Health effects of cow's milk consumption in infants up to 3 years of age: a systematic review and meta-analysis.

OBJECTIVE: To summarize the best available evidence regarding the short- and long-term health effects of cow's milk intake in healthy, full-term infants up to 3 years of age. DESIGN: We conducted a systematic review and meta-analysis. SETTING: We searched MEDLINE (via PubMed), EMBASE and the Cochrane Library between 1960 and July 2013 and manually reviewed reference lists of pertinent articles. Two researchers independently reviewed abstracts and full-text articles and extracted relevant data. SUBJECTS: We included (randomized/non-randomized) controlled trials and observational studies. RESULTS: We included data from twenty-three studies (one randomized controlled trial, four non-randomized controlled trials, eight case-control studies and ten cohort studies) for the evidence synthesis. Pooled results of four studies revealed a higher risk of Fe-deficiency anaemia for infants consuming cow's milk compared with those consuming follow-on formula (relative risk=3·76; 95 % CI 2·73, 5·19). For type 1 diabetes mellitus, six out of seven case-control studies did not show a difference in the risk of developing this disease based on the age of introduction of cow's milk. We did not find negative associations for other health effects. CONCLUSIONS: Cow's milk consumption in infancy is associated with an increased risk of developing Fe-deficiency anaemia. Limiting cow's milk consumption may be important to ensure an adequate Fe intake for infants and toddlers. High-quality patient information for caregivers is needed on how infants' Fe requirements can be met.

Metabolic rates in female guinea pigs during different reproductive stages.

Reproduction in female mammals is characterized by major changes in steroid hormone concentrations, which can be linked to fluctuations in energy expenditure (EE). Estradiol and cortisol can increase EE and metabolic rates (MRs), but knowledge on MR changes during the estrous cycle and gestation is scarce for many species. This also applies to the domestic guinea pig, a species exhibiting an exceptional estrous cycle among rodents. In this study, MRs were measured through oxygen (O2) consumption in female guinea pigs during different reproductive stages. Mean O2 consumption over 2.5 h, resting metabolic rate (RMR, lowest and most stable O2 consumption over 3 min), body mass, fecal estrogen and progesterone, and saliva cortisol concentrations were measured in twelve female guinea pigs in a repeated measurements design during diestrus, estrus, and the second trimester of gestation. In estrus, body mass was significantly lower and estrogen and cortisol concentrations were significantly higher compared to diestrus and gestation. Mean O2 consumption and RMR both were significantly increased in estrus compared to diestrus. Additionally, a positive effect of body mass on MRs detected during diestrus and gestation was not found during estrus. Mean O2 consumption was also higher during gestation compared to diestrus, and a significant increase in cortisol concentrations during the 2.5-h MR measurement was recorded. The results indicate that estrus in guinea pigs is energetically demanding, which probably reflects catabolic effects of estrogens and cortisol that uncoupled MRs from body mass. Knowledge on the energetic requirements associated with different reproductive stages is important for future physiological and behavioral studies on female guinea pigs.