Differences in magnesium needs between infants fed human milk and those fed infant formula are described in the “Special Considerations ” section.

AI Summary: Ages 0 through 6 Months

Based on data from a summary of recent studies in North America and the United Kingdom (Atkinson et al., 1995), the concentration of magnesium in human milk is about 34 mg (1.4 mmol)/liter, and the concentration remains relatively constmlt over the first year of lactation (Allen et al., 1991; Dewey et al., 1984). The AI is set based on a reported average intake of human milk of 780 ml/day (Allen et al., 1991; Butte et al., 1984; Heinig et al., 1993) and the average milk magnesium concentration of 34 mg (1.4 mmol)/liter. This gives an AI of 30 mg (1.3 mmol)/day. The balance data cited above support an AI of 30 mg (1.3 mmol)/day for this age range, as it would allow infants to maintain a positive magnesium balance of at least 10 mg (0.4 mmol)/day during early infancy.

AI Summary: Ages 7 through 12 Months

During the second 6 months of life, solid foods become a more important part of the infant diet and add a significant but poorly defined amount of magnesium. The absorption of magnesium from solid foods and the effects of solid foods on absorption of magnesium from human milk are unknown. To set an AI for infants from 7 through 12 months of age, the average magnesium intake from solid foods—55 mg (2.2 mmol)/day—for 9- to 12-month-old formula-fed infants (Specker et al., 1997) was used. This approach assumes that infants who are fed human milk have intakes of solid food similar to those fed formulas.

Based on the data of Heinig et al. (1993), the mean volume of human milk consumed between 7 and 11 months of age would be 600 ml/day. Thus, magnesium intake from human milk with an average magnesium concentration of 34 mg (1.4 mmol)/liter would be about 20 mg (0.8 mmol)/day. Summing the intake from human milk and from solid food, the AI for magnesium for infants 7 through 12 months of age is set at 75 mg (3.1 mmol)/day.

AI for Infants

0 through 6 months

30 mg (1.1 mmol)/day


7 through 12 months

75 mg (3.1 mmol)/day

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