EAL

BF: Dietary Factors, Breast Milk and Infant Outcomes (2008)

Citation:

Gibson, RA , Neumann, MA, and Makrides, M. Effect of increasing breast milk docosahexaenoic acid (DHA) on plasma and erythrocyte phospholipid fatty acids and neural indices of exclusively breast fed infants. European Journal of Clinical Nutrition 1997; 51: 578-584.

PubMed ID: 9306083

Study Design:

Randomized Controlled Trial

Class:

A - Click here for explanation of classification scheme.

Quality Rating:

NEUTRAL: See Quality Criteria Checklist below.

Research Purpose:

To determine the effect of increasing DHA in breast milk on infant fatty acid profiles; to examine aspects of neural development and their dependency on DHA concentration of breast milk.

Inclusion Criteria:

Mothers of term infants (>37 weeks gestation) who intended to breastfeed for at least 12 weeks were recruited to participate
Healthy infants, appropriate weight for gestation, Apgar scores >7 at five minutes post-birth.

Exclusion Criteria:

Infants not exclusively breast-fed for 12 weeks; no others reported.

Description of Study Protocol:

Recruitment

Moms of healthy term infants who planned to breastfeed for at least 12 weeks recruited.

Design

Placebo-controlled trial.

Blinding used

Double-blind.

Intervention

Mothers randomized to receive one of five doses of DHA-rich algal oil between day five and week 12 post-partum:

Doses: zero, 0.2, 0.4, 0.9, or 1.3g DHA per day
Oil contained 43% DHA, 1% n-6 PUFA, 38% saturates and 18% monounsaturates.

Statistical Analysis

One-way ANOVA to examine differences in plasma and erythrocyte fatty acids between groups and test for differences between groups in neural indices; Pearson correlations co-efficients (associations of DHA in breast milk, DHA status of infant, and neural indices). Stepwise multiple regression to predict independent factors associated with neural indices.

Data Collection Summary:

Timing of Measurements

12 weeks, one and two years of age: Infant growth assessed (weight, length head circumference)
12 and 16 weeks of age (post-12-week supplementation): Visual function assessed
One and two years of age: Global development assessed
12 weeks of age (post-supplementation): Breast milk DHA levels measured to assess infants' dietary intake of DHA.

Dependent Variables

DHA supplementation.

Independent Variables

Visual function, infant growth and development, infant DHA status.

Control Variables

12-week supplementation trial; exclusively breast-fed for at least 12-weeks; timing of measurements.

Description of Actual Data Sample:

Initial N

52 infants.

Attrition (final N):

52 at 12, 16 weeks, and one year of age; 50 at two years of age follow-up.

Age

Maternal age 30±4 years.

Other relevant demographics

Of completers: Middle-class families, highly-educated parents; above-average stimulation in the home; average duration of breastfeeding 37±15 weeks (20 of 52 infants exclusively breastfed for 52 weeks); predominance of male infants in group that received highest dose of DHA (seven male: one female).

Anthropometrics

All infants grew well and were appropriate weight, length, and head circumference at all time points.

Location

Flinders University and Medical Center, Adelaide, Australia.

Summary of Results:

Infant plasma and erythrocyte phospholipid DHA were related to breast milk in a saturable curvilinear manner (r=0.89, P<0.001 for plasma; r=0.88, P<0.001 for erythrocytes). DHA in plasma and erythrocytes reached a plateau when breast milk DHA was 0.80% total fatty acids. Levels of 22:5n-3 in infant tissues were negatively related to dietary DHA, though the effect was small.

Increase in infant plasma and erythrocyte DHA was matched by a decline in total n-6 fatty acids, as arachidonic acid was negatively associated with breast milk DHA, despite the constant intake of this fatty acid from breast milk. There were negative associations between breast milk DHA and infant linoleic acid (r=-0.33, P<0.05 plasma; r=-0.37 P<0.05 erythrocytes), 22:4n-6 (r=-0.65, P<0.001 plasma; r=-0.60, P<0.001 erythrocytes), and 22:5n-6 (r=-0.68, P<0.001 plasma; r=-0.61, P<0.0001 erythrocytes).

Other Findings

No relationship between visual acuity and DHA status. Infant erythrocyte DHA at 12 weeks and home stimulation were the only independent factors associated with Bayley's MDI (development scale) at one year (r^2=0.18, P<0.005).

Author Conclusion:

Increasing breast milk DHA levels caused a dose-dependent saturable increase in infant plasma and erythrocyte phospholidpid DHA. There were no long-term effects of infant DHA status on indices of neurodevelopment. It is likely, however, that the effect of a single dietary factor (DHA in breast milk) will be small compared with social and environmental influences in healthy term-infants. Studies with a large sample size are needed to examine these subtle effects.

Funding Source:

Government:

National Health and Medical Research Council, Australia

Industry:

Reviewer Comments:

Sample may not be free from bias-those completing the 12-weeks supplementation trial (e.g. those choosing to breastfeed exclusively for at least 12 weeks) were mature, educated women, providing above-average stimulation in the home.

Quality Criteria Checklist: Primary Research
Relevance Questions
	1.	Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)	Yes
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	Yes
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes

Validity Questions
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
2.	Was the selection of study subjects/patients free from bias?		No
	2.1.	Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	No
3.	Were study groups comparable?		Yes
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	Yes
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	Yes
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	Yes
	3.4.	If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?	N/A
	3.5.	If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)	N/A
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	N/A
4.	Was method of handling withdrawals described?		Yes
	4.1.	Were follow-up methods described and the same for all groups?	Yes
	4.2.	Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)	Yes
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	Yes
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	N/A
5.	Was blinding used to prevent introduction of bias?		Yes
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	Yes
	5.2.	Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)	Yes
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	N/A
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	N/A
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	N/A
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		Yes
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	Yes
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	N/A
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	Yes
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	Yes
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	N/A
	6.6.	Were extra or unplanned treatments described?	N/A
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	Yes
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	N/A
7.	Were outcomes clearly defined and the measurements valid and reliable?		Yes
	7.1.	Were primary and secondary endpoints described and relevant to the question?	Yes
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	Yes
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	Yes
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	Yes
	7.5.	Was the measurement of effect at an appropriate level of precision?	Yes
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	Yes
	7.7.	Were the measurements conducted consistently across groups?	Yes
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		Yes
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	Yes
	8.2.	Were correct statistical tests used and assumptions of test not violated?	Yes
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	Yes
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?	Yes
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	Yes
	8.6.	Was clinical significance as well as statistical significance reported?	Yes
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	N/A
9.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	Yes
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes