Effects of lactose-containing vs lactose-free infant formula on postprandial superior mesenteric artery flow in term infants.

BACKGROUND

Dietary dextrose and fructose may promote vascular inflammation and endothelial dysfunction. In certain infant populations, altered postprandial mesenteric hyperemia (PPH) may increase risk for feeding intolerance.

OBJECTIVE

To compare superior mesenteric artery (SMA) PPH following feeds of lactose-containing (LC) formula vs lactose-free (LF; dextrose + sucrose) formula.

METHODS

In a 2 × 2 crossover study with 6 term newborns, 3 received LC first followed by LF 3 hours later. The remaining 3 received the reverse order. Ultrasound measures of pre- and postprandial SMA flow, diameter, and resistance were taken 5 minutes preprandial and 10, 30, and 40 minutes postprandial.

RESULTS

Mean ± SD age and weight (n = 6) were 24.1 ± 2.3 hours and 3.1 ± 0.21 kg. Formula intake was similar for LC and LF (22.5 ± 2.8 mL and 25 ± 1.8 mL, respectively; P = .076). Both formulas increased SMA flow at 10 and 30 minutes. However, postprandial flow was greater for LC overall (P = .004) and especially at 30 minutes (LC 103 ml/min, 52% increase vs LF 92.7 ml/min, 31% increase; P = .014). For both formulas, vasodilation was seen at 10 and 30 minutes and was overall significantly greater following LC than following LF (9.1% VS 6.5%; P = .028). Both formulas elicited significant decreases in sma vascular resistance over the 10- to 30-minute period (overall P = .016). However, decreases did not differ across formulas (P = .672).

CONCLUSIONS

The LC formula elicited a greater SMA PPH response than did LF. SMA flow for both formulas was within normal limits; thus, differences are likely inconsequential for a term newborn. However, in a vulnerable preterm infant, differences may become significant.