Abstract
Background: Despite a dearth of well-controlled studies comparing the gastric emptying (GE) of casein- and whey-based formulas in humans and lack of clear evidence suggesting that such a difference influences patient symptoms, prevailing opinion among healthcare professionals continues to purport that a clinically meaningful difference exists between the two.
Aim: To review the literature related to the influence of casein and whey on GE in humans.
Methods: A PubMed literature search was executed using a combination of the following search terms: gastric emptying, human, casein, and whey. Our primary interest was experimental design strategies with respect to established physiologic factors controlling GE.
Results: Our search resulted in 11 citations; 5 directly compared GE rates of casein- and whey-based formulas and 3 of the 5 suggested a difference. Critical review of these studies revealed numerous experimental design weaknesses that included: 1) lack of control over osmolality, caloric density, feeding volume and macronutrients (protein, fat, and carbohydrate), 2) small sample sizes, and 3) use of heterogeneous subjects with respect to age, symptom types, symptom severity, and general health status.
Conclusion: No convincing evidence exists to support the prevailing notion that casein- and whey-predominant formulas differently influence GE rates.
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