Growth, thiamin status, erythrocyte fatty acid composition, and visual acuity in fullterm infants fed breastmilk, formula, or evaporated milk

McCloy, Ursula (1996) Growth, thiamin status, erythrocyte fatty acid composition, and visual acuity in fullterm infants fed breastmilk, formula, or evaporated milk. Masters thesis, Memorial University of Newfoundland.

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Abstract

The effects of feeding breastmilk (BM), commercial formulas (F), or evaporated milk formula (EM) on growth, thiamin status, erythrocyte phosphatidylethanolamine (PE) fatty acid composition and visual acuity in 100 healthy full term infants were determined. Growth, thiamin status, and erythrocyte PE fatty acid composition was determined at birth, 3, and 6 months of age. Thiamin status was assessed by determining the erythrocyte transketolase activity (TKA) and the fatty acid composition of milk and blood was determined by gas-liquid-chromatography. Preferential looking acuity was assessed at 3 and 6 months of age using the acuity card procedure. -- There were no significant differences in weight, length, or head circumference between any feeding groups. However, daily weight gain between three and six months was significantly lower for the BM group (weight gain: ﻌ ± SD, BM 15.5 ± 4.0 g, F= 20.4 ± 5.8 g, EM = 20.2 ± 6.8 g, p < 0.05). As well, breastfed infants had slightly lower head circumference growth velocity between three and six months of age. -- There were no differences in the thiamin pyrophosphate effect between groups, however, BM infants had significantly lower transketolase activity than the F group which correlated with energy but not thiamin intake. -- The breastmilk obtained from mothers in the study contained on average (% total fatty acids by weight), 12.1 % linoleic acid (18:2(n-6)), 2.1% linolenic (18:3(n-3)), and 0.2% docosahexaenoic acid (22:6(n-3)). Infants in the F group consumed either Similac or Enfalac. Similac contained 30.5% 18:2(n-6), and 4.9% 18:3(n-3). Enfalac contained 17.1% 18:2(n-6) and 1.8% 18:3(n-3). EM contained (% total fatty acids) 2.1% 18:2(n-6), and 0.8% 18:3(n-3). Only breastmilk contained 22:6(n-3). -- In the circulation, F fed and EM fed infants had lower arachidonic acid (20:4(n-6)) at 3 months (p < 0.05) than BM fed infants (ﻌ ± SD, 20.3±2.8, BM, 18.3 ± 2.7, F, 18.7 ± 2.7, EM, % total fatty acids) but not at 6 months, and EM fed infants had lower adrenic acid (22:4(n-6)) at both 3 and 6 months. 22:6(n-3) was the highest in the BM group at both 3 (6.0 ± 1.7,BM, 3.1 ± 0.8, F, 4.1 ±0.9, EM, % total fatty acids) and 6 months of age (5.3 ± 1.6, BM, 2.9 ± 0.8, F, and 4.2 ± 1.3, EM, % total fatty acids) followed by EM then F. Visual acuity was higher in the BM group than EM (3.86 ± 0.29 cycles/degree vs 3.29 ± 0.41, 3 mos, 9.03 ± 0.29 vs 7.54 ± 0.25,6 mos, p < 0.05) with intermediate values in the F group (NS compared to EM and BM). Differences seen in visual acuity may be due to the low 18:3(n-3) in EM of 0.3 % of energy and are not reflective of 22:6(n-3) in circulation. -- From the results of the present study it appears that EM formulas may not meet the essential fatty acid requirements for optimal visual acuity, however, it may be adequate for thiamin and optimum growth. The differences seen in the BM group in growth and TKA can be related to lower energy intakes and do not indicate any deficiencies.

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