Manganese Absorption and Metabolism

Manganese, a vital trace mineral essential for all living organisms, plays a pivotal role in the consistent development, growth, and functioning of the human body. It serves as a cofactor for a diverse range of enzymes, including manganese superoxide dismutase, arginase, and pyruvate carboxylase. Brown rice, rice bran, wheat bran, wheat germ, molasses, beans, nuts, and tea are notable for being excellent sources of whole foods rich in manganese.

The absorption of manganese predominantly takes place in the small intestine through an active transport system, with the possibility of diffusion at elevated intake levels. Regulatory mechanisms ensure that an uptick in dietary manganese intake leads to a reduction in gastrointestinal absorption. Following absorption, some manganese remains unbound, while the majority binds to transferrin, albumin, and plasma alpha-2-macroglobulin. Although the process of manganese uptake by the liver and other tissues is not fully understood, it is generally acknowledged as a mineral with absorption rates that are less than optimal.

Various elements, such as fiber, phosphorus, oxalates, and iron, can impede manganese absorption, and alkalinity may diminish manganese uptake. The liver expedites the elimination of manganese from the bloodstream through biliary excretion, with less than 5 percent of ingested manganese typically being absorbed by adults.

Numerous enzymes activated by manganese play pivotal roles in the metabolism of carbohydrates, amino acids, and cholesterol.
Manganese Absorption and Metabolism

Aspartame metabolism in human body

Unlike many other intense sweeteners, aspartame is metabolized by the body. Aspartame is metabolized in the gastrointestinal tract to aspartic acid, phenylalanine and methanol.

The aspartic acid is primarily used for energy through conversion to CO2 in the Krebs cycle. The phenylalanine is primarily incorporated into body protein, either unchanged or as tyrosine.

People with the rare human genetic disease, phenylketonuria have a deficiency in their ability to metabolize phenylalanine and unable to dispose of any excess phenylalanine. Their intake of this essential amino acid must be very strictly controlled from birth to adulthood.

Therefore, they must include phenylalanine content of aspartame in their dietary calculations.

The accumulation of phenylalanine and its by–product is toxic to the developing nervous system, causing irreversible brain damage.

Aspartame is non-carcinogenic and has calorific value of approximately 3 cal/g. The level of daily consumption that is judged to be safe by the FDA is 50 milligrams per kilogram of body weight per day.

Aspartame metabolism in human body 

Catabolism of fatty acids

Catabolic pathways ware characteristically energy yielding, whereas anabolic pathways are energy requiring. Catabolism involves the oxidative degradation of complex nutrient molecules obtained either from the environment or from cellular reserves.

 Fatty acids are released from triglycerides stories in adipose tissue, transported in plasma in association with albumin and delivered to cells for metabolism. The fatty acids are catabolised by β-oxidation. The products of catabolism of phenyl derivatives of benzoic acid or phenylacetic acid, or their higher homologs, are excreted in urine. These products are always the derivatives of benzoic acid or phenylacetic acid.

In the fatty acid catabolism, two carbon units are sequentially removed, beginning from the carboxyl-terminal end. The major end products are acetyl co enzymes A and the reduced forms of the nucleotides FADH2 an NADH.
Catabolism of fatty acids

What is glycogen in human body?

During and immediately after a meal, glucose is converted in the liver into the storage polysaccharide glycogen by a process known as glycogenesis.

Although the total quantity of glycogen in the human body is low, considerably less than one-tenth percent of the total body weight, its role is primarily that of a storage carbohydrate, similar to the role of starch in plants cells. It occurs predominantly in the liver where it is important in the homeostatic mechanism regulating glucose level of the blood.

Glycogen is a branched chain polymer of 6,000 to 30,000 glucose units, that contains two types of glycosidic linkages, extended chains of alpha1-- 4 linked glucose residues with alpha 1-- 6 branches spaced about every four to six residues along the alpha 1-- 4 chain. It is similar to amylopectin in structure but is more highly branched. The average chain length is only 10 to 24 glucose units with 3 to 4 glucose units between branching points.

The highly branched structure of glycogen makes it possible for several glucose residues to be released at once to meet energy needs. 

Glycogen is stored in two tissues. In the liver, glycogen is stored for the short-termed maintenance of blood glucose. In muscle, glycogen is stored as a source of energy. Muscle glycogen is estimated to have a molecular weight of about 1000000 where as the liver of glycogen molecule is much larger, approximately 5 X 1000000. Both molecules, however, constantly change in size as glucose molecules are added or removed.

Glycogen plays an important role in the glucose cycle. The release of glycogen stored in the liver is triggered by low levels of glucose in blood. Liver glycogen breaks down to glucose-6-phosphate, which is hydrolyzed to give glucose.

The release of glucose from the liver by these breakdowns of glycogen replenishes the supply of glucose in the blood.

The most common disease in which glycogen metabolism becomes abnormal is diabetes, in which, because of abnormal amounts of insulin, liver glycogen can be abnormally accumulated or depleted.

Several hereditary defects have been identified in the synthesis and catabolism of glycogen including: Gierke’s disease, Type II glycogen disease, Type III glycogen, Type IV disease, and McArdle’s disease.
What is glycogen in human body?

Glucose functions in human body

Glucose is a monosaccharide, which is derived from dietary carbohydrates. Glucose is the only simple sugar that is transported in the bloodstream and it is commonly referred to as ‘blood sugar’.

Human body derived the glucose they need primarily from starch, a carbohydrate produce by plants. Glucose is found naturally in fruits, honey, sugarcane, sugar beets sweet potatoes, parsnip, onions and many other vegetables.

In the digestive system, starch is broken down into glucose molecules. Glucose then enters the blood stream.

The body cells use as much glucose as they can for their energy needs of the moment. Excess glucose is linked together and stored as glycogen.

Glycogen is the form in which the body store glucose in the liver and skeletal muscle cells. Glycogen is composed of long, highly branched chains of glucose molecules. When the blood glucose levels fall the human body are able to convert liver glycogen into glucose, which is called glycogenolysis.

To handle the glucose that’s still coming in, body tissues shift to burning more glucose for energy instead of fat.

As a result, more fat is left to circulate in the bloodstream until it is picked by the fatty tissues and stored there.

In healthy individuals, a decline in blood glucose is normally prevented by homeostatic mechanisms. Serious problems can result in people whole glucose homeostasis is not operating properly.

A low level of glucose in the blood is called hypoglycemia. And is as harmful to the brain as is lack of oxygen.

A high level of glucose in the blood is called hyperglycemia and can lead to glucose in the urine – glycosuria.
Glucose functions in human body

Functions of Protein and Individual Amino Acids

Functions of Protein and Individual Amino Acids
Traditionally amino acids have been described as ketogenic and glucogenic, that is, they tend to give rise to acetoacetate or carbohydrate intermediates.

In light of the present knowledge of interrelated metabolic pathways, these terms are obsolete. Nonetheless, it is perhaps useful to remember that phenylalanine, tyrosine, leucine and isoleucine are degraded in part to acetoacetate whereas other amino acids are degraded chiefly to pyruvate, oxaloacetate, alpha-ketoglutarate, succinate and fumarate.

The dietary requirements of certain of the amino acids are influenced by the intake of other nutrients. For example, phenylalanine is converted to tyrosine in the animal cell.

The dietary requirement for phenylalanine, therefore is a function of the total aromatic amino acid content of the diet.

Similarly, methionine may function metabolically as a precursor of other sulfur-containing amino acids so that both of the dietary methionine and cystine determine the requirement for methionine.

The relationship between tryptophan and nicotinic acid is another important example. Tryptophan may be metabolized to form nicotinic acid, and in so doing, contributes to the total amount of the vitamin available for cellular metabolism.

Many of the amino acids are precursors of other significant compounds required in metabolic processes. For example, tyroxine and therefore, phenylalanine give rose to the hormones tyroxine and epinephrine.

Glutamic acid cysteine, and glycine are components of a tripeptide glutathione, which functions in cellular oxidation-reduction reactions.

Sulfur containing amino acids give rise to taurine a bile acid component,. Tryptophan may be metabolized to form serotonin (5-hydroxytryptamine), a tissue hormone that is found predominantly in serum, blood platelets, gastrointestinal mucosa and nerve tissue.

Methionine provides methyl groups for synthesis of choline, creatine and methylation of nicotinamide to its major excretion product N’-methylnicotinamide.

Glycine contributes to the porphyrin ring of hemoglobin and, along with serine, provides part of the structure of the purine and pyrimidines of the nuclei acids.

Two hydroxylated amino acids – hydroxyproline and hydroxylysine – are important constituents of collagen; approximately 12 percent of the total amino acids content of collagen is hydroxyproline.
Functions of Protein and Individual Amino Acids

Carbohydrates

Carbohydrates
Unlike proteins, the carbohydrates in the body contribute nothing to the structure of tissue and although they contribute to the regulation of metabolism, they do not control individual molecular events as the enzymes (proteins) do. Their major function is the provision of energy to a variety of tissues, especially to the brain and nervous system which cannot utilize other nutrients for energy.

The carbohydrates in a typical breakfast – toast and tea with milk and sugar – are roughly representative of the distribution of carbohydrate in the average diet: starch from bread, potatoes, rice, pasta: sucrose from sugar: and lactose from milk. Starch is large molecule made up of many glucose units joined together, all glucose units being of similar structure. It is rapidly digested to its basic glucose units which are readily absorbed.

Lactose and sucrose are by contrast very much small molecules, each of which is digested to become effectively (in the liver) two units. The enzymes responsible for their digestion are, respectively, lactase and sucrase. There is rarely a problem is the digestion of sucrose but a great number of number people encounter problems with lactose digestion, most of which are associated with and inadequate supply of lactase.

Undigested lactose passes from small intestine, where digestion and absorption of its glucose units should occur, into the large intestine, where bacteria (a normal non pathogenic population of microbes) ferment the lactose and cause digestive upsets and diarrhea. The bulk of the population of Africa, Southern Europe, and the near East develop lactose intolerance during later childhood and adult life.

Under normal conditions, however the great majority of carbohydrates in our typical meal are digested and absorbed as glucose, if you measured blood glucose levels before such a meal and at half hourly intervals thereafter, you would see a rise in blood glucose, peaking at about the half hour mark and returning to fasting levels almost as quickly. If you were to abstain from carbohydrates for a considerable period say a week, your blood glucose levels would still be normal in spite of a minimal or zero intake, the body’s capacity to maintain blood glucose within specific limits is achieved by a variety of hormones, the two most important of which are insulin and glucagon. Both are secreted by the pancreas into bloodstream, as required.
Carbohydrates