Bryndis E. Birgisdottir

Birth weight and risk of type 2 diabetes: A systematic review

CONTEXT Low birth weight is implicated as a risk factor for type 2 diabetes. However, the strength, consistency, independence, and shape of the association have not been systematically examined. OBJECTIVE To conduct a quantitative systematic review examining published evidence on the association of birth weight and type 2 diabetes in adults. DATA SOURCES AND STUDY SELECTION Relevant studies published by June 2008 were identified through literature searches using EMBASE (from 1980), MEDLINE (from 1950), and Web of Science (from 1980), with a combination of text words and Medical Subject Headings. Studies with either quantitative or qualitative estimates of the association between birth weight and type 2 diabetes were included. DATA EXTRACTION Estimates of association (odds ratio [OR] per kilogram of increase in birth weight) were obtained from authors or from published reports in models that allowed the effects of adjustment (for body mass index and socioeconomic status) and the effects of exclusion (for macrosomia and maternal diabetes) to be examined. Estimates were pooled using random-effects models, allowing for the possibility that true associations differed between populations. DATA SYNTHESIS Of 327 reports identified, 31 were found to be relevant. Data were obtained from 30 of these reports (31 populations; 6090 diabetes cases; 152 084 individuals). Inverse birth weight-type 2 diabetes associations were observed in 23 populations (9 of which were statistically significant) and positive associations were found in 8 (2 of which were statistically significant). Appreciable heterogeneity between populations (I(2) = 66%; 95% confidence interval [CI], 51%-77%) was largely explained by positive associations in 2 native North American populations with high prevalences of maternal diabetes and in 1 other population of young adults. In the remaining 28 populations, the pooled OR of type 2 diabetes, adjusted for age and sex, was 0.75 (95% CI, 0.70-0.81) per kilogram. The shape of the birth weight-type 2 diabetes association was strongly graded, particularly at birth weights of 3 kg or less. Adjustment for current body mass index slightly strengthened the association (OR, 0.76 [95% CI, 0.70-0.82] before adjustment and 0.70 [95% CI, 0.65-0.76] after adjustment). Adjustment for socioeconomic status did not materially affect the association (OR, 0.77 [95% CI, 0.70-0.84] before adjustment and 0.78 [95% CI, 0.72-0.84] after adjustment). There was no strong evidence of publication or small study bias. CONCLUSION In most populations studied, birth weight was inversely related to type 2 diabetes risk.

Maternal dietary patterns and preterm delivery: results from large prospective cohort study

Objective To examine whether an association exists between maternal dietary patterns and risk of preterm delivery. Design Prospective cohort study. Setting Norway, between 2002 and 2008. Participants 66 000 pregnant women (singletons, answered food frequency questionnaire, no missing information about parity or previously preterm delivery, pregnancy duration between 22+0 and 41+6 gestational weeks, no diabetes, first enrolment pregnancy). Main outcome measure Hazard ratio for preterm delivery according to level of adherence to three distinct dietary patterns interpreted as “prudent” (for example, vegetables, fruits, oils, water as beverage, whole grain cereals, fibre rich bread), “Western” (salty and sweet snacks, white bread, desserts, processed meat products), and “traditional” (potatoes, fish). Results After adjustment for covariates, high scores on the “prudent” pattern were associated with significantly reduced risk of preterm delivery hazard ratio for the highest versus the lowest third (0.88, 95% confidence interval 0.80 to 0.97). The prudent pattern was also associated with a significantly lower risk of late and spontaneous preterm delivery. No independent association with preterm delivery was found for the “Western” pattern. The “traditional” pattern was associated with reduced risk of preterm delivery for the highest versus the lowest third (hazard ratio 0.91, 0.83 to 0.99). Conclusion This study showed that women adhering to a “prudent” or a “traditional” dietary pattern during pregnancy were at lower risk of preterm delivery compared with other women. Although these findings cannot establish causality, they support dietary advice to pregnant women to eat a balanced diet including vegetables, fruit, whole grains, and fish and to drink water. Our results indicate that increasing the intake of foods associated with a prudent dietary pattern is more important than totally excluding processed food, fast food, junk food, and snacks.

Relationship between size at birth and hypertension in a genetically homogeneous population of high birth weight.

Objective To investigate the association between birth size and hypertension within a genetically homogenous population of high birth weight. Design Cohort-study with retrospectively collected data on size at birth. Subjects and setting The study included 4601 men and women born 1914–1935 in Reykjavik, Iceland, who participated in the Reykjavik Study of the Icelandic Heart Association. Main outcome measures Birth size measurements, adult blood pressure (BP) and body mass index (BMI), and family history of hypertension. Results Birth weight was inversely related to hypertension in adulthood in women (P for trend < 0.001). The relationship was of borderline significance in men (P for trend = 0.051). A low ponderal index was significantly associated with high BP in women (P for trend = 0.025) but not men (P > 0.05). For women with an adult BMI > 26 kg/m2, the odds ratio for hypertension for those born weighing < 3.45 kg was 2.1 [95% confidence interval, 1.3–3.3, compared with women born weighing > 3.75 kg. The association was only significant in women without a family history of hypertension. Conclusions An inverse association between size at birth and adult hypertension was seen in a population of greater birth size than has previously been investigated. The relation was strongest among women born small who were overweight in adulthood, and for those without a family history of hypertension. The results support the hypothesis that the association between birth weight and hypertension is not of genetic origin only. The large birth size of Icelanders might be protective and partly explain the lower mean systolic blood pressure in Iceland than in related nations.

Does high sugar consumption exacerbate cardiometabolic risk factors and increase the risk of type 2 diabetes and cardiovascular disease

Consumption of sugar has been relatively high in the Nordic countries; the impact of sugar intake on metabolic risk factors and related diseases has been debated. The objectives were to assess the effect of sugar intake (sugar-sweetened beverages, sucrose and fructose) on association with type 2 diabetes, cardiovascular disease and related metabolic risk factors (impaired glucose tolerance, insulin sensitivity, dyslipidemia, blood pressure, uric acid, inflammation markers), and on all-cause mortality, through a systematic review of prospective cohort studies and randomised controlled intervention studies published between January 2000 and search dates. The methods adopted were as follows: the first search was run in PubMed in October 2010. A second search with uric acid as risk marker was run in April 2011. The total search strategy was rerun in April 2011 in SveMed+. An update was run in PubMed in January 2012. Two authors independently selected studies for inclusion from the 2,743 abstracts according to predefined eligibility criteria. The outcome was that out of the 17 studies extracted, 15 were prospective cohort studies and two were randomised controlled crossover trials. All of the studies included only adults. With respect to incident type 2 diabetes (nine studies), four of six prospective cohort studies found a significant positive association for sugar-sweetened beverage intake. In general, larger cohort studies with longer follow-up more often reported positive associations, and BMI seemed to mediate part of the increased risk. For other metabolic or cardiovascular risk factors or outcomes, too few studies have been published to draw conclusions. In conclusion, data from prospective cohort studies published in the years 2000–2011 suggest that sugar-sweetened beverages probably increase the risk of type 2 diabetes. For related metabolic risk factors, cardiovascular disease or all-cause mortality and other types of sugars, too few studies were available to draw conclusions.

Association between size at birth, truncal fat and obesity in adult life and its contribution to blood pressure and coronary heart disease; study in a high birth weight population.

Objective: The aim of the study was to assess the relationship between size at birth and obesity as well as truncal fat, and its contribution to cardiovascular risk in a high birth weight population.Design: Cohort-study with retrospectively collected data on size at birth.Setting: Reykjavik, Iceland.Subjects: A total of 1874 men and 1833 women born in Reykjavik during 1914–1935.Main outcome measures: Size at birth. Adult weight, height and skinfold thickness measurements, systolic and diastolic blood pressure, fatal and nonfatal coronary heart disease (CHD).Results: Birth weight was positively related to adult body mass index (BMI) in both genders (B=0.35±0.14 kg/m2, adj. R2=0.015, P=0.012 and B=0.34±0.17 kg/m2, adj. R2=0.055, P=0.043 in men and women, respectively). However, high birth weight was not a risk factor for adult obesity (BMI≥30 kg/m2). In the highest birth weight quartile, the odds ratio (95% CI) for being above the 90th percentile of truncal fat was 0.7 (0.6–1.0, P=0.021) for men and 0.4 (0.3–0.8, P=0.002) for women, compared with the lowest birth weight quartile. Truncal fat and BMI were positively related to blood pressure in both genders (P<0.05), but not to CHD. The regression coefficient for the inverse association between birth weight and blood pressure hardly changed when adding truncal fat to the model.Conclusion: In this high birth weight population, high birth weight was related to higher BMI in adulthood without being a risk factor for adult obesity. The inverse association between birth weight and truncal fat in adulthood suggests a role for foetal development in determining adult fat distribution. The inverse relationship of birth weight to blood pressure seems not to be mediated through the same pathway as to truncal fat.

Dietary fiber and the glycemic index: a background paper for the Nordic Nutrition Recommendations 2012

The aim of this study is to review recent data on dietary fiber (DF) and the glycemic index (GI), with special focus on studies from the Nordic countries regarding cardiometabolic risk factors, type 2 diabetes, cardiovascular disease, cancer, and total mortality. In this study, recent guidelines and scientific background papers or updates on older reports on DF and GI published between 2000 and 2011 from the US, EU, WHO, and the World Cancer Research Fund were reviewed, as well as prospective cohort and intervention studies carried out in the Nordic countries. All of the reports support the role for fiber-rich foods and DF as an important part of a healthy diet. All of the five identified Nordic papers found protective associations between high intake of DF and health outcomes; lower risk of cardiovascular disease, type 2 diabetes, colorectal and breast cancer. None of the reports and few of the Nordic papers found clear evidence for the GI in prevention of risk factors or diseases in healthy populations, although association was found in sub-groups, e.g. overweight and obese individuals and suggestive for prevention of type 2 diabetes. It was concluded that DF is associated with decreased risk of different chronic diseases and metabolic conditions. There is not enough evidence that choosing foods with low GI will decrease the risk of chronic diseases in the population overall. However, there is suggestive evidence that ranking food based on their GI might be of use for overweight and obese individuals. Issues regarding methodology, validity and practicality of the GI remain to be clarified.

Association between healthy maternal dietary pattern and risk for gestational diabetes mellitus.

Background/Objectives:Gestational diabetes mellitus (GDM) is associated with negative health effects for mother and child. The aim was to investigate the association between maternal dietary patterns and GDM.Subjects/Methods:Prospective observational study including 168 pregnant women aged 18–40 years, recruited at routine 20-week ultrasound. All participants kept a 4-day weighed food record following recruitment (commencement: gestational weeks 19–24). Principal component analysis was used to extract dietary patterns from 29 food groups. A Healthy Eating Index (HEI) was constructed. All women underwent an oral glucose tolerance test in weeks 23–28.Results:One clear dietary pattern (Eigenvalue 2.4) was extracted with positive factor loadings for seafood; eggs; vegetables; fruits and berries; vegetable oils; nuts and seeds; pasta; breakfast cereals; and coffee, tea and cocoa powder, and negative factor loadings for soft drinks and French fries. This pattern was labeled a prudent dietary pattern. Explained variance was 8.2%. The prevalence of GDM was 2.3% among women of normal weight before pregnancy (n=86) and 18.3% among overweight/obese women (n=82). The prudent dietary pattern was associated with lower risk of GDM (OR: 0.54; 95% CI: 0.30, 0.98). When adjusting for age, parity, prepregnancy weight, energy intake, weekly weight gain and total metabolic equivalent of task the association remained (OR: 0.36; 95% CI: 0.14, 0.94). Similar results were found when only including overweight or obese women (OR: 0.31; 95% CI: 0.13, 0.75).Conclusions:Adhering to a prudent dietary pattern in pregnancy was clearly associated with lower risk of GDM, especially among women already at higher risk because of overweight/obesity before pregnancy.

Childhood Growth and Adult Hypertension in a Population of High Birth Weight

Low birth weight has consistently been associated with increased adult blood pressure. The relative importance of childhood growth is, however, less well established. This study examined sex-specific associations between childhood growth and adult blood pressure in 2120 subjects born from 1921 to 1935 in Reykjavik who were recruited into a longitudinal study in 1967–1991. Size at birth and growth at regular intervals between 8 and 13 years were collected from national archives. Hypertensive males did not differ from normotensive males at birth but were increasingly taller and of higher body mass index between 8 and 13 years. No differences in adult height were observed between hypertensive and normotensive males. For boys, growth-velocity (change in growth per year) for body mass index and height between 8 to 13 years was positively associated (P<0.05) with adult blood pressure. The association for body mass index-velocity was fully accounted for by concurrent body size, whereas height-velocity was independent of birth weight and concurrent body size. Males in the highest compared with the lowest tertile in the height-velocity distribution had 66% increased risks of hypertension (95% CI: 15% to 139% increased risks of hypertension) corresponding with 5.0 mm Hg increase (95% CI: 1.5 to 8.5 mm Hg increase) and 3.1 mm Hg increase (95% CI: 1.1 to 5.0 mm Hg increase) in systolic and diastolic blood pressures, respectively. Hypertensive females weighed less at birth but did not differ markedly from normotensive girls between 8 and 13 years, and no association was observed for growth-velocity. In conclusion, rapid linear growth between 8 and 13 years predicts elevated adult blood pressure in boys. This association is likely to reflect relatively early onset of puberty among hypertensive males.

Fish consumption among young overweight European adults and compliance to varying seafood content in four weight loss intervention diets.

BACKGROUND Fish is considered an important part of a healthy diet and is frequently recommended as a main course at least twice a week. OBJECTIVE To study the frequency of fish consumption among young overweight European adults and their compliance to varying seafood consumption in weight loss intervention diets. DESIGN After meeting the inclusion criteria, the subjects seafood intake was evaluated. Subjects were randomly assigned into four groups and were advised energy-restricted diets for 8 weeks, including no seafood (control), cod, salmon or fish oil. A validated FFQ was used to evaluate the consumption of seafood at baseline, midpoint and endpoint, and long-chain n-3 fatty acids in blood erythrocytes were measured. SETTING Iceland, Ireland and Spain. SUBJECTS The sample (n 324); 20-40-year-olds with BMI = 27.5-32.5 kg/m2; 85 % participated. RESULTS At baseline, 34 % of the participants reported eating fish at least twice a week as the main course. During the intervention, six participants reported that they did not finish their fish portions, 15 % of the participants consumed small amount of fish additional to the study protocol in weeks 1-4 and 23 % in weeks 5-8 (P = 0.010). Changes in erythrocyte long-chain n-3 fatty acids confirmed good compliance, with increases in the salmon (P < 0.001) and fish oil (P < 0.001) groups, smaller increase in the cod group (P = 0.037) and decrease in the control group (P = 0.030). CONCLUSION Frequency of fish consumption among 66 % of young European overweight adults is lower than frequently recommended. Compliance to varying seafood consumption was good. Therefore, including more fish in the diet of this group should be encouraged.

Possibilities and considerations when merging dietary data from the world's two largest pregnancy cohorts: the Danish National Birth Cohort and the Norwegian Mother and Child Cohort Study

To elucidate the research possibilities when merging data on maternal diet from the Danish National Birth Cohort (DNBC) and the Norwegian Mother and Child Cohort Study (MoBa), through comparison of (i) the methodology used for dietary assessment and (ii) the estimated intake of selected food groups in the two cohorts.