Interplay of the Mediterranean diet and genetic hypertension risk on blood pressure in European adolescents: Findings from the HELENA study.

Early-life onset of high blood pressure is associated with the development of cardiovascular diseases in adulthood. In adolescents, limited evidence exists regarding the association between adherence to the Mediterranean Diet (MedDiet) and normal blood pressure (BP) levels, as well as its potential to modulate genetic predisposition to HTN. This study investigated the interaction between a MedDiet score and a recently developed HTN-genetic risk score (HTN-GRS) on blood pressure levels in a European adolescent cohort. The MedDiet score was derived from two non-consecutive 24-h dietary recalls and ranged from 0 (indicating low adherence) to 9 (indicating high adherence). Multiple linear regression models, adjusted for covariates, were employed to examine the relationship between the MedDiet score and BP z-scores and to assess the interaction effects between the MedDiet score and HTN-GRS on BP z-scores. MedDiet score showed a negative association with z-systolic BP (SBP) (ß = -0.40, p < 0.001) and z-diastolic BP (DBP) (ß = -0.29, p = 0.001). Additionally, a significant interaction effect was identified between the MedDiet score and HTN-GRS on z-SBP (ß = 0.02, p < 0.001) and z-DBP (ß = 0.02, p < 0.001). The modulatory effect of the MedDiet was more pronounced in females than in males, and HTN-GRS exhibited a stronger influence on DBP than on SBP.   Conclusion: The study suggests that higher adherence to the MedDiet is associated with reduced BP levels in adolescents and provides evidence of a genetic-diet interaction influencing BP in adolescents. What is Known: • Adherence to the Mediterranean diet may reduce BP levels. What is New: • It is the first study to assess the connection between adherence to a Mediterranean diet, a hypertension genetic risk score, and how they interact in influencing blood pressure. • It is conducted within a multicenter cohort of European adolescents.

The body mass index increases the genetic risk scores' ability to predict risk of hepatic damage in European adolescents: The HELENA study.

BACKGROUND: Hepatic disorders are often complex and multifactorial, modulated by genetic and environmental determinants. During the last years, the hepatic disease has been progressively established from early stages in life. The use of genetic risk scores (GRS) to predict the genetic susceptibility to a particular phenotype among youth has gained interest in recent years. Moreover, the alanine aminotransferase (ALT) blood biomarker is often considered as hepatic screening tool, in combination with imaging techniques. The aim of the present study was to develop an ALT-specific GRS to help in the evaluation of hepatic damage risk in European adolescents. METHODS: A total of 972 adolescents (51.3% females), aged 12.5-17.5 years, from the Healthy Lifestyle in Europe by Nutrition in Adolescence study were included in the analyses. The sample incorporated adolescents in all body mass index (BMI) categories and was divided considering healthy/unhealthy ALT levels, using sex-specific cut-off points. From 1212 a priori ALT-related single nucleotide polymorphisms (SNPs) extracted from candidate gene selection, a first screening of 234 SNPs univariately associated was established, selecting seven significant SNPs (p < .05) in the multivariate model. An unweighted GRS (uGRS) was developed by summing the number of reference alleles, and a weighted GRS (wGRS), by multiplying each allele to its estimated coefficient. RESULTS: The uGRS and wGRS were significantly associated with ALT (p < .001). The area under curve was obtained integrating BMI as clinical factor, improving the predictive ability for uGRS (.7039) and wGRS (.7035), using 10-fold internal cross-validation. CONCLUSIONS: Considering BMI status, both GRSs could contribute as complementary tools to help in the early diagnosis of hepatic damage risk in European adolescents.

Association between PTPN1 polymorphisms and obesity-related phenotypes in European adolescents: influence of physical activity.

BACKGROUND: To study the associations of Protein Tyrosine Phosphatase-N1 (PTPN1) polymorphisms with obesity-related phenotypes in European adolescents, and the influence of physical activity on these relationships. METHODS: Five polymorphisms of PTPN1 were genotyped in 1057 European adolescents (12-18 years old). We measured several phenotypes related to obesity, such as adiposity markers, and biochemical and clinical parameters. Physical activity was objectively measured by accelerometry. RESULTS: The T, A, T, T and G alleles of the rs6067472, rs10485614, rs2143511, rs6020608 and rs968701 polymorphisms, respectively, were associated with lower levels of obesity-related phenotypes (i.e., body mass index, body fat percentage, hip circumference, fat mass index, systolic blood pressure and leptin) in European adolescents. In addition, the TATTG haplotype was associated with lower body fat percentage and fat mass index compared to the AACCA haplotype. Finally, when physical activity levels were considered, alleles of the rs6067472, rs2143511, rs6020608 and rs968701 polymorphisms were only associated with lower adiposity in active adolescents. CONCLUSIONS: PTPN1 polymorphisms were associated with adiposity in European adolescents. Specifically, alleles of these polymorphisms were associated with lower adiposity only in physically active adolescents. Therefore, meeting the recommendations of daily physical activity may reduce obesity risk by modulating the genetic predisposition to obesity. IMPACT: Using gene-phenotype and gene*environment analyses, we detected associations between polymorphisms of the Protein Tyrosine Phosphatase-N1 (PTPN1) gene and obesity-related phenotypes, suggesting a mechanism that can be modulated by physical activity. This study shows that genetic variability of PTPN1 is associated with adiposity, while physical activity seems to modulate the genetic predisposition. This brings insights about the mechanisms by which physical activity positively influences obesity.

Relative validity of the Planetary Health Diet Index by comparison with usual nutrient intakes, plasma food consumption biomarkers, and adherence to the Mediterranean diet among European adolescents: the HELENA study.

PURPOSE: The EAT-Lancet Commission proposed an evidence-based global reference diet to improve human health within planetary boundaries. Recently, the Planetary Health Diet Index (PHDI) was developed based on the EAT-Lancet recommendations and validated among Brazilian adults. However, the relative validity of the PHDI in adolescents has yet to be assessed. Thus, we aimed to evaluate the relative validity of the PHDI in European adolescents. METHODS: We used cross-sectional data from 1804 adolescents (12.5-17.5 years) enrolled in the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study. The PHDI (0-150 points) was calculated based on dietary intake data from two non-consecutive 24-h dietary recalls. Associations between the PHDI and usual nutrient intakes, plasma food consumption biomarkers, and adherence to the Mediterranean diet were evaluated using multivariable-adjusted mixed-effects linear regression models. RESULTS: Higher PHDI score was associated with greater intakes of nutrients predominantly from plant-source foods, such as vegetable protein, vitamin E, and folate and with lower intake of nutrients predominately from animal-source foods, such as total and saturated fat, cholesterol, and animal protein. Furthermore, a higher PHDI score was also positively associated with plasma ß-carotene, vitamin C, vitamin D, folate, and ferritin concentrations, while negatively associated with trans-fatty acids concentration. Moreover, higher PHDI was related to a greater adherence to the Mediterranean dietary pattern. CONCLUSIONS: The PHDI showed good relative validity among adolescents in the HELENA study. Hence, future research should assess adherence to the PHDI and long-term health outcomes.

New indices in predicting cardiometabolic risk and its relation to endothelial dysfunction in adolescents: The HELENA study.

BACKGROUND AND AIMS: Blood pressure (BP) changes and insulin resistance (IR) are important cardiometabolic risk (CMR) factors; their early identification can contribute to the reduction of cardiovascular events in adulthood. This necessitates the search for more accessible and easily applied indicators for their prediction. Therefore, this study aimed to evaluate the predictive power of the indices, TyG, TG/HDL-c, height-corrected lipid accumulation product (HLAP), and visceral adiposity index (VAI), in identifying the CMR obtained by high BP and IR and to verify their relationship with biomarkers of endothelial dysfunction (ED) in European adolescents. METHODS AND RESULTS: The anthropometric data and blood biomarkers of 744 adolescents (343 boys and 401 girls) from the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS), with a mean age of 14.67 (SD 1.15) years, were assessed. The adolescents were then classified according to the presence or absence of high BP and IR. The cut-off points of the indices evaluated for the identification of CMR were determined. The relationship between CMR diagnosed using these indices and ED biomarkers was tested. The HLAP and TG/HDL-c were fair predictors of CMR obtained by IR in male adolescents. These indices showed association with hsCRP in sVCAM-1 in boys, but it lost significance after adjusting for age and body mass index. CONCLUSION: TG/HDL-c and HLAP indices showed a fair performance in predicting CMR, obtained by IR, in male adolescents. ED showed no association with the CMR identified by the indices.

Adolescents' dietary polyphenol intake in relation to serum total antioxidant capacity: the HELENA study.

We evaluated the association between intake of total polyphenols, polyphenol classes and the 10 most consumed individual polyphenols with serum total antioxidant capacity (TAC) in 749 European adolescents (53% girls; 15% overweight; 12.5-17.5 years-old) from the cross-sectional HELENA study of 2006-2007. Dietary polyphenol intake was calculated from two non-consecutive 24-h recalls matched with the Phenol-Explorer database. Multilevel linear models examined the associations between dietary polyphenols and TAC. Polyphenol intake was rather low (median = 321mg/day; p25 = 158; p75 = 536) and TAC was comparable to other literature findings (median = 1.57 mmol/L; p25 = 1.45; p75 = 1.74). Total polyphenol intake, polyphenol classes and the top 10 compounds were not associated with TAC in a linear, quadratic or cubic way in partially or fully confounder-adjusted models. A direct anti-oxidative effect of dietary polyphenol intake was not observed in European adolescents. Polyphenol biomarkers and additional antioxidant measures are needed in future prospective studies to confirm these results.

Cardiometabolic Risk is Positively Associated with Underreporting and Inversely Associated with Overreporting of Energy Intake Among European Adolescents: The Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) Study.

BACKGROUND: Dietary misreporting is the main limitation of dietary assessments and has been associated with BMI during youth. However there are no prior studies assessing misreporting and cardiometabolic risks (CMRs) in adolescence. OBJECTIVES: To examine the associations between dietary misreporting and CMR factors in adolescents and to assess the potential bias in the association between CMR and energy intake (EI) driven by dietary misreporting. METHODS: Two 24-hour dietary recalls were obtained from 1512 European adolescents (54.8% girls) aged 12.5-17.5 years. Physical activity was measured by accelerometry. Cut-offs suggested by Huang were applied to identify misreporters. Height, waist circumference (WC), the sum of 4 skinfold thicknesses, diastolic blood pressure (DBP), systolic blood pressure (SBP), and cardiorespiratory fitness (CRF) measurements were taken and serum triglycerides and total-/high-density lipoprotein cholesterol ratio were analyzed. A sex- and age-specific clustered CMR score (n = 364) was computed. Associations were investigated by multilevel regression analyses adjusting for age, sex, center, socioeconomic status, and physical activity. RESULTS: Underreporting (24.8% adolescents) was significantly (P < 0.05) associated with a higher WC, waist-to-height ratio (WHeR), and sum of skinfold thickness, whereas overreporting (23.4% adolescents) was significantly associated with a lower WC, WHeR, sum of skinfold thickness, and SBP. Associations between CMR factors and EI were significantly affected by misreporting, considering various approaches. Significant, positive associations became inverse after adjusting for misreporting for WC and WHeR. The opposite was true for the sum of skinfold thickness, SBP, and CMR score. The associations between EI and DBP and CRF did not remain significant after adjusting for misreporting. CONCLUSIONS: CMR factors differed among misreporting groups, and both abdominal and total fat mass indicators were more strongly associated with all forms of misreporting than was BMI. Moreover, misreporting seems to bias EI and CMR associations in adolescents. Therefore, energy misreporting should be taken into account when examining diet-CMR associations.

School time is associated with cardiorespiratory fitness in adolescents: The HELENA study.

We assessed the association between school time and physical fitness in adolescents. The study included 2,024 adolescents, aged 12.5-17.5 years, who participated in the Healthy Lifestyle in Europe by Nutrition in Adolescence study. Health-related physical fitness components were assessed using the physical fitness tests battery. Cardiovascular risk was categorized using the sex-specific cut-offs for a healthy cardiorespiratory fitness level in adolescents proposed by FitnessGram®. School time was classified as short or long. Multivariate analysis accounted for confounding factors such age, sex, body mass index, time spent in moderate to vigorous physical activity, pubertal status, and parents' educational level. Cardiorespiratory fitness was higher in adolescents with a long school time than in those with a short school time (42.0 ± 7.6 vs 40.7 ± 7.2 mL.kg-1.min-1, respectively; p < 0.05). The percentage of adolescents at cardiovascular risk in adulthood was higher in the short than in the long time group (45.2% vs 31.7%, respectively) (p < 0.05). These findings suggest that a long school day is associated with higher cardiorespiratory fitness in adolescents and that school time should be considered in interventions and health promotion strategies.

Total Polyphenol Intake Is Inversely Associated with a Pro/Anti-Inflammatory Biomarker Ratio in European Adolescents of the HELENA Study.

BACKGROUND: Although high dietary polyphenol intake is negatively associated with risk of certain inflammation-associated chronic diseases, the underlying mechanisms are not fully understood and few studies have explored this in adolescents. OBJECTIVE: This study aimed to evaluate the association between intakes of total polyphenols, polyphenol classes, and the 10 most commonly consumed individual polyphenols with inflammatory biomarkers in the blood of European adolescents. METHODS: In the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) Study, 526 adolescents (54% girls; 12.5-17.5 y) had data on inflammatory biomarkers and polyphenol intake from 2 nonconsecutive 24-h recalls via matching with the Phenol-Explorer database. Inflammatory biomarkers in serum were IL-1, IL-2, IL-4, IL-5, IL-6, IL-10, transforming growth factor ß1 (TGF-ß1), TNF-α, IFN-γ, soluble vascular adhesion molecule 1 (sVCAM-1), soluble intercellular adhesion molecule 1 (sICAM-1), soluble E-selectin (sE-selectin), white blood cells, lymphocytes, T cells, and C-reactive protein. Multilevel linear models were used to test associations of polyphenol intake with a pro/anti-inflammatory biomarker ratio [(zTNF-α + zIL-6 + zIL-1)/3/zIL-10] as well as with separate inflammatory biomarkers, adjusted for sociodemographic variables, diet inflammation index, BMI z score, and serum triglycerides. RESULTS: The pro/anti-inflammatory biomarker ratio was linearly inversely associated with the intake of total polyphenols (ß = -0.11, P = 0.040). When other inflammation biomarkers were considered, the serum IL-10 concentration was inversely associated with total polyphenol (ß = -0.12, P = 0.017) and flavonoid (ß = -0.12, P = 0.013) intakes, findings that were inconsistent with the biomarker ratio results. However, the anti-inflammatory capacity of polyphenols was confirmed by positive associations of IL-4 with phenolic acid (ß = 0.09 P = 0.049) and stilbene (ß = 0.13, P = 0.019) intakes and the negative association of IL-1, IL-2, and IFN-γ with lignan intake (ß = -0.10, P = 0.034; ß = -0.09, P = 0.049; ß = -0.11, P = 0.023). CONCLUSIONS: The negative relation with the overall pro/anti-inflammatory biomarker ratio suggests a potential anti-inflammatory role of high polyphenol intakes among European adolescents. Nevertheless, associations are dependent on polyphenol type and the inflammatory biomarker measured.

Polyphenol intake and metabolic syndrome risk in European adolescents: the HELENA study.

PURPOSE: The role of polyphenol intake during adolescence to prevent metabolic syndrome (MetS) is little explored. This study aimed to evaluate the association between intake of total polyphenols, polyphenol classes and the 10 most consumed individual polyphenols with MetS risk in European adolescents. METHODS: Of the cross-sectional HELENA study, 657 adolescents (54% girls; 14.8% overweight; 12.5-17.5 year) had a fasting blood sample and polyphenol intake data from two non-consecutive 24-h recalls matched with the Phenol-Explorer database. MetS was defined via the pediatric American Heart Association definition. Multilevel linear regressions examined the associations of polyphenol quartiles with MetS components, while logistic regression examined the associations with MetS risk. RESULTS: After adjusting for all potential confounders (socio-demographics and nine nutrients), total polyphenol intake, polyphenol classes and individual polyphenols were not associated with MetS risk. From all MetS components, only BMI z-score was modestly inversely associated with total polyphenol intake. Further sub analyses on polyphenol classes revealed that flavonoid intake was significantly associated with higher diastolic blood pressure and lower BMI, and phenolic acid intake was associated with higher low-density cholesterol. For individual polyphenols, the above BMI findings were often confirmed (not independent from dietary intake) and a few associations were found with insulin resistance. CONCLUSION: Higher intakes of total polyphenols and flavonoids were inversely associated with BMI. No consistent associations were found for other MetS components.

Canned tuna tolerance in children with IgE-mediated fish allergy: an allergological and nutritional view.

Scientific research, diagnostic tools and clinical experience have shown that children suffering from IgE-mediated fish allergy do not need to follow a strict exclusion diet. In fact, they could tolerate some species of fish, which could be reintroduced in the diet by verifying their tolerance with an oral food challenge in a clinical setting. Consequently, it is possible to look a new insight on diagnosis and management of IgE-mediated fish allergy in children, considering the use of canned tuna in clinical settings. Authors performed a literature search through the Cochrane Library and Medline/PubMed databases. All quantitative and qualitative pediatric studies involving diagnosis and management of IgE-mediated fish allergy and the use of canned tuna in clinical settings were considered. Articles related to allergological and nutritional features of fish, and especially canned tuna, were selected. This research was conducted on May 2020. Canned tuna shows peculiar allergological and nutritional characteristics. Relating to allergy, canning process, characterized by cooking the fish under pressure for a time equal to about 7 hours, can lead a conformational change in parvalbumin, making it less allergenic. In terms of nutrition, canned tuna contains B, D and A vitamins and, above all, omega-3 fatty acids and shows a favourable and significantly sustainable nutritional profile. Lower allergenicity, adequate nutritional value and its rich availability in markets at reasonable costs, could make the use of canned tuna as a solution with an excellent risk/benefit ratio in the field of IgE-mediated fish allergy.

Dietary Patterns and Their Relationship With the Perceptions of Healthy Eating in European Adolescents: The HELENA Study.

Objective: The aim of this study was to identify dietary patterns (DPs) in European adolescents and to examine the association between perceptions of healthy eating and the obtained DPs.Method: A multinational cross-sectional study was carried out in adolescents aged 12.5 to 17.5 years and 2,027 (44.9% males) were considered for analysis. A self-reported questionnaire with information on food choices and preferences, including perceptions of healthy eating, and two 24-hour dietary recalls were used. Principal component analysis was used to obtain sex-specific DPs, and linear analyses of covariance were used to compare DPs according to perceptions of healthy eating.Results: Three and four DPs for boys and girls were obtained. In boys and girls, there were significant associations between some perceptions about healthy food and the Breakfast-DP (p < 0.05). In boys, Breakfast-DP and Healthy Beverage-DP were associated with the perception of the own diet as healthy (p < 0.05). Healthy Beverage-DP was associated with those disliking fruits and vegetables (p < 0.05). Girls considering the own diet as healthy were associated with Mediterranean-DP, Breakfast-DP, and Unhealthy Beverage and Meat-DP (p < 0.05). The perception of snacking as a necessary part of a healthy diet was associated with Breakfast-DP in both genders (p < 0.05).Conclusions: In European adolescents, perceptions of healthy eating were mainly associated with a DP characterized by foods consumed at breakfast. Future studies should further explore these findings in order to implement health promotion programs to improve healthy eating habits in adolescents.

Adherence to the Mediterranean diet in metabolically healthy and unhealthy overweight and obese European adolescents: the HELENA study.

PURPOSE: To examine the adherence to the Mediterranean dietary pattern (MDP) in metabolically healthy overweight or obese (MHO) and metabolically unhealthy obese (MUO) European adolescents. METHODS: In this cross-sectional study, 137 overweight/obese adolescents aged 12-17 years old from the HELENA study were included. Height, weight, waist circumference and skinfold thickness were measured and body mass index and body fat percent were calculated. Systolic and diastolic blood pressure, glucose, HDL cholesterol, triglycerides and cardiorespiratory fitness (20 m shuttle run test) were measured. MHO and MUO phenotypes were categorized following the Jolliffe and Janssen criteria. Two non-consecutive 24 h recalls were used for dietary intake assessment and the adherence to the MDP was calculated using the Mediterranean dietary pattern score (MDP score) (range 0-9). RESULTS: A total of 45 (22 girls) adolescents (32.8%) were categorized as MHO. The adherence to the MDP was significantly higher in MHO than in MUO adolescents regardless of age, sex, body fat percentage, energy intake and center (MDP score: 4.6 ± 1.6 vs. 3.9 ± 1.5, p = 0.036), but this difference became non-significant after further adjustment for cardiorespiratory fitness. Participants who had a low adherence to the MDP (MDP score ≤ 4) had a higher likelihood of having MUO phenotype regardless of sex, age, energy intake, center and body fat percentage (OR 2.2; 95% CI 1.01-4.81, p = 0.048). CONCLUSIONS: Adherence to the MDP might be beneficial to maintain metabolic health in overweight/obese adolescents, yet cardiorespiratory fitness seems to play a key role on the metabolic phenotype.

Diet as moderator in the association of adiposity with inflammatory biomarkers among adolescents in the HELENA study.

AIM: Our aim is to demonstrate that a healthy diet might reduce the relation between adiposity and inflammation, whereas an unhealthy diet may increase the effect of adiposity on inflammatory biomarkers. METHODS: In 618 adolescents (13-17 years) of the European HELENA study, data were available on body composition, a set of inflammation markers, and food intake determined by a self-administered computerized 24-h recall. A 9-point Mediterranean diet score and an antioxidant-rich diet score were used as dietary parameters and tested as moderator. Total body fat was represented by the sum of six skinfold thicknesses and central adiposity by waist circumference. A set of inflammation-related biomarkers was used as outcome: a pro/anti-inflammatory interleukins ratio, TGFß-1, C-reactive protein, TNF-α, 3 cell adhesion molecules, and 3 types of immune cells; gamma-glutamyltransferase (GGT) and homocysteine were used as cardiovascular disease risk biomarkers, and alanine transaminase (ALT) as liver dysfunction biomarker. Multiple linear regression analyses tested moderation by diet in the adiposity-inflammation association and were adjusted for age, sex, country, puberty, socioeconomic status. RESULTS: Both the Mediterranean and antioxidant-rich diet, and overall and central adiposity, were important in the moderation. Diet was a significant protective moderator in the effect of adiposity on the pro/anti-inflammatory interleukins ratio, TGFß-1, GGT, and ALT. CONCLUSION: In conclusion, in some cases, a diet rich in antioxidants and essential nutrients may attenuate the concentration of inflammatory biomarkers caused by adiposity, whereas a poor diet appears to contribute to the onset of early oxidative stress signs.

Diet as a moderator in the association of sedentary behaviors with inflammatory biomarkers among adolescents in the HELENA study.

AIM: To assess if a healthy diet might attenuate the positive sedentary-inflammation relation, whereas an unhealthy diet may increase the effect of sedentary behaviors on inflammatory biomarkers. METHODS: In 618 adolescents (13-17 years) of the European HELENA study, data were available on body composition, a set of inflammation markers, and food intake assessed by a self-administered computerized 24 h dietary recall for 2 days. A 9-point Mediterranean diet score and an antioxidant-rich diet z-score were used as dietary indices and tested as moderators. A set of low-grade inflammatory characteristics was used as outcome: several cytokines in an inflammatory ratio (IL-6, IL-10, TNF-α, TGFß-1), C-reactive protein, three cell-adhesion molecules (sVCAM-1, sICAM-1, sE-selectin), three cardiovascular risk markers (GGT, ALT, homocysteine) and three immune cell types (white blood cells, lymphocytes, CD3). Sedentary behaviors were self-reported and analyzed as total screen time. Multiple linear regression analyses tested moderation by diet in the sedentary behaviors-inflammation association adjusted for age, sex, country, adiposity (sum of six skinfolds), parental education, and socio-economic status. RESULTS: Both diet scores, Mediterranean and antioxidant-rich diet, were significant protective moderators in the effect of sedentary behaviors on alanine-transaminase enzyme (P = 0.014; P = 0.027), and on the pro/anti-inflammatory cytokine ratio (P = 0.001; P = 0.004), but not on other inflammatory parameters. CONCLUSION: A higher adherence to the Mediterranean diet or an antioxidant-rich diet may attenuate the onset of oxidative stress signs associated by sedentary behaviors, whereas a poor diet seems to increase inflammation.

Estimated dietary intake of polyphenols in European adolescents: the HELENA study.

PURPOSE: Knowledge about polyphenols intakes and their determinants among adolescents might be helpful for planning targeted prevention strategies at an early age. METHODS: In the European multicenter cross-sectional HELENA study of 2006-2007, 2428 subjects (47% boys) had data on dietary intake of polyphenols from 2 non-consecutive 24 h recalls via linking with the Phenol-Explorer database. Differences by sex, age, country, BMI, maternal education, paternal education, family affluence, smoking status, alcohol use, and physical activity were explored by linear regression. RESULTS: Median, lower and upper quartiles of polyphenol intakes were 326, 167 and 564 mg/day, respectively. Polyphenol intake was significantly higher in the oldest (16-17.49 years), girls, non-Mediterranean countries, lowest BMI, highest paternal education, and alcohol consumers. Main food contributors were fruit (23%, mainly apple and pear, i.e., 16.3%); chocolate products (19.2%); and fruit and vegetable juices (15.6%). Main polyphenol classes were flavonoids (75-76% of total) and phenolic acids (17-19% of total). The three most consumed polyphenols were proanthocyanidin polymers (> 10 mers), hesperidin, and proanthocyanidin 4-6 oligomers. CONCLUSION: The current study provided for the first time numbers on the total polyphenol intake and their main food sources in a heterogeneous group of European adolescents. Major differences with adult populations are the lower polyphenol consumption and the major food sources, such as chocolate and biscuits. The discussed determinants and polyphenol types already point to some important population groups that need to be targeted in future public health initiatives.

Measuring nutritional knowledge using Item Response Theory and its validity in European adolescents.

OBJECTIVE: To analyse the Nutritional Knowledge Test (NKT) using Item Response Theory (ITR) analysis and to assess the construct validity of the Nutritional Knowledge Scale (NKTS) and its associations with adolescent food group consumption and nutritional biomarkers. DESIGN: Cross-sectional study. SETTING: Multicentre investigation conducted in ten European cities.ParticipantsAdolescents aged 12·5-17·5 years (n 3215) who completed over 75 % of the NKT. RESULTS: Factor analysis indicated that the NKT can be analysed with a one-dimensional model. Eleven out of twenty-three items from the NKT presented adequate parameters and were selected to be included in the NKTS. Nutrition knowledge was positively associated with consumption of fruits, cereals, dairy products, pulses, meat and eggs, and fish, as well as with blood concentrations of vitamin C, ß-carotene, n-3 fatty acids, holo-transcobalamin, cobalamin and folate; nutrition knowledge was negatively associated with intake of olives and avocado, alcohol and savoury snacks. CONCLUSIONS: The NKTS assessed nutritional knowledge adequately and it is proposed as a new tool to investigate this subject in future studies.

Relative validation of the adapted Mediterranean Diet Score for Adolescents by comparison with nutritional biomarkers and nutrient and food intakes: the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study.

OBJECTIVE: To investigate whether adherence to the adapted Mediterranean Diet Score for Adolescents (MDS_A) and the adapted Mediterranean Diet Quality Index for Adolescents (KIDMED_A) is associated with better food/nutrient intakes and nutritional biomarkers. DESIGN: The Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study is a cross-sectional study aiming to obtain comparable data on a variety of nutritional and health-related parameters in European adolescents aged 12·5-17·5 years. SETTING: Nine European countries. PARTICIPANTS: European adolescents (n 2330) recruited to the HELENA study. Dietary intake was obtained with 24 h dietary recalls, an FFQ and a Food Choices and Preferences questionnaire. MDS_A was calculated as a categorical variable using cut-offs (MDS_A), as a continuous variable (zMDS_A) and with energy adjustments (zEnMDS_A). The KIDMED_A score was also calculated. RESULTS: Multilevel linear regression analysis showed positive associations for zMDS_A and KIDMED_A with serum levels of vitamin D, vitamin C, plasma folate, holo-transcobalamin, ß-carotene and n-3 fatty acids, while negative associations were observed with trans-fatty acid serum levels. For categorical indices, blood biomarkers showed few significant results. zMDS_A and KIDMED_A showed positive associations with vegetables and fruits intake, and negative associations with energy-dense and low-nutritious foods. zMDS_A and KIDMED_A were positively associated with all macronutrients, vitamins and minerals (all P < 0·0001), except with monosaccharides and PUFA for KIDMED_A and cholesterol for both indices (P < 0·05). CONCLUSIONS: zMDS_A and KIDMED_A have shown the strongest associations with the dietary indicators and biomarkers that have been associated with the Mediterranean diet before, and are therefore considered the most appropriate and valid Mediterranean diet scores for European adolescents.

Mediation of psychosocial determinants in the relation between socio-economic status and adolescents' diet quality.

PURPOSE: To examine the underlying reasons for the positive relation between socio-economic status (SES) and the diet quality of adolescents. METHODS: In 2081 adolescents (12.5-17.5 years) of the European HELENA study, a continuous variable on diet quality via 2-day 24-h recalls was available. SES was reflected by parental education, parental occupation and family affluence. Mediation by several psychosocial determinants was tested: self-efficacy, availability at school and home, social support, barriers, benefits, awareness and some self-reported influencers (parents, school, taste, health, friends, food readily available, easy preparation, hunger, price and habits). Multiple mediation analyses were adjusted for age, sex and country. RESULTS: The availability of soft drinks and fruit at home, social support, parental influence, barriers, price influence, taste influence, health influence and food being readily available were significant mediators. The multiple mediation indirect effect accounted for 23-64% of the total effect. Both occupation and education and both maternal and paternal factors could be explained by the mediation. The unavailability of soft drinks was the strongest mediator (17-44% of the total effect). CONCLUSION: Up to 64% of the positive relation between SES and the diet quality in adolescence could be explained by several healthy eating determinants. Focusing on these factors in low-SES populations can minimize social inequalities in diet and health by improving the diet of these specific adolescents.

Associations between a Mediterranean diet pattern and inflammatory biomarkers in European adolescents.

AIM: To test whether the Mediterranean diet score and each food-subgroup is associated with inflammatory biomarkers in European adolescents. METHODS: In 464 adolescents (13-17 years) of the European HELENA study, data were available on body composition, inflammation markers, and food intake determined by two computerized 24-h recalls. The Mediterranean diet score and its food-subgroups (Vegetables, Fruits and Nuts, Pulses, Cereal and Roots, Monounsaturated/Saturated fat ratio, Dairy, Fish, Meat and Alcohol) were evaluated. A set of inflammation-related biomarkers was measured: IL-1, IL-2, IL-4, IL-5, IL-6, IL-10, TGFß-1, TNF-α, sVCAM-1, sICAM1, sE-selectin, white blood cells, lymphocytes, CD3, CRP, GGT, ALT, and homocysteine. Multivariate and multiple linear regression analyses were adjusted for age, sex, country, socioeconomic status, paternal and maternal education, adiposity, and smoking habits. RESULTS: The Mediterranean diet score was positively associated with CRP, and negatively with sVCAM-1. The subgroups showed the following positive/negative associations: Vegetables with IL-10(+), CRP(+), CD3(+), ALT(+), lymphocytes(+), sE-selectin(-); Fruits and Nuts with IL-4(-), TNF-alpha; Pulses with IL-5(+), IL-6(+), IL-2(-); Cereals and Roots with IL-6(-), IL-10(-); Monounsaturated/Saturated-fat ratio with IL-6(+), TGFß-1(+), sVCAM-1(+boys, -girls), homocysteine(-); Dairy with IL-1(+), IL-5(+), IL-6(+), IL-10(+), TGFß-1(+), homocysteine(-); Fish with homocysteine(-); Meat with IL-2(+), IL-10(+); Alcohol with CRP(+), lymphocytes(-). Sex differences were found. CONCLUSION: Some specific food-inflammation associations were found, suggesting that diet is to a certain extent already related to inflammation in adolescents and can be used in disease prevention. Also some counterintuitive results were found, which might be due to grouping very different foods into a single group, besides considering that the human body may respond differently depending on the interaction between diet, lifestyle, genetics, biochemical individuality, age and sex.