Prevalence of iodine deficiency among vegan compared to vegetarian and omnivore children in the Czech Republic: cross-sectional study

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.

Health aspects of vegan diets among children and adolescents: a systematic review and meta-analyses

Health effects of vegan diets among children and adolescents are a controversial public health topic. Thus, the aim of the present systematic review is to evaluate a broad range of health outcomes among vegan children and adolescents aged 0 to 18 years. 18 studies met the inclusion criteria (17 cross-sectional, 1 RCT). Meta-analyses showed lower protein, calcium, vitamin B2, saturated fatty acid, and cholesterol intakes, and lower ferritin, HDL and LDL levels as well as height in vegan compared to omnivorous children/adolescents. Higher intakes of carbohydrates, polyunsaturated fatty acids, fiber, folate, vitamins C and E, magnesium, iron, and potassium were observed in vegans. Blood levels of vitamin B12 were higher among vegan children due to supplement use. Single study results suggested further differences between vegan and non-vegan children, such as lower bone mineral content or urinary iodine among vegan children. Risk of Bias was rated as high or very high in 7 out of 18 studies. The certainty of evidence for the meta-analyses was low (n = 2) or very low (n = 46). Overall, the available evidence points to both risks and benefits associated with a vegan diet among children, although more and better designed studies are needed.

Cross-Sectional Study of the Prevalence of Cobalamin Deficiency and Vitamin B12 Supplementation Habits among Vegetarian and Vegan Children in the Czech Republic

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.

Iodine intake monitoring in neonatal population in the Czech Republic: alarming numbers in 2020

Thanks to comprehensive and long-term preventive programs, the Czech Republic has taken its place among the countries with a resolved iodine deficiency at all population levels since 2004. A sensitive indicator of iodine supply to the population, which can also be used to monitor the efficiency of prophylactic programs, is the TSH assessment in the nationwide neonatal screening of congenital hypothyroidism. Nevertheless, recent results of neonatal TSH show that newborns and pregnant women remain very risky groups and their iodine saturation is borderline. In recent years, the percentage of newborns with TSH 5-15 mIU/l has already risen above the 3% mark, i.e. mild iodine deficiency in major part of the Czech Republic (3.8 % in Bohemia, 2.8% in Moravia in 2019 and 4.7 % in Bohemia, 2.9% in Moravia in 2020). For some smaller areas, the values are even higher, which can be related, for example, to the social patterns of the population. The result may be not only the exclusion of the Czech Republic from the list of countries with resolved iodine deficiency, but especially adverse consequences for the cognitive development of the future generation. Therefore, it is essential to intensify nation-wide intervention among both the professional and general public. In this regard, adherence to the supplementation of pregnant and breastfeeding women is crucial with 150-200 &#956;g of iodide in addition to nutritional iodine intake.

Problematics of iodine saturation among children on the vegan diet

Plant-based diets, which includes veganism, is now rapidly gaining popularity. In the absence of the knowledge how to provide all the risky nutrients, this style of eating can lead to nutritional deficits that result in disruption of the physiological development of the child. One of the risk elements also includes iodine. The vegan population is at risk not only of developing an iodine deficiency, but also of complications from its excessive consumption, since vegan alternatives, such as these made of seaweed, contain an excess amount of it. Iodine is essential for the proper functioning of the thyroid gland, whose hormones are involved in the development of the nervous system during intrauterine and postnatal development, and in the regulation of metabolism, as well as growth in children. Several physical (thyroid palpation), imaging (ultrasound) and laboratory methods (TSH, fT3/fT4 ratio, TG level, median of ioduria) are used to investigate iodine supply. For vegans it is essential to closely monitor iodine saturation and to edify the need to adequately supplement the diet of vegan diets. A possible vegan iodine source are precisely measured doses of mineral water (Vincentka) or iodine tablets. On the contrary, uncontrolled consumption of seaweed must be strictly discouraged. In terms of iodine supply, vegans are a risk group, and pregnant and breastfeeding women and children on vegan diets deserve increased attention.

Problematics of iodine saturation among children on the vegan diet

Plant-based diets, which includes veganism, is now rapidly gaining popularity. In the absence of the knowledge how to provide all the risky nutrients, this style of eating can lead to nutritional deficits that result in disruption of the physiological development of the child. One of the risk elements also includes iodine. The vegan population is at risk not only of developing an iodine deficiency, but also of complications from its excessive consumption, since vegan alternatives, such as these made of seaweed, contain an excess amount of it. Iodine is essential for the proper functioning of the thyroid gland, whose hormones are involved in the development of the nervous system during intrauterine and postnatal development, and in the regulation of metabolism, as well as growth in children. Several physical (thyroid palpation), imaging (ultrasound) and laboratory methods (TSH, fT3/fT4 ratio, TG level, median of ioduria) are used to investigate iodine supply. For vegans it is essential to closely monitor iodine saturation and to edify the need to adequately supplement the diet of vegan diets. A possible vegan iodine source are precisely measured doses of mineral water (Vincentka) or iodine tablets. On the contrary, uncontrolled consumption of seaweed must be strictly discouraged. In terms of iodine supply, vegans are a risk group, and pregnant and breastfeeding women and children on vegan diets deserve increased attention.