Vegetarian (VG) and vegan (VN) diets in childhood are of growing interest due to their perceived health and environmental benefits. Concerns remain due to the possible disruption of healthy growth and development of children because of the scarcity of evidence-based studies. Among the nutrients of special concern is vitamin B12. Therefore, the Czech Vegan Children Study (CAROTS) decided to examine the relationship between B12 metabolism parameters and B12 intake through diet and supplementation. We analyzed laboratory parameters within n = 79 VG, n = 69 VN, and n = 52 omnivores (OM) children (0–18 years old). There were no significant differences in levels of holotranscobalamin (aB12), folate, homocysteine (hcys), or mean corpuscular volume. However, there was a significant difference in levels of cyanocobalamin (B12) (p = 0.018), even though we identified only n = 1 VG and n = 2 VN children as B12 deficient. On the other hand, we identified n = 35 VG, n = 28 VN, and n = 9 OM children with vitamin B12 hypervitaminosis (p = 0.004). This finding was related to a high prevalence of over-supplementation in the group (mean dose for VG 178.19 ± 238.5 µg per day; VN 278.35 ± 394.63 µg per day). Additionally, we found a significant (p < 0.05) difference between B12, aB12, and hcys levels of supplemented vs. non-supplemented VG/VN children. This can show that the intake of vitamin B12 via diet in the VG group might not be sufficient. Secondly, we analyzed a relation between supplement use in pregnancy and breastfeeding and its impact on vitamin B12 levels of children aged 0–3 years. Out of n = 46 mothers, only n = 3 (e.g., 6.5%) were not supplemented at all. We have not identified any clinical manifestation of B12 deficiency and only n = 1 child with low serum cobalamin, a child who did not receive vitamin B12 supplementation and whose mother took only low doses of vitamin B12 (25/µg/day).To conclude, we did not observe any life-threatening or severe consequences of laboratory-stated vitamin B12 deficiency; thus, our group was well supplemented. On the other hand, we have identified many subjects with vitamin B12 hypervitaminosis of unknown impact on their health. Further research and new guidelines for B12 supplementation among VG and VN children are needed.

Background: The intake and homeostasis of iodine, an essential micronutrient that plays a vital role in thyroid physiology, is of particular concern with the increasing popularity of vegetarian (VG) and vegan (VN) diets. Children on these restrictive diets may be at risk of possible adverse effects on growth and development, but there is currently a lack of recent epidemiological studies on this topic. Methods: We gathered clinical, anthropometric, and blood/urine data on iodine status and thyroid function from children aged 0–18 years who followed either a VG diet (n = 91), VN diet (n = 75), or omnivore diet (OM, n = 52). Cross-sectional comparison of the groups and linear regression was used. Stratified analyses were performed based on age (according to WHO): 0–5 years and 6–18 years. Results: Our study revealed no significant differences in levels of thyroid-stimulating hormone (TSH), triiodothyronine (fT3), thyroglobulin (TG) or anti-thyroid peroxidase antibody (ATPOc) between the VG, VN, and OM groups. However, thyroxine (fT4) levels were found to be higher in the VN group compared to the OM group (15.00 ± 1.73 vs. 16.17 ± 1.82 pmol/l, p < 0.001). The presence of anti-thyroglobulin antibodies (AhTGc) was notably more common in the VG (18.2%)/VN (35.0%) groups than in the OM group (2.1%) (p < 0.001). Regarding iodine status, the concentration of iodine in spot urine (UIC) was found to be highest in the OM group (197.28 ± 105.35 vs. VG: 177.95 ± 155.88 vs. VN: 162.97 ± 164.51 µg/l, p < 0.001). Notably, the lowest (5.99 µg/l) and highest (991.80 µg/l) levels were measured in the VN group. Of the participants, 31 VN, 31 VG and 10 OM children met the criteria for iodine deficiency (i.e., UIC < 100 µg/l). We found that children with regular iodine supplementation had higher UIC (p < 0.001). Importantly, the median UIC was above 100 µg/l in all three groups, through the recommended intake (RDI) of iodine was rarely met throughout the groups. Conclusion: We have observed a trend to lower UIC values in VN as compared to OM. This trend is also reflected in the median UIC values, even though the median UIC values were above the WHO cut-off (e.g., 100 µg/l) for iodine deficiency in all dietary groups. These results suggest that VN and VG children may be more at higher risk of iodine deficiency, this theory is also supported by higher prevalence of AhTGc positivity. Further research is needed to investigate the long-term impact of these dietary patterns on iodine status and thyroid function in children. Given our findings, it may also be necessary to consider new guidelines for supplementing children following VG and VN diets to ensure their iodine needs are met.

Background: Vegetarian (VG) and vegan (VN) diets are becoming increasingly popular among children. These restrictive types of diet remain a concern as they may impair growth and development, although up-to-date epidemiological studies are lacking. Iodine, an essential micronutrient, is of specific concern due to its important role in thyroid gland physiology. Methods: We collected clinical, anthropometric, and blood/urine parameters of iodine status as well as thyroid function among children following VG (n = 91), VN (n = 75), and omnivores (OM, n = 52), aged 5.4 (± 4.3) years. Results: We found no significant differences in levels of thyroid-stimulating hormone (TSH), triiodothyronine (fT3), or thyroglobulin (TG) between the groups. Thyroxine (fT4) levels were higher in OM compared to VN (15.00 ± 1.73 vs. 16.17 ± 1.82 pmol/L, p < 0.001). There were strong differences in anti-thyroglobulin antibodies (AhTGc) between groups (OM: 2.54 ± 8.31 vs. VG: 16.24 ± 44.46 vs. VN: 13.93 ± 9.16 UI/L, p < 0.001). Iodine concentration in spot urine (UIC) was highest in OM (195.31 ± 105.28 vs VG: 177.27 ± 155.13 vs. VN: 162.94 ± 163.39 µg/L, p < 0.001). The lowest (5.99 µg/L) but also the highest (991.80 µg/L) levels were measured in VN. 31 VN and 31 VG children met the criteria for iodine deficiency (i.e., UIC < 100 µg/L). Children with regular iodine supplementation had higher UIC (p < 0.001). Conclusion: We observed a higher prevalence of iodine deficiency in VN and VG group than in OM, with possible impact on thyroidal health (i.e., positivity of antibodies). Further research and new guidelines for iodine supplementation among VG and VN children are therefore warranted.

Introduction The dietary habits of the population are undergone dramatic changes in recent years, with an increasing proportion of people adopting different variants of plant-based diets, limiting their consumption of food of animal origin. Moreover, the shift toward a plant-based diet is supported by scientific reports promoting them as a more sustainable dietary option, which is necessary to adopt on a global scale to mitigate the human influence on climate change. However, despite their growing popularity, many questions regarding their safety and long-term health effects remain unanswered. One of the biggest concerns is the health impact during childhood and adolescence, due to the higher risk of development of severe nutritional deficiencies accompanied by the lack of good quality evidence to guide clinical recommendations and management in those groups. To close the knowledge gap, we decided to establish a family cohort study with increased representation of vegetarian and vegan families with the aim to describe not only adult and child-specific outcomes associated with plant-based diet, but also shared family risks. The aim of the presented manuscript is to introduce the background of the establishment of the family cohort study and provide a description of its protocol. Methods To investigate the long-term effect of these newly emerging dietary habits, a cohort of families with at least one child under 7 years of age and with the same diet followed by all members was established. The goal for the first year of the study was to recruit at least 40 vegetarian, 40 vegan, and 60-80 omnivore families. At the time of enrollment, biological samples, as well as medical history, together with 3 day dietary records, were taken. The initial active follow-up is planned for at least 5 years. Ethics and dissemination The study was approved by the Institutional Review Board no. EK-VP/391012. The results of the study will serve as a basis for future research, as well as clinical guidelines and dietary recommendations in Czechia and neighboring regions.