Nutrition experts estimate that 9-month-old breastfed infants must rely on complementary foods for 90% of their requirement for iron and zinc.  This has long been recognized in the case of iron, with iron-fortified cereals commonly recommended to help prevent iron deficiency.  However, recent recognition of world-wide zinc deficiency, often accompanied by iron deficiency, highlights the need for early complementary foods to be good sources of both iron and zinc. Different strategies have been proposed to increase iron and zinc needs for the older infant including the increased use of animal products. 

A study reported in the Journal of Pediatric Gastroenterology and Nutrition compared the effects of either meat or iron-fortified infant cereal as the first complementary food given to exclusively breastfed infants. They were started on either meat or iron-fortified cereal as a first weaning food by no later than 6 months of age.  After 7 months, all food choices were left to the parents' discretion but until then, infants in the meat group were not given cereal and infants in the cereal group were not given meat.

At 5 and 7 months, infants in the meat group had significantly higher zinc and protein intake, while infants in the cereal group had significantly higher iron intake at 7 months.  By 9 months, 2 months after the intervention concluded, there were no differences in iron and zinc intake but protein was still somewhat higher for the meat group.

The only significant difference in growth rates between the two groups was the greater rate of growth in head circumference for the meat group during the 7 to 12 month interval. Protein and zinc intakes at 7 months were predictors of head circumference growth from 7 to 12 months.

Though parents reported that infants from both groups in this study easily accepted either food, differences in nutrient intakes between the groups was notable. Estimates indicate that infants in the meat group were consuming 90% of the Estimated Average Requirement (EAR) for zinc at 7 months, while those randomized to the cereal group were consuming less than 50% of the EAR. Since a high proportion of infants have marginal zinc and iron status, the authors suggest that this study indicates the feasibility of introducing meat as a first complementary food for breastfed infants.

Citation:
Meat as a First Complementary Food for Breastfed Infants: Feasibility and Impact on Zinc Intake and Status. Krebs NF, Westcott JE, Butler N, Robinson C, Bell M, Hambidge KM. Journal of Pediatric Gastroenterology and Nutrition. 2006 Feb 42:207-214.

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Meat as a First Complementary Food for Breastfed Infants: Feasibility and Impact on Zinc Intake and Status

Total and plant protein intakes are consistently associated with decreased blood pressure (BP).  However, the effect of increased animal protein intake, substituted for carbohydrate intake, on BP has not been previously studied. The authors of this Australian study surmised that increased protein intake in most populations is likely to be from animal sources and come at the expense of carbohydrate rather than fat intake. The objective of their study was to determine the effects on BP in hypertensive individuals when a modest increase in protein from lean red meat is substituted for high-glycemic-index carbohydrates. Persons assigned to the intervention group had a mean increase in animal protein intake by approximately 43g/day with a slight reduction in plant protein intake.

At the end of the eight-week intervention there was a 4-mm Hg reduction in the 24-h ambulatory systolic BP, with no significant effect on diastolic BP, for the protein group. The authors reference estimates from the International Study of Salt and Blood Pressure  which indicate that an increase of 37g protein/day would lead to an approximate 3 mm Hg reduction in the population mean systolic BP.  A mean reduction of this magnitude among the population would result in a substantial reduction in the prevalence of cardiovascular disease. Since hypertension is a serious disease worldwide with  increasing rates of occurrence, the authors speculate that the findings in this study may have important public health implications.

Citation:
Partial substitution of carbohydrate intake with protein intake from lean red meat lowers blood pressure in hypertensive persons. Hodgson M, Burke V, Beilin LJ, Puddey IB. The American Journal of Clinical Nutrition. 2006;83:780-7.

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Partial substitution of carbohydrate intake with protein intake from lean red meat lowers blood pressure in hypertensive persons

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