fertilizers and water used in irrigation. 21,22 Additionally, salt iodization programs have been implemented in many regions worldwide to prevent iodine deficiency disorders.…”

“…21 Varying levels of iodine can be found in plant foods, dependent on the levels of iodine in soil, crop fertilizers and water used in irrigation. 21,22 Additionally, salt iodization programs have been implemented in many regions worldwide to prevent iodine deficiency disorders. However, in the U.S salt iodization is not mandatory.…”