Tryptophan food sources

The fact that the leaves contain significant amounts of tryptophan has at least two implications. First, for those people for whom baobab leaves are a staple, this food source may provide significant amounts of tryptophan. Second, since a part of the niacin requirement in humans can be satisfied by the conversion of tryptophan to niacin (Satyanaryana and Fao, 1983, cited in (2)), baobab leaf may also serve as a niacin source. 

People who do not eat meat must be careful to eat a diet that includes the essential amino acids. This can be accomplished by eating complementary proteins. For example, com has many essential amino acids but is low in tryptophan. Beans, however, have ample tryptophan cultures that use cornmeal often complement this food source with beans. Similarly, cultures in Asia often eat rice with soy sauce this combination provides complementary proteins in the diet. 

Riboflavin in its coenzyme forms (FMN and FAD) plays key metabolic roles in biological oxidation-reduction reactions involving carbohydrates, amino acids and lipids, and in energy production via the respiratory chain. These coenzymes also act in cellular metabolism of other water-soluble vitamins through the production and activation of folate and pyridoxine (vitamin Bg) to their respective coenzyme forms and in the synthesis of niacin (vitamin B3) from tryptophan. In addition, some neurotransmitters and other amines require FAD for their metabolism. Recently, Chocano-Bedoya et al. (2011) suggested a possible benefit of high intakes of riboflavin (about 2.5 mg/ day) from food sources on the reduction of incidence of premenstrual syndrome. 

An understanding of the mode and sequence of production of the components and factors affecting protein synthesis could be of considerable use to plant breeders and geneticists. Proteins of some seeds form an important part of the human diet in many countries, but are often deficient in certain amino acids, and if these are not provided from alternative food sources serious deficiency symptoms ensue. In normal maize, zein (the major protein body constituent) is poor in lysine and tryptophan, and is the protein which is synthesized late during maturation. Glutelins (the non-sequestered proteins) are synthesized... 

Not all foods provide sufficient amounts of the 10 essential amino acids, to meet our minimum daily needs. Most meat and dairy products are sat isfactoiy, but many vegetable sources, such as wheat and com, are incomr plete-, that is, many vegetable proteins contain too little of one or mow essential amino acids to sustain the growth of laboratory animals. Wheat is low in lysine, for example, and corn is low in both lysine and tryptophan. 

Albumin also functions as an amino acid source for peripheral tissue. After ingestion and absorption of amino acid-containing foods, albumin transports them to tissue. In addition, pinocytosed albumin itself can serve as a source of amino acids for tissue. The synthesis of albumin by the liver increases after meals, apparently in an attempt to prevent loss or catabolism of essential amino acids. Complexing by albumin appears to be necessary for the transport of some amino acids across membranes, in particular the transport of tryptophan across the blood-brain barrier. 

Tryptophan is exceptional in the diversity of its biological functions, which are covered throughout this book. It is appropriate to give limited attention to the chemistry of tryptophan. Many complex transformations of tryptophan in foods can occur. Also, a great diversity of derivatives can be formed, some of which conceivably have antinutritional and toxic manifestations. For details concerning such aspects of tryptophan, the reader is referred to sources that cover these aspects in detail.49 50 The following selected aspects are cited to emphasize some important chemical reactions that may affect humans. 

Dietary protein sources differ widely in their proportions of the EAA. In general, complete proteins (those containing sufficient quantities of EAA) are of animal origin (e.g., meat, milk, and eggs). Plant proteins often lack one or more EAA. For example, gliadin (wheat protein) has insufficient amounts of lysine, and zein (com protein) is low in both lysine and tryptophan. Because plant proteins differ in their amino acid compositions, plant foods can provide a high-quality source of essential amino acids only if they are eaten in appropriate combinations. One such combination includes beans (low in methionine) and cereal grains (low in lysine). 

Soybean proteins are widely used as food additives in European derived societies, primarily in processed foods, and this trend continues to grow annually. This makes soybean proteins a pervasive component of the human diet in industrialized countries. Solvent extracted soybean meal is also widely used as an animal feed additive (ref. 5, for review), because it is an inexpensive source of high quality protein that contains more of essential amino acids lysine and tryptophan than most cereal crops. Combined with corn, the other primary feed grain used in the United States, a ration can be assembled that is adequate in both sulfur amino acid and lysine contents, and provides a high protein diet that is well balanced for poultry and pigs. 

Riboflavin has a wide distribution in foods, and small amounts are present as coenzymes in most plant and animal tissues. Eggs, lean meats, milk, broccoli, and enriched breads and cereals are especially good sources. A portion of our niacin requirement can be met by synthesis from tryptophan. Meat (especially red meat), liver, legumes, milk, eggs, alfalfa, cereal grains, yeast, and fish are good sources of niacin and tryptophan. 

In many ways, this is an easier task than eating for serotonin. The amino acids used to produce these energizing biochemicals are tyrosine for dopamine and phenylalanine for norepinephrine—amino acids readily found in all sorts of protein foods and more easily assimilated into the brain than is tryptophan. So if you re suffering from a norepi/dopa deficiency, your main goal is to eat enough high-quality proteins throughout the day and to combine your protein sources with other appropriate foods. 

These foods don t contain any tryptophan themselves, but they are terrific sources of the B vitamins and minerals that the brain needs to turn tryptophan into serotonin. They re also are great sources of fiber, antioxidants, and cancer-preventing agents. 

The presence of indole or an indole derivative in a food is not always desirable. Some white wines develop an off-flavor described as ...floor polish like... within a few months of storage [33]. The chemical responsible for this unpleasant flavor was identified as 2-aminoacetophenone 16 in 1993 [34]. Reported in a series of papers over the next 10 years, researchers traced the ultimate source of this agent to indole-3-acetic acid 15 that was present in the grapes before harvesting Indole-3-acetic acid itself is derived from another indole L-tryptophan. The proposed mechanism for this transformation is shown in Scheme 14 [35]. 

Sources. Niacin and substances that are convertible to niacin are found naturally in meat (especially red meat), poultry, fish, legumes, and yeast. In addition to preformed niacin, some L-tryptophan found in the proteins of these foods is metabolized to niacin. Niacin is also present in cereal grains, such as corn and wheat. However, consumption of corn-rich diets has resulted in niacin deficiency in certain populations. The reason for this is that niacin exists in cereal grains in bound forms, such as the glycoside niacytin, which exhibit little or no nutritional availability. Interestingly, niacin deficiency is not common in Mexico and Central America even though the diets of those in these countries are based on com. Alkaline treatment, such as soaking corn in a lime solution—the process used by the populations of Mexico and Central America in the production of com tortillas—yields release of bound niacin and increased availability of the vitamin. 

Nicotinic acid is also known as niacin, and the deficiency syndrome pellagra occurs when dietary niacin is lacking. It is thought that about 15mg/day of niacin is needed for an adult. The main sources of niacin in the diet are tryptophan-containing proteins, like meats and foods that also contain nicotinic acid itself. However, a very small amount of tryptophan is included in corn. So, pellagra will occur frequently on a diet derived from corn as a main food. 

There are numerous sources of niacin that are essential and these include poultry, fish (tuna, salmon), meat (beef), yeast, legumes, milk and fortified eereals. In addition, niacin is naturally occurring in tiny amounts and the human body can make nicotinic acid from the metabolism of dietary tryptophan (Vosper 2009). The body requires tryptophan for two main reasons (i) for the synthesis of niacin and (ii) to raise serotonin levels, which is essential for the regulation of sleep, appetite and mood. The vast majority of proteins contain about 1 % of tryptophan and it is suggested that approximately 100 g of protein intake a day will be sufficient to ensure optimum levels of niacin in the body. The recommended dose of niacin is higher when there is an increase in physiological states such as pregnancy and lactation. Importantly, the Committee of Medical Aspects of Food Policy (COMA) in the UK stated that the Reference Nutrient Intake (RNI) for niacin was 17 mg/day and 13 mg/day. 

In the organism that Is required In small amounts In food to sustain the normal metabolic functions of life. The key to this definition Is that this chemical compound must be supplied to the organism because the animal cannot synthesize vitamins. Lack of It produces a specific deficiency syndrome and supplying It cures that deficiency. An exception to this definition Is vitamin D, which can be made In the skin upon adequate exposure to sunlight. However, without adequate exposure, the animal Is dependent on a dietary source. Biotin, panthothenlc acid, and vitamin R are made by bacteria In the human Intestine, based on a symbiotic relation-ship and, thus, are not required by the human. Niacin can also be synthesized In humans from the amino acid tryptophane. 

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