Which type of formula tends to have higher osmolality due to smaller particle size?

• A. Standard intact protein
• B. Hydrolyzed protein and free amino acid formulas
• C. Soy-based formulas
• D. Elemental formulas

Answer: (B)

Osmolality reflects the number of osmotically active particles in solution. Smaller particles create more particles per unit volume, raising osmolality. Hydrolyzed protein provides small peptides and free amino acids, so there are many small solutes in the formula. Each of these acts as an osmotic particle, increasing the overall osmolality more than intact protein formulas, which contain larger molecules that contribute fewer particles per unit mass. That’s why formulas with hydrolyzed protein and free amino acids tend to have higher osmolality.