Enteral nutrition (EN) has been reported to have some physiological importance for critically ill patients. However, the advantage of EN over parenteral nutrition remains controversial in recent paradigms. To maximize the benefits and efficiency of EN, implementing measures based on comprehensive evidence is essential. Here, we systematically reviewed EN-related studies and integrated them into the best and most up-to-date EN practices. We extracted studies from 13 systematic reviews during the development of Japanese Critical Care Nutrition Guidelines, summarizing findings on the assessment of enteral feeding intolerance (EFI), the timing of EN, formula composition and nutrients, and method of administration in critically ill adult patients. Multifaceted EFI assessment may be needed in patients for high-risk patients. Early EN may reduce infectious complications, and initiating EN even earlier may offer an additional advantage. High protein intake (≥1.2 g/kg/day) could maintain muscle mass and physical function without increasing gastrointestinal complications. Probiotics, prebiotics, and synbiotics may serve as beneficial options for preventing infection and gastrointestinal complications, although their efficacy depends on the strains, types, and combinations used. For patients with EFI, post-pyloric feeding could be an effective approach, while intermittent feeding may be a safer approach. Both methods should be utilized to achieve nutritional targets. Integrating these nutritional interventions into EN strategies may help maximize their effectiveness and minimize complications. However, careful consideration regarding timing, dosage, nutrient selection, administration methods, and patient selection is required.

Exposure to an exogenous chemical via milk causes superimposition on the body burden that might have already existed in the neonatal organism due to in utero exposure. Such exposure via breast milk is avoidable, although transplacental exposure cannot be avoided at present. In this paper, mercury exposure via breast milk was examined in an animal model. Maternal guinea pigs were shortly exposed to mercury vapor at the mean concentrations of 6–70 mg/m³ immediately after parturition. Newborn guinea pigs were then nursed by the natural mothers. Mercury concentrations in breast milk and tissue samples were determined on d 3, 5, and 10 postpartum. Mercury concentrations in breast milk were slightly lower than plasma mercury concentrations of the maternal guinea pigs over the observation period. However, the decrease in the mercury concentration in breast milk with time was slower than that in maternal plasma. Mercury concentrations in major organs of the neonates were highest in kidney, followed by liver and lung. In brain and whole blood, mercury concentrations were slightly elevated compared with the nonexposed control. Organ distribution of mercury in the suckling neonates indicated that they were exposed via breast milk to inorganic, not elemental, mercury.