Longitudinal Development of Infant Complementary Diet Diversity in 3 International Cohorts.

OBJECTIVES: To evaluate international differences in the development of minimum dietary diversity (MDD) between 6 and 12 months of age. STUDY DESIGN: Breastfed infants (115, 100, and 109 in Shanghai, Cincinnati, and Mexico City, respectively) were enrolled near birth and dietary intake assessed weekly by 24-hour recall of food frequency. Diet diversity per month from age 6-12 months was assessed as at least 4 of 7 food groups provided on the previous day. RESULTS: Across all cohorts, dietary diversity increased from 6 (31%) to 12 (92%) months of age. Shanghai infants were significantly more likely to achieve MDD than the other cohorts at each month of age. Meat/seafood accounted for a higher proportion of infant feeds in Shanghai compared with the other cohorts, and eggs were only fed in Shanghai, and proportional intake of dairy, grains, and fruit were highest in Cincinnati. Only 28% of Cincinnati infants fed >50% human milk achieved MDD between 6 and 12 months. CONCLUSIONS: The proportion of infants between 6 and 12 months achieving MDD was significantly higher in Shanghai than in Mexico City or Cincinnati at all ages. Of particular concern was low dietary diversity among highly breastfed Cincinnati cohort infants, suggesting a need for greater education of breastfeeding mothers about the need to introduce a diverse complementary food diet.

Rapid deterioration of insulin secretion in obese adolescents preceding the onset of type 2 diabetes.

OBJECTIVE: To identify pathophysiologic changes that lead to the onset of type 2 diabetes (T2DM) in adolescents. STUDY DESIGN: Obese adolescents with normal glucose tolerance (n = 41) were studied longitudinally over the course of 4 years with serial measure of the acute insulin response to glucose (AIRg) as well as proinsulin (PI) concentrations. Insulin resistance was estimated with the homeostatic model assessment of insulin resistance (HOMA-IR), the disposition index (DI) computed as AIRg × 1/HOMA-IR, and intravenous glucose tolerance estimated as the glucose disappearance constant. RESULTS: Four adolescents developed diabetes mellitus (DM) during the study, and the rest of the cohort remained nondiabetic. Baseline PI exceeded the IQR of the nondiabetic group in 3 of 4 subjects with DM, and all had >85% reduction from baseline AIRg, and DI, within 6 months of diagnosis. All the subjects with DM gained weight over the course of the study, but these changes paralleled those for the nondiabetic group. HOMA-IR increased substantially in 1 of the subjects with DM at the time of diagnosis but was comparable with baseline in the other 3. The DI and glucose disappearance constant of the subjects with DM was less than the 10th percentile of the nondiabetic group before and after diagnosis. CONCLUSION: Conversion from normal glucose tolerance to T2DM in adolescents can occur rapidly, and the onset of T2DM is heralded by a substantial decrease in AIRg and DI, as well as increased release of PI. These results support loss of ß-cell function as the proximate step in the development of T2DM in this age group.

Heightened attention to supplementation is needed to improve the vitamin D status of breastfeeding mothers and infants when sunshine exposure is restricted.

Although exclusively breastfed infants are at increased risk of vitamin D (vit D) deficiency if vit D supplementation is lacking and sun exposure is limited, assessment of both risk factors in the first year of life is lacking. We evaluated the contribution of vit D intake and sunlight exposure to vit D status in 120 healthy, breastfeeding mother-infant dyads, who were followed up for 1 year. Vitamin D intake and skin sunlight exposure were evaluated using questionnaires. Serum 25-hydroxyvitamin D, parathyroid hormone (PTH) and alkaline phosphatase levels were determined post-natally in mothers at 4 weeks and in infants at 4, 26 and 52 weeks. Vitamin D supplementation was low (<20%) and sunlight exposure was common (93%) in study infants. At 4 weeks, 17% of mothers were vit D deficient (<50 nmol L(-1)) and 49% were insufficient (50-<75 nmol L(-1)), while 18% of infants were severely vit D deficient (<25 nmol L(-1)) and 77% were deficient (<50 nmol L(-1)). At 26 weeks, winter/spring birth season and shorter duration of months of exclusive breastfeeding were protective of vit D deficiency in infants. Vitamin D deficiency in infants decreased to 12% at 52 weeks with sunlight exposure. Serum PTH levels were significantly higher in severely vit D deficient than sufficient infants. Vitamin D deficiency was widespread in early post-partum breastfeeding mothers and infants, and declined to one in eight infants at 52 weeks due mostly to sunshine exposure. When sunlight exposure is limited or restricted, intensified vit D supplementation of breastfeeding mothers and infants is needed to improve vit D status.

Specific infant feeding practices do not consistently explain variation in anthropometry at age 1 year in urban United States, Mexico, and China cohorts.

Infant feeding practices generally influence infant growth, but it is unclear how introduction of specific foods affects growth across global populations. We studied 3 urban populations in the Global Exploration of Human Milk study to determine the association between infant feeding and anthropometry at 1 y of age. Three hundred sixty-five breastfeeding mother-infant pairs (120 US, 120 China, and 125 Mexico) were recruited soon after the infant's birth. Enrollment required agreement to breastfeed ≥75% for at least 3 mo. Weekly, 24-h, food frequency data were conducted on infants for 1 y and exclusive breastfeeding (EBF) duration and timing of specific complementary food introduction were calculated. Weight and length were measured at age 1 y and anthropometry Z-scores calculated using WHO standards. Cohorts in the 3 urban populations (Shanghai, China; Cincinnati, USA; and Mexico City, Mexico) differed by median EBF duration (5, 14, and 7 wk, respectively; P < 0.001), timing of introduction of meat/eggs/legumes (4.8, 9.3, and 7.0 mo, respectively; P < 0.0001), and other feeding practices. By age 1 y, infants in Shanghai were heavier and longer than Cincinnati and Mexico City infants (P < 0.001). Adjusting for nonfeeding covariates, the only feeding variable associated with anthropometry was EBF duration, which was modestly inversely associated with weight-for-age but not length-for-age or BMI Z-scores at 1 y. Although feeding variables differed by cohort, their impact on anthropometry differences was not consistent among cohorts. Overall, across these urban, international, breast-fed cohorts, differences in specific feeding practices did not explain the significant variation in anthropometry.

ß-cell dysfunction in adolescents and adults with newly diagnosed type 2 diabetes mellitus.

OBJECTIVE: To compare ß-cell function in adolescents and adults with newly diagnosed type 2 diabetes (T2DM). STUDY DESIGN: Thirty-nine adolescents with T2DM, 38 age- and weight-matched control subjects, and 19 adults with T2DM were studied. The adolescent subjects with diabetes were divided on the basis of whether they needed insulin to control their initial hyperglycemia. The primary outcome variable was the disposition index, computed from the acute insulin response to glucose corrected for insulin sensitivity (1/Homeostatic model assessment of insulin resistance). RESULTS: The disposition index was significantly reduced in all 3 diabetic groups (control n=3360, adolescents with T2DM without insulin n=630, adolescents with T2DM with insulin n=120, adults with T2DM n=200; P<.001), and the adolescents with more severe hyperglycemia at diagnosis had lower disposition index than those with a more modest presentation (P<.05). CONCLUSION: At the time of diagnosis, adolescents with T2DM have significant ß-cell dysfunction, comparable with adults newly diagnosed with T2DM. Thus, severe ß-cell impairment can develop within the first two decades of life and is likely to play a central role in the pathogenesis of T2DM in adolescents.