Breastfeeding protects against infectious diseases during infancy in industrialized countries. A systematic review.

Firstly, this review was performed to assess the effect of breastfeeding on infections during infancy in industrialized countries. Secondly, the effect of duration and exclusiveness of breastfeeding were explored. Studies were identified using Medline, Cochrane Library, Science Citation Index and by a manual search from bibliographies of articles from August 1986 to January 2008. Follow-up, case-control and randomized controlled trial (RCT) studies performed in an industrialized country, published in English, with breastfeeding as a determinant, with overall infections, gastrointestinal or respiratory tract infections as a major outcome, and at least 40 participants in the study were included. Using Bauchner's criteria published in a review in 1986, two reviewers and a peer reviewer assessed the internal validity of those studies. Twenty-one studies that met the inclusion and internal validity criteria were included. These included 16 follow-up and four case-control studies and one RCT. Four out of five studies observed decreased effects on overall infections in breastfed infants. With regard to gastrointestinal infections, six out of eight studies suggested that breastfeeding had a protective effect. Thirteen out of 16 studies concluded that breastfeeding protects infants against respiratory tract infections. Five studies combined duration and exclusiveness of breastfeeding. All studies observed a protective dose/duration-response effect on gastrointestinal or respiratory tract infections. These studies strongly suggest that breastfeeding protects infants against overall infections, gastrointestinal and respiratory tract infections in industrialized countries. The optimal duration of exclusive breastfeeding for protection against infectious diseases needs to be studied in more detail.

Innate handedness and disease-specific mortality in women.

BACKGROUND: Left-handedness has been reported to be associated with reduced life expectancy, but the evidence is far from conclusive. METHODS: We studied the association between innate handedness and total mortality, as well as cause-specific mortality, in a cohort of 12,178 middle-aged Dutch women who were followed for almost 13 years. The relation between handedness and mortality was analyzed using Cox regression in a case-cohort approach, in which a random sample of 1500 women was used to represent person-years under observation for the entire cohort. RESULTS: During a median follow-up of 12.6 years, 252 women died. Hazard ratios comparing left-handed women with other women were 1.4 for all-cause mortality (95% confidence interval = 0.9-2.0), 1.7 for total cancer mortality (1.0-2.7), 2.0 for breast cancer mortality (0.8-4.6), 4.6 for colorectal cancer mortality (1.5-14.3), 1.3 mortality from diseases of the circulatory system (0.5-3.3), and 3.7 for cerebrovascular mortality (1.1-12.1), after adjusting for potential confounders (socioeconomic status, age, body mass index, and cigarette smoking status at study recruitment). CONCLUSIONS: Left-handedness is associated with higher mortality in women.

Increased occurrence of left-handedness after severe childhood bacterial meningitis: support for the pathological left-handedness hypothesis.

The hypothesis that brain damage during infancy causes pathological left-handedness was tested by assessing handedness in 182 survivors of childhood non-Hemophilus influenza type b bacterial meningitis in the Netherlands (mean age of 9.7 years). These children were selected randomly after clustering them into those with or without parental report on academic and behavioural problems. Medical records were obtained from the hospitals, while handedness and neurodevelopmental outcome were assessed at school age. Logistic regression analysis was used to study the relationship between a severity score of bacterial meningitis and handedness. Fifteen percent were left-handed. Severity of childhood bacterial meningitis was related to left-handedness (Odds ratio (OR) 6.2, 95% confidence interval (CI) 2.0-18.6 for those with a total severity score above the median as compared to those below). Compared to non-left-handed children, left-handed children had lower IQ (mean difference -6.6, 95% CI -12 to -1.2), tended to have lower vocabulary scores on WISC-r (-1.0, -2.1 to 0), and lower Beery scores on visual-motor integration (-4.9, -10.1 to 0.4). Left-handed children also tended to have more combined academic and behavioural limitations (OR 2.7, 95% CI 0.9-8.6), lower manual speed of the dominant hand (mean difference -9 taps, p < 0.05) and better manual steadiness in the non-dominant hand (mean difference of contact's time -2.7 s, p < 0.05). Left-handed post-meningitic children generally have worse neurodevelopmental outcome than non-left-handed survivors. Our results support the role of early life brain damage in left-handedness.

Lower birth weight predicts metabolic syndrome in young adults: the Atherosclerosis Risk in Young Adults (ARYA)-study.

OBJECTIVE: To study the relationship between intrauterine growth and the metabolic syndrome, particularly fasting serum lipids in young adulthood. METHODS: Seven hundred and forty-four young adults aged 26-31 years participated in the ARYA birth cohort. Birth characteristics were available from charts kept by the Municipal Health Service, Utrecht, The Netherlands. Adult medical history and lifestyle information were assessed by questionnaires. Adult anthropometry, blood pressure, fasting plasma glucose, total cholesterol, HDL-cholesterol, triglycerides were measured, and LDL-cholesterol was calculated. RESULTS: Subjects in the lower tertiles of birth weight (1250-3209 and 3210-3649 g) had higher risks for metabolic syndrome than those in the highest birth weight tertile (3650-5500 g): odds ratio, 1.8; 95% confidence interval (CI) 1.0-3.5 and 1.4; 0.7-2.7, respectively; p for trend = 0.064, adjusted for gender, cardiovascular disease family history and current education. Birth weight was inversely related to systolic blood pressure (linear regression coefficient, -1.9 mmHg/kg birth weight; 95% CI -3.4 to -0.3) and to (log) triglycerides in mmol/L (-0.03/kg birth weight; 95% CI -0.06 to -0.01), adjusted for gender, current body mass index and current education. Birth weight showed inverse relations to diastolic blood pressure, serum glucose, total and LDL cholesterol and positive relations to waist circumference and HDL cholesterol levels, although not statistically significant. Birth length and ponderal index were not related to the metabolic syndrome or lipid profiles. CONCLUSION: Lower birth weight indicates a higher risk for metabolic syndrome in young adults, particularly through higher serum triglycerides and higher systolic blood pressure.