Introduction Actual recommendations for parenteral fat intake in preterm infants are based on clinical studies where fat administration was adjusted to achieve safe fat levels (triglyceride:1.71 mmol/L, cholesterol:4.2 mmol/L). Such cut-offs were chosen with regard to prevent adult atherosclerosis. However, intake of breast milk fed preterm infants may be considerably higher: up to 7 g/kg/d, serum levels have not been published so far. We tested the hypothesis whether high fat intake by breast milk leads to serum fat levels that are higher than those achieved under full parenteral fat administration, thus making an increase of intravenous fat plausible.

Methods 51 healthy infants, fed fortified breast milk (gestational age:31±4 weeks, birth weigth:1500±600 g, day of life:25±16 d); triglycerides, cholesterol, VLDL, LDL and HDL (preprandial) and daily weight gain were measured.

Results Study weight: (n) (<1000(6)/<1500(13)/<2000(11)/<2500(10)/⩾2500(10)); oral intake[mL/kg/d]: (177±13/174±8/183±26/174±18/184±21); weight gain[g/kg/d]: (13±7/19±6/20±5/17±5/13±5); triglyceride[mmol/L]: (0.8±0.1/0.7±0.2/0.8±0.3/1.5±1.8/1.0±0.4); cholesterol[mmol/L]: (3.0±1.4/2.9±0.4/3.0±0.9/3.1±0.7/3.4±1.2); VLDL[mmol/L]: (0.5±0.1/0.4±0.1/0.6±0.4/0.6±0.3/0.5±0.2); LDL[mmol/L]: (1.7±1.2/1.6±0.4/1.2±0.6/1.5±0.3/1.7±1.0); HDL[mmol/L]: (0.8±0.2/0.9±0.1/1.1±0.3/1.1±0.4/1.2±0.4).

Discussion Though higher by factor of two, oral intake of breast milk leads to lower lipid levels when compared with parenteral fat intake. In sight of the appropriate feeding volumes and mean weight gain of 17±6 g/kg/d the low levels are not caused by oral undernutrition. The rise of triglyceride levels with weight may indicate increased fat metabolism via increased fat mass. The results suggest that either fat absorption is reduced in preterm infants, or the composition of breast milk supports a lower profile of fat levels when compared to commercially available parenteral fat emulsion. When this is true the lipid patterns used in these emulsions should be reconsidered.