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Bodil Larsen, BSc, RD
Neonatal and Pediatric Intensive Care,
Stollery Children’s Hospital,
Edmonton, AB, Canada T6G 2B7
John Van Aerde, MD, PhD, FAAP, FRCPC
Departments of Pediatrics and Neonatology,
Stollery Children’s Hospital,
Edmonton, AB, Canada T6G 2B7
To the Editor.—
Koo et al1 studied the effects of a palm olein formula versus a formula without palm olein on bone mineral content (BMC) and bone mineral density (BMD) in term infants. They suggest that matching the fatty acid profile of human milk by using palm olein in infant formulas may result in an unintended depression of bone mass accretion and may potentially be detrimental to optimum bone health. The article does not mention that infants fed human milk and other currently marketed formulas have BMC and BMD values well below either of the 2 study formulas and all are well within published normative values at both 3 and 6 months of age (see Table 1).
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The authors go on to state that it is not known whether the differences in BMC and BMD between infants fed formulas with or without palm olein would present beyond 6 months, because there is no literature available. However, it is well published that the bone health of mother’s milk feeders is lower than formula feeders and does not correct itself until the toddler years. 2
Similar studies on bone health have been conducted on both formula- and human-milk–fed infants.2–8 These studies have the same time intervals for testing as Koo et al, ie, baseline, 3 months, and 6 months. The clinical significance of the Koo et al article is not established, because there is no evidence that bone mineral accretion higher than that found in breastfed infants is beneficial.9
REFERENCES
In Reply.—
We appreciate the opportunity to respond to the views expressed by Clandinin et al regarding our recent publication comparing bone mineral content (BMC) in groups of infants randomized to receive 1 of 2 infant formulas.1 The premise that generally applicable, normative reference values for BMC already exist in infants is incorrect. Unlike the situation in adults, there are no established reference normative bone data from a large number of infants. Furthermore, the variability of the values and the differences in methodology used to obtain the cited values render the Clandinin et al synthesis of these studies of little value in creating a context for interpretation of our recently published study.
The data on BMC generated in infant populations have used many types of devices from multiple manufacturers. For example, single-photon absorptiometry and dual-energy x-ray absorptiometry (DXA) from several manufacturers have both been used in these studies. Single-photon absorptiometry measured BMC from a small segment of the forearm, whereas DXA measures total body BMC. Some of these systems are better validated than others for use in infants. There are also software complexities even with the use of a single device in a study. Some studies have directly assessed total body BMC, and others have used extrapolations from regional measurements. The populations studied have also differed from the standpoints of geographical location, ethnic background, body size, and gestational and postnatal ages of the subjects. No synthesis of this literature can lead to meaningful normative values.
To date, our BMC data represent the most valid and realistic bone data in infants, because 80% of our data were collected on the most recent generation of a DXA device with the highly efficient fan-beam scan. The remainder was collected by using pencil-beam DXA, still the most used DXA technique worldwide. BMC data collected on both instruments in our laboratory have been validated and verified with chemically analyzed whole-body calcium and ash content (the accepted true measures of BMC) of piglets.2,3 Most available data on BMC in growing subjects lack this validation, and pencil-beam DXA underestimated the true BMC.4–6 Our pencil-beam DXA data were appropriately cross calibrated7 and converted to the fan-beam values. The data presented in our article1 are closer to the true BMC than the historical data cited by Clandinin et al.
Because of the limitations of the existing methods and studies, comparisons of absolute BMC among feeding groups is best done within a study. Even within a study, the exclusivity of breastfeeding varies with increasing age,8,9 and the use of several versions of software9,10 can adversely affect the validity of DXA measurements.11,12
Studies8,13 have demonstrated that exclusively breastfed infants have BMC similar to those fed milk-based formula without palm olein (PO) but higher than those fed PO milk-based formula when evaluated in the same study. One of these studies8 evaluated BMC in normal infants fed either a PO-containing formula or a PO-free formula, with a breastfed reference group. At 1 month of age, the breastfed group (when 28 of 31 infants were exclusively breastfed) had significantly higher BMC than those in the PO group. However, as the infants in the breastfed group became older, they consumed increasing amounts of PO-containing formula and averaged 16 oz/day at 3 months and 23 oz/day at 6 months. As the breastfed infants were given increasing amounts of the PO formula, their bone mass accretion resembled that of infants who consumed the PO formula exclusively. Consequently, their bone mass was significantly lower than the infants fed formula without PO at 3 and 6 months of age.
It was not the purpose of our article to compare the formulas evaluated with breastfed infants. Such a comparison, especially with exclusively breastfed infants, would be of potential interest and, at this point, of unknown significance. The high prevalence of clinical complications of osteoporosis is related to insufficient bone mass,14 and even the association of childhood fractures with low bone mass15 or calcium intake16 indicate higher rather than lower BMC to be of likely clinical benefit. To this end, life-cycle strategies to encourage initial accretion and later maintenance of higher BMC are becoming an important nutrition goal of primary practice.14 Infancy is a period of extremely rapid skeletal growth with a gain of 
25 to 30 cm in length17 and tripling of the bone mass.18 The data from our randomized, double-blind, controlled clinical trial indicate that avoidance of PO-oil–dominant formulas in infancy can contribute to achieving this goal of optimize bone mass accretion.
REFERENCES
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