Nutritional value or nutritive value as part of food quality is the measure of a well-balanced ratio of the essential nutrients carbohydrates, fat, protein, minerals, and vitamins in items of food or diet in relation to the nutrient requirements of their consumer. Several nutritional rating systems and nutrition facts label have been invented to be able to rank food in terms of its nutritional value, but absolute scales are open for debate and tend to ignore particular consumer needs. On a biological scale, nutritive value of food may vary for different health conditions (leading to dietary recommendations and particular diet foods), seasonal differences, age and sexual differences, and interspecies or greater taxonomic differences. An absolute scale with fixed ratings even for humans only is questionable because of the complexity of the ingredient interplay involved and will lead to unintended consequences when applied generally. In colloquial speech, "nutritional value" is often taken to mean the caloric value of a food item only, a restriction that can lead to confusion when comparing the values of different diets.