Evaluation of dietary intake in a Danish population: the Inter99 study

Timing and Frequency of Daily Energy Intake in Adults with Prediabetes and Overweight or Obesity and Their Associations with Body Fat

Knowledge on how energy intake and macronutrients are distributed during the day and the role of daily eating patterns in body composition among adults with overweight/obesity and prediabetes is lacking. Therefore, we evaluated the diurnal dietary intake and studied the associations of daily eating patterns with body fat percentage. A total of 119 adults with prediabetes were included (mean (SD) HbA_1c 41 (2.3) mmol/mol, BMI 31.5 (5.0) kg/m², age 57.8 (9.3) years, 44% men). Information on dietary intake was obtained from self-reported food records for three consecutive days. All foods and beverages (except water) were registered with information on time of ingestion. Body fat was measured by dual-energy X-ray absorptiometry. A total of 60.5% of the participants reported a daily eating window of 12 or more hours/day, and almost half of the daily total energy intake was reported in the evening. In analyses adjusted for age, gender, and total daily energy intake, having the first daily energy intake one hour later was associated with slightly higher body fat percentage (0.64% per hour, 95% CI: 0.28; 1.01; p < 0.001), whereas higher meal frequency was associated with slightly lower body fat percentage (0.49% per extra daily meal, 95% CI: −0.81; −0.18; p = 0.002). Prospective studies are warranted to address the clinical implications of daily eating patterns on body fat and cardiometabolic health.

Serum 25(OH)D and type 2 diabetes association in a general population: a prospective study

OBJECTIVE This study aimed to examine vitamin D status as a determinant for development of type 2 diabetes and deterioration of glucose homeostasis. RESEARCH DESIGN AND METHODS A random sample of the general population of Copenhagen, Denmark, was taken as part of the Inter99 study. Included were 6,405 men and women aged 30-65 years at baseline (1999-2001), with 4,296 participating in the follow-up examination 5 years later (2004-2006). Vitamin D was determined at baseline as serum 25-hydroxyvitamin D [25(OH)D]. Diabetes was defined based on an oral glucose tolerance test and a glycosylated hemoglobin (HbA(1c)) test. Secondary outcomes included continuous markers of glucose homeostasis. RESULTS The risk of incident diabetes associated with a 10 nmol/L increase in 25(OH)D was odds ratio (OR) 0.91 (95% CI 0.84-0.97) in crude analyses. The association became statistically nonsignificant after adjustment for confounders, with an OR per 10 nmol/L of 0.94 (0.86-1.03). Low 25(OH)D status was significantly associated with unfavorable longitudinal changes in continuous markers of glucose homeostasis after adjustment for confounders. Fasting and 2-h glucose and insulin as well as the degree of insulin resistance increased significantly more during follow-up among those with low 25(OH)D levels compared with those with higher levels. CONCLUSIONS Low 25(OH)D status was not significantly associated with incident diabetes after adjustment for confounders. However, it was significantly associated with unfavorable longitudinal changes in continuous markers of glucose homeostasis, indicating that low vitamin D status could be related to deterioration of glucose homeostasis.

The effects of adding group-based lifestyle counselling to individual counselling on changes in plasma glucose levels in a randomized controlled trial: the Inter99 study

AIM

This study aimed to assess whether group-based lifestyle counselling offered to a high-risk population subgroup had any effect beyond individual multifactorial interventions on fasting plasma glucose (FPG) and 2-h plasma glucose (2hPG) changes.

METHODS

In a population-based study of 6784 participants, 4053 were determined to be at high risk based on a risk estimate of ischaemic heart disease or the presence of risk factors (smoking, hypertension, hypercholesterolaemia, obesity, impaired glucose tolerance). Of these subjects, 90% were randomized to high-intensity intervention (group A) and 10% to low-intensity intervention (group B). All participants went through health examinations, risk assessments and individual lifestyle counselling. Participants in group A were further offered group-based lifestyle counselling. The intervention was repeated after 1 and 3 years. A total of 2738 participants free of diabetes at baseline (1999-2001) and with at least one FPG and/or 2hPG measurement during 5 years of follow-up were included in the analyses. Differences in changes of plasma glucose between groups A and B were analyzed using multilevel linear regression.

RESULTS

For FPG, crude 5-year changes were significantly different between the two groups (group A: -0.003 mmol/L vs group B: -0.079 mmol/L; P=0.0427). After adjusting for relevant confounders, no differences in FPG changes were observed (P=0.116). Also, no significant differences in the 5-year changes in 2hPG between the two groups were observed (group A: - 0.127 mmol/L vs group B: -0.201 mmol/L; P=0.546).

CONCLUSION

Offering additional group-based intervention to a high-risk population subgroup had no clinical effects on changes in plasma glucose beyond those of individualized multifactorial interventions.

Predictors of future fasting and 2-h post-OGTT plasma glucose levels in middle-aged men and women-the Inter99 study

AIMS

Screening and prevention strategies for Type 2 diabetes require insight into the aetiological and potentially different risk factors leading to early impairments of fasting plasma glucose (FPG) and 2-h post-load plasma glucose (2hPG) levels. We studied whether risk factors predicting subtle elevations of FPG levels were different from those predicting elevations of 2hPG levels in men and women.

METHODS

We used baseline and 5-year follow-up data from middle-aged men and women with normal glucose tolerance (NGT) at baseline in the Danish population-based Inter99 study (n = 3164). Anthropometric and non-anthropometric baseline predictors of the 5-year FPG and 2hPG levels were estimated in linear regression models stratified by gender.

RESULTS

In men, but not in women, smoking and family history of diabetes predicted increased FPG levels, whereas high physical activity predicted a decline in 2hPG levels. Among the anthropometric variables, large waist circumference was the strongest predictor of increased FPG levels in men, whereas high body mass index (BMI) was the strongest predictor of increased FPG levels in women. In both men and women, BMI and waist circumference were equally strong in predicting 2hPG levels. Furthermore, short height predicted increased 2hPG levels in men, and short height and low hip circumference predicted increased 2hPG levels in women.

CONCLUSIONS

Risk factors that predict future FPG levels are different from those predicting future 2hPG levels. Furthermore, different risk factors predict glycaemic levels in men compared with women. These findings indicate that different aetiological pathways may lead to Type 2 diabetes in men and women.

Dietary patterns predict changes in two-hour post-oral glucose tolerance test plasma glucose concentrations in middle-aged adults

We examined whether the adherence to major dietary patterns at baseline of 5824 nondiabetic Danes (30-60 y) enrolled in the nonpharmacological Inter99 intervention predicted changes in fasting plasma glucose (FPG) and postchallenge 2-h plasma glucose (2h-PG) concentrations during a 5 y period and whether a potential association was dependent on baseline glucose tolerance status. Through principal component analysis, a score for a traditional dietary pattern (characterized by higher intakes of high-fat sandwich spreads, red meat, potatoes, butter and lard, low-fat fish, sandwich meat, and sauces) and a score for a modern dietary pattern (characterized by higher intakes of vegetables, fruit, vegetable oil/vinegar dressing, poultry, pasta, rice, and cereals) were estimated for each person at baseline. Random effect models adjusting for relevant confounders were used to estimate changes in repetitive measures of FPG and 2h-PG. A higher modern score (of 1 SD) predicted an annual decrease in 2h-PG of 0.015 mmol/L (P < 0.01) regardless of glucose tolerance status. For individuals with isolated impaired glucose tolerance, a higher traditional score (of 1 SD) predicted an annual increase in 2h-PG of 0.083 mmol/L (P < 0.0001). In conclusion, glucose tolerance status did not, in general, affect the predictive effect of the dietary patterns. The study suggests that the risk of worsening 2h-PG concentrations may be smaller for individuals with a high modern dietary pattern score characterized by high intakes of vegetables, fruit, vegetable oil/vinegar dressing, poultry, pasta, rice, and cereals.

Glycemic load, glycemic index, and body mass index in Spanish adults

BACKGROUND

Studies on obesity and glycemic index (GI) or glycemic load (GL) have had inconsistent results, perhaps in part because of underreporting or to heterogeneous dietary patterns across food cultures.

OBJECTIVES

We examined associations between body mass index (BMI) and GI or GL in a Mediterranean population, accounting for underreporting. We also constructed dietary factors related to GI and GL to better understand food patterns related to these measures.

DESIGN

Cross-sectional data on 8195 Spanish adults aged 35-74 y were analyzed. A validated food-frequency questionnaire was used to estimate GI and GL, with glucose as the reference value. Reduced-rank regression was used to construct dietary patterns that explained variation in GI and GL. Multivariate linear regression was used to estimate associations between BMI and GI, GL, and their respective diet factors with and without adjusting for energy, which may lie on the causal pathway between glycemic quality and obesity. Effects of excluding underreporters (ratio of energy intake:basal metabolic rate < 1.20) were examined.

RESULTS

Food patterns underlying high GI differed substantially from those of high GL, with fruits, vegetables, and legumes related positively to GL but negatively to GI. After excluding underreporters, GL was negatively associated with BMI, adjusting for energy. GI was not associated with BMI in any model.

CONCLUSIONS

After adjusting for energy, GL was associated with reduced BMI in this Mediterranean population. Underreporting did not explain this inverse relation, which was observed among subjects with plausible intakes.

Identification and reproducibility of dietary patterns in a Danish cohort: the Inter99 study

We aimed to identify dietary patterns in a Danish adult population and assess the reproducibility of the dietary patterns identified. Baseline data of 3372 women and 3191 men (30–60 years old) from the population-based survey Inter99 was used. Food intake, assessed by a FFQ, was aggregated into thirty-four separate food groups. Dietary patterns were identified by principal component analysis. Confirmatory factor analysis and Bland Altman plots were used to assess the reproducibility of the dietary patterns identified. The Bland Altman plots were used as an alternative and new method. Two factors were retained for both women and men, which accounted for 15·1–17·4 % of the total variation. The ‘Traditional’ pattern was characterised by high loadings ( ≥ 0·40) on paté or high-fat meat for sandwiches, mayonnaise salads, red meat, potatoes, butter and lard, low-fat fish, low-fat meat for sandwiches, and sauces. The ‘Modern’ pattern was characterised by high loadings on vegetables, fruit, mixed vegetable dishes, vegetable oil and vinegar dressing, poultry, and pasta, rice and wheat kernels. Small differences were observed between patterns identified for women and men. The root mean square error approximation from the confirmatory factor analysis was 0·08. The variation observed from the Bland Altman plots of factors from explorativev. confirmative analyses and explorative analyses from two sub-samples was between 18·8 and 47·7 %. Pearson's correlation was >0·89 (P < 0·0001). The reproducibility was better for women than for men. We conclude that the ‘Traditional’ and ‘Modern’ dietary patterns identified were reproducible.

Commuting physical activity is favourably associated with biological risk factors for cardiovascular disease

BACKGROUND

Little is known about the effects of commuting physical activity on biological cardiovascular risk factors although such knowledge may form an important basis for interventions aimed at reducing cardiovascular disease (CVD) by increasing physical activity. We examined the associations between commuting, leisure time and total physical activity and biological risk factors for CVD. Design A cross-sectional study of men and women, who participated in a health screening programme.

METHODS

The study population comprised persons aged 30-60 years from a population-based random sample, response rate 53% (n = 6,906). Weight, height, waist circumference and blood pressure were measured and blood samples were collected. Physical activity was assessed by a self-administered questionnaire.

RESULTS

Time spent on commuting, leisure time and total physical activity was positively associated with high-density lipoprotein cholesterol and negatively associated with low-density lipoprotein cholesterol, triglycerides, waist circumference and body mass index. Time spent on total physical activity was negatively associated with total cholesterol and diastolic blood pressure. Among men there was no relationship between time spent on physical activity and systolic blood pressure. Time spent on commuting physical activity and total physical activity was negatively associated with systolic blood pressure among women.

CONCLUSION

Commuting physical activity, independent of leisure time physical activity, was associated with a healthier level of most of the cardiovascular risk factors. An increase in commuting physical activity in the population may therefore reduce the incidence of CVD.

Association between dietary glycemic index, glycemic load, and body mass index in the Inter99 study: is underreporting a problem?

BACKGROUND

The few studies examining the potential associations between glycemic index (GI), glycemic load (GL), and body mass index (BMI) have provided no clear pictures. Underreporting of energy intake may be one explanation for this.

OBJECTIVE

We examined the associations between GI, GL, and BMI by focusing on the confounding factor of total energy intake and the effect of exclusion of low energy reporters (LERs).

DESIGN

This was a cross-sectional study of 6334 subjects aged 30-60 y. Dietary intake was estimated from a food-frequency questionnaire. GI and GL were estimated by using white bread as the reference food. Underreporting of energy intake was assessed as reported energy intake divided by basal metabolic rate (EI/BMR); LERs were defined as those having an EI/BMR < 1.14. Univariate and multiple linear regression models were used to test for associations between GI, GL, and BMI. The confounders were sex, age, smoking, physical activity, alcohol intake, and energy intake. All analyses were conducted on 1) the entire population and 2) a subsample excluding LERs.

RESULTS

In the univariate analyses of the entire population, GL was inversely associated with BMI. No association was observed for GI. After full adjustment (including energy intake), both GI and GL were positively associated with BMI. When LERs were excluded, GL was positively associated with BMI in all analyses, and GI was positively associated with BMI in the multiple analyses.

CONCLUSIONS

We showed a positive association between GI, GL, and BMI. Energy adjustment and the exclusion of LERs significantly affected the results of the analysis; thus, we stress the importance of energy adjustment.

The Dietary Quality Score: validation and association with cardiovascular risk factors: the Inter99 study

OBJECTIVE

To develop and assess the validity of the Dietary Quality Score (DQS) and investigate the association with cardiovascular risk factors.

DESIGN

Cross-sectional population-based study.

SETTING

Copenhagen County, Glostrup, Denmark.

SUBJECTS

A random sample of 12,934 men and women aged 30-60 years were invited to a health examination. A total of 6542 participants were included in the statistical analysis.

METHODS

The DQS was developed using eight questions from a 48-item food frequency questionnaire (FFQ) and validated using a 198-item FFQ. Associations between the DQS and fasting serum lipids, homocysteine, blood pressure and the absolute risk of ischaemic heart disease (IHD) were explored.

RESULTS

A higher DQS was shown to be associated with higher dietary quality in general, including a low intake of fat, especially saturated fat; a high intake of fibre; various vitamins and minerals; and fruit, fish, vegetables and whole-grain products. A higher score according to the DQS was significantly negatively associated with total cholesterol (P=0.0031), triglyceride (P=0.0406), low-density lipoprotein-cholesterol (P=0.0071), homocysteine (P<0.0001) and the absolute risk of IHD (P<0.0001), adjusted for sex, age, smoking habits and physical activity level.

CONCLUSIONS

The DQS is a simple, valid and quick tool to make a rough classification of individuals into groups with high, average and low dietary quality. The DQS is negatively associated with serum lipids, homocysteine and the absolute risk of IHD.

SPONSORSHIP

The Inter99 study is supported economically by The Danish Medical Research Council, The Danish Centre for Evaluation and Health Technology Assessment, Novo Nordisk, Copenhagen County, The Danish Heart Foundation, The Danish Pharmaceutical Association, Augustinus Foundation, Ib Henriksen Foundation and Becket Foundation, Copenhagen County.

The association between atopy and factors influencing folate metabolism: is low folate status causally related to the development of atopy?

BACKGROUND

Deficiency of folate has been associated with several disorders characterized by enhanced activation of the cellular immune system (non-allergic th1 type immune response). Whether folate status is also associated with atopic disease (allergic th2 type immune response) is unknown. We aimed at examining the association between atopy and markers of impaired folate metabolism, i.e. MTHFR(C677T) genotype, plasma total homocysteine, and dietary intakes of methionine, folates, and vitamins B12, B6, and B2.

METHODS

Cross-sectional population-based study of 1,671 male and female residents of Copenhagen County, Denmark, aged 30-60 years participating in a health examination during 1999-2001. Atopy was defined as positive levels of specific IgE against a panel of inhalant allergens. MTHFR(C677T) genotype was determined by PCR followed by restriction fragment length polymorphism analyses. Total homocysteine was measured by fluorescent polarization immunoassay. Dietary vitamin intakes were estimated from a semi-quantitative food frequency questionnaire.

RESULTS

The prevalence of atopy was associated with MTHFR(C677T) genotype. TT individuals had a significantly higher risk of atopy compared with CC/CT individuals [odds ratio 1.76, 95% confidence interval (95% CI) 1.19-2.60]. Additionally, gene-diet interaction effects were identified. Dietary markers were negatively associated with risk of atopy in persons with the TT genotype. Total homocysteine was not related to atopy (odds ratio per 5 mumol/l = 1.12, 95% CI 0.98-1.29).

CONCLUSIONS

The results suggest that an impaired folate metabolism may be causally related to the development of atopy.

A statistical approach based on substitution of macronutrients provides additional information to models analyzing single dietary factors in relation to type 2 diabetes in danish adults: the Inter99 study

Most studies analyzing diet-disease relations focus on single dietary factors rather than combining different nutrients into the same statistical model. The objective of this study was to identify dietary factors associated with the probability of having diabetes identified by screening (SDM) in Danish men and women aged 30-60 y. A specific objective was to examine whether an alternative statistical approach could provide additional information to already existing statistical approaches used in nutritional epidemiology. Baseline data from the Danish population-based Inter99 study were used. The dietary intake of 262 individuals with SDM was compared with that of 4627 individuals with normal glucose tolerance (NGT) using 2 different types of multiple logistic regression models adjusted for potential confounders. The first model included single dietary factors, whereas the second model was based on substitution of macronutrients. In the models with single dietary factors, high intakes of carbohydrates, dietary fiber, and coffee were inversely associated with SDM (P < 0.01), whereas high intakes of total fat and saturated fat were positively associated with SDM (P < 0.05). A modest U-shaped association was found between alcohol consumption and SDM (P = 0.10) [corrected] Results from the substitution model showed that when 3% of energy (En%) as carbohydrate replaced 3 En% fat or alcohol, the probability of having SDM decreased by 9 and 10%, respectively (P < 0.01) [corrected] No other macronutrient substitutions resulted in significant associations. Hence, the statistical approach based on substitution of macronutrients provided additional information to the model analyzing single dietary factors.

Dietary glycemic index, glycemic load, fiber, simple sugars, and insulin resistance: the Inter99 study

OBJECTIVE

To examine the relationship between daily glycemic index, daily glycemic load, simple sugars, dietary fiber, and the prevalence of a measure of insulin resistance in 30- to 60-year-old nondiabetic Danish men and women.

RESEARCH DESIGN AND METHODS

The Inter99 study is a nonpharmacological intervention study. We used baseline data and examined cross-sectional associations between carbohydrate-related dietary factors and an estimate of insulin resistance in 5,675 subjects at 30-60 years. The dietary intake was estimated from a self-administered food frequency questionnaire, and insulin resistance was estimated using the homeostasis model assessment of insulin resistance (HOMA-IR). Multiple regressions were performed with HOMA-IR as the dependent variable and carbohydrate-related factors as explanatory variables. All models were adjusted for age, sex, smoking, physical activity, total energy intake, BMI, and waist circumference.

RESULTS

Intake of lactose was positively associated with HOMA-IR (P < 0.0001), whereas daily glycemic load and intake of glucose, fructose, dietary fiber, total carbohydrate, fruit, and vegetables were inversely associated with HOMA-IR (P < 0.05). Intake of dietary fiber explained the associations with daily glycemic load and total carbohydrate and attenuated the association with fruit and vegetables. No significant associations were observed for daily glycemic index or sucrose.

CONCLUSIONS

Habitual intake of diets with a high glycemic index and high glycemic load or diets with a high content of total carbohydrate including simple sugars was not associated with the probability of having insulin resistance. Furthermore, intake of dietary fiber was inversely associated with the probability of having insulin resistance.