Which vitamin becomes nadh

In plants, vitamin C has roles in processes such as growth, programmed cell death, pathogen responses, hormone responses, flowering, and senescence, as well as protection against environmental stresses [ 1 — 5 ]. Vitamin C also plays an important role in abiotic stress tolerance, and considerable interest has focused on it due to its ability to induce a protective effect on plants under stress.

It has been supported that vitamin C induced increases in the resistance of plants on heavy metal stress [ 5 ]. The role of exogenously applied ascorbic acid AsA under heavy metal stress on the photosynthetic pigments, membrane permeability, and mineral uptake of plants is not still clear [ 5 , 6 ]. In animals, biosynthesis of vitamin C is included in the glucuronic acid metabolic pathway, which is involved in the metabolism of sugars under normal and disease conditions, and in regulation of physiological functions Figure 1a.

Glucuronic acid metabolic pathway is also an important pathway for detoxification processes [ 3 , 4 ]. While most animals can convert d -glucose into l -ascorbic acid, humans and other primates, guinea pigs, some fish and birds, and insects are unable to produce ascorbic acid endogenously.

The major plant pathway is different from the animal l -ascorbate synthesis pathway that involves 10 enzymatic steps from d -glucose to l -ascorbate via the intermediate formation of GDP- d -mannose and l -galactose [ 3 ] Figure 1a. The oxidized form, dehydroascorbic acid, can be reduced back to ascorbic acid by glutathione GSH. Vitamin C l -ascorbic acid is a dibasic acid with an enediol group built into a five-membered heterocyclic lactone ring Figure 1b.

The chemical and physical properties of ascorbic acid are related to its structure [ 7 ]. The structure of dehydroascorbic acid, the first oxidation product of ascorbic acid, has been analyzed by X-ray crystallography to be a dimer Figure 1c.

Electrochemical studies have indicated that ascorbic acid and dehydroascorbic acid form a reversible redox couple Figure 1d. Free radicals and oxidants play a dual role as both toxic and beneficial compounds, in metabolic processes and in response to exogenous stimulations.

They are produced either from normal metabolic activities or from environmental factors pollution, cigarette smoke, and radiation. When an overload of free radicals cannot be scavenged, their accumulation in the body generates oxidative stress [ 3 ]. Oxidative stress occurs when free radical formation exceeds the ability of protection against them.

This process leads in the development of chronic and degenerative illnesses such as cancer, autoimmune disorders, aging, cataract, rheumatoid arthritis, cardiovascular, and neurodegenerative diseases [ 8 — 10 ]. An antioxidant is a molecule that prevents the oxidation of other molecules. Oxidation process is a chemical reaction that produces free radicals, leading to chain reactions that may damage cells. The antioxidant effect of vitamin C has been well documented [ 8 , 9 , 11 ].

Vitamin C is a powerful antioxidant having ability to donate a hydrogen atom and form a relatively stable ascorbyl-free radical. In the presence of redox-active ions iron, copper , vitamin C acts as a prooxidant, contributing to the formation of hydroxyl radicals, that may lead to lipid, DNA, or protein oxidation [ 8 — 10 ].

There are different mechanisms to alleviate oxidative stress and repair damaged macromolecules. Enzymatic and nonenzymatic antioxidants have important roles in scavenging free radicals and reactive oxygen species ROS. Antioxidant compounds can prevent the uncontrolled formation of free radicals or inhibit their reaction with biological sites; also, the destruction of most free radicals depends on the oxidation of endogenous antioxidants mainly by scavenging and reducing molecules [ 8 , 9 ].

Vitamin C is thought to be an important water soluble antioxidant which is reported to neutralize ROS and reduce the oxidative stress [ 8 , 10 ]. Vitamin C is a potent reducing agent and scavenger of free radicals in biological systems [ 11 ]. It is involved in the first line of antioxidant defense, protecting lipid membranes, and proteins from oxidative damage. As a water soluble molecule, vitamin C can work both inside and outside the cells, and can neutralize free radicals and prevent free radical damage.

Vitamin C is an excellent source of electrons for free radicals that are seeking out an electron to regain their stability. Vitamin C can donate electrons to free radicals and quench their reactivity [ 8 , 9 ]. Vitamin C has been shown to be an effective scavenger against oxygen and nitrogen oxide species, such as superoxide radical ion, hydrogen peroxide, the hydroxyl radical, and singlet oxygen.

This property of vitamin C has vital processes in protection of cellular components from free radical-induced damage. In addition, vitamin C is effective in regenerating the antioxidant form of vitamin E by reducing tocopheroxyl radicals.

This process protects membranes and other compartments of the cell from free radical-induced damage [ 8 , 9 ] Figure 2. Ascorbate peroxidase APX is an enzyme reducing H 2 O 2 to water by using ascorbate as an electron donor. Monodehydroascorbate is an oxidized ascorbate that is regenerated by monodehydroascorbate reductase MDAR. Monodehydroascorbate radical rapidly disproportionates into ascorbate and dehydroascorbate.

Dehydroascorbate may be reduced nonenzymatically or catalyzed by proteins with dehydroascorbate reductase DHAR activity. Ascorbate and redox cycling antioxidants. Glutathione-ascorbate cycle operates in the cytosol, mitochondria, plastids, and peroxisomes in plants [ 8 , 9 ].

It is suggested that the glutathione-ascorbate cycle plays a key role for H 2 O 2 detoxification, because of the high concentrations of glutathione, ascorbate, and NADPH in plant cells. Other enzymes, such as ascorbate and glutathione peroxidases, which use thioredoxins or glutaredoxins as reducing substrates, also take roles in the removal of H 2 O 2 in plants [ 8 , 9 ] Figure 2.

Vitamin C also forms the semidehydroascorbyl radical, a relatively long-lived radical, in regenerating vitamin E from its radical form, as well as in scavenging radicals.

The table below shows the RDA or adequate intake for niacin. These values are the estimated amount of niacin that most people It also shows the tolerable upper intake limit UL , which is the highest daily intake considered safe for most people. The main symptoms of pellagra include inflamed skin, mouth sores, diarrhea, insomnia and dementia.

Like all deficiency diseases, it is fatal without treatment. Deficiency is much more common in developing countries where people commonly follow diets that lack diversity. Cereal grains are especially low in available niacin, since most of it is bound to fiber in the form of niacytin. However, your body can synthesize it from the amino acid tryptophan. As a result, severe niacin deficiency can often be avoided on a high-protein diet However, high supplemental doses of niacin may cause niacin flush , nausea, vomiting, stomach irritation and liver damage.

Niacin flush is a side effect of immediate-release nicotinic acid supplements. It is characterized by a flush in the face, neck, arms and chest 18 , Liver damage is associated with the long-term use of very high doses 3—9 grams per day of sustained-release or slow-release nicotinic acid 20 , 21 , Additionally, taking niacin supplements for a long time may increase insulin resistance and raise blood sugar levels 23 , Nicotinic acid may also increase the circulating levels of uric acid, worsening symptoms in people who are predisposed to gout Nicotinic acid supplements at doses ranging from 1,—2, mg per day are commonly used to normalize blood lipid levels 26 , Triglyceride levels may also drop in those taking supplements.

Some studies also suggest nicotinic acid reduces heart disease risk, but its benefits are controversial and study results have been inconsistent 28 , Preliminary evidence also indicates that niacin supplements may improve cognition, but further studies are needed before strong claims can be made Niacin, also known as vitamin B3, is a group of two related compounds — niacinamide and nicotinic acid.

They serve many vital functions in the body. Niacin is found in many different foods, such as liver, fish, poultry, eggs, dairy products, sunflower seeds and peanuts, to name few. Additionally, it is commonly added to processed food like flour and breakfast cereals.

Deficiency is rare in Western nations. People who eat low-protein diets that lack diversity are at an increased risk. But supplements may also have some negative side effects, such as liver damage, reduced insulin sensitivity and niacin flush. Pantothenic acid is found in virtually all food. There are multiple forms of pantothenic acid or compounds that release the active form of the vitamin when digested.

In addition to free pantothenic acid, these include:. It is required for the formation of coenzyme A, which is necessary for the synthesis of fatty acids, amino acids, steroid hormones, neurotransmitters and various other important compounds.

The chart below shows some of its best dietary sources 1. Other rich sources include yeast extract spread, shiitake mushrooms, caviar, kidneys, chicken, beef and egg yolks. Several plant foods are also good sources. In addition to those mentioned above, these include root vegetables, whole grains, tomatoes and broccoli. The table below shows the adequate intake AI of pantothenic acid for most people. The RDA has not been established. Pantothenic acid deficiency is rare in industrialized countries.

In fact, this vitamin is so widespread in foods that deficiency is virtually unheard of, except in severe malnutrition. However, its requirements may be higher in people with diabetes and those who regularly consume excessive amounts of alcohol. Studies in animals show that pantothenic acid deficiency has an adverse impact on most organ systems.

It is associated with numerous symptoms, including numbness, irritability, sleep disturbances, restlessness and digestive problems Pantothenic acid does not appear to have any adverse effects at high doses. The tolerable upper limit has not been established. In mice, the lethal dose was estimated to be around 4. Studies have not provided any good evidence of benefits from pantothenic acid supplements in people who get adequate amounts from their diets.

While people take supplements to treat various disorders, including arthritis, dry eyes and skin irritation, there is no strong evidence for its effectiveness in the treatment of any of these disorders Almost all food contains this vitamin. The best sources include liver, sunflower seeds, mushrooms , root vegetables and whole grains.

Since pantothenic acid is so widespread in foods, deficiency is virtually unknown and is usually only associated with severe malnutrition. Supplements are safe and do not have any adverse effects. However, very high doses may cause diarrhea and other digestive issues. Although some people regularly take pantothenic acid supplements, there is currently no strong evidence for their effectiveness in the treatment of diseases in those who get adequate amounts from food.

Vitamin B6 is a group of nutrients that are required for the synthesis of pyridoxal phosphate, a coenzyme involved in more than different metabolic processes. In the liver, all dietary forms of vitamin B6 are converted into pyridoxal 5-phosphate, the active form of the vitamin. It is involved in red blood cell formation as well as energy and amino acid metabolism. It is also required for the release of glucose sugar from glycogen, the molecule the body uses to store carbs. Vitamin B6 also supports the formation of white blood cells and helps the body synthesize several neurotransmitters.

Vitamin B6 is found in a wide variety of foods. The chart below shows some of its richest sources and their content 1. Other good sources include tuna, pork, turkey, bananas, chickpeas and potatoes.

Vitamin B6 is also added to breakfast cereals and soy-based meat substitutes. The availability of this vitamin is generally higher in animal-sourced foods, compared to plant foods The table below shows the RDA for vitamin B6. The RDA is the daily intake estimated to be sufficient for most people. Vitamin B6 deficiency is rare. People with alcoholism are at the greatest risk Deficiency has also been associated with an increased risk of cancer 36 , In contrast, very large supplemental doses of pyridoxine — 2, mg per day or more — are linked to sensory nerve damage and skin lesions High intake of pyridoxine supplements may also suppress milk production in breastfeeding women Large doses of pyridoxine have been used to treat carpal tunnel syndrome and premenstrual syndrome.

However, its benefits are controversial. No strong evidence proves that pyridoxine supplements are an effective treatment for these conditions 40 , Because of the adverse health effects of high-dose pyridoxine supplements, they should only be taken under medical supervision. Vitamin B6 is a group of nutrients that are required for the formation of pyridoxal phosphate, a coenzyme that plays a vital role in numerous metabolic pathways.

The richest dietary sources are liver, salmon, sunflower seeds and pistachio nuts, to name a few. While adequate vitamin B6 intake is healthy, no good evidence demonstrates that vitamin B6 supplements are useful in the treatment of diseases. People often take biotin supplements to nourish their hair, nails and skin, although strong evidence for these benefits is lacking. When proteins that contain biotin are digested they release a compound called biocytin.

The digestive enzyme biotinidase then breaks biocytin into free biotin and lysine, an amino acid. Same as all B vitamins, biotin functions as a coenzyme. It is required for the function of five carboxylases, enzymes involved in several fundamental metabolic processes. For instance, biotin serves an essential role in fatty acid synthesis, glucose formation and amino acid metabolism. Animal-sourced foods rich in biotin include organ meats, fish, meat, egg yolk and dairy products.

Good plant sources include legumes, leafy greens, cauliflower, mushrooms and nuts. The table below shows the adequate intake AI for biotin. Untreated biotin deficiency can cause neurological symptoms, such as seizures, intellectual disability and loss of muscle coordination Deficiency has also been reported in animals fed high amounts of raw egg whites. Egg whites contain a protein called avidin, which prevents the absorption of biotin Biotin does not have any known adverse effects at high doses and the tolerable upper limit has not been established.

Limited evidence suggests that biotin supplements may improve health in those who otherwise get adequate amounts from their diets. For instance, studies suggest biotin may improve symptoms in people with multiple sclerosis MS 47 , Observational studies also indicate that biotin supplements may improve brittle nails in women. However, higher quality studies are needed before any claims can be made 49 , It is found in a wide range of foods.

Good sources include organ meats, egg yolk, meat, legumes, cauliflower, mushrooms and nuts. Deficiency is uncommon and adverse effects are unknown, even at high supplemental doses. Brad Wenderoth, Pharm. With over 16 years of healthcare experience, Brad is bringing his expertise and passion for patient care to the Mobile IV Medics patient population.

He holds a doctorate in pharmacy from the University of Arizona , a pharmacy practice residency from USC, and a lean six sigma green belt from Johns Hopkins.

Simultaneously, it works with proteins to benefit your body in ways like: Maintaining muscle tone and function. Aiding healthy cell growth.

Counteracting tissue damage. Reversing damage done to the mitochondria. Slowing down aging. Combating age-related diseases. Improving metabolism. Maintaining muscle tone and function.