The food industry relies on high market share, market exclusivity, or first to market advantage for functional ingredients. Researchers test individual ingredients (added to traditional and non-traditional delivery foods), often at high doses, to confirm health benefits. Unfortunately, testing the activity of an ingredient alone does not necessarily define how it functions in foods, and a single test, such as that of glycaemic index, does not address all food functionalities. In addition, food functionality may be affected by a variety of factors including storage, methods of preparation, endogenous enzymes in other food ingredients and concentration. We found in a recent meal test for effects of glucan on appetite control that results varied for blood glucose and insulin, appetite hormones and subjective appetite ratings. Depending on the outcomes assessed, the fibre dose which varied. Ingredient testing showed all doses (approximately 2-5g) had high viscosity and solubility, likely to increase gastrointestinal transit time. Repeated measures analysis of variance (RMANOVA) for glucose variation unexpectedly showed no significant effects at varied doses, while insulin secretion decreased with increasing fibre dose (P=0.011). Some appetite hormone measures (ghrelin) showed no dose response while others (cholecystokinin) showed promising results. Subjective satiety was apparent at low dose (RMANOVA, P=0.039), but subsequent meal intake only decreased at high dose. Combining the results of all assessments provides comprehensive evidence for the use of an ingredient. Research addressing only a single measure, may greatly under- or over-estimate ingredient functionality.