A comparison of macronutrient-based methods for deriving energy values in human milk

Area of Science:

• Nutritional Biochemistry
• Pediatric Nutrition

Background:

• Accurate determination of energy values in human milk is crucial for infant nutrition, particularly for vulnerable preterm infants.
• Current clinical practices lack standardized methods for deriving human milk energy values, leading to variability.

Purpose of the Study:

• To compare the results of different published calorie calculation methods for human milk.
• To assess the impact of various conversion factors on derived energy values.

Main Methods:

• Ten human milk samples were analyzed for gross and digestible macronutrient content.
• Four distinct calorie conversion factors were applied: Atwater general (ATW-GEN), Atwater milk specific (ATW-MILK), human milk specific (HUM-MILK), and combustible conversions (COMBUST).
• Analysis of variance (ANOVA) was used to determine significant differences in derived calorie values.

Main Results:

• A statistically significant difference (P < 0.001) was found in calorie values obtained using different methods.
• The highest calorie values were derived using combustible conversion factors with gross macronutrients (19.4 ± 1.4 kcal/ounce).
• The lowest calorie values were obtained using human milk specific conversion factors with digestible macronutrients (16.3 ± 1.3 kcal/ounce), showing a mean difference of 3.1 kcal/ounce.

Conclusions:

• The mean difference of 3.1 kcal/ounce between the highest and lowest calorie values is clinically significant for preterm infants.
• The findings underscore the critical need for standardization in human milk calorie calculation methods to ensure consistent and accurate nutritional assessment.