Chromium is not an essential trace element for mammals: effects of a "low-chromium" diet.

Chromium was proposed to be an essential trace element over 50 years ago and has been accepted as an essential element for over 30 years. However, the studies on which chromium's status are based are methodologically flawed. Whether chromium is an essential element has been examined for the first time in carefully controlled metal-free conditions using a series of purified diets containing various chromium contents. Male Zucker lean rats were housed in specially designed metal-free cages for 6 months and fed the AIN-93G diet with no added chromium in the mineral mix component of the diet, the standard AIN-93G diet, the standard AIN-93G diet supplemented with 200 µg Cr/kg, or the standard AIN-93G diet supplemented with 1,000 µg Cr/kg. The chromium content of the diet had no effect on body mass or food intake. Similarly, the chromium content of the diet had no effect on glucose levels in glucose tolerance or insulin tolerance tests. However, a distinct trend toward lower insulin levels under the curve after a glucose challenge was observed with increasing chromium content in the diet; rats on the supplemented AIN-93G diets had significantly lower areas (P < 0.05) than rats on the low-chromium diet. The studies reveal that a diet with as little chromium as reasonably possible had no effect on body composition, glucose metabolism, or insulin sensitivity compared with a chromium-"sufficient" diet. Together with the results of other recent studies, these results clearly indicate that chromium can no longer be considered an essential element.

Benefits of postpyloric enteral access placement by a nutrition support dietitian.

BACKGROUND: Although enteral nutrition is considered the preferred strategy for nutrition support, it is often precluded by nasogastric feeding intolerance or the inability to place feeding access into the postpyloric position. In an effort to improve enteral nutrition (EN) outcomes at our institution, the nutrition support dietitian (NSD) began placing postpyloric feeding tubes (PPFT) in intensive care unit patients. METHODS: Intensive care unit patients who received blind, bedside PPFT placements by the NSD (n = 18) were compared with a concurrent age- and diagnosis-matched control group that received standard nutritional care without NSD intervention (n = 18). Interruption of EN infusion, appropriateness of parenteral nutrition (PN) prescription (based on American Society of Parenteral and Enteral Nutrition guidelines), and incidence of ventilator-associated pneumonia (VAP), as defined by the American College of Chest Physicians practice guidelines, were determined in each group. RESULTS: The NSD was successful in positioning the PPFT at or distal to the third portion of the duodenum in 83% of attempts. The PPFT group demonstrated no interruption of enteral feeding compared with 56% in the control group (p < .01) and required 1 (6%) PN initiation in contrast to 8 (44%) in the control group (p < .01). There was a trend toward reduced VAP in the PPFT group (6% vs 28%, p = .07). Of the PN initiations in the control group, 88% were deemed to be potentially avoidable; 6 of 8 PNs were initiated because of gastric residuals. CONCLUSIONS: Enteral nutrition facilitated by NSD placement of postpyloric feeding access is associated with improved tube feeding tolerance and reduced PN use. Further studies are needed to evaluate a possible effect of postpyloric feeding on the incidence of VAP.