Iodine content of semi-skimmed milk available in the Netherlands depending on farming (organic versus conventional) and heat treatment (pasteurized versus UHT) and implications for the consumer

Invited review: Iodine level in dairy products-A feed-to-fork overview

The theme of iodine in the dairy sector is of particular interest due to the involvement and the interconnection of several stakeholders along the dairy food chain. Iodine plays a fundamental role in animal nutrition and physiology, and in cattle it is an essential micronutrient during lactation and for fetal development and the calf's growth. Its correct use in food supplementation is crucial to guarantee the animal's recommended daily requirement to avoid excess intake and long-term toxicity. Milk iodine is fundamental for public health, being one of the major sources of iodine in Mediterranean and Western diets. Public authorities and the scientific community have made great efforts to address how and to what extent different drivers may affect milk iodine concentration. The scientific literature concurs that the amount of iodine administered through animal feed and mineral supplements is the most important factor affecting its concentration in milk of most common dairy species. Additionally, farming practices related to milking (e.g., use of iodized teat sanitizers), herd management (e.g., pasture vs. confinement), and other environmental factors (e.g., seasonality) have been identified as sources of variation of milk iodine concentration. Overall, the aim of this review is to provide a multilevel overview on the mechanisms that contribute to the iodine concentration of milk and dairy products.

Thyroidal and Extrathyroidal Requirements for Iodine and Selenium: A Combined Evolutionary and (Patho)Physiological Approach

Iodide is an antioxidant, oxidant and thyroid hormone constituent. Selenoproteins are needed for triiodothyronine synthesis, its deactivation and iodine release. They also protect thyroidal and extrathyroidal tissues from hydrogen peroxide used in the ‘peroxidase partner system’. This system produces thyroid hormone and reactive iodine in exocrine glands to kill microbes. Exocrine glands recycle iodine and with high urinary clearance require constant dietary supply, unlike the thyroid. Disbalanced iodine-selenium explains relations between thyroid autoimmune disease (TAD) and cancer of thyroid and exocrine organs, notably stomach, breast, and prostate. Seafood is iodine unconstrained, but selenium constrained. Terrestrial food contains little iodine while selenium ranges from highly deficient to highly toxic. Iodine vs. TAD is U-shaped, but only low selenium relates to TAD. Oxidative stress from low selenium, and infection from disbalanced iodine-selenium, may generate cancer of thyroid and exocrine glands. Traditional Japanese diet resembles our ancient seashore-based diet and relates to aforementioned diseases. Adequate iodine might be in the milligram range but is toxic at low selenium. Optimal selenoprotein-P at 105 µg selenium/day agrees with Japanese intakes. Selenium upper limit may remain at 300–400 µg/day. Seafood combines iodine, selenium and other critical nutrients. It brings us back to the seashore diet that made us what we currently still are.

Iodine content in goat and sheep milk related to herd size, seasonality, farming practice and breed effect

Iodine is a milk micronutrient whose concentration is highly variable and depends on several factors. The aim of this work was to monitor the prevailing concentration of iodine in raw goat (n = 71) and sheep (n = 68) milk from farms in the Czech Republic, to assess the variation in iodine levels and evaluate them with farming practices, herd size, breed and season. Iodine was determined by a spectrophotometric method according to Sandell-Kolthoff. The mean prevailing iodine concentration in goat and sheep milk was 249.73 and 264.21 μg/L, respectively. In addition to inter-species variability, we found statistically significant differences depending on the both sheep and goat herd size. The differences between conventional and organic farming were relatively minor and without statistical significance.

Macromineral and trace element concentrations and their seasonal variation in milk from organic and conventional dairy herds

To study the effects of dairy production system on milk macromineral and trace element concentrations, milk samples were collected monthly in 2019 from 43 conventional and 27 organic farms. Organic milk contained more Ca (1049.5 vs. 995.8 mg/kg), K (1383.6 vs. 1362.4 mg/kg), P (806.5 vs. 792.5 mg/kg) and Mo (73.3 vs. 60.6 μg/kg) but less Cu (52.4 vs. 60.6 μg/kg), Fe (0.66 vs 2.03 mg/kg), Mn (28.8 vs. 45.0 μg/kg), Zn (4.51 vs. 5.00 mg/kg) and Al (0.32 vs. 1.14 μg/kg) than conventional milk. Significant seasonal variation was observed in all determined minerals' concentrations. Milk I concentration was not consistently affected by production system, whereas organic milk contained less I in June and July than conventional milk. Dietary factors contributing to different milk mineral concentrations between production systems included intakes of maize silage, dry-straights and oils (higher in conventional diets), and pasture, clover and wholecrop (higher in organic diets).

Perceptions about Healthy Eating and Emotional Factors Conditioning Eating Behaviour: A Study Involving Portugal, Brazil and Argentina

This study analysed the perceptions about healthy eating as well as some emotional factors conditioning eating behaviour in a sample of people from Portugal, Brazil and Argentina. This is a descriptive cross-sectional study involving a non-probabilistic sample of 2501 participant. Data was collected through a questionnaire applied to adult citizens residing in their respective countries. For data analysis chi-square tests were used, and associations were evaluated by Cramer's coefficients. Moreover, a tree classification analysis was conducted for variables related with perceptions about healthy eating and emotional conditioning of eating behaviour. The results revealed that participants' perceptions are generally in agreement with healthy eating. However, significant differences were found between countries (p = 0.018) and by levels of education (p < 0.0005), with a more accurate perception for Portugal and at the university level. The existence of statistically significant associations between all sociodemographic variables considered and the conditioning of eating behaviour by emotional motivations should be noted. Tree classification analysis showed that the most important discriminant sociodemographic variable for perceptions about healthy eating was education, followed by professional area and country, while the most relevant discriminants for emotional conditioning of eating behaviour were country and then living environment and sex. Thus, it is important to consider these variables in initiatives that aim to promote adherence to behaviours that contribute to the health and well-being of the population.

Bioavailability of Micronutrients From Nutrient-Dense Whole Foods: Zooming in on Dairy, Vegetables, and Fruits

In order to fully exploit the nutrient density concept, thorough understanding of the biological activity of single nutrients in their interaction with other nutrients and food components from whole foods is important. This review provides a narrative overview of recent insights into nutrient bioavailability from complex foods in humans, highlighting synergistic and antagonistic processes among food components for two different food groups, i.e., dairy, and vegetables and fruits. For dairy, bioavailability of vitamins A, B2, B12 and K, calcium, phosphorous, magnesium, zinc and iodine are discussed, whereas bioavailability of pro-vitamin A, folate, vitamin C and K, potassium, calcium, magnesium and iron are discussed for vegetables and fruits. Although the bioavailability of some nutrients is fairly well-understood, for other nutrients the scientific understanding of uptake, absorption, and bioavailability in humans is still at a nascent stage. Understanding the absorption and bioavailability of nutrients from whole foods in interaction with food components that influence these processes will help to come to individual diet scores that better reflect absorbable nutrient intake in epidemiologic studies that relate dietary intake to health outcomes. Moreover, such knowledge may help in the design of foods, meals, and diets that aid in the supply of bioavailable nutrients to specific target groups.