Anja Kroke

Critical review: vegetables and fruit in the prevention of chronic diseases

BackgroundVegetables and fruit provide a significant part of human nutrition, as they are important sources of nutrients, dietary fibre, and phytochemicals. However, it is uncertain whether the risk of certain chronic diseases can be reduced by increased consumption of vegetables or fruit by the general public, and what strength of evidence has to be allocated to such an association.MethodsTherefore, a comprehensive analysis of the studies available in the literature and the respective study results has been performed and evaluated regarding obesity, type 2 diabetes mellitus, hypertension, coronary heart disease (CHD), stroke, cancer, chronic inflammatory bowel disease (IBD), rheumatoid arthritis (RA), chronic obstructive pulmonary disease (COPD), asthma, osteoporosis, eye diseases, and dementia. For judgement, the strength of evidence for a risk association, the level of evidence, and the number of studies were considered, the quality of the studies and their estimated relevance based on study design and size.ResultsFor hypertension, CHD, and stroke, there is convincing evidence that increasing the consumption of vegetables and fruit reduces the risk of disease. There is probable evidence that the risk of cancer in general is inversely associated with the consumption of vegetables and fruit. In addition, there is possible evidence that an increased consumption of vegetables and fruit may prevent body weight gain. As overweight is the most important risk factor for type 2 diabetes mellitus, an increased consumption of vegetables and fruit therefore might indirectly reduces the incidence of type 2 diabetes mellitus. Independent of overweight, there is probable evidence that there is no influence of increased consumption on the risk of type 2 diabetes mellitus. There is possible evidence that increasing the consumption of vegetables and fruit lowers the risk of certain eye diseases, dementia and the risk of osteoporosis. Likewise, current data on asthma, COPD, and RA indicate that an increase in vegetable and fruit consumption may contribute to the prevention of these diseases. For IBD, glaucoma, and diabetic retinopathy, there was insufficient evidence regarding an association with the consumption of vegetables and fruit.ConclusionsThis critical review on the associations between the intake of vegetables and fruit and the risk of several chronic diseases shows that a high daily intake of these foods promotes health. Therefore, from a scientific point of view, national campaigns to increase vegetable and fruit consumption are justified. The promotion of vegetable and fruit consumption by nutrition and health policies is a preferable strategy to decrease the burden of several chronic diseases in Western societies.

Dietary patterns and their association with food and nutrient intake in the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam study.

Dietary pattern analysis has recently received growing attention, as it might be more appropriate in studies of diet-disease associations than the single food or nutrient approach that has dominated past epidemiological research. Factor analysis is a technique which is commonly used to identify dietary patterns within study populations. However, the ability of factor solutions to account for variance of food and nutrient intake has so far remained unclear. The present study therefore explored the statistical properties of dietary patterns with regard to the explained variance. Food intake of 8975 men and 13 379 women, assessed by a food-frequency questionnaire, was aggregated into forty-seven separate food groups. Dietary patterns were identified by principal component analysis and subsequent varimax rotation. Seven factors were retained for both men and women, which accounted for about 31 % of the total variance. The explained variance was relatively high (>40 %) for cooked vegetables, sauce, meat, dessert, cake, bread other than wholemeal, raw vegetables, processed meat, high-fat cheese, butter and margarine. Factor scores were used to investigate associations between the factors and nutrient intake. The patterns accounted for relatively large proportions of variance of energy and macronutrient intake, but for less variance of alcohol and micronutrient intake, especially of retinol, beta-carotene, vitamin E, Ca and ascorbic acid. In addition, factors were related to age, BMI, physical activity, education, smoking and vitamin and mineral supplement use.

Recent weight changes and weight cycling as predictors of subsequent two year weight change in a middle-aged cohort.

Objective: To evaluate the influence of recent weight changes (weight gain, loss and cycling) on subsequent weight changes.Design: Prospective cohort study with 2 y of follow-up. Data analysis with a polytomous logistic regression model.Subjects: A total of 18 001 non-smoking subjects, 6689 men and 11 312 women, from the general population.Measurements: Body height and weight measurements and interview data on lifestyle habits and medical history at baseline. For follow-up, self-administered questionnaires for assessment of body weight and incident diseases.Results: Recent changes in body weight, that is weight gain, weight loss and weight cycling, were significant predictors of subsequent weight changes in both men and women after controlling for age, baseline BMI and several lifestyle and behavioural characteristics as potential confounding factors. Weight cycling before baseline was the strongest predictor of subsequent large weight gain (≥2 kg) with an odds ratio (OR) of 4.84 (95% confidence interval (CI) 3.34–7.02) in men. In women, prior weight loss was the strongest predictor of subsequent large weight gain (OR 4.77; 95% CI 3.63–6.03), followed by weight cycling (OR 3.02; 95% CI 2.15–4.25).Conclusion: These data indicate the need for thorough weight history assessment to identify those who are most likely to gain weight. Effective weight control before the development of obesity or after intentional weight loss due to obesity should be a primary goal in the management of obesity.

Dietary Protein Intake throughout Childhood Is Associated with the Timing of Puberty

Early puberty onset is associated with hormone-related cancers, but whether diet in childhood influences pubertal timing is controversial. We examined the association of protein intake in early and mid-childhood with the ages at take-off of the pubertal growth spurt (ATO), peak height velocity (APHV), and menarche in girls and voice break in boys using data from the longitudinal Dortmund Nutritional and Anthropometric Longitudinally Designed Study. Among participants who provided 3-d weighed dietary records at 12 mo, 18-24 mo, 3-4 y, and 5-6 y, 112 had sufficient anthropometric measurements between 6 and 13 y to allow estimation of ATO. Life-course plots were used to identify critical periods of total, animal, and vegetable protein intake (percentage of total energy intake) for pubertal timing. At these ages, the association between tertiles of protein intake (T1-T3) and the outcomes was investigated using multiple linear regression analysis. A higher total and animal protein intake at 5-6 y was related to an earlier ATO. In the highest tertile of animal protein intake at 5-6 y, ATO occurred 0.6 y earlier than in the lowest [(mean, 95% CI) T1: 9.6, 9.4-9.9 vs. T2: 9.4, 9.1-9.7 vs. T3: 9.0, 8.7-9.3 y; P-trend = 0.003, adjusted for sex, total energy, breast-feeding, birth year, and paternal university degree]. Similar findings were seen for APHV (P-trend = 0.001) and the timing of menarche/voice break (P-trend = 0.02). Conversely, a higher vegetable protein intake at 3-4 and 5-6 y was related to later ATO, APHV, and menarche/voice break (P-trend = 0.02-0.04). These results suggest that animal and vegetable protein intake in mid-childhood might be differentially related to pubertal timing.

Birth and early life influences on the timing of puberty onset: results from the DONALD (DOrtmund Nutritional and Anthropometric Longitudinally Designed) Study

BACKGROUND Early age at puberty onset may predispose an individual to many currently prevalent diseases, including cancer and adiposity. OBJECTIVE The objective was to investigate whether early life exposures influence the timing of puberty, as defined by both early and late markers, in healthy German girls and boys. DESIGN Term participants (n = 215; 49.8% female) of the DONALD (DOrtmund Nutritional and Anthropometric Longitudinally Designed) Study, with sufficient repeated anthropometric measurements between 6 and 13 y to allow estimation of age at take-off of the pubertal growth spurt (ATO) and information on a variety of early life exposures, including birth weight, breastfeeding status, velocity of weight gain, and parental characteristics, were studied. Age at peak height velocity (APHV) and menarche were also considered. RESULTS Children who weighed between 2500 and <3000 g at birth were approximately 7 mo younger at ATO than were the other children (beta +/- SE: -0.56 +/- 0.20 y; P = 0.006). Children who had gained weight rapidly between birth and 24 mo (increase in weight SD score >0.67) experienced ATO 4 mo earlier than those who had gained weight normally (-0.34 +/- 0.15 y; P = 0.02). Rapid weight gain was also associated with an earlier APHV (P = 0.0006) and, in girls, with an earlier menarche (P = 0.002). Adjustment for body mass index SD score or body fat percentage 1, 2, or 3 y before ATO did not account for these effects. CONCLUSION In both boys and girls, intrauterine and early postnatal growth factors appear to influence both early and later markers of puberty onset independently of prepubertal body composition.

Measures of Quality Control in the German Component of the EPIC Study

Quality control is an indispensable part of quality assurance in any study, intending to ensure high standards during data acquisition. The aim of this paper is to describe the measures of quality control undertaken in the German EPIC study centers and to present selected results of these procedures (EPIC = European Prospective Investigation into Cancer and Nutrition). For all data assessment tools applied in the German EPIC study, procedures were developed to monitor both the personnel as well as the technical instruments. These procedures combined quantitative and qualitative measurements of quality control. Interviewer performance was evaluated through direct observation and rated according to an evaluation score. Blood pressure and anthropometric measurements were both controlled through direct observation of measurement procedures as well as through periodical technical control of measurement devices. Blood sampling procedures were directly monitored and subsequent handling of the probes tightly recorded, including information on time sequence of work-up and room temperature. With these diverse control measurements and the obtained rating of assessment procedures a broad pool of information has been made available to support a critical evaluation of the data obtained in the EPIC study centers in Heidelberg and Potsdam.

Beyond overweight: nutrition as an important lifestyle factor influencing timing of puberty

Early onset of puberty may confer adverse health consequences. Thus, modifiable factors influencing the timing of puberty are of public health interest. Childhood overweight as a factor in the earlier onset of menarche has been supported by prospective evidence; nonetheless, its overall contribution may have been overemphasized, since secular trends toward a younger age at menarche have not been a universal finding during the recent obesity epidemic. Current observational studies suggest notable associations between dietary intakes and pubertal timing beyond contributions to an energy imbalance: children with the highest intakes of vegetable protein or animal protein experience pubertal onset up to 7 months later or 7 months earlier, respectively. Furthermore, girls with high isoflavone intakes may experience the onset of breast development and peak height velocity approximately 7-8 months later. These effect sizes are on the order of those observed for potentially neuroactive steroid hormones. Thus, dietary patterns characterized by higher intakes of vegetable protein and isoflavones and lower intakes of animal protein may contribute to a lower risk of breast cancer or a lower total mortality.

The Relation between Dietary Protein, Calcium and Bone Health in Women: Results from the EPIC-Potsdam Cohort

Background/Aims: The role of dietary protein in bone health is controversial. The objective of the present study was to examine the association between protein intake, dietary calcium, and bone structure measured by broadband ultrasound attenuation (BUA). Methods: Our analysis includes 8,178 female study participants of the European Prospective Investigation into Cancer and Nutrition (EPIC) Potsdam Study. Ultrasound bone measurements were performed on the right os calcis, and BUA was determined. Dietary intake was assessed by a standardized food frequency questionnaire. We applied linear regression models to estimate the association between dietary protein and BUA. Results: After multivariate adjustment, high intake of animal protein was associated with decreased BUA values (β = –0.03; p = 0.010) whereas high vegetable protein intake was related to an increased BUA (β = 0.11; p = 0.007). The effect of dietary animal protein on BUA was modified by calcium intake. Conclusion: High consumption of protein from animal origin may be unfavourable, whereas a higher vegetable protein intake may be beneficial for bone health. Our results strengthen the hypothesis that high calcium intake combined with adequate protein intake based on a high ratio of vegetable to animal protein may be protective against osteoporosis.

Quantity and Quality of Dietary Fat, Carbohydrate, and Fiber Intake in the German EPIC Cohorts

Aim: This evaluation aims to describe the quantity and quality of dietary fat, carbohydrate and fiber intake in both German cohorts participating in the European Prospective Investigation into Cancer and Nutrition (EPIC). Methods: Estimates are based on standardized computer-guided 24-hour dietary recalls from 1,078 women and 1,013 men in Heidelberg and 898 women and 1,032 men in Potsdam. In a subsample, plasma phospholipid (PL) fatty acids were analyzed as well. Results: Adjusted mean dietary intake estimates demonstrated that the contribution of fat as well as n–6 and n–3 polyunsaturated fatty acids (PUFA) to the total daily energy intake was higher in both women and men of EPIC-Potsdam compared to EPIC-Heidelberg. Surprisingly, the dietary n–6/n–3 PUFA ratio was lower in the Potsdam cohort. These results were confirmed by means of the PL fatty acid pattern. Besides the higher contribution of polysaccharides to total energy intake in EPIC-Heidelberg, women of the Heidelberg cohort revealed a significantly lower contribution of mono- and disaccharides (sucrose) to total energy intake. Although total fiber intake data were similar in both cohorts, analysis by food groups showed differences in dietary fiber intake originating from the food groups cereals, fruits and potatoes. Conclusion: The results demonstrate distinct differences in the dietary fat, carbohydrate and fiber intake between both German EPIC cohorts, which contribute to the exposure variation in the whole of EPIC.

The influence of habitual protein intake in early childhood on BMI and age at adiposity rebound: results from the DONALD Study

Objective:To analyse the influence of habitual protein intake in early childhood on age and body mass index (BMI) at adiposity rebound (AR), a potential critical period for the development of obesity.Subjects:A total of 313 children (161 boys, 152 girls) participating in the Dortmund Nutritional and Anthropometric Longitudinally Designed Study.Methods:Weighted summary indices were created reflecting habitual, energy-adjusted protein intake (expressed as % of energy) and protein intake per kg reference body weight per day (g/kg RBW/day) between the age of 12 and 24 months. Body mass index standard deviation scores (BMI-SDS), age at AR and covariates (mothers BMI, gestational age, breastfeeding and siblings) were included in the final models.Results:After adjusting for potential confounders, girls in the highest tertile (T3) of habitual energy-adjusted protein intake had a significantly higher BMI-SDS at AR than those in T1 (T1: −0.61 (95% CI: −0.90; −0.31), T2: −0.49 (−0.79; −0.20), T3: −0.08 (−0.36; 0.20), P for difference=0.01). A comparable association existed with habitual protein intake expressed as g/kg RBW/day (T1: −0.64 (−0.93; −0.36), T2: −0.22 (−0.52; 0.09), T3: −0.25 (−0.54; 0.04), P=0.04). In boys, there were no differences in BMI-SDS at AR between tertiles of habitual protein intake (% of energy or g/kg RBW/day) (P>0.05). Boys in the lowest tertile of habitual energy-adjusted protein intake tended to experience a later AR (T1: 6.0 (5.6; 6.4), T2: 5.5 (5.1; 5.9), T3: 5.4 (5.0; 5.9) years, P=0.07). But neither in girls nor in boys was age at AR significantly different between tertiles of habitual protein intake (% of energy or g/kg RBW/day) (P>0.05).Conclusion:A higher habitual protein intake between the age of 12 and 24 months was associated with a higher BMI-SDS at AR in girls, but not in boys. There was no consistent relation between habitual protein intake in early childhood and timing of AR.