Cereal protein intake

Kwashiorkor is a type of malnutrition associated with insufficient protein intake, usually affecting children aged 1-4 years, although it can also occur in older children and adults. It is likely caused by a combination of factors (protein deficiency, energy and micronutrient deficiency). The absence of lysine in low-grade cereal proteins (used as a dietary mainstay in many underdeveloped countries) can lead to kwashiorkor. 

Cereals have low confenfs of essential amino acids, particularly lysine and tryptophan. In developing countries especially, this creates nutritional deficiencies for a large proportion of the population because a single cereal may account for a major part of the protein intake. In some countries (Central and South America and sub-Saharan Africa), people rely on maize as their principal food. In order to counter the problem, high-lysine mutants of maize have been identified. However, these mutants are associated with negative effects on yield and they have soft, chalky kernels that are susceptible to disease and insect damage. 

The most important role of animal protein is to correct the amino acid deficiencies of the cereal proteins, which supply about two-thirds of the total protein intake, and which are notably deficient in the amino acid, lysine. The latter deficiency can also be filled by soyhtean meal, fish, protein concentrates and isolates, synthetic lysine, or high-lysine com. But such products have neither the natural balance in amino acids nor the appetite appeal of animal protein. 

FIGURE 1.12 Comparison of cereals with different types of food sources in terms of per capita food, caloric, and protein intake. (From FAO (Food Agriculture Organization). 2009. Statistical Database. Rome, Italy. Electronic page http //faostat.fao.org)... 

FIGURE 1.13 Per capita food, caloric, and protein intake of the different types of cereals.35... 

The beneficial effects of dielary fiber, including both soluble and insoluble fiber, are generally recognized. Current recommendations arc for daily intakes of 20-35 g in a balanced diet of cereal products, fruits, vegetables, and legumes. However, the specific preventive role of dietary fiber in certain diseases has been difficult to establish, in pan because dielary risk factors such as high saturated fat and high protein levels are reduced as fiber levels increase. 

Cereal grains, such as maize, barley, wheat and sorghum, are the main ingredients of poultry diets and usually provide 30-60% of the total AA requirements. Other sources of protein such as soybean meal and canola meal must be provided to ensure adequate amounts and a proper balance of essential AAs. The protein levels necessary to provide adequate intakes of essential AAs will depend on the feedstuffs used. Feedstuffs that contain high-quality proteins (i.e. with an AA pattern similar to the bird s needs) or mixtures of feedstuffs in which the AA pattern of one complements the pattern in another will meet the essential AA requirements at lower dietary protein levels than feedstuffs with a less desirable AA pattern. This is important if one of the goals is to minimize N excretion. 

A functional food is one that offers a benefit over and above its nutritional value. Our body needs an intake of six essential dietary components in order to sustain life and regenerate cells they are carbohydrates, proteins, fats, vitamins, minerals, and water. Many meals provide most or all of them. A functional food has to offer something extra and not just more of one of these essential components, and it must actively promote the health of those who consume it. Merely fortifying a food with calcium or vitamin C does not turn it into a functional food. Most breakfast cereals have added iron, and adding more iron in the form of iron powder to make Kellogg s Special K does not make this a functional breakfast cereal. 

The nutritive characteristics of rice and its relative low cost make of this cereal a staple food in many countries, meeting almost completely (up to 80 percent) the food needs of half of the world population, and contributing over 50 percent of protein to the daily food intake [2]. From a general viewpoint, the major rice-producing countries are also large rice consumers and exporters. In fact, China and India, because of their hot and humid climates, favorable to the cultivation of rice, cover more than 50 percent of the world rice production and account for about 25 percent of the worldwide export of rice [3, 4]. 

The accepted amount of protein required to maintain nitrogen balance is 28 g per day for a 70-kg person, i.e, about 3,8 g of nitrogen. This is estimated by measuring the N excretion over 6 to 7 days on a protein-free diet. If the protein source is from cereal, then the daily intake would have to be increased to about 40 g per day for a 70-kg person. The difference is due to the variable amounts of essential amino acids found in proteins. The amount required by growing children is larger the accepted figure is about 0.6 g per kilogram per day. 

Almost all the evidence showing that phytate decreases zinc absorption in man and animals is based on pure phytate added to the diet. The effect of natural phytate is variable (18). It has, however, been reported that phytate in bran affected zinc bioavailability in the same way as sodium phytate (19). Dietary fibre in the rural Iranian diet was considered to be the main cause of zinc deficiency in Iran (20). However, the addition of 26 g of fibre from various sources to the American diet did not have any significant effect on the zinc requirements of male adults (21). Similarly, Indian men consuming a diet containing only 10.8 mg of zinc were reported to be in balance in spite of a dietary fibre intake of 50 g per day (22). Moreover, the presence of fibre and phytate in soy flour did not affect the bioavailability of zinc added as zinc carbonate, to the diet of rats (17), although others (23) have reported that the bioavailability of zinc in breakfast cereals depends mainly on their phytate-zinc molar ratio. Our results indicate that there is some, as yet, undetermined difference in the phytate or the fibre of cereals which affects the bioavailability of zinc. It may be some component of dietary fibre (24) or the intrinsic differences in the protein-phytate-mineral complex (10). 

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