Enteral compared with parenteral nutrition: a meta-analysis

BACKGROUND

The difference in outcomes in patients is unclear when 2 types of enteral nutrition, ie, tube feeding and conventional oral diets with intravenous dextrose (standard care), are compared with parenteral nutrition.

OBJECTIVE

We reviewed systematically and aggregated statistically the results of prospective randomized clinical trials (PRCTs) to examine the relations among the nutrition interventions, complications, and mortality rates.

DESIGN

We conducted a MEDLINE search for PRCTs comparing the effects of enteral and parenteral nutrition in adults. Two different people abstracted data for the method and outcomes separately. We used fixed-effects meta-analysis technique to combine the relative risks (RRs) of the outcomes of infection, nutrition support complications, other complications, and mortality.

RESULTS

Twenty-seven studies in 1828 patients met the study criteria. Aggregated results showed a significantly lower RR of infection with tube feeding (0.64; 95% CI: 0.54, 0.76) and standard care (0.77; 95% CI: 0.65, 0.91). A priori hypotheses showed a lower RR of infection with tube feeding than with parenteral nutrition, regardless of nutritional status, presence of cancer, year of study publication, or quality of the study method. In studies in which participants had high rates of protein-energy malnutrition, there was a significantly higher risk of mortality (3.0; 95% CI: 10.9, 8.56) and a trend toward a higher risk of infection with standard care than with parenteral nutrition (1.17; 95% CI: 0.88, 1.56).

CONCLUSIONS

Tube feeding and standard care are associated with a lower risk of infection than is parenteral nutrition; however, mortality is higher and the risk of infection tends to be higher with standard care than with parenteral nutrition in malnourished populations.

Trial of the route of early nutritional support in critically ill adults

BACKGROUND

Uncertainty exists about the most effective route for delivery of early nutritional support in critically ill adults. We hypothesized that delivery through the parenteral route is superior to that through the enteral route.

METHODS

We conducted a pragmatic, randomized trial involving adults with an unplanned admission to one of 33 English intensive care units. We randomly assigned patients who could be fed through either the parenteral or the enteral route to a delivery route, with nutritional support initiated within 36 hours after admission and continued for up to 5 days. The primary outcome was all-cause mortality at 30 days.

RESULTS

We enrolled 2400 patients; 2388 (99.5%) were included in the analysis (1191 in the parenteral group and 1197 in the enteral group). By 30 days, 393 of 1188 patients (33.1%) in the parenteral group and 409 of 1195 patients (34.2%) in the enteral group had died (relative risk in parenteral group, 0.97; 95% confidence interval, 0.86 to 1.08; P=0.57). There were significant reductions in the parenteral group, as compared with the enteral group, in rates of hypoglycemia (44 patients [3.7%] vs. 74 patients [6.2%]; P=0.006) and vomiting (100 patients [8.4%] vs. 194 patients [16.2%]; P<0.001). There were no significant differences between the parenteral group and the enteral group in the mean number of treated infectious complications (0.22 vs. 0.21; P=0.72), 90-day mortality (442 of 1184 patients [37.3%] vs. 464 of 1188 patients [39.1%], P=0.40), in rates of 14 other secondary outcomes, or in rates of adverse events. Caloric intake was similar in the two groups, with the target intake not achieved in most patients.

CONCLUSIONS

We found no significant difference in 30-day mortality associated with the route of delivery of early nutritional support in critically ill adults. (Funded by the United Kingdom National Institute for Health Research; CALORIES Current Controlled Trials number, ISRCTN17386141.).

Does enteral nutrition compared to parenteral nutrition result in better outcomes in critically ill adult patients? A systematic review of the literature

OBJECTIVE

Nutritional support is part of the standard of care for the critically ill adult patient. In the average patient in the intensive care unit who has no contraindications to enteral nutrition (EN) or parenteral nutrition (PN), the choice of route for nutritional support may be influenced by several factors. Because EN and PN are associated with risks and benefits, we systematically reviewed and critically appraised the literature to compare EN with PN the critically ill patient.

METHODS

We searched computerized bibliographic databases, personal files, and relevant reference lists to identify potentially eligible studies. Only randomized clinical trials that compared EN with PN in critically ill patients with respect to clinically important outcomes were included in this review. In an independent fashion, relevant data on the methodology and outcomes of primary studies were abstracted in duplicate. The studies were subsequently aggregated statistically.

RESULTS

There were 13 studies that met the inclusion criteria and, hence, were included in our meta-analysis. The use of EN as opposed to PN was associated with a significant decrease in infectious complications (relative risk = 0.64, 95% confidence interval = 0.47 to 0.87, P = 0.004) but not with any difference in mortality rate (relative risk = 1.08, 95% confidence interval = 0.70 to 1.65, P = 0.7). There was no difference in the number of days on a ventilator or length of stay in the hospital between groups receiving EN or PN (Standardized Mean Difference [SMD] = 0.07, 95% confidence interval = -0.2 to 0.33, P = 0.6). PN was associated with a higher incidence of hyperglycemia. Data that compared days on a ventilator and the development of diarrhea in patients who received EN versus PN were inconclusive. In the EN and PN groups, complications with enteral and parenteral access were seen. Four studies documented cost savings with EN as opposed to PN.

CONCLUSION

The use of EN as opposed to PN results in an important decrease in the incidence of infectious complications in the critically ill and may be less costly. EN should be the first choice for nutritional support in the critically ill.

Chromium deficiency, glucose intolerance, and neuropathy reversed by chromium supplementation, in a patient receiving long-term total parenteral nutrition

A white female, now age 40 and receiving total parenteral nutrition for more than 5 years, developed unexpected 15% weight loss after 3 1/2 years of regimen, together with peripheral neuropathy confirmed by nerve conduction measurements. An intravenous glucose tolerance test showed that the fractional rate (K) had decreased to 0.89%/min (normal greater than 1.2). There was observed during this glucose infusion a borderline normal insulin response with a fall in plasma free fatty acids and in plasma leucine. During daily infusion of well over 400 g of glucose, the respiratory quotient was 0.66. Chromium balance was negative. Chromium levels were, in blood 0.55 ng/ml (normal 4.9 to 9.5) and in hair 154 to 175 ng/g (normal greater than 500). Regular insulin daily (45 micron) in the infusate nearly maintained euglycemia but despite this, and even with further glucose intake to restore weight loss, intravenous glucose tolerance test (K) and respiratory quotient were unchanged. Administration of insulin was then stopped and 250 microng of Cr added to the daily total parenteral nutrition infusate for 2 weeks. After this the intravenous glucose tolerance test (K) and respiratory quotient became normal (1.35 and 0.78, respectively). Over the next 5 months insulin was not needed and glucose intake had to be reduced substantially to avoid overweight. In this period nerve conduction and well-being returned to normal. With a maintenance addition of chromium to the total parenteral nutrition infusate (tentatively this addition is 20 microng/day) the patient has remained well for 18 months (to July 1976). These results suggest that relatively isolated chromium deficiency in man, hitherto poorly documented, causes 1) glucose intolerance, 2) inability to utilize glucose for energy, 3) neuropathy with normal insulin levels, 4) high free fatty acid levels and low respiratory quotient and, 5) abnormalities of nitrogen metabolism.

Pathogenesis of catheter sepsis: a prospective study with quantitative and semiquantitative cultures of catheter hub and segments

Our purpose was to study prospectively the causes, routes of infection, and frequency of catheter-related sepsis in patients on total parenteral nutrition. From January 1981 to January 1984, cultures of 135 subclavian catheters from 135 adult patients were done by quantitative and semiquantitative methods. Twenty patients (14.8%) had catheter-related sepsis. Fourteen episodes (70%) stemmed from an colonized hub. Skin infection (Staphylococcus aureus, 2 cases), total parenteral nutrition mixture contamination (Enterobacter cloacae, 2 cases), and hematogenous seeding of the catheter tip (Yersinia enterocolitica, 1 case, and Streptococcus faecalis, 1 case) accounted for the remaining six septic episodes. The catheter hub is, in our experience, the most common site of origin of organisms causing catheter tip infection and bacteremia.

Postoperative enteral versus parenteral nutrition in malnourished patients with gastrointestinal cancer: a randomised multicentre trial

BACKGROUND

Although current opinion favours the use of enteral over parenteral nutrition, the clinical benefits of early postoperative nutrition in patients undergoing elective surgery have never been clearly shown. We aimed to test the hypothesis that postoperative enteral nutrition is better (fewer postoperative complications) than parenteral nutrition containing similar energy and nitrogen amounts (112 kJ kg(-1) day(-1) and 1.4 g aminoacid kg(-1) day(-1)).

METHODS

We did a randomised multicentre clinical trial in patients with gastrointestinal cancer who were malnourished and candidates for major elective surgery. 159 patients were assigned to enteral nutrition and 158 to parenteral nutrition. The primary endpoint was the occurrence of postoperative complications, and secondary endpoints were length of postoperative hospital stay, adverse effects, and treatment crossover. Analysis was by intention to treat.

FINDINGS

Postoperative complications occurred in 54 (34%) patients fed enterally versus 78 (49%) fed parenterally (relative risk 0.69, 95% CI 0.53-0.90, p=0.005). Length of postoperative stay was 13.4 days and 15.0 days in the enteral nutrition and parenteral nutrition groups, respectively (p=0.009). Adverse effects occurred in 56 (35%) patients fed enterally versus 22 (14%) patients fed parenterally (2.50, 1.61-3.86, p<0.0001). 14 (9%) patients on enteral nutrition had to switch to parenteral nutrition, whereas none of those fed parenterally crossed over to enteral feeding.

INTERPRETATION

We conclude that early enteral nutrition significantly reduces the complication rate and duration of postoperative stay compared with parenteral nutrition, although parenteral nutrition is better tolerated than enteral nutrition.

Parenteral nutrition is associated with intestinal morphologic and functional changes in humans

BACKGROUND

Numerous animal studies have demonstrated intestinal villus atrophy occurs when luminal nutrition is withheld and total parenteral nutrition (TPN) is provided. Intestinal morphologic and functional changes have not been well studied in humans during TPN.

METHODS

Eight normal volunteers were hospitalized in the Clinical Research Center for 3 weeks. The subjects received TPN as an exclusive means of nutritional support for 14 days followed by 5 days of enteral refeeding with either a standard or a glutamine and arginine-supplemented formula. Endoscopic jejunal biopsies were taken before and after TPN and after enteral refeeding. Intestinal morphology was examined by light and transmission electron microscopy. Mucosa DNA, RNA, and protein concentrations were measured. Lactose breath hydrogen and intestinal permeability testing (urinary lactulose and mannitol excretion after an oral dose) were performed before and after TPN and after enteral refeeding.

RESULTS

Total mucosal thickness decreased after TPN (645 +/- 19 to 512 +/_ 19 microns, p = .003) and increased significantly towards baseline after enteral refeeding (575 +/- 19 microns, p = .04). The change was related solely to villus height; crypt depth was unaffected. Villus cell count decreased from 179 +/- 15 to 163 +/- 12 after TPN (p = .03) and increased after enteral refeeding to 176 +/- 21 (p = .06). Crypt cell count was unaffected by TPN or refeeding. A nonsignificant decrease in the mitotic index after TPN was seen. Intracellular edema developed during TPN and resolved with enteral refeeding. The urinary lactulose-mannitol ratio increased with TPN [0.06 +/- 0.03 to 0.11 +/- 0.05 after TPN and 0.14 +/_ 0.09 after short-term enteral refeeding (p = .05)], indicating increased intestinal permeability. The urinary lactulose-mannitol ratio was significantly greater after refeeding with standard formula than the free amino acid peptide formula with glutamine and arginine (0.20 +/- 0.05, vs 0.08 +/- 0.01, p = .05). No significant differences were noted in mucosal RNA, DNA, protein, DNA-protein or RNA-DNA rations or breath hydrogen after lactose ingestion after either TPN or enteral refeeding. No significant difference in plasma glutamine was found during TPN (462.7 +/ 38.7 vs 491.8 +/- 46.1 mumol/L) or after enteral refeeding (457.3 +/- 51.4 mumol/L).

CONCLUSIONS

Intestinal morphologic and functional changes occur in human for whom TPN is the sole nutritional source, although the findings in humans are substantially less significant than observed in animal models. The loss of mucosal structure may be sufficient to cause increased intestinal permeability, the clinical significance of which remains to be defined. Enteral nutrition is important in restoring and probably preventing morphologic intestinal changes associated with TPN, and a peptide and free amino acid-based formula supplemented with glutamine and arginine may have some added role. Our findings also suggest sepsis is associated with gut adaptation rather than degradation.

Parenteral vs. enteral nutrition in the critically ill patient: a meta-analysis of trials using the intention to treat principle

OBJECTIVE

Controversy surrounds the use of parenteral nutrition in critical illness. Previous overviews used composite scales to identify high-quality trials, which may mask important differences in true methodological quality. Using a component-based approach this meta-analysis investigated the effect of trial quality on overall conclusions reached when standard enteral nutrition is compared to standard parenteral nutrition in critically ill patients.

METHODS

An extensive literature search was undertaken to identify all eligible trials. We retrieved 465 publications, and 11 qualified for inclusion. Nine trials presented complete follow-up, allowing the conduct of an intention to treat analysis.

RESULTS

Aggregation revealed a mortality benefit in favour of parenteral nutrition, with no heterogeneity. A priori specified subgroup analysis demonstrated the presence of a potentially important treatment-subgroup interaction between studies of parenteral vs. early enteral nutrition compared to parenteral vs. late enteral. Six trials with complete follow-up reported infectious complications. Infectious complications were increased with parenteral use. The I(2) measure of heterogeneity was 37.7%.

CONCLUSIONS

Intention to treat trials demonstrated reduced mortality associated with parenteral nutrition use. A priori subgroup analysis attributed this reduction to trials comparing parenteral to delayed enteral nutrition. Despite an association with increased infectious complications, a grade B+ evidence-based recommendation (level II trials, no heterogeneity) can be generated for parenteral nutrition use in patients in whom enteral nutrition cannot be initiated within 24 h of ICU admission or injury.

Reversal of parenteral nutrition-associated liver disease in two infants with short bowel syndrome using parenteral fish oil: implications for future management

Here we report the reversal of cholestasis in 2 infants with intestinal failure and parenteral nutrition-associated liver disease. Treatment involved the substitution of a conventional intravenous fat emulsion with one containing primarily omega-3 fatty acids. Biochemical tests of liver function improved significantly. One child was removed from the liver transplantation list because of improved hepatic function, and the second child had complete resolution of cholestasis while solely on parenteral nutrition. This suggests that fat emulsions made from fish oils may be an effective means of treating and preventing this often-fatal condition. A randomized, controlled trial is necessary to study the efficacy of this new approach to parenteral nutrition-associated liver disease.

Pediatric short bowel syndrome: redefining predictors of success

OBJECTIVE

To determine predictors of survival and of weaning off parenteral nutrition (PN) in pediatric short bowel syndrome (SBS) patients.

SUMMARY BACKGROUND DATA

Pediatric SBS carries extensive morbidity and high mortality, but factors believed to predict survival or weaning from PN have been based on limited studies. This study reviews outcomes of a large number of SBS infants and identifies predictors of success.

METHODS

Multivariate Cox proportional hazards analysis was conducted on 80 pediatric SBS patients. Primary outcome was survival; secondary outcome was ability to wean off PN. Nonsignificant covariates were eliminated. P < 0.05 was considered significant.

RESULTS

Over a mean of 5.1 years of follow-up, survival was 58 of 80 (72.5%) and 51 weaned off PN (63.8%). Cholestasis (conjugated bilirubin > or =2.5 mg/dL) was the strongest predictor of mortality (relative risk [RR] 22.7, P = 0.005). Although absolute small bowel length was only slightly predictive, percentage of normal bowel length (for a given infant's gestational age) was strongly predictive of mortality (if <10% of normal length, RR of death was 5.7, P = 0.003) and of weaning PN (if > or =10% of normal, RR of weaning PN was 11.8, P = 0.001). Presence of the ileocecal valve (ICV) also strongly predicted weaning PN (RR 3.9, P < 0.0005); however, ICV was not predictive of survival.

CONCLUSIONS

Cholestasis and age-adjusted small bowel length are the major predictors of mortality in pediatric SBS. Age-adjusted small bowel length and ICV are the major predictors of weaning from PN. These data permit better prediction of outcomes of pediatric SBS, which may help to direct future management of these challenging patients.

Intestinal failure-associated liver disease: what do we know today?

Intestinal failure-associated liver disease develops in 40% to 60% of infants who require long-term total parenteral nutrition (TPN) for intestinal failure and 15% to 40% of adults on home parenteral nutrition. The clinical spectrum includes hepatic steatosis, cholestasis, cholelithiasis, and hepatic fibrosis. Progression to biliary cirrhosis and the development of portal hypertension and liver failure occurs in a minority but is more common in infants and neonates than in adults. The pathogenesis is multifactorial. In infants it is related to prematurity, low birth weight, duration of PN, short bowel syndrome requiring multiple laparotomies, and recurrent sepsis. Other important mechanisms include lack of enteral feeding, which leads to reduced gut hormone secretion; reduction of bile flow and biliary stasis, which leads to the development of cholestasis; and biliary sludge and gallstones, which exacerbate hepatic dysfunction. In adults, IFALD is less common and related to age, length of time on PN, total caloric intake, and lipid or glucose overload. In preterm infants, a deficiency of taurine or cysteine may play a role, whereas in both adults and children, choline deficiency may exacerbate IFALD. Lipid emulsions, choline deficiency, and manganese toxicity are associated with both hepatic steatosis and cholestasis in adults and children. Management strategies for the prevention of intestinal failure-induced liver disease include early enteral feeding, a multidisciplinary approach to the management of parenteral nutrition, and aseptic catheter techniques to reduce sepsis. The addition of choline, taurine, and cysteine to PN solutions may also play a role. Oral administration of ursodeoxycholic acid may improve bile flow and reduce gallbladder stasis. Survival after either isolated small bowel or combined liver and small bowel transplantation is approximately 50% at 5 years, making this an acceptable therapeutic option in adults and children with irreversible liver and intestinal failure.

Hepatic dysfunction during hyperalimentation

Liver biopsy specimens were studied in 26 patients in whom liver function abnormalities developed during intravenous hyperalimentation (IVH). The clinical manifestations and duration of IVH were evaluated in relation to the morphological changes seen in the liver. Early hepatic changes consisted of fatty metamorphosis, and progressive intrahepatic cholestasis developed as IVH was continued. Essential fatty acid deficiency, amino acid imbalance, caloric excess, and toxic manifestations of certain amino acids are postulated as causative factors. The hepatic steatosis secondary to IVH may be treated by lowering the dextrose concentration of the infusion or by administering dextrose-free amino acid solutions. The clinical importance of this common complication of IVH is the difficulty in distinguishing it from other causes of cholestasis in seriously ill patients.

Manganese toxicity in children receiving long-term parenteral nutrition

BACKGROUND

In patients receiving long-term parenteral nutrition (PN), cholestatic disease and nervous system disorders have been associated with high blood concentrations of manganese. In such patients, the normal homoeostatic mechanisms of the liver and gut are bypassed and the requirement for this trace element is not known; nor has it been certain whether hypermanganesaemia causes the cholestasis or vice versa. We explored the direction of effect by serial tests of liver function after withdrawal of manganese supplements from children receiving long-term PN. We also examined the relation between blood manganese concentrations and brain lesions, as indicated by clinical examination and magnetic resonance imaging (MRI).

METHODS

From a combined group of 57 children receiving PN we identified 11 with the combination of hypermanganesaemia and cholestasis; one also had a movement disorder. Manganese supplements were reduced in the first three and withdrawn in the remainder. MRI was done in two of these children. We also looked at manganese concentrations and MRI scans in six children who had received PN for more than 2 years without developing liver disease.

FINDINGS

In the hypermanganesaemia/cholestasis group, four of the 11 patients died. In the seven survivors baseline whole-blood manganese was 615-1840 nmol/L, and after 4 months it had declined by a median of 643 nmol/L (p < 0.01). Over the same interval total bilirubin declined by a median of 70 mumol/L (p < 0.05). Two of these children had movement disorders, one of whom survived to have an MRI scan; this showed, with T1 weighted images, bilateral symmetrically increased signal intensity in the globus pallidus and subthalamic nuclei. Such changes were also seen in five other children--one from the hypermanganesaemia/cholestasis group and four of six in the long-term PN group without liver disease (in all of whom blood manganese was above normal).

INTERPRETATION

The cholestasis complicating PN is multifactorial, but these results add to the evidence that manganese contributes. In view of the additional hazard of basal ganglia damage from high manganese levels in children receiving long-term PN, we recommend a low dose regimen of not more than 0.018 mumol/kg per 24 h together with regular examination of the nervous system.

Nutrition for the patient with respiratory failure: glucose vs. fat

High glucose intakes given during administration of total parenteral nutrition (TPN) have been demonstrated to increase CO2 production. The workload imposed by the high CO2 production may precipitate respiratory distress in patients with compromised pulmonary function. Changes in CO2 production and O2 consumption induced by TPN using either glucose as the entire source of non-protein calories, or fat emulsions as 50 per cent of the non-protein calories, have been analyzed either in patients with chronic nutritional depletion or in acutely ill patients secondary to injury and infection. In patients with chronic nutritional depletion, shifting from the lipid to the glucose system caused a 20 per cent (P less than 0.025) increase in CO2 production which resulted in a 26 per cent increase in minute ventilation (P less than 0.01). In the acutely ill patients receiving the glucose system, CO2 production was significantly higher than in those receiving the lipid system (179 vs. 147 ml.min-1.m-2; P less than 0.01. Fat emulsions can serve as a source of non-protein calories and are associated with lesser degrees of CO2 production than isocaloric amounts of glucose.

Malnutrition in older adults

Malnutrition is a highly prevalent condition in older adults, and poses a substantial burden on health, social, and aged-care systems. Older adults are vulnerable to malnutrition due to age-related physiological decline, reduced access to nutritious food, and comorbidity. Clinical guidelines recommend routine screening for malnutrition in all older adults, together with nutritional assessment and individually tailored nutritional support for older adults with a positive screening test. Nutritional support includes offering individualised nutritional advice and counselling; oral nutritional supplements; fortified foods; and enteral or parenteral nutrition as required. However, in clinical practice, the incorporation of nutritional guidelines is inadequate and low-value care is commonplace. This Review discusses the current evidence on identification and treatment of malnutrition in older adults, identifies gaps between evidence and practice in clinical care, and offers practical strategies to translate evidence-based knowledge into improved nutritional care. We also provide an overview of the prevalence, causes, and risk factors of malnutrition in older adults across health-care settings.

A syndrome of acute zinc deficiency during total parenteral alimentation in man

Changes in the plasma and urine levels of the trace metal zinc have been followed in a series of 37 adult patients totally supported by intravenous alimentation. Copper has also been determined in more recent cases. In such a seriously ill group, although urinary zinc loss may be very high at the height of catabolism, severe plasma depletion does not occur unless there is a subsequent phase of sustained anabolism and weight gain. In four patients plasma zinc fell to very low levels during this phase and three of this group developed a syndrome characterized by diarrhea, mental depression, para-nasal, oral and peri-oral dermatitis, and alopecia. The response to oral or intravenous zinc therapy is striking, except for hair regrowth which is delayed but eventually complete. The syndrome we have recognized in adult man has not been previously described. It resembles however the parakeratosis of zinc deficient swine and it is also very similar to Acrodermatitis enteropathica, a genetically determined disorder of infants very recently linked to zinc deficiency. Zinc is clearly essential to human metabolism and it should be included in all parenteral alimentation regimes particularly during the period of rapid, sustained, weight gain.

Aluminum is associated with low bone formation in patients receiving chronic parenteral nutrition

Patients treated with chronic total parenteral nutrition may develop metabolic bone disease. We evaluated 22 bone biopsy specimens from 16 patients. Compared with those of age- and sex-matched normal controls, these specimens had significantly higher osteoid area and lower total bone area and bone formation rate, as measured by double tetracycline labels. Aluminum was found in specimens from the 14 patients receiving casein hydrolysate but not in the two receiving amino acids as their nitrogen source. The reduced bone formation correlated inversely with the logarithm of the aluminum level. Aluminum was localized to the surface of mineralized bone; tetracycline uptake was absent at those sites. These bone findings are similar to those from aluminum intoxicated patients on hemodialysis. Both groups also have low parathyroid hormone levels. Thus, aluminum appears to be an important pathogenic factor in the osteodystrophy of patients receiving dialysis or total parenteral nutrition.

The role of phytosterols in the pathogenesis of liver complications of pediatric parenteral nutrition

Long-term parenteral nutrition of infants who have had major gut resections is associated with a high incidence of cholestatic liver disease. Affected infants have high plasma concentrations of phytosterols--compounds that resemble cholesterol but have an alkylated side chain. The phytosterols that accumulate in patients receiving parenteral nutrition are derived from the soya oil and/or soya lecithin used to make the intravenous lipid emulsion. There is a striking association between phytosterolemia and cholestatic liver disease. This has led us to put forward the hypothesis that phytosterols can cause cholestasis in susceptible infants. Experiments using neonatal piglets indicate that phytosterols (given without any of the other components of parenteral nutrition) can indeed reduce bile flow. We suggest that increasing the content of phytosterols in cell membranes may interfere with the function of important transport proteins involved in the secretion of bile. Other factors that might contribute to cholestasis (such as inhibition of cholesterol 7 alpha-hydroxylase) are discussed.