Grains and tubers crops play a pivotal role in the human diet. … Thus, they add variety to the diet in addition to offering numerous desirable nutritional and health benefits such as antioxidative, hypoglycemic, hypocholesterolemic, antimicrobial, and immunomodulatory activities and they are also one of the most high-fibre foods, and a great source of resistant starch as well as complex carbs, which provide energy for the body to function. The main nutritional value of roots and tubers lies in their potential ability to provide one of the cheapest sources of dietary energy, in the form of carbohydrates, in developing countries. This energy is about one-third of that of an equivalent weight of grain and tubers, such as rice or wheat, because tubers have a high water content. However, the high yields of most root crops ensure an energy output per hectare per day which is considerably higher than that of grains . Sweet potato for example has a tremendous capacity for producing high yields, up to 85 t/ha have been recorded on experimental plots, though most plantation yields do not exceed 20 t/ha. As shown in Table 4. 1, potato is one of the highest calorie-yielding crops in the world. Such root crops are particularly valuable in the tropics where most of the population depends on carbohydrate foods as dietary staples.
Undernutrition is often the outcome of either an insufficient food intake or poor utilization of food by the body, or both simultaneously. Recent surveys show that very few people in tropical countries suffer from a simple protein deficiency. The most prevalent deficiency is protein-energy, in which an overall energy deficiency forces the metabolism to utilize the limited intake of protein as a source of energy. This is an area in which root crops could play a more significant role as additional sources of dietary energy and protein. Increasing the consumption of root crops could help save the much-needed protein provided essentially by other foods such as cereals and legumes. Traditionally, in Africa, root crops such as cassava are eaten with a soup or stew made of fish, meat or vegetables, providing an excellent supplement to cassava meal.