Human milk fatty acids and growth of infants in Brazzaville (The Congo) and Ouagadougou (Burkina Faso).

OBJECTIVE To estimate the role of human milk n-6 and n-3 polyunsaturated fatty acids (PUFA) in term infant growth in two African urban populations. DESIGN Observational study. Weight gains at 5 months of age and dietary habits were compared between Congolese infants (n=102) and Burkinabè infants (n=101). Socio-economic status and anthropometry of the mothers were also recorded. SETTING One suburban district in Brazzaville (capital of The Congo) and one in Ouagadougou (capital of Burkina Faso). SUBJECTS Two random samples of nursing mothers and their 5-month-old infants. RESULTS All infants were born at term and there was no difference in birth weights. At 5 months of age, infants in Ouagadougou were thinner but not shorter than their counterparts in Brazzaville (average weight gain (standard deviation): 614 (168) g month-1 vs. 720 (176) g month-1; P= 0.0001). Drastic differences were found in infant diets with regard to extra fluid intake and n-6 and n-3 PUFA concentrations in breast milk. In Ouagadougou, all infants were given fluids other than milk from birth. Breast milk had highly unbalanced 18:2n-6/18:3n-3 and n-6/n-3 long-chain PUFA ratios (53:1 and 5:1, respectively). In Brazzaville, half of the infants received fluids other than milk, and breast milk showed balanced 18:2n-6/18:3n-3 and n-6/n-3 long-chain PUFA ratios (12:1 and 1:1, respectively). A non-linear relationship between 18:2n-6/18:3n-3 ratio and growth was established in Brazzaville (P= 0.0027). The 18:2n-6/18:3n-3 ratio adjusted with covariates had an even more significant effect on weight gain (P= 0.0011). Applying the same model in Ouagadougou did not show such a relation. CONCLUSION : Data strongly suggest that a balanced ratio of 18:2n-6/18:3n-3 (between 5:1 and 15:1) in breast milk leads to higher weight gain of infants during the first 5 months of life.