Iodine: Essential for Thyroid Health and Metabolic Function

Iodine plays a crucial physiological role in the human body, primarily in the synthesis of thyroid hormones by the thyroid gland. The primary hormone produced is thyroxin, also known as T4. Thyroxin is integral to various bodily functions, including regulating heart rate, body temperature, and overall metabolism.

Dietary iodine is absorbed throughout the gastrointestinal tract, where it is first converted into the iodide ion. Once absorbed, iodide is utilized by the thyroid gland to synthesize thyroid hormones. The kidneys then excrete any excess iodide through urine. Since the body only absorbs the amount of iodine needed by the thyroid at any given time, it is vital to consume iodine-rich foods regularly because the body does not store excess iodine.

When the body lacks sufficient iodine, the thyroid gland attempts to compensate by increasing its secretory activity. This overactivity can lead to the enlargement of the gland, a condition known as goiter.

Iodine can be found in various dietary sources, with seafood being a particularly rich source. However, the iodine content varies significantly between seawater and freshwater fish. Other protein-rich foods, such as milk, yogurt, eggs, and meat, also supply iodine. Additionally, breads and grain products made from iodized dough are important sources of iodine in many diets.

The importance of maintaining adequate iodine intake cannot be overstated, especially given the critical role of thyroxin in overall health. With recent health trends emphasizing whole foods and natural diets, it is crucial to ensure that iodine-rich foods are not overlooked. For those living in areas with iodine-deficient soil or those who consume primarily plant-based diets, considering iodized salt or supplements may be necessary to prevent thyroid-related health issues like goiter.
Iodine: Essential for Thyroid Health and Metabolic Function

The Essential Role of Vitamin E and the Consequences of Its Deficiency

Vitamin E, discovered in 1922, has been recognized as an essential nutrient for human health since 1983. This fat-soluble antioxidant plays a crucial role in protecting cells from oxidative damage. The importance of vitamin E was initially observed in children with fat malabsorption syndromes, such as abetalipoproteinemia, cystic fibrosis, and cholestatic liver disease. These conditions impair the body’s ability to absorb dietary fats, leading to a deficiency in vitamin E.

Symptoms of vitamin E deficiency have also been reported in individuals suffering from protein-calorie malnutrition, though such cases are rare. In the general population, vitamin E deficiency is uncommon due to its wide availability in various foods like nuts, seeds, and vegetable oils. However, individuals with fat malabsorption disorders are particularly vulnerable to this deficiency. For these at-risk groups, supplementation is often recommended to prevent the onset of deficiency symptoms.

The absence of sufficient vitamin E in the body has significant consequences. One of the most severe effects is the destruction of red blood cells, a condition known as erythrocyte hemolysis. This occurs because vitamin E protects the polyunsaturated fatty acids in cell membranes from oxidative damage. Without this protection, the cells break open, spilling their contents and leading to anemia. Premature infants are particularly susceptible to erythrocyte hemolysis because they miss the critical transfer of vitamin E from the mother during the last weeks of pregnancy.

Vitamin E deficiency primarily manifests as peripheral neuropathy, a condition characterized by the degeneration of large axons in sensory neurons. This leads to symptoms such as numbness, tingling, and loss of coordination. Other neurological symptoms include spinocerebellar ataxia, skeletal myopathy, and pigmented retinopathy. In severe cases, prolonged deficiency can result in neuromuscular dysfunction affecting the spinal cord and retina, leading to irreversible damage.

Given the essential functions of vitamin E in maintaining cellular integrity and neurological health, ensuring adequate intake is vital, particularly for those at risk of deficiency.
The Essential Role of Vitamin E and the Consequences of Its Deficiency

Vitamin E Food Sources

Vitamin D: The Versatile Nutrient and Hormone Essential for Health

Vitamin D, a unique compound in the realm of human health, can be classified either as a vitamin or a hormone. Its active form, calcitriol, functions similarly to a hormone because it is synthesized in one part of the body and exerts regulatory effects on distant tissues.

A crucial role of vitamin D is its regulation of calcium and phosphorus absorption in the digestive tract, facilitating their deposition in bones. This process is vital for the formation and maintenance of strong bones. When dietary calcium is insufficient, vitamin D mobilizes calcium from skeletal reserves to meet the body's needs. This interaction is part of a complex regulatory system involving parathyroid hormone (PTH) from the parathyroid glands and calcitonin from the thyroid glands.

In addition to its skeletal functions, vitamin D influences cell differentiation and growth. It modulates the transcription of cell cycle proteins, reducing cell proliferation and enhancing differentiation in various cell types, including osteoclastic precursors (bone-resorbing cells), enterocytes (intestinal lining cells), and keratinocytes (skin cells). This regulatory capability has implications for cancer prevention, notably colorectal cancer, where adequate vitamin D levels may offer protective benefits.

Moreover, vitamin D plays a significant role in immune defense. It is found in high concentrations in T-lymphocytes, critical cells in the immune system. Emerging research suggests that adequate vitamin D levels in early life might prevent the onset of autoimmune diseases such as type 1 diabetes by modulating immune responses.

Vitamin D synthesis begins in the skin, where 7-dehydrocholesterol is converted to cholecalciferol upon exposure to sunlight. Cholecalciferol then enters the bloodstream and travels to the liver for further conversion to its active form. This fat-soluble steroid hormone precursor is essential for maintaining normal calcium and phosphorus levels in the blood, which are critical for bone mineralization, muscle contraction, nerve conduction, and overall cellular function.

Recent studies underscore the broader health implications of vitamin D. Its deficiency has been linked to various disorders, including osteoporosis, cardiovascular diseases, and certain infections. Ensuring adequate vitamin D levels through sunlight exposure, diet, or supplementation is crucial for maintaining overall health and preventing a spectrum of diseases. As research progresses, the understanding of vitamin D's multifaceted roles continues to expand, highlighting its importance as both a nutrient and a regulatory hormone in human physiology.
Vitamin D: The Versatile Nutrient and Hormone Essential for Health

Morning Market Fish: Rich in Vitamin D

What are the functions of ileum?

The lowest part of small intestine is the ileum. The ileum is the last and longest section of the small intestine.

In ileum, the walls of the small intestine begin to thin and narrow, and blood supply is reduced. Food spends the most time in the ileum, where the most water and nutrients are absorbed.

The ileum helps to further digest food coming from the stomach and other parts of the small intestine. It absorbs nutrients (bile acid, vitamins, minerals, carbohydrates, fats, proteins) and water from food so they can be used by the body. Finger-shaped structures called villi line the entire small intestine. They help absorb nutrients.

The main difference between jejunum and ileum is that jejunum absorbs fully-digested carbohydrates and proteins whereas ileum absorbs the non-absorbed particles from the jejunum.

In case of protein, it starts to break down in the stomach. Absorption of protein starts in duodenum which breakdowns protein into smaller forms called amino acids and these amino acids are finally absorbed by ileum and then they are used by different parts of the body via blood.

In the ileum, segmentation slows down and peristalsis takes over, moving food waste gradually toward the large intestine.
What are the functions of ileum?

Function, deficiency and food sources of calcium

Physical Function
Structural component of bones and teeth; role in intracellular and hormonal secretion regulation, muscle contraction, and activation of some enzyme systems.

Calcium is maintained relatively high concentration in the blood and extracellular fluids, where it is needed to facilitate such functions as blood coagulation and intercellular communications. Blood calcium levels are rigorously controlled so that if blood levels drop the body will rapidly respond by stimulating bone resorption, thereby releasing stored calcium into the blood.

Calcium also enables human blood to clot normally and regulates our muscle contractions, including heartbeat

The most well-known calcium function is to build and strengthen bones and teeth. The calcium in bones serves as a reservoir for calcium that is needed throughout the body. Calcium helps human bones to grow strong until the age of 20-25, when bone density reaches its peak. About 99% of the body’s calcium is stored in bones, and the remaining 1% is found in blood, muscle, and other tissues.

Calcium also is the key factor in normal transmission of nerve impulses. Calcium binds to vesicles that contain neurotransmitters, causing a release into the neural synapses (junction between nerve cells). This allows the flow of ions in and out of nerve cells. If calcium is lacking, nerve-cell function will fail.

Calcium is a key component of the cell membrane and controls cell permeability and electrical properties.

In order to perform daily functions, the body works to keep a steady amount of calcium in the blood and tissues. If calcium levels drop too low in the blood, parathyroid hormone (PTH) will signal the bones to release calcium into the bloodstream.

Deficiency symptoms
A low calcium intake during the growing years limits the bones’ ability to reach their optimal mass and density.

The symptoms of calcium deficiency include rickets, osteomalacia, osteoporosis, scurvy, tetany, parathyroid hyperplasia, stunted growth, laryngospasm.

Deficiency of calcium in young girls causes late puberty, irregular menstruation, excessive bleeding with crampy pain during this period, anemia and lowered state of body resistance against infection.

A more serious deficiency of calcium, called hypocalcemia, results from diseases such as kidney failure, surgeries of the digestive tract like gastric bypass, or medications like diuretics that interfere with absorption.

Food sources
Calcium is found in milk, milk products, sardines, clams, oysters, cheese and dairy foods, dark green vegetables (turnip greens, broccoli, legumes), dried fruits and nuts.

Calcium is classically associated with dairy products: milk, yoghurt and cheeses are rich sources of calcium, providing the major share of calcium from foods in the general diet in the United States and Canada.

When substantial amounts of grains are consumed, for like breads or as maize, these can be important sources, although the calcium in cereals tends to be less bioavailable than that in dairy products.
Function, deficiency and food sources of calcium

What are the functions of vitamin A?

A fat-soluble nutrient, vitamin A, also known as retinol, has many important functions. Vitamin A is converted to light sensitive pigments in receptor cells of the retina, the light sensitive layer of the eye.

Vitamin A is also required for healthy reproduction and lactation. Vitamin A helps form and maintain healthy teeth, mucous membranes, skeletal and soft tissues and skin. It supports cell growth, immune function, fetal development, and vision. It is also known as retinol because it produces the pigments in the retina of the eye.

Vitamin A helping human body's natural defense against illness and infection (the immune system) work properly. Scientists claim that vitamin A is ‘the anti-infective vitamin,’ enabling body surfaces to act as a barrier to invading micro-organism and toxins.

One of its physiological functions is the formation and maintenance of epithelial tissue, which contributes to the body immune system. Epithelial cells (those cells present in the lining of body cavities and in the skin and glands) require vitamin A.

Provitamin A carotenoids, β -carotene is an antioxidant. Antioxidants protect cells from damage caused by substances called free radicals.

Free radicals are believed to contribute to certain long-term diseases and also play a role in aging Lack of vitamin A in the diet will result in the drying up of the body cells which could lead to dermatitis, dry hair or night blindness.

Good sources of vitamin A (retinol) include: cheese, eggs, oily fish, fortified low-fat spreads, milk, yoghurt, and liver. Vitamin A is also available in dietary supplements. It most often comes in the form of retinyl acetate or retinyl palmitate (preformed vitamin A), beta-carotene (provitamin A) or a combination of preformed and provitamin A.
What are the functions of vitamin A?

Vitamin E: Main functions in human body

Vitamin E is present in human tissues and it is necessary for normal metabolism. It is found to be widely distributed in foods. Vitamin E is the collective term given to a group of fat-soluble compounds first discovered in 1922 by Evans and Bishop; these compounds have distinct antioxidant activities essential for health.

Deficiency of vitamin E in man has not been reported and so there is no recommended daily intake. Vitamin E deficiency occurs only as a result of genetic abnormalities in α–tocopherol transfer protein, as a result of various fat malabsorption syndromes, or as a result of protein-energy malnutrition.

It has numerous important roles within the body because of its antioxidant activity. For example, vitamin E protecting substances such as unsaturated fatty acids, carotene and ascorbic acid, which are easily oxidized.

Vitamin E is an essentially naturally occurring fat-soluble nutrient that is involved in several biological processes such as immunity, protection against tissue damage (hear, nerve, etc) reproduction, growth and development.

Vitamin E helps to prevent arteries from clogging by blocking the conversion of cholesterol into the waxy fat deposits called ‘plaque’ that stick to blood vessel walls. Vitamin E also thins the blood, allowing it to flow more easily through arteries even when plaque is present.

One of the few generally recognized uses for vitamin E is in the treatment of hemolytic anemia in premature babies.

Because of its antioxidant action, vitamin E may help protect against clouding of the lens of the eye (cataracts) and a progressive deterioration in the retina, the back part of the eye (age-related macular degeneration, AMD).

There were also studies indicate that vitamin E may slow the aging process and prevent premature aging by prolonging the useful life of human cells, thus maintaining the function of human organs.

Vitamin E is found in various foods and oils. Nuts, seeds and vegetable oils contain high amounts of α-tocopherol, and significant amounts are also available in green leafy vegetables and fortified cereals.
Vitamin E: Main functions in human body

Compounds of flavonoids

Flavonoids are plant compounds that are found in almost all fruits and vegetables. Flavonoids are classified into subgroups based on their chemical structure: flavanones, flavones, flavonols, flavan-3-ols, anthocyanins and isoflavones. In plants, flavonoids have long been known to be synthesized in particular sites and are responsible for the color and aroma of flowers, and in fruits to attract pollinators and consequently fruit dispersion to help in seed and spore germination, and the growth and development of seedlings.

Flavonoids are the largest group of phytonutrients, with more than 6,000 types. Flavonoids have roles against frost hardiness, drought resistance and may play a functional role in plant heat acclimatisation and freezing tolerance.

In addition, they have antioxidant, antiviral and antibacterial properties. They also regulate gene expression and modulate enzymatic action.

Flavonols are flavonoids with a ketone group. They are building blocks of proanthocyanins. Flavonols occur abundantly in a variety of fruits and vegetables. The most studied flavonols are kaempferol, quercetin, myricetin and fisetin.

Flavonoids are now considered as an indispensable component in a variety of nutraceutical, pharmaceutical, medicinal and cosmetic applications. Research on flavonoids received an added impulse with the discovery of the low cardiovascular mortality rate and also prevention of coronary heart disease.
Compounds of flavonoids

Gastrointestinal hormones

Early studies on the motility and secretory activity of the gastrointestinal tract indicated that control was not only by the autonomic nervous system but also by a series of gastrointestinal hormones whose release is stimulated when specific hormones reach particular loci in the tract.

Gastrointestinal hormones are chemical messengers that are implicated by many aspects of physiological functions of the gastrointestinal tract, including the regulation of secretion, absorption and digestion, and gut motility.

Gastrointestinal hormones are a large family of peptides and are secreted by endocrine cells that are widely distributes throughout the gastrointestinal mucosa and pancreas. Hormones were originally identifies by four primary actions.
Sccretin: stimulates secretion of HCO3 and H2O
Gastrin: stimulates gastric secretion of acid
Cholecystokinin: contract gallblader
Pancreozymin: stimulates pancreatic secretion of enzymes

And as of today there are more than 50 gut hormones genes and a multitude of bioactive peptides, which makes the gut as the largest endocrine organ of the body.

The gastrointestinal hormones are synthesized in various segments of the gastrointestinal tract but only gastrin appears to be present in the stomach of healthy individuals. The remaining hormones are present in greatest amounts in the duodenum and jejunum, with tapering expression of cholecystokinin and secretin into the ileum in addition.
Gastrointestinal hormones

Functional use of vitamin E in human body

Vitamin E is the collective term given to a group of fat-soluble compounds first discovered in 1922 by Evans and Bishop.

Vitamin E consists of two families of compounds, the tocopherols and tocotrienols, characterized by a 6-chromanol ring and an isoprenoid side chain. The members of each family are designated alpha((α)-, beta(β)-, gamma(γ)-, or delta(δ)- according to the position of methyl groups attached to the chroman nucleus.

Vitamin E functions as a chain-breaking antioxidant that prevents the propagation of free radical reactions. It is primarily located in the cell and organelle membranes where it can exert its maximum protective effect, even when its concentration ratio may be only one molecule for every 2,000 phospholipid molecules. It acts as the first line of defense against lipid peroxidation, protecting the cell membranes from free radical attack.

It has been found that alpha-tocopherol mainly inhibits the production of new free radicals, while gamma-tocopherol traps and neutralises the existing free radicals. Oxidation has been linked to numerous possible conditions/diseases including: cancer, ageing, arthritis and cataracts.

The vitamin is a peroxyl radical scavenger and especially protects polyunsaturated fatty acids (PUFAs) within membrane phospholipids and in plasma lipoproteins.

Vitamin E increases the orderliness of the membrane lipid packaging, thus allowing for a tighter packing of the membrane and, in turn, greater stability to the cell. In 2011, study showed that vitamin E is necessary for maintaining proper skeletal muscle homeostasis and that the supplementation of cultured myocytes with α -tocopherol promotes plasma membrane repair.

α-tocopherol appears unique in regulating phosphorylation cascades. Such a role may be important in heart disease where cell adhesion, proliferation, and oxidant production may all be modified through vitamin E-sensitive pathways.
Functional use of vitamin E in human body

Glycoproteins and plasma membrane

Proteins can be bound to other compounds to form nucleoproteins, glycoproteins, and lipoproteins. Of particular interest are the glycoproteins associated with the plasma membrane of the cells that coat the membrane surface.

The membrane glycoproteins are crucial to the life of the cell, very possibly serving as the receptors for hormone, certain nutrients, and various other substances that influence cellular functions.

The glycoprotein surface coat is considered to be an integral part of the plasma membrane. These glycoproteins are played an important role in ion transport and intercellular communication.

Glycoproteins also help regulate the intracellular communications necessary for cell growth and tissue formation. Intracellular communication occurs through pathways that convert information from one part of a cell to another in response to external stimuli.
Glycoproteins and plasma membrane

Forms of Vitamin K

Vitamin K actually comes in three different forms:
First, there’s vitamin K1, or phylloquinone. Phylloquinone is ubiquitously distributed in plants, green leafy, vegetables oils, and algae and is the main source of vitamin K in the human body. This group of lipophilic vitamins, mostly required for blood coagulation, also plays important roles in bone metabolism, calcification and vascular health.

Next, there’s Vitamin K2, also called menaquinone. This the form friendly bacteria in the intestines make. Vitamin K2 helps the body turn on biological switches that activate three critical preteens: osteocalcin, calcitonin, and matrix G1a. Osteocalcin, calcitonin, and matrix G1a are calcium-binding proteins that are essential in guiding into the bone.

The September 2003 International Journal of Oncology revealed that treating lung cancer patients with vitamin K2 slowed the growth of cancer cells. Among food sources of vitamin K2 are green vegetables, parsley, cilantro, watercress, culinary herbs and green drinks”.

The last form would be called vitamin K3. This is the artificial form, also called menadione. All vitamin K ends up in liver, where it’s used to make some of the substance that make blood clot.
Forms of Vitamin K

Carbohydrates in biological system

Carbohydrates are polyhydroxy aldehydes, ketones, alcohol, acids, their simple derivatives and their polymers having linkages of the acetal type.

Carbohydrates are an essential component of the human diet responsible for supplying energy to the host and its complex gastrointestinal microflora, but also for having an overall role in physiology including maintaining gastric function, hepatic metabolism and glycosylation of lipids and proteins necessary for other physiological functions.

Each gram of starch or sugar gives four calories to the body. About 65 top 80 –percent of energy is supplied by the carbohydrates, mainly in the form of starch.

Some of this energy is used as glucose to supply immediate energy needs of the body, a small portion is stored as glycogen (about 350 g) mainly in the muscles and liver; and any excess intake is converted to fat and stored as adipose tissue. Glucose is the source of energy for the central nervous system.

Another important function is to spare proteins for their main function of tissue building and maintenance. It is important to supply sufficient carbohydrates and fats to meet the essential energy needs of the body, otherwise proteins are metabolized to meet energy requirement of the body.

A third functions is related to proper utilization of fat from the diet. It is that fats burn in the flame of carbohydrates, indicating the need for major part of energy to be supplied in the form of carbohydrates.

Carbohydrate-containing foods are vehicles for important micronutrients and phytochemicals. Dietary carbohydrate is important to maintain glycemic homeostasis and for gastrointestinal integrity and function.

Certain carbohydrates have special role in the body. Lactose aids the absorption of calcium, Ribose a five carbon sugar, is a part of the important compounds DNA and RNA. Cellulose and other indigestible carbohydrates aid the movements of food through the digestive tract by their capacity to absorb water and help to maintain muscle tone.

There are many researches linking the consumption of complex nonstarch polysaccharides with a reduced risk of chronic disease including diabetes, cardiovascular and cancers.
Carbohydrates in biological system

The roles and functions of mucosal cells

All cells depend on their external environment for their supply of nutrients. Food in the lumen is not technically inside the body because it has not been absorbed.

Mucosa is the innermost layer and this layer line the interior of the digestive tract and thus is in direct contact with essential nutrients (in food) available in the external environment. It becomes obligatory, therefore for this mucosal cells to take in all the nutrient essential not only for their own metabolisms but also for that the whole organism.

The mucosal cells are uniquely adapted to perform this primary functions: transporting from the external environment to the internal environment the nutrients essential for all of the cells that comprise the total organism.

In some cases, these cells secret a mucus layer that serves to lubricate the passage and protect the cells. Epithelial cells of mucosa are arranged into folds to increase the surface area. The amount of folding is dependent on the region of the gastrointestinal tract.

Because mucosal cells are in direct contact with churning food and harsh digestive secretions, they live only about two to five days.
The roles and functions of mucosal cells 

Vitamin A: functions and food sources

Vitamin plays a central role in many essential biological processes. Vitamin A (retinol) functions in reproduction, growth, the maintenance of skin and mucous membranes and the visual process.

Vitamin A is needed to process incoming light to visual images and to keep the eye’s surface healthy. Vitamin is known to be involved in fetal development and in the regulation of proliferation and differentiation of many types of cells throughout life. It plays a role in immune function, both as a cell regulator and by helping maintain the skin and mucous membranes.

Vitamin A is normally transported in the blood linked to a specific protein, retinol binding protein (RBP). Specific proteins on cell surfaces and within cells are also involved with intracellular transport of the vitamin.

Vitamin A is fat soluble and is primarily stored in the liver, where RBP is synthesized. The liver holds over 90 percent of the body’s vitamin A reserves, with the rest deposited in fat tissue, lungs and kidneys.

In a well nourished person, vitamin A stores are generally sufficient to last many months on a vitamins A-deficient diet before signs of deficiency appear.

The initial symptoms of vitamin A deficiency are night blindness and keratinization of hair follicles. Continued deficiency leads to damage to eye tissue and irreversible blindness.

The US recommended Daily Allowance (RDA) of vitamin A for adults is 5000 IU (1000 retinol equivalents). Main dietary sources of vitamin A are the carotenoids from fruits and vegetables. These carotenoids do seen to have a separate function as antioxidants in addition to their pro-vitamins A function.

Rich dietary sources of retinol (preformed vitamin A) include dairy products, eggs and organ meats. Some carotenoids (found in deep-yellow and dark green vegetables) can be converted to vitamin A during digestion. In the US diet, approximately half of the vitamin A activity is derived from B-carotene and other carotenoids.
Vitamin A: functions and food sources

Food minerals: classification and functions

Most foods contain mineral.  When burned, they leave a residue – a gray or whitish ash. Minerals are heat stable and classified into:
Main elements
Trace elements
Ultra trace elements

The main elements or major minerals include Na, K, Ca, Mg, Cl, P are essential for human beings in amounts >50 mg/day. Sulfur also belongs to this group.

Trace elements include Fe, I, F, Zn, Se, Cu, Mn, Cr, Mo, Co, and Ni are essential in concentrations of <50 mg/day: their biochemical actions have been elucidated

Although trace minerals are present in minute amounts, they play very important roles in the diet, and modern analytical methods are extremely sensitive to accurately measure them in foods.

Ultra – trace element (Al, As, Ba, Bi, B, Br, Cd, Cs, Ge, Hg, Li, Pb, Rb, Sb, Si, Sm, Sn, Sr, TI, Ti, W) are elements whose essentially has been tested in animal experiments over several generations and deficiency symptoms have been found these extreme conditions.

Minerals elements are used by the body in a great variety of ways. They may present in the cell fluids (potassium is particularly important) or like sodium, in extracellular fluids. Main and trace elements have very varied functions, e.g., as electrolytes, as enzymes constituents and a building materials, e.g., in bones and teeth.

The importance of minerals as food ingredients depends not only on their nutritional and physiological roles. They contribute to food flavor, texture and when digested provide the cofactors for enzymes that assists digestion.

Minerals are also responsible for food spoilage while in storage and must be viewed in the context of shelf life and food safety.
Food minerals: classification and functions

The importance of ascorbic acid

Ascorbic acid was recognized as early as 1734 as the factor in fresh fruit and vegetables that prevent the development of scurvy.

Ascorbic acid or vitamin C is required for the formation of intercellular substances in the body, including dentine, cartilage, and the protein network or bone. Hence, it is important in tooth formation, the healing of broken bones, and the healing of wounds.

It may be important to oxidation –reduction reactions in the body and to the production of certain hormones.

In the brain, ascorbic acid may perform important functions related to the metabolism and release of several neurotransmitter.

Vitamin C is not only an important nutrient but is also used as an antioxidant in various foods.

Vitamin C recharges fat soluble vitamin E and water soluble glutathione, allowing them, to be reused many times.

Tomato juice, if it has been processed properly, is a fair source of this vitamin. Green peppers, cabbage, broccoli, and sprout are excellent to good sources of vitamin C, while other vegetables such as peas, spinach, and lettuce are good to fair sources. Many fruit contain fair amounts of vitamin C.

Overdoses of vitamin C induce perspiration, nervous tension, and lowered pulse rate.
The importance of ascorbic acid

What are the functions of protein and amino acids?

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.  Results from clinical experiments involving the oral administration of tyrosine or phenylalanine to patients with tyrosinosis led Grace Medes to conclude in 1932 that phenylalanine also can be converted into tyrosine in humans.

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 methionine metabolic pathway supports numerous functions within the central nervous system beyond providing an essential amino acid precursor for protein synthesis.

These functions include neurotransmitter synthesis, methyl group donation, polyamine precursor, osmotic protection, antioxidant synthesis, and DNA salvage synthesis.
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.

L-arginine is a precursor for biosynthesis of other amino acids present in protein (glutamate and proline) or not present in proteins (ornithine, citruline). Arginine is a precursor of urea, polyamines, creatine and nitric acid. Polyamines are involved in cell mitosis.
 
Glutamic acid cysteine, and glycine are components of a tripeptide glutathione, which functions in cellular oxidation-reduction reactions. Glutamic acid can undergo conversion to alpha-ketoglutarate and ammonium. As such, glutamate is an oxidative substrate in several cell types.

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.
What are the functions of protein and amino acids?