For infants taking less than how many mL of formula per day should vitamin D also be supplemented?

The correct answer is based on established guidelines regarding the nutritional needs of infants, particularly in relation to vitamin D supplementation. Infants who consume less than 1000 mL of formula per day are at risk of inadequate vitamin D intake because infant formula is typically fortified with this vitamin.

Breast milk, while an excellent source of nutrition, generally contains insufficient levels of vitamin D. Because vitamin D is essential for bone health and development, the recommendation is that if an infant's intake of formula is below 1000 mL per day, vitamin D supplementation is necessary to help prevent deficiencies. This supplementation is particularly important to avoid conditions such as rickets, which can occur from prolonged low vitamin D levels.

In contrast, higher volumes of formula intake beyond this threshold typically provide enough vitamin D, reducing the need for additional supplementation. Consequently, the value of 1000 mL serves as a critical cut-off in nutritional guidelines for pediatric care.