Concordance for bulimia nervosa in twins

27 pairs of twins with bulimia nervosa according to DSM-III-R were assessed concerning concordance for bulimia nervosa and other eating disorders. There were 6 monozygotic females, 1 monozygotic male, 15 dizygotic females and 5 dizygotic twins of opposite sex. The concordance rates for bulimia nervosa (83.3 versus 26.7%) and for any eating disorder according to DSM-III-R (83.3 versus 33.3%) were significantly higher for monozygotic, as compared to dizygotic females. 27 (54%) of 50 twins had a diagnosis of depression according to ICD-9 criteria, with a small difference between monozygotic (60%) and dizygotic (53%) twins of the same sex. According to our data, monozygotic bulimic twins appear to have an increased genetic-biological vulnerability for a mental or eating disorder. Possible effects of disturbances in the process of individuation and in the development of an autonomous self due to social consequences of their physical identity with the cotwin are discussed.     

Intrapair comparisons of diet and food preference in adult twins

OBJECTIVES: An investigation was conducted on the influence of genetic and lifestyle factors related to the determination of eating behavior of human beings. The objective was to obtain information about lifestyle factors that may help health professionals intervene in terms of the prevention of diet-related diseases. METHODS: The subjects were 180 pairs of adult twins aged over thirty, comprising of 134 monozygotic (MZ) and 46 dizygotic (DZ) pairs. Every subject was given an interview concerning dietary habits, food preference, food intake, as a part of medical examination. The intake of food containing salt and fat, the intake of food meals, the frequency of daily meals, and the frequency of eating 18 sorts of food were assessed on an individual basis, with a questionnaire on nutrition. The expected and observed values of intrapair concordance rates were calculated, and compared within each zygosity, using the chi-square test. RESULTS: Significant differences between the expected and observed for intrapair concordance rates were shown with monozygotic twins, regarding every category of question. Comparing MZ pairs who had lived apart before their twenties with the other MZ pairs, the latter had a tendency to show significant differences between the expected and observed values of intrapair concordance rate, regarding every category of question. In each case, the observed values were higher than the expected values. CONCLUSIONS: The study implied that both genetic and lifestyle factors influence the determinants of eating behavior of human beings. This finding shows the importance of understanding individual characteristics of food preference and eating behavior for intervention regarding lifestyle factors for prevention of diet-related diseases.     

Genetic effects on weight change and food intake in Swedish adult twins

BACKGROUND: Obesity is influenced by genetic and environmental factors. Additionally, synergistic effects of genes and environments may be important in the development of obesity. OBJECTIVE: The aim of this study was to test for genetic effects on food consumption frequency, food preferences, and their interaction with subsequent weight gain. DESIGN: Complete data on the frequencies of consumption of 11 foods typical of the Swedish diet were available for 98 monozygotic and 176 dizygotic twin pairs aged 25-59 y who are part of the Swedish Twin Registry. The data were collected in 1973 as part of a questionnaire study. Body mass index was measured in 1973 and again in 1984. RESULTS: There was some evidence that genetic effects influenced the frequency of intake of some foods. Similarity among monozygotic twins exceeded that among dizygotic twins for intake of flour and grain products and fruit in men and women, intake of milk in men, and intake of vegetables and rice in women, suggesting that genes influence preferences for these foods. Analyses conducted for twins reared together and apart also suggested greater monozygotic than dizygotic correlations, but cross-twin, cross-trait correlations were all insignificant, suggesting that the genes that affect consumption frequencies are not responsible for mediating the relation between the frequency of intake and weight change. CONCLUSIONS: Genetic effects and the frequency of intake are independently related to change in body mass index. However, there was no suggestion of differential genetic effects on weight gain that were dependent on the consumption frequency of the foods studied.     

Family environment, not heredity, accounts for family resemblances in food preferences and attitudes: a twin study

Monozygotic and same-sex dizygotic twin pairs reported on their food preferences, the variety of foods of the same general category (e.g. types of soup) in their diet, and their concern about contact of their food with disgusting or other unacceptable substances (contamination sensitivity). Although there was substantial resemblance between siblings for many of these items, there was no clear evidence for a heritable component on any item. The only case for which there was an interpretable and significantly greater resemblance among monozygotic than among dizygotic twins (out of 23 questions) was preferred degree of hotness resulting from chili pepper in foods. These results confirm the prediction that in omnivorous animals, such as humans, genetic predispositions will be minimal with respect to food. The modest sibling resemblances on a number of measures are primarily attributable to a shared environment.     

Genetic and environmental influences on eating patterns of twins aged >/=50 y.

BACKGROUND: Clinicians and researchers could benefit from a greater understanding of the role of genetic and environmental factors in human eating behavior. OBJECTIVE: Our aim was to estimate the relative influence of genetic and environmental factors on habitual eating patterns in middle-aged and elderly men and women. DESIGN: Male and female twins (n = 4640) aged >/=50 y completed a mailed version of the National Cancer Institute food-frequency questionnaire. Factor analysis was performed to identify eating patterns among respondents. Estimates of genetic, common environmental (shared by family members), and specific environmental (unique to an individual) influences were obtained for food use, serving size, and consumption frequency by comparing monozygotic and dizygotic twin-pair groups with structural equation analysis. RESULTS: Two independent eating patterns were identified: the first consisted of items high in fat, salt, and sugar, and the second reflected healthful eating habits. Although the influence of environmental factors was larger, between 15% and 38% of the total variation in pattern 1 and between 33% and 40% in pattern 2 were explained by genetic influences. Models accounting for sex differences in genetic and environmental estimates fit the data significantly better for food use and serving size of foods in eating pattern 1 and for food use in eating pattern 2. CONCLUSION: Although 60-85% of the variability in eating patterns was associated with environmental factors, genetic influences were also apparent and there was some evidence of sex specificity. These findings may be important in crafting dietary interventions and predicting adherence to these interventions.     

Genetic and shared environmental influences on children's 24-h food and beverage intake: sex differences at age 7 y

BACKGROUND: The genetics of habitual food and beverage intake in early childhood is poorly understood. OBJECTIVE: The objective was to test the magnitude of genetic and environmental influences on 24-h food and beverage intake in 7-y-old children. The association between intake of specific food-beverage categories and child body mass index (BMI; in kg/m(2)) was also tested. DESIGN: A classic twin design was conducted, using the MacArthur Longitudinal Study of Twins. There were 792 children, including 396 boys from 102 monozygotic and 96 dizygotic twin pairs and 396 girls from 112 monozygotic and 86 dizygotic twin pairs; Children's 24-h dietary intake was estimated by parental recall, from which 9 composite food-beverage categories were derived. Height and weight were converted to BMI. Biometrical analyses of children's daily intake of food-beverage categories and BMI were conducted. RESULTS: There was consistent evidence of genetic influences on children's 24-h intake of food and beverages (servings/d), especially among boys. Seven categories showed significant heritability estimates among boys, ranging from 12% (fish and lemon) to 79% (peanut butter and jelly). Only 3 categories showed significant heritability estimates among girls, ranging from 20% (bread and butter) to 56% (fish and lemon). BMI showed a genetic correlation only with bread and butter intake in girls. CONCLUSION: The magnitude of genetic and environmental influences on children's 24-h food and beverage intake differed for boys and girls, which suggests sex differences in the development of eating patterns. Heritability estimates were generally large, although other eating phenotypes may be necessary for identifying genetic correlations with adiposity.     

Factor-analytic structure of food preferences in four-year-old children in the UK

Studying the correlative structure of young children's food preferences may help us to understand the influences on the development of eating habits. We investigated patterns of food preferences in 214 same-sex twin pairs aged 4 to 5 years. Mothers completed a questionnaire of their children's likes and dislikes for 94 common foods. The proportion of children having tried each food, and their liking for it, were examined. These two measures were strongly positively correlated (r=0.61). Principal components analysis was used to examine the inter-relationships among preferences for 76 foods that had been tried by at least 75% of the children. Four factors emerged, interpreted from food factor loadings as "Vegetables", "Desserts", "Meat and Fish", and "Fruit", explaining 24% of the variance. Thus, children tended consistently to like or dislike foods within each of these factor categories, independently of patterns of liking in the other factors. Factor loadings were unrelated to average liking for or likelihood of exposure to these foods. The distribution of factor loadings refutes the common assumption that simple sensory properties such as sweetness, saltiness or fattiness predict food preferences. Instead, a preference structure may develop for more complex multimodal sensory syntheses, which could have both biological and learnt bases. Future work comparing the food preference structure of mono- and dizygotic twins should help determine the relative contribution of genetic and environmental influences.     

The heritability of smoking behaviour in pregnancy, and the birth weights of offspring of smoking-discordant twins

Questionnaire information on smoking habits in pregnancy was collated in 341 monozygotic (MZ) and 321 dizygotic (DZ) female twin pair cases from a population-based Norwegian Twin Panel. In a multifactorial model, the intra-pair correlation in smoking was 0.797 (+/- 0.042) in monozygotic (MZ) and 0.443 (+/- 0.075) in dizygotic (DZ) twin pairs, indicating a substantial genetic influence on liability to smoke in pregnancy. The questionnaire information was linked with birth records in the Medical Birth Registry of Norway, and birth weights of offspring of 62 MZ and 100 DZ smoking-discordant twin pairs were studied. Offspring of smoking MZ twins weighed 127 g less than birth order matched offspring of the non-smoking co-twins. This finding is additional evidence that smoking is a direct cause of reduced birth weight in offspring.     

Contribution of genetic and environmental influences to ankle-brachial blood pressure index in the NHLBI Twin Study. National Heart, Lung, and Blood Institute

The ankle-brachial index (ABI) is widely used in the clinical diagnosis of peripheral arterial disease. The contributions of genetic and environmental influences to normal and abnormal ABI values are unknown. In this study, the authors used available data on 94 monozygotic pairs and 90 dizygotic pairs of elderly, White, male twins examined in 1995-1997 to investigate the contributions of genetic and environmental influences to normative ABI values. Within-twin-pair correlations for normative ABI values were statistically significant, and the correlation in monozygotic twin pairs was significantly greater than that in dizygotic pairs. Structural equation modeling of the variance-covariance matrices of monozygotic and dizygotic twins indicated that 48% of the observed variability in ABI values could be attributed to additive genetic effects. In contrast, concordance rates for low ABI values (ABI< or =0.9) for both monozygotic and dizygotic twins were significantly greater than would be expected by chance alone, but within-pair monozygotic similarity was not significantly greater than dizygotic similarity. A matched-cotwin analysis in 21 pairs that were discordant for low ABI values found that twins with low ABI values were physically less active and more likely to be persistent smokers than their normal-control brothers. These findings reinforce the role of individual health practices (e.g., physical activity, smoking) in the manifestation of peripheral arterial disease among subjects matched for age, genetics, and early shared environment.     

Characteristics associated with excessive weight gain after smoking cessation in men.

OBJECTIVES. Data from two surveys of the National Academy of Sciences-National Research Council Twin Registry, conducted 16 years apart, were used to determine characteristics of individuals that were predictive of excessive weight gain after smoking cessation. METHODS. Over the follow-up, 2179 men quit smoking and averaged a weight gain of 3.5 kg. Quitters were grouped into four categories of weight change: lost weight, no change, gained weight, and excessive weight gain ("super-gainers"). RESULTS. In comparison with quitters reporting no change in weight, super-gainers were younger, were of lower socioeconomic status, and differed on a number of health habits before quitting (all Ps < .05). At follow-up, super-gainers reported changes in health habits that were significantly different from those seen in quitters reporting stable weight (all Ps < .05). Pairwise concordance for weight change in 146 monozygotic and 111 dizygotic twin pairs in which both twins quit smoking was significantly greater in monozygotic than dizygotic pairs (P < .01). CONCLUSIONS. These results indicate that super-gainers differ in important ways from those who do not gain weight after smoking cessation and that these weight changes may be influenced by underlying genetic factors.     

Comparison of the Coincidence of Osteoporosis,Fracture, Arthritis Histories,and DEXA T-Score between Monozygotic and Dizygotic Twins: A Cross-Sectional Study Using KoGES HTS Data

We explored the genetic and environmental inter-relationships among osteoporosis, fracture, arthritis, and bone mineral density concordance in monozygotic twins compared to those in dizygotic twins. This cross-sectional research assessed data of 1032 monozygotic and 242 dizygotic twin pairs aged >20 years included in the Healthy Twin Study data of the Korean Genome and Epidemiology Study between 2005 and 2014. Outcomes of interest included illness concordance and absolute differences in dual-energy X-ray absorptiometry (DEXA) T-scores. We found comparable concordances of osteoporosis, fractures, osteoarthritis, and rheumatoid arthritis between monozygotic and dizygotic twins. Medical histories of osteoporosis, fractures caused by accident or falling, osteoarthritis, and rheumatoid arthritis were not distinct between monozygotic and dizygotic twins. Accidental fracture occurrence in both monozygotic twins showed significantly lower odds than that in dizygotic twins. Genetic influence on liability to fracture risk might thus be maintained. DEXA T-scores for bone mineral density indicated more comparable tendencies within monozygotic twin pairs than within dizygotic ones, suggesting the relative importance of genetic contribution to bone mineral density. The relative importance of genetic factors in bone mineral density is sustained between monozygotic twins; overt disease expression of osteoporosis, fractures, or arthritis may be affected by environmental factors.     

Genetic and environmental influences on eating behavior: the Swedish Young Male Twins Study

BACKGROUND: Eating behavior may be implicated in the increasing prevalence of overweight and obesity, presumably in relation to easy access to energy-dense and highly palatable foods. OBJECTIVE: The aim of the present study was to disentangle genetic and environmental influences on eating behavior in a population-based cohort of male twins. DESIGN: The study included 326 dizygotic and 456 monozygotic male twin pairs aged 23-29 y from Sweden. The revised 21-item version of the Three-Factor Eating Questionnaire (TFEQ-R21) was used to assess eating behavior. This validated instrument consists of 3 dimensions: cognitive restraint, emotional eating, and uncontrolled eating. Structural equation modeling was used to estimate the heritability of eating behavior. RESULTS: Cognitive restraint was the only TFEQ-R21 scale that significantly correlated with BMI (r = 0.39, P < 0.0001). The best-fitted models gave a heritability of 59% (95% CI: 52%, 66%) for cognitive restraint, 60% (95% CI: 52%, 67%) for emotional eating, and 45% (95% CI: 36%, 53%) for uncontrolled eating. CONCLUSIONS: These results show the great importance of genetic factors in the eating behavior of a large, unselected population of young adult male twins. Nonshared environmental factors were also important, whereas shared environmental factors did not contribute to eating behavior.     

Frequency of consumption of cariogenic food items by 4-month-old to 24-month-old children: comparison between two rural communities in KwaZulu-Natal, South Africa

The objective of the study was to compare the frequency of consumption of cariogenic food items among 4-month-old to 24-month-old children in two neighbouring rural areas in KwaZulu-Natal Province, South Africa: Nyuswa/Embo (Area A) (n = 127) and Ndunakazi (Area B) (n = 105). Dietary intake was assessed using a food frequency questionnaire. Mothers or caregivers were interviewed by a team of Zulu-speaking fieldworkers. The percentage of children consuming the individual food items (consumers) and the weekly consumption for consumers were calculated for the two areas separately. The food items were ranked in descending order according to the combined group of children and reported for each area within five selected food groups (carbohydrates, sugars, fruit and vegetables, milk and milk products, and other foods and snacks). Food items were 'flagged' according to their cariogenic potential. Fisher's exact test on absolute numbers tested for significant differences in the frequency of intake between individual food items between the two groups. Significance was set at P < 0.05. The frequency of consumption of certain listed cariogenic food items showed significant differences between the two areas. A higher percentage of children in Area A than in Area B consumed most of the food items and also more frequently. Children mainly consumed foods with a cariogenic score of 2, solid foods with 8-20% sugars as well as foods high in starch with less than 10% sugars. This knowledge is essential to gain insight into the eating pattern among rural communities and will provide a baseline for developing and adapting dietary advice specifically for young rural South African children with particular emphasis on the prevention of dental caries.     

TracheobronchiaI Clearance in Twins

Tracheobronchial clearance was studied with a lest aerosol of 6μ-7μ monodisperse fluorinated ethylene propylene (Teflon 120) particles tagged with technetium 99m (half-life, 6.0 hours) and external measurements of the radioactivity in the lungs. Nine pairs of monozygotic and nine pairs of dizygotic twins were studied. The clearance patterns in the monozygotic pairs were highly similar. In the dizygotic pairs there was a tendency to similarity. Among the pairs there was a remarkable difference in the clearance patterns, Consequently the result indicates that tracheobronchial clearance to a great extent is constitutionally determined. The medical implications of this are discussed.     

Traditional foods and practices of Spanish-speaking Latina mothers influence the home food environment: implications for future interventions

This study aimed to obtain in-depth information from low-income, Spanish-speaking Latino families with young children to guide the development of culturally appropriate nutrition interventions. Focus groups were used to assess parent's knowledge about healthful eating, the home food environment, perceived influences on children's eating habits, food purchasing practices, and commonly used strategies to promote healthful eating among their children. Thirty-four Latino parents (33 women; 27 born in Mexico; 21 food-insecure) of preschool-aged children participated in four focus group discussions conducted in Spanish by a trained moderator. The focus groups were audiotaped, transcribed, translated, and coded by independent raters. Results suggest that in general, parents were very knowledgeable about healthful eating and cited both parents and school as significant factors influencing children's eating habits; at home, most families had more traditional Mexican foods available than American foods; cost and familiarity with foods were the most influential factors affecting food purchasing; many parents had rules regarding sugar intake; and parents cited role modeling, reinforcement, and creative food preparation as ways to encourage children's healthful eating habits. Finally, parents generated ideas on how to best assist Latino families through interventions. Parents indicated that future interventions should be community based and teach skills to purchase and prepare meals that include low-cost and traditional Mexican ingredients, using hands-on activities. In addition, interventions could encourage and reinforce healthy food-related practices that Latino families bring from their native countries.     

The role of genetic and environmental factors in the association between birthweight and blood pressure: evidence from meta-analysis of twin studies

BACKGROUND: An inverse association between birthweight and later blood pressure has been found in many studies in singletons. Twin studies have been used to examine whether genetic factors or family environment could account for this association. METHODS: A systematic review identified 10 studies covering 3901 twin pairs. Meta-analysis of regression coefficients for the association between birthweight and systolic blood pressure was carried out for unpaired versus paired associations and for paired associations in dizygotic versus monozygotic pairs. RESULTS: After adjustment for current weight or body mass index (BMI), the difference in systolic blood pressure per kg birthweight was -2.0 (95% CI: -3.2, -0.8) mmHg in the unpaired analysis and -0.4 (95% CI: -1.5, 0.7) mmHg in the paired analysis in the same subjects. In the paired analysis by zygosity, in all twins the coefficients were -0.7 (95% CI: -2.3, 0.8) mmHg in dizygotic pairs and -0.8 (95% CI: -2.1, 0.4) mmHg in monozygotic pairs, but in studies which included zygosity tests the coefficients were -1.0 (95% CI: -3.3, 1.6) mmHg in dizygotic pairs and -0.4 (95% CI: -1.9, 1.3) mmHg in monozygotic pairs. CONCLUSIONS: The attenuation of the regression coefficient in the paired analysis provides support for the possibility that factors shared by twins contribute to the association between birthweight and blood pressure in singletons. Comparison of paired analysis in monozygotic and dizygotic pairs could not provide conclusive evidence for a role for genetic as opposed to shared environmental factors.     

Differences in Nutritional Intake,Total Body Fat,and BMI Score between Twins

The present study aimed to investigate the coincidence of obesity and nutritional intake in monozygotic twins compared to dizygotic twins. The data from the Korean Genome and Epidemiology Study (KoGES) from 2005 through 2014 were analyzed. Participants ≥ 20 years old were enrolled. The 1006 monozygotic twins and 238 dizygotic twins were analyzed for differences in self-reported nutritional intake, total body fat, and body mass index (BMI) using a linear regression model. The estimated values (EV) with 95% confidence intervals (95% CI) of the difference in dietary intake, total body fat, and BMI score were calculated. The monozygotic twin group and the dizygotic twin group showed similar differences in nutritional intake, DEXA fat, and BMI (all p > 0.05). The differences in nutritional intake of total calories and carbohydrates were lower in the monozygotic twin group than in the dizygotic twin group (all p < 0.05). The differences in total body fat were lower in monozygotic twins than in dizygotic twins (adjusted EV = 2427.86 g, 95% CI = 1777.19–3078.53 and adjusted EV = 1.90%, 95% CI = 1.33–2.46). Monozygotic twins had more similar dietary habits for total calories and carbohydrate intake. Other nutritional factors did not show differential similarity between monozygotic and dizygotic twins. Total body fat was more concordant in monozygotic twins.     

Genetic contribution to sour taste preference

Genetic contribution to individual differences in sour taste perception and preference was investigated in a cohort of young adult Finnish twins (n=328, 21-25 years) including 46 complete monozygotic and 92 dizygotic twin pairs and 52 twin individuals without their co-twin. Responses to sour taste were recorded as pleasantness and intensity ratings of orange juice with added citric acid (4.2g/L) relative to untainted orange juice (sensory traits). Pleasantness and use-frequency of 21 food items varying in sourness were rated in a questionnaire. Three food categories emerged in factor analysis: sour berries and fruits, less-sour berries and fruits, and sour dairy products (questionnaire traits). The contribution of genetic and environmental factors to variation and co-variation of the traits were analyzed using quantitative genetic modeling. Genetic factors played a larger role than shared environment, explaining 14% and 31% of the variation in pleasantness and intensity of sour taste, respectively, and 34-50% of the variation in pleasantness and use-frequency of sour foods. Relatively large genetic correlations existed between sensory traits and between questionnaire traits. These results demonstrate a genetic contribution to preference for sour foods.     

Comparison of the Concordance of Cardiometabolic Diseases and Physical and Laboratory Examination Findings between Monozygotic and Dizygotic Korean Adult Twins: A Cross-Sectional Study Using KoGES HTS Data

This study investigated the contribution of genetic and environmental factors to cardiometabolic diseases (CMDs) by comparing disease concordance in monozygotic and dizygotic twins. This cross-sectional study analyzed 1294 (1040 monozygotic and 254 dizygotic) twin pairs (>20 years) based on the Korean Genome and Epidemiology Study data (2005–2014). The odds ratios of disease concordance were calculated using binomial and multinomial logistic regression models. The occurrence of CMDs (hypertension, hyperlipidemia, type 2 diabetes, cerebral stroke, transient ischemic attack, and ischemic heart disease) and related physical and laboratory levels did not differ between the monozygotic and dizygotic twin groups. The odds for concordance of the presence/absence of CMDs and the likelihood of incident CMD within monozygotic twins were comparable to that of dizygotic twins. The absolute differences in hemoglobin A1c, insulin, low- and high-density lipoprotein cholesterol, total cholesterol, triglycerides, and systolic blood pressure were lower in monozygotic twins than in dizygotic twins. Absolute differences in fasting glucose and diastolic blood pressure did not differ between groups. Although baseline levels of several laboratory parameters related to CMD showed a strong likelihood of heritability in monozygotic twins, CMD phenotype appears to be largely affected by environmental factors.     

Food choice of tactile defensive children

OBJECTIVE: We explored whether tactile defensive children have picky eating habits because fussy or picky eaters are a general problem to parents and different health professionals. METHODS: Children (n = 62) of both sexes, ages 3 to 10 y, were assigned to an experimental tactile defensive (TD) group (n = 29) or a control non-TD group (n = 33). A questionnaire on eating habits was compiled and given to parents for completion during personal interviews (children were screened with a checklist and evaluated for tactile defensiveness with the Winnie Dunn Caregiver profile questionnaire). RESULTS: This research confirmed that the eating habits and food choices of TD and non-TD children differ significantly. TD children had a fair to poor appetite. They hesitated to eat unfamiliar foods, did not eat other people's houses, and refused certain foods because of the smell and temperature. They also had a problem eating vegetables. They often gagged and/or bit their inner lips and cheeks. The results showed a definite difference in the limited selection of foods that TD children chose and a pronounced aversion toward textures or consistencies, smells, and temperatures of food as compared with integrated children. CONCLUSIONS: Fussy or picky eaters should evaluated more widely than to treat only the feeding problem. Tactile or oral defensiveness can be treated. This report underlines the team approach of health professionals.