High versus low medium chain triglyceride content of formula for promoting short-term growth of preterm infants

  • Review
  • Intervention

Authors


Abstract

Background

In-hospital growth of most very low birth weight infants remains below the 10th percentile of reference intrauterine growth curves (Ehrenkranz 1999). To improve growth, fat is added to preterm formula in the form of medium chain triglycerides (MCT) or long chain triglycerides (LCT). MCT are easily accessible to the preterm infant with an immature digestive system while LCT are beneficial for central nervous system development and visual function. Both have been incorporated into preterm formulas in varying amounts, but their effect on the preterm infant's short-term growth is unclear.

Objectives

To determine the effect of high MCT as opposed to low MCT (high LCT) formula on short-term growth rates in preterm formula fed infants.

Search methods

MEDLINE (1966 - 2007), CINAHL (1982 - 2007), Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2007), conference proceedings, and reference lists of articles were searched.

Selection criteria

All randomized trials comparing the effects of exclusive feeding of high versus low MCT formula (for a minimum of one week) on the short-term growth of healthy, preterm infants.

Data collection and analysis

The reviewers assessed each study's quality and extracted data on growth parameters as well as adverse effects from included studies. All data used in analysis were continuous; therefore, weighted mean differences with 95% confidence intervals were reported.

Main results

Eight randomized trials studying a total of 182 infants were included.

There was no evidence of difference in short-term growth parameters when high and low MCT formulas were compared. The meta-analysis of weight gain based on five studies yielded a WMD of -0.35 g/kg/d (95% CI -1.44, 0.74). Similarly, meta-analysis of weight gain in g/d based on two studies showed no evidence of difference (WMD 2.09 g/d, 95% CI -1.46, 5.64). Length gain, based on five studies, showed a non-significant WMD of 0.14 cm/wk (95% CI -0.04, 0.31). Head circumference gain, based on data from five studies, showed a non-significant WMD -0.03 cm/wk (95% CI -0.15, 0.08). Only one study reported a statistically non-significant skin fold thickness gain, with a mean difference -0.15 mm/wk (95% CI -0.41, 0.11).

Subgroup analyses according to % MCT in the high MCT formula, by 10% intervals showed no evidence of effect of high MCT on short-term weight gain within any subgroup.

There are conflicting data (two studies) as to formula tolerance.

There is no evidence of effect on incidence of necrotizing enterocolitis (NEC), based on small numbers in two trials.

No studies were located addressing long-term growth parameters or neurodevelopmental outcomes.

Authors' conclusions

There is no evidence of difference between MCT and LCT on short-term growth, gastrointestinal intolerance, or necrotizing enterocolitis. Therefore, neither formula type could be concluded to improve short-term growth or have less adverse effects. Further studies are necessary because the results from the included eight studies are imprecise due to small numbers and do not address important long-term outcomes. Additional research should aim to clarify effects on formula tolerance and on long-term growth and neurodevelopmental outcomes, and include larger study populations to better evaluate effect on NEC incidence.

摘要

背景

高含量或低含量中鏈三酸甘油脂的配方對促進早產兒短期成長的比較

大部分的極低出生體重嬰兒在醫院時的成長,還總是低於百分之十的胎內生長參考值曲線 (Ehrenkranz 1999) 。為了改善生長,脂質常以中鏈三酸甘油脂 (MCT) 或長鏈三酸甘油脂 (LCT) 的形式加入早產兒的配方之中。MCT較易為未具成熟消化系統的早產兒接受,而LCT對中樞神經系統的發育和視覺功能是有幫助的。兩種成分都以不同的量合併加入早產兒配方之中,但他們對早產兒短期成長的功效並不清楚。

目標

得知含高量MCT的配方相較於含低量MCT (高量LCT) 的配方,對於使用配方哺育早產兒短期成長的效果。

搜尋策略

MEDLINE (1966 – 2007) 、CINHAL (1982 – 2007) 、Cochrane Central Register of Controlled Trial (CENTRAL, The Cochrane Library, Issue 2, 2007) 、學術會議記錄、 和參考文獻的文章都被列入搜尋對象。

選擇標準

所有有關比較全部以高或低量MCT配方哺育 (至少1週) 健康早產兒對短期生長影響的隨機試驗。

資料收集與分析

評論者分析每個研究的品質,且從納入的研究中擷取生長相關數值和不良影響的資料。所有分析的資料都是連續性數值;因此採95% 信賴區間的重量平均差 (WMD) 來報告。

主要結論

有八個隨機性試驗,全部共182位嬰孩被納入。比較高和低量MCT的配方對短期生長數值,並無證據顯示兩者有差別。根據五個研究所做,體重增加的統合分析得到WMD為 −0.35 g/kg/d (95% CI −1.44, 0.74) 。類似地,根據兩個研究所做,每天體重增加的統合分析顯示,並無證據有所差別 (WMD 2.09 g/d, 95% CI −1.46, 5.46) 。依據五個研究的結果,身高的增加並無明顯的差別,WMD為0.14cm/wk (95% CI −0.04, 0.31) 。而根據五個研究所得的資料也呈現,頭圍增加並無差別,WMD為 −0.03 cm/wk (95% CI −0.15, 0.08). 。僅有一個研究報告在皮膚皺摺厚度的增加上並無統計學上的意義,其平均差是 −0.15mm/wk (95% CI −0.41, 0.11) 。針對高量MCT的配方中MCT的百分比,以10% 的間距做小群組分析,顯示並無證據指出高量MCT配方在任何小群組對短期增重有證據顯示效果。在配方的耐受度上有相互矛盾的資料 (兩個研究) 。

作者結論

在短期的生長、胃腸的耐受度或造成壞死性腸炎方面,並無證據顯示MCT和LCT之間有所差別。因此也不能做結論說哪種配方的成份能改進短期的生長或副作用較少。進一步的研究是必要的,因為從這八個納入的研究所得的資料並不夠精確,源於個案數太少或是未指出重要的長期生長預後資料。後續的研究應著重於釐清配方耐受度和對長期生長與神經發展預後的影響,且需包括較大的研究個案數以便更好地評估造成壞死性腸炎的發生率。a

翻譯人

本摘要由馬偕醫院謝雨潤翻譯。

此翻譯計畫由臺灣國家衛生研究院 (National Health Research Institutes, Taiwan) 統籌。

總結

出生後大多數的極低出生體重嬰兒在醫院時都長得很慢。這原因被關心是因為生長缺乏與神經發育的不良包含在學齡時有較差的智商 (IQ), 語言能力和閱讀能力有關。脂肪提供了母奶中約一半的熱量來源,其中大部分是長鏈的脂肪酸三酸甘油脂。為了改善生長,在配方中可加入脂肪來餵食早產兒們。配方中加入脂肪可以包含有長鏈脂肪酸和較短的中鏈脂肪酸的三酸甘油脂。中鏈脂肪酸 (MCT) 較容易被有著不成熟的消化系統的新生兒來吸收。長鏈脂肪酸對視力的發育及細胞膜和腦部的發展仍然是相當重要的。這些回顧的作者找尋一些醫學文獻。他們發現有8個小型的隨機控制試驗研究給予早產兒不同量的中鏈脂肪酸對短期生長的影響 (體重、身高和頭圍的增加) 。在給予新生兒餵食絕對的高量的中鏈脂肪酸和少量的中鏈脂肪酸至少一星期後,他們的生長情形並無明顯不同 (5個研究包含182位嬰兒) 。這些嬰兒他們的平均妊娠週數是29週至32週,平均出生體重介於1公斤至1.5公斤而年齡為1至6週。有一個研究顯示嬰兒對高含量的中鏈脂肪酸有相當程度的不耐性而另一個研究則沒有此發現。形成壞死性腸炎的機率也沒有不同。並無任何研究著眼於長期的生長和神經發育的預後。

Plain language summary

High versus low medium chain triglyceride content of formula for promoting short-term growth of preterm infants

Most very low birth weight infants grow slowly in hospital after delivery. This causes concern because poor growth can link to neurodevelopmental impairments including decreased cognitive ability (IQ), speech, and reading skills when school-aged. Fat provides about half of the energy source (calories) in human breast milk, mostly as long-chain fatty acid triglycerides (LCT). As a way of improving growth, fat can be added to formula used to feed preterm infants. Fats in formula can contain triglycerides with long chain fatty acids or shorter medium chain fatty acids (MCT). MCT are more easily absorbed by the newborn infant with an immature digestive system. LCT are still important in the development of visual acuity and development of cell membranes and the brain. The review authors searched the medical literature. They found eight small controlled randomized studies looking at short-term growth (weight, length, and head circumference gain) in preterm infants fed with varying amounts of medium chain fats. The pattern of growth in infants fed exclusively with high MCT or low MCT formula for at least one week did not differ (five studies with 182 infants). These infants had a mean gestational age between 29 and 32 weeks, mean birth weights between 1 kg and 1.5 kg, and were aged one to six weeks. One study found a high degree of gastrointestinal intolerance with high MCT content and another did not. Development of necrotizing enterocolitis was not different. No studies addressed long-term growth or neurodevelopmental outcomes.