ABSTRACT
Plant tissues, through the agency of photosynthesis, are ultimately the supplier of all food for humans. An estimated 150 billion tons of carbon are fixed annually by more than 300,000 taxonomically distinct plant species. Worldwide, plant tissues directly provide about 70% of the protein consumed by humans. In affluent countries, like the United States, about 30% of dietary protein comes directly from plants. Cereal grain contains 10,000-15,000 kJ/kg, about 10-20 times more energy per unit weight
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INQ for Seven Major Nutrients in Selected Plant-and Animal-Derived Food Products
than most succulent fruits and vegetables. They are estimated to directly provide 50% of human calories in the world and 70-80% of all food calories consumed in China and India. Horticultural products are an important source of other dietary nutrients, as shown by the relatively high “index of nutritional quality” (INQ, defined as the ratio of the percentage of nutrient need provided to the percentage of caloric need provided) of several succulent crops [60]; the sum of INQ values for seven major nutrients is about ten times greater for spinach, broccoli, or lettuce than it is for whole milk, egg, or meat (Table 17.1).
