Dietary intake of vitamin D in premenopausal, healthy vegans was insufficient to maintain concentrations of serum 25-hydroxyvitamin D and intact parathyroid hormone within normal ranges during the winter in Finland

OBJECTIVE: To study vitamin D status and bone metabolism of premenopausal vegetarians and omnivores during a 1-year period. DESIGN: Longitudinal, observational study. Bone mineral density was measured, blood samples from fasting subjects were obtained, and 24-hour urinary samples were collected in February 1994, August 1994, and January 1995. Serum 25-hydroxyvitamin D [S-25(OH)D] and intact parathyroid hormone (S-iPTH) concentrations were measured and intestinal calcium absorption was estimated. Dietary intakes of vitamin D and calcium were calculated. SUBJECTS/SETTING: Six vegans, 6 lactovegetarians, and 16 omnivores living in Helsinki, Finland. STATISTICAL ANALYSES PERFORMED: Student-Newman-Keuls test; unbalanced, repeated-measures multiple analysis of variance; analysis of covariance; Pearson correlation test; and linear regression analysis. RESULTS: Dietary intake of vitamin D was significantly lower in vegans (P < .05, yearly mean +/- standard deviation = 0.09 +/- 0.06 microgram/day) and in lactovegetarians (P < .05, 0.7 +/- 0.4 microgram/day) compared with omnivores (4.0 +/- 2.1 micrograms/day). Throughout the year S-25(OH)D (P = .01) concentrations were lower and S-iPTH (P = .01) concentrations were higher in vegans than in omnivores and lactovegetarians. Bone mineral density in the lumbar region of the spine was lower in vegans (yearly mean +/- standard deviation = 1.034 +/- 0.174 g/cm2) than in omnivores (P = .05, 1.177 +/- 0.099 g/cm2) and tended to be lower than that in lactovegetarians (P = .17, 1.138 +/- 0.06 g/cm2). Bone mineral density in the neck of the femur tended to be lower in vegans (0.843 +/- 0.116 g/cm2) than in omnivores (P = .07, 0.999 +/- 0.138 g/cm2) and lactovegetarians (P = .15, 0.961 +/- 0.059 g/cm2). No seasonal variation was found in bone mineral density in the study groups. CONCLUSIONS: At northern latitudes, dietary intake of vitamin D in vegans was insufficient to maintain S-25(OH)D and S-iPTH concentrations within normal ranges in the winter, which seems to have negative effects on bone mineral density in the long run. APPLICATIONS: An increase in vitamin D intake should generally be recommended for vegans at least during winter, or selections of foodstuffs fortified with vitamin D should be broadened in northern latitudes.     

Nutrient intake and iron status of Australian male vegetarians

OBJECTIVE: The study was designed to investigate the iron intake and status of Australian, male vegetarians aged between 20 and 50 y. DESIGN: Cross-sectional comparison of male vegetarians and age/sex matched omnivores. SETTING: Free-living community subjects. SUBJECTS: 39 ovolactovegetarians, 10 vegans and 25 omnivores were recruited by local advertisement. OUTCOME MEASURES: A 12-d semiquantitative dietary record to assess iron and zinc intake. Iron status was assessed by measurement of serum ferritin and haemoglobin concentrations. RESULTS: Mean (s.d.) daily iron intakes of both the ovolactovegetarians (20.4 (7.7) mg/d) and vegans (22.9 (6.2) mg/d), were significantly higher than the omnivores' intake of 15.8 (4.5) mg/d. Ovo-lactovegetarians and vegans had significantly (P < 0.001 and P < 0.05, respectively) lower serum ferritin concentrations than omnivores: mean (s.d.): 64 (46.9), 65 (49.9) and 121 (72.5) ng/ml, respectively. Significantly more ovolactovegetarians and vegans than omnivores had serum ferritin concentrations below 25 ng/ml and below 12 ng/ml (P < 0.05). A higher proportion of omnivores had concentrations above 200 ng/ml (P < 0.05). The differences in serum ferritin concentrations between the vegetarians and omnivores remained significant even after exclusion of iron supplement users. CONCLUSION: Australian male vegetarians had iron intakes higher than those of omnivores and above recommended levels, but their iron status was significantly lower.     

Zinc intake and status in Australian vegetarians

Vegetarians have a lower incidence of many chronic diseases than omnivores. However, vegetarian diets could potentially result in lower intakes of some minerals, particularly Zn. In a cross-sectional study, dietary Zn intake was measured using 12 d weighed records in ninety-nine vegetarians (ten vegans) aged 18-50 years and forty-nine age- and sex-matched omnivores. In men, the mean daily Zn intake and Zn density values were similar in omnivores, ovolactovegetarians and vegans, but in women they were significantly lower in vegetarians (mean intake 6.8 mg v. 8.4 mg in omnivores) and few achieved the recommended intake. Significantly more vegetarian than omnivorous women had a daily Zn intake < 6 mg (44% v. 13%). Mean serum Zn concentrations were similar in female omnivores and vegetarians, despite the differences in intake. However, omnivorous men had a lower mean serum Zn concentration (0.85 microgram/ml v. 0.95 microgram/ml) and more subjects had levels below the reference range of 0.72-1.44 micrograms/ml than ovolactovegetarians (P < 0.01). Overall more women than men had low Zn concentrations; and these women generally had intakes below 6 mg/d. There was a significant correlation between serum Zn concentration and dietary Zn density in vegetarians, especially females (P < 0.001), but not in omnivores. Ovolactovegetarians did not have a significantly greater risk of low Zn status than omnivores.     

Vegan Diet and Bone Health—Results from the Cross-Sectional RBVD Study

Scientific evidence suggests that a vegan diet might be associated with impaired bone health. Therefore, a cross-sectional study (n = 36 vegans, n = 36 omnivores) was used to investigate the associations of veganism with calcaneal quantitative ultrasound (QUS) measurements, along with the investigation of differences in the concentrations of nutrition- and bone-related biomarkers between vegans and omnivores. This study revealed lower levels in the QUS parameters in vegans compared to omnivores, e.g., broadband ultrasound attenuation (vegans: 111.8 ± 10.7 dB/MHz, omnivores: 118.0 ± 10.8 dB/MHz, p = 0.02). Vegans had lower levels of vitamin A, B2, lysine, zinc, selenoprotein P, n-3 fatty acids, urinary iodine, and calcium levels, while the concentrations of vitamin K1, folate, and glutamine were higher in vegans compared to omnivores. Applying a reduced rank regression, 12 out of the 28 biomarkers were identified to contribute most to bone health, i.e., lysine, urinary iodine, thyroid-stimulating hormone, selenoprotein P, vitamin A, leucine, α-klotho, n-3 fatty acids, urinary calcium/magnesium, vitamin B6, and FGF23. All QUS parameters increased across the tertiles of the pattern score. The study provides evidence of lower bone health in vegans compared to omnivores, additionally revealing a combination of nutrition-related biomarkers, which may contribute to bone health. Further studies are needed to confirm these findings.     

Vitamin B-12 status,particularly holotranscobalamin II and methylmalonic acid concentrations,and hyperhomocysteinemia in vegetarians

BACKGROUND: Vegetarians have a lower intake of vitamin B-12 than do omnivores. Early and reliable diagnosis of vitamin B-12 deficiency is very important. OBJECTIVE: The objective was to investigate vitamin B-12 status in vegetarians and nonvegetarians. DESIGN: The study cohort included 66 lactovegetarians or lactoovovegetarians (LV-LOV group), 29 vegans, and 79 omnivores. Total vitamin B-12, methylmalonic acid, holotranscobalamin II, and total homocysteine concentrations were assayed in serum. RESULTS: Of the 3 groups, the vegans had the lowest vitamin B-12 status. In subjects who did not consume vitamins, low holotranscobalamin II (< 35 pmol/L) was found in 11% of the omnivores, 77% of the LV-LOV group, and 92% of the vegans. Elevated methylmalonic acid (> 271 nmol/L) was found in 5% of the omnivores, 68% of the LV-LOV group, and 83% of the vegans. Hyperhomocysteinemia (> 12 micromol/L) was present in 16% of the omnivores, 38% of the LV-LOV group, and 67% of the vegans. The correlation between holotranscobalamin II and vitamin B-12 was weak in the low serum vitamin B-12 range (r = 0.403) and strong in the high serum vitamin B-12 range (r = 0.769). Holotranscobalamin II concentration was the main determinant of total homocysteine concentration in the vegetarians (beta = -0.237, P < 0.001). Vitamin B-12 deficiency led to hyperhomocysteinemia that was not probable in the upper folate range (> 42.0 nmol/L). CONCLUSIONS: Vegan subjects and, to a lesser degree, subjects in the LV-LOV group had metabolic features indicating vitamin B-12 deficiency that led to a substantial increase in total homocysteine concentrations. Vitamin B-12 status should be monitored in vegetarians. Health aspects of vegetarianism should be considered in the light of possible damaging effects arising from vitamin B-12 deficiency and hyperhomocysteinemia.     

Iodine Status and Thyroid Function in a Group of Seaweed Consumers in Norway

Seaweeds, or macroalgae, may be a good dietary iodine source but also a source of excessive iodine intake. The main aim in this study was to describe the iodine status and thyroid function in a group of macroalgae consumers. Two urine samples were collected from each participant (n = 44) to measure urinary iodine concentration (UIC) after habitual consumption of seaweed. Serum thyroid stimulating hormone (TSH), free thyroxine (fT₄), free triiodothyronine (fT₃), and peroxidase autoantibody (TPOAb), were measured in a subgroup (n = 19). A food frequency questionnaire and an iodine-specific 24 h recall were used to assess iodine intake and macroalgae consumption. The median (p25–p75) UIC was 1200 (370–2850) μg/L. Median (p25–p75) estimated dietary iodine intake, excluding macroalgae, was 110 (78–680) μg/day, indicating that seaweed was the major contributor to the iodine intake. TSH levels were within the reference values, but higher than in other comparable population groups. One third of the participants used seaweeds daily, and sugar kelp, winged kelp, dulse and laver were the most common species. Labelling of iodine content was lacking for a large share of the products consumed. This study found excessive iodine status in macroalgae consumers after intake of dietary seaweeds. Including macroalgae in the diet may give excessive iodine exposure, and consumers should be made aware of the risk associated with inclusion of macroalgae in their diet.     

Nutrient Intake and Status of German Children and Adolescents Consuming Vegetarian,Vegan or Omnivore Diets: Results of the VeChi Youth Study

There is a lack of data on associations between modern vegetarian and vegan diets and health among children and adolescents. The aim of the Vechi Youth Study was to cross-sectionally examine anthropometry, dietary intakes and nutritional status in a sample of 149 vegetarian, 115 vegan and 137 omnivore children and adolescents (6–18 years old, mean age: 12.7 ± 3.9 years). Group differences of dietary intake (calculated from three-day dietary records), nutrient biomarker and blood lipid concentrations were assessed using an analysis of covariance, adjusted for sex, age and other covariates. The total energy intake did not differ significantly between groups, but intake of carbohydrates was higher among vegetarians and vegans than among omnivores (p = 0.0002, respectively). The median protein intake exceeded 0.9 g/kg body weight/day in all diet groups and was lowest among vegetarians (p < 0.02). There was no significant difference of haemoglobin, vitamin B2, 25-OH vitamin D3, HDL-C and triglycerides blood concentrations between diet groups. Vegan participants had higher folate concentrations than vegetarian participants (p = 0.0053). Ferritin concentration was significantly higher in omnivores than in vegetarians (p = 0.0134) and vegans (p = 0.0404). Vegetarians had lower concentrations of holotranscobalamin (p = 0.0042) and higher concentrations of methylmalonic acid (p = 0.0253) than omnivores. Vegans had the lowest non-HDL-C and LDL-C concentrations in comparison to vegetarians (p = 0.0053 and p = 0.0041) and omnivores (p = 0.0010 and p = 0.0010). A high prevalence (>30%) of 25-OH vitamin D3 and vitamin B2 concentrations below reference values were found irrespective of the diet group. In conclusion, the Vechi Youth Study did not indicate specific nutritional risks among vegetarian and vegan children and adolescents compared to omnivores.     

Dietary intake and nutritional status of young vegans and omnivores in Sweden

BACKGROUND: Adolescents sometimes become vegetarian for ethical rather than health reasons. This may result in health problems caused by lack of interest in and knowledge of nutrition. OBJECTIVE: We compared the dietary intake and nutritional status of young Swedish vegans and omnivores. DESIGN: The dietary intakes of 30 vegans (15 males and 15 females; mean age: 17.5 +/- 1.0 y) and 30 sex-, age-, and height-matched omnivores were assessed with the use of a diet-history interview and validated by the doubly labeled water method and by measuring nitrogen, sodium, and potassium excretion in urine. Iron status and serum vitamin B-12 and folate concentrations were measured in blood samples. RESULTS: The diet-history method underestimated energy intake by 13% and potassium intake by 7% compared with the doubly labeled water method and 24-h urine excretion, respectively. Reported dietary nitrogen and sodium intakes agreed with the 24-h urinary excretion measure. Vegans had higher intakes of vegetables, legumes, and dietary supplements and lower intakes of cake and cookies and candy and chocolate than did omnivores. Vegans had dietary intakes lower than the average requirements of riboflavin, vitamin B-12, vitamin D, calcium, and selenium. Intakes of calcium and selenium remained low even with the inclusion of dietary supplements. There was no significant difference in the prevalence of low iron status among vegans (20%) and omnivores (23%). Two vegans with low intakes of vitamin B-12 had low serum concentrations. CONCLUSION: The dietary habits of the vegans varied considerably and did not comply with the average requirements for some essential nutrients.     

Short- and Branched-Chain Fatty Acids as Fecal Markers for Microbiota Activity in Vegans and Omnivores

A vegan diet could impact microbiota composition and bacterial metabolites like short-chain (SCFA) and branched-chain fatty acids (BCFA). The aim of this study was to compare the concentrations of SCFA, BCFA, ammonia, and fecal pH between vegans and omnivores. In this cross-sectional study (vegans n = 36; omnivores n = 36), microbiota composition, fecal SCFA, BCFA, and ammonia concentrations and pH were analyzed in complete stool samples. A random forest regression (RFR) was used to identify bacteria predicting SCFA/BCFA concentrations in vegans and omnivores. No significant differences in SCFA and BCFA concentrations were observed between vegans and omnivores. Fecal pH (p = 0.005) and ammonia concentration (p = 0.01) were significantly lower in vegans than in omnivores, while fiber intake was higher (p < 0.0001). Shannon diversity was higher in omnivores compared to vegans on species level (p = 0.04) only. In vegans, a cluster of Faecalibacterium prausnitzii, Prevotella copri, Dialister spp., and Eubacterium spp. was predictive for SCFA and BCFA concentrations. In omnivores, Bacteroides spp., Clostridium spp., Ruminococcus spp., and Prevotella copri were predictive. Though SCFA and BCFA did not differ between vegans and omnivores, the results of the RFR suggest that bacterial functionality may be adapted to varying nutrient availability in these diets.     

Methods to assess iron and iodine status

Four methods are recommended for assessment of iodine nutrition: urinary iodine concentration, the goitre rate, and blood concentrations of thyroid stimulating hormone and thyroglobulin. These indicators are complementary, in that urinary iodine is a sensitive indicator of recent iodine intake (days) and thyroglobulin shows an intermediate response (weeks to months), whereas changes in the goitre rate reflect long-term iodine nutrition (months to years). Spot urinary iodine concentrations are highly variable from day-to-day and should not be used to classify iodine status of individuals. International reference criteria for thyroid volume in children have recently been published and can be used for identifying even small goitres using thyroid ultrasound. Recent development of a dried blood spot thyroglobulin assay makes sample collection practical even in remote areas. Thyroid stimulating hormone is a useful indicator of iodine nutrition in the newborn, but not in other age groups. For assessing iron status, haemoglobin measurement alone has low specificity and sensitivity. Serum ferritin remains the best indicator of iron stores in the absence of inflammation. Measures of iron-deficient erythropoiesis include transferrin iron saturation and erythrocyte zinc protoporphyrin, but these often do not distinguish anaemia due to iron deficiency from the anaemia of chronic disease. The serum transferrin receptor is useful in this setting, but the assay requires standardization. In the absence of inflammation, a sensitive method to assess iron status is to combine the use of serum ferritin as a measure of iron stores and the serum transferrin receptor as a measure of tissue iron deficiency.     

Testosterone, sex hormone-binding globulin, calculated free testosterone, and oestradiol in male vegans and omnivores

Total testosterone (T), total oestradiol (E2) and sex hormone-binding globulin (SHBG) concentrations were measured in plasma samples from fifty-one male vegans and fifty-seven omnivores of similar age. Free T concentration was estimated by calculation. In comparison with the omnivores, the vegans had 7% higher total T (P = 0.250), 23% higher SHBG (P = 0.001), 3% lower free T (P = 0.580), and 11% higher E2 (P = 0.194). In a subset of eighteen vegans and twenty-two omnivores for whom 4 d diet records were available, there were statistically significant correlations between T and polyunsaturated fatty acids (r 0.37), SHBG and fat (r 0.43 for total fat, 0.46 for saturated fatty acids and 0.33 for polyunsaturated fatty acids), and SHBG and alcohol (r-0.39). It is concluded that a vegan diet causes a substantial increase in SHBG but has little effect on total or free T or on E2.     

Validity of reported energy expenditure and energy and protein intakes in Swedish adolescent vegans and omnivores

BACKGROUND: It is difficult to obtain accurate reports of dietary intake; therefore, reported dietary intakes must be validated. Researchers need low-cost methods of estimating energy expenditure to validate reports of energy intake in groups with different lifestyles and eating habits. OBJECTIVE: We sought to validate the reported energy expenditure and energy and protein intakes of Swedish adolescent vegans and omnivores. DESIGN: We compared 16 vegans (7 females and 9 males; mean age: 17.4 +/- 0.8 y) with 16 omnivores matched for sex, age, and height. Energy expenditure as reported in a physical activity interview and energy and protein intakes as reported by diet history were validated by using the doubly labeled water method and by measuring urinary nitrogen excretion. RESULTS: The validity of reported energy expenditure and energy and protein intakes was not significantly different between vegans and omnivores. The physical activity interview had a bias toward underestimating energy expenditure by 1.4 +/- 2.6 MJ/d (95% CI: 2.4, 0.5 MJ/d). The diet-history interview had a bias toward underestimating energy intake by 1.9 +/- 2.7 MJ/d (95% CI: 2.9, 1.0 MJ/d) but showed good agreement with the validation method for nitrogen (protein) intake (underestimate of 0.40 +/- 1.90 g N/d; 95% CI: 1.10, 0.29 g N/d). CONCLUSIONS: The physical activity and diet-history interviews underestimated energy expenditure and energy intake, respectively. Energy intake and expenditure were underestimated to the same extent, and the degree of underestimation was not significantly different between vegans and omnivores. Valid protein intakes were obtained with the diet-history method for both vegans and omnivores.     

Vegans,Vegetarians and Pescatarians Are at Risk of Iodine Deficiency in Norway

Low iodine intakes have been documented in different population groups in Norway. We aimed to assess iodine status, dietary intake, supplement and macroalgae use, and iodine knowledge in vegans, vegetarians and pescatarians. In this study, 115 vegans, 55 vegetarians and 35 pescatarians from the Oslo region of Norway, aged 18–60 years, participated. A spot urine sample was collected along with a dietary assessment of iodine intake, supplement and macroalgae use. The median urinary iodine concentration (MUIC) in vegans was 43 µg/L (moderate iodine deficiency), in vegetarians 67 µg/L and in pescatarians 96 µg/L (mild iodine deficiency). In multiple linear regression analysis, use of iodine supplements was one of the strongest predictors of UIC. About half of the participants had median 24-h iodine intakes below estimated average requirement (EAR) of 100 µg/day. Fifty percent had low knowledge score, while 27% had very low knowledge score. Vegans, vegetarians and possibly pescatarians in Norway, are unable to reach the recommended iodine intake merely from food and are dependent on iodine supplements. There is an urgent need for dietary guidance targeting vegans, vegetarians and pescatarians to avoid inadequate iodine intake in non-supplement users, as well as avoiding excess iodine intake in macroalgae users.     

Relations between various measures of iodine intake and thyroid volume,thyroid nodularity,and serum thyroglobulin

BACKGROUND: Iodine intake can be measured in various ways, and each method may have advantages and disadvantages. OBJECTIVE: We sought to investigate the potential associations of various measures of iodine intake with thyroid volume, prevalence of thyroid nodules, and serum thyroglobulin. We also sought to identify, if possible, groups at risk of thyroid disease because of their food choices. DESIGN: This cohort study included 4649 randomly selected subjects with mild-to-moderate iodine deficiency; the subjects lived in 2 cities in Denmark. Iodine intake was estimated by using a food-frequency questionnaire and by measuring iodine excretion in spot urine samples. Thyroid volume and nodularity were measured with ultrasonography. RESULTS: In multiple linear regression models, significant inverse relations were found between thyroid volume and estimated 24-h iodine excretion, iodine intake from diet plus supplements, iodine intake from diet/kg body wt, and milk intake (P = 0.001 for all), but not urinary iodine excretion measured as a concentration (P = 0.40). All measures of iodine intake were significantly related to serum thyroglobulin concentration (P 相似文献   

Assessment of iodine intake in vegans: weighed dietary record vs duplicate portion technique

OBJECTIVE: To compare iodine intakes estimated from weighed dietary records with iodine intakes obtained by direct analysis of duplicate diets in a group of vegans. DESIGN: Cross-sectional study. SETTING: London and the south-east of England. SUBJECTS: Thirty-three vegans consuming their habitual diet were recruited through the UK Vegan Society; 26 subjects (11 males, 15 females), age 21-84 y, completed the study. INTERVENTIONS: Iodine intakes were estimated from 4 day weighed dietary records and compared with iodine intakes obtained by direct analysis of concurrent 4 day duplicate diets. RESULTS: There was wide variation in iodine intakes. Mean daily iodine intake in males was significantly lower (P<0.05) when estimated from dietary records (42 microg) compared with that analysed from duplicate diets (137 microg). Conversely, in females the mean daily iodine intake from dietary records (1448 microg) was higher (P=0.43) than from duplicate diets (216 microg). Variation in iodine intakes determined by the two different methods may be attributed to the absence of iodine content of some foods, in particular foods suitable for vegan consumption, in food composition tables and the variability in iodine content of seaweed. CONCLUSIONS: The use of current food tables to estimate iodine intake in vegans is limited. It is not always practical to determine iodine intake using the duplicate portion technique, therefore more reliable information on iodine content of foods, incorporating the variation within foods, is needed.     

某地区妊娠早期妇女碘营养状况与甲状腺功能减退症的相关性分析

目的研究分析甘肃地区妊娠早期妇女碘营养的实际情况,探究妊娠早期妇女碘营养的情况与其甲状腺功能减退症之间存在的关系。方法选取2015年2月至2016年5月于甘肃省平凉市庄浪县计划生育服务站进行常规产前检查的早期妊娠妇女200例作为研究对象,采用分光光度法测定其在空腹状态下尿碘水平以及血清中的促甲状腺激素、血清游离甲状腺素水平。结果选取的200例中早期妊娠妇女中尿碘水平的范围为8.2~1 857.8mg/L,中位数为178.3mg/L,碘缺乏总例数为79例,所占比例为39.5%,尿碘异常患者总例数为121例,所占比例为60.5%;早期妊娠妇女不同碘水平状态下血清中的促甲状腺激素有明显差异(P0.05),但血清游离甲状腺素水平无显著差异(P0.05);碘摄入异常患者的甲状腺功能减退症发生率为7.1%(9/126),显著高于碘摄入正常者的1.4%(1/74),具有统计学差异(χ~2=3.661,P0.05)。结论甘肃省平凉市庄浪县地区妊娠早期妇女中碘摄取量普遍不足,存在着碘缺乏的现象,碘摄取量不同会明显影响促甲状腺激素水平,且可能是导致甲状腺功能减退症的重要影响因素。     

Comparison of the dietary cobalt intake in three different Australian diets

Differences in the dietary intake of cobalt were assessed for vegans, lacto-ovo-vegetarian and non-vegetarian Australians using food intake logs, and daily or average trend recall over three months. A significant decrease in cobalt intake was observed for the lacto-ovo-vegetarian population compared with the intake in vegans and omnivores. There is no RDI for cobalt, however, the cobalt intake of Australians was similar to that reported in other countries. Microflora above the terminal ileum have been shown to produce significant amounts of biologically available vitamin B12. This study was unable to demonstrate a correlation between elemental cobalt intake and serum vitamin B12 concentrations in humans, as has been shown in vitro.     

The impact of smoking on thyroid volume and function in relation to a shift towards iodine sufficiency

The aim of the study was to investigate whether the influence of smoking on thyroid volume and function changes in relation to a higher iodine intake in the population. The study comprised a total of 8,219 individuals each examined in one of two separate cross-sectional studies performed before (n = 4,649) and after (n = 3,570) a mandatory iodization of salt in year 2000 in two areas with established mild and moderate iodine deficiency. Participants answered questionnaires regarding life style factors and a thyroid ultrasonography was performed. Blood samples were analysed for serum thyroid stimulating hormone, free thyroxin and free tri-iodothyronine. All procedures used were similar in the two cross-sectional studies. The overall difference in thyroid volume between heavy smokers and non-smokers across the age groups was reduced after iodization of salt from 24% (19-29%) to 12% (6-18%). After the iodization the odds ratio for having thyroid enlargement was still increased for smokers (OR: 1.9 (CI: 1.5-2.6)) compared to non-smokers. The aetiological fraction of thyroid enlargement due to smoking was 39.3% before the iodization and 24.2% after the iodization. Like before iodization smokers had a lower mean thyroid stimulating hormone and a higher free thyroxin in serum than non-smokers. Conclusively, in areas approaching iodine sufficiency a decline in the impact of smoking on thyroid volume was seen. The effect of smoking on hormonal level was unchanged after the iodization. Thus the effect of smoking on thyroid volume seems to be dependent on iodine intake, whereas the effect on function seems mainly to depend on other factors.     

Comparison of Five Oxidative Stress Biomarkers in Vegans and Omnivores from Germany and Finland

When the amount of reactive oxygen species produced by human metabolism cannot be balanced by antioxidants, this phenomenon is commonly referred to as oxidative stress. It is hypothesised that diets with high amounts of plant food products may have a beneficial impact on oxidative stress status. However, few studies have examined whether a vegan diet is associated with lower oxidative stress compared to an omnivorous diet. The present cross-sectional study aimed to compare the levels of five oxidative stress biomarkers in vegans and omnivores. Data of 36 vegans and 36 omnivores from Germany and of 21 vegans and 18 omnivores from Finland were analysed. HPLC coupled with mass spectrometry or fluorescence detection and ELISA methods were used to measure the oxidative stress biomarkers malondialdehyde (MDA), protein carbonyls and 3-nitrotyrosine in plasma and 8-hydroxy-2′-deoxyguanosine (8-OHdG) and 8-iso-prostaglandin F2α (8-iso-PGF2α) in 24 h urine. Analyses of variance and covariance, considering potential confounders, were used. Vegans and omnivores showed no differences in MDA and protein carbonyl concentrations. In Finnish but not in German vegans, the concentrations of 3-nitrotyrosine were lower compared to those in omnivores (p = 0.047). In Germany, vegans showed lower excretion levels of 8-iso-PGF2α than omnivores (p = 0.002) and with a trend also of 8-OHdG (p = 0.05). The sensitivity analysis suggests lower 8-iso-PGF2α excretion levels in women compared to men, independently of the dietary group. The present study contributes to expanding our knowledge of the relationship between diet and oxidative stress and showed that 3-nitrotyrosine, 8-OHdG and 8-iso-PGF2α tended to be lower in vegans. Furthermore, studies are recommended to validate the present findings.     

High Iodine Urinary Concentration Is Associated with High TSH Levels but Not with Nutrition Status in Schoolchildren of Northeastern Mexico

According to the Iodine Global Network, Mexico is considered a country with adequate national iodine intake (297 mg/L), but some regions have not been studied. We aimed to evaluate urinary iodine concentration (UIC) and its association with thyroid stimulating hormone (TSH) levels and the nutritional status in 307 children (aged 5 to 11 years) from three elementary schools of Monterrey, northern Mexico. UIC in spot urine samples and capillary TSH levels were measured to assess thyroid function, in addition to weight, height, body mass index (BMI), and waist circumference (WC). We found a median UIC of 442 mg/L and a significant association between UIC and TSH levels by logistic regression when data were adjusted for (1) age and sex; (2) age, sex, and WC; and (3) age, sex, and weight status. UIC values were higher in 7-year-old children compared to 11-year-old children. High prevalences of overweight/obesity (41%) and WC >90 pctl (22%) were observed. This study identified higher UIC levels in children than those previously reported in the country. The UIC showed a positive and significant correlation between TSH levels in the three models evaluated. More studies are needed to assess the causes and possible outcomes of high UIC levels.