Vitamins

Question

This piglix contains articles or sub-piglix about Vitamins

Answer 1

Vitamin A

Vitamin A is a group of unsaturated nutritional organic compounds that includes retinol, retinal, retinoic acid, and several provitamin A carotenoids (most notably beta-carotene). Vitamin A has multiple functions: it is important for growth and development, for the maintenance of the immune system and good vision. Vitamin A is needed by the retina of the eye in the form of retinal, which combines with protein opsin to form rhodopsin, the light-absorbing molecule necessary for both low-light (scotopic vision) and color vision. Vitamin A also functions in a very different role as retinoic acid (an irreversibly oxidized form of retinol), which is an important hormone-like growth factor for epithelial and other cells.

In foods of animal origin, the major form of vitamin A is an ester, primarily retinyl palmitate, which is converted to retinol (chemically an alcohol) in the small intestine. The retinol form functions as a storage form of the vitamin, and can be converted to and from its visually active aldehyde form, retinal.

All forms of vitamin A have a beta-ionone ring to which an isoprenoid chain is attached, called a retinyl group. Both structural features are essential for vitamin activity. The orange pigment of carrots (beta-carotene) can be represented as two connected retinyl groups, which are used in the body to contribute to vitamin A levels. Alpha-carotene and gamma-carotene also have a single retinyl group, which give them some vitamin activity. None of the other carotenes have vitamin activity. The carotenoid beta-cryptoxanthin possesses an ionone group and has vitamin activity in humans.

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Answer 2

Vitamin Angels

Vitamin Angels

Vitamin Angels is a non-profit, non-governmental organization focused on bringing essential nutrition to children around the world through vitamin supplementation.

Vitamin Angels states that its mission is to mobilize and deploy private sector resources to advance availability, access and use of micronutrients, especially vitamin A, by newborns, infants and children in need.

Vitamin Angels aims to reduce child mortality worldwide by connecting essential micronutrients, especially vitamin A, with infants and children under five. Essential micronutrients enables the immune system to fight infectious diseases and may help to prevent childhood diseases. Vitamin A deficiency in particular can lead to blindness, stunting and a deficient immune system.

According to his biography, founder and President Howard Schiffer worked in the natural products industry for many years. He apparently launched a number of "nationally recognized brands", although these are not listed. After the 1994 Northridge earthquake in California, Schiffer was asked to donate vitamins to victims. As a result of this experience, Schiffer realized the capabilities of vitamin supplements in providing vital nutrition. He started Vitamin Angels in 1994. It is now an international charity working in 50 countries with 800 field partners.

It is a large misconception that severe malnutrition is caused by not getting enough to eat. Often the issue lies in not getting the right micronutrients. New York Times Op-Ed columnist Nicholas Kristof calls this the "hidden hunger". Approximately 670,000 children under the age of five die due to lack of vitamin A in their diets every year. Children who are micronutient deficient do not have the proper nutrition necessary to develop a proper immune system and bodily function, leaving them more susceptible to disease and overall mortality.

Micronutrient supplementation has received the support and attention of top global health experts and organizations, including the World Health Organization, UNICEF, and the Copenhagen Consensus. Studies show that for deficient children, the periodic supply of high-dose vitamin A has resulted in reducing mortality by 23%. The 2008 Copenhagen Consensus, a panel of world class economists, analyzed cost-effective solutions to the world's ten biggest challenges. They ranked micronutrient supplementation for children as the #1 global priority. The report notes that providing micronutrient supplements (vitamin A and zinc) for 80% of the 140 million children who lack essential vitamins would cost $60 million per year. This action would hold yearly benefits of more than $1 billion. Each dollar spent on the program would create benefits worth more than 17 dollars, seen in the form of better health, fewer deaths, increased future earnings, etc.

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Answer 3

Vitamin C

Vitamin C

Vitamin C, also known as ascorbic acid and L-ascorbic acid, is a vitamin found in food and used as a dietary supplement. As a supplement it is used to treat and prevent scurvy. Evidence does not support use in the general population for the prevention of the common cold. It may be taken by mouth or by injection.

It is generally well tolerated. Large doses may cause gastrointestinal upset, headache, trouble sleeping, and flushing of the skin. Normal doses are safe during pregnancy. Vitamin C is an essential nutrient involved in the repair of tissue. Foods that contain vitamin C include citrus fruit, tomatoes, and potatoes.

Vitamin C was discovered in 1912, isolated in 1928, and first made in 1933. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. Vitamin C is available as a generic medication and over the counter. The wholesale cost in the developing world is about 0.19 to 0.54 USD per month. In some countries ascorbic acid may be added to foods such as breakfast cereal.

A 2012 Cochrane review found no effect of vitamin C supplementation on overall mortality.

Although rare in modern times, scurvy and its associated destabilization of collagen, connective tissue, and bone can be prevented by adequate vitamin C intake.

A 2014 review found that, "Currently, the use of high-dose IV vitamin C [as an anticancer agent] cannot be recommended outside of a clinical trial."

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Answer 4

Vitamin C and the Common Cold (book)

Vitamin C and the Common Cold:A Nobel Prize-winning Scientist Tells how You May Avoid Colds and Improve Your Health

Vitamin C and the Common Cold is a popular book by Linus Pauling, first published in 1970, on vitamin C, its interactions with common cold and the role of vitamin C megadosage in human health. The book promoted the idea that taking large amounts of vitamin C could reduce the duration and severity of the common cold. A Nobel Prize-winning chemist and activist, Pauling promoted a view of vitamin C that is strongly at odds with most of the scientific community, which found little evidence for the alleged health benefits of greatly increased vitamin C intake. The book went through multiple editions, and a revised version that discussed the flu and other diseases, retitled Vitamin C, the Common Cold & the Flu, came out in 1976.

The book characterizes the inability of humans and some other animals to produce vitamin C in terms of evolution and Pauling's concept of "molecular disease" (first articulated in his 1949 study, "Sickle Cell Anemia, a Molecular Disease"). Pauling argues that the loss of vitamin C synthesis first arose as a molecular disease, because of a genetic mutation that resulted in the loss of the biochemical capacity to make the vitamin, but because diets of the primate ancestors of humans consisted of high levels of vitamin C from plant sources, the loss of that biochemical mechanism was not harmful and may have even been beneficial. He argues, however, that the subsequent shift to a high-meat, lower-plant diet resulted in widespread vitamin C deficiency.

Pauling began studying vitamin C mega-dosage, and orthomolecular medicine more broadly, after he was contacted in 1966 by biochemist Irwin Stone, who suggested that taking enough vitamin C would let him live another fifty years. Pauling reinterpreted the large body of research on vitamin C based on comparative studies of the biochemical genetics of vitamin C synthesis in different species, as well his own theories about "molecular disease" and recent developments in molecular evolution. He criticized the design of studies that did not find positive results for vitamin C mega-dose treatment, and promoted those that did. He and other vitamin C advocates thought the vitamin boosts the body's ability to fight all kinds of infection. By 1970, after following Stone's regimen for 4 years and studying and debating the issue extensively, Pauling was sure enough that organized medicine had it wrong that he wrote Vitamin C and the Common Cold to popularize his vitamin C message.

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Answer 5

Vitamin D

Vitamin D

Vitamin D refers to a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, iron, magnesium, phosphate, and zinc. In humans, the most important compounds in this group are vitamin D₃ (also known as cholecalciferol) and vitamin D₂ (ergocalciferol).Cholecalciferol and ergocalciferol can be ingested from the diet and from supplements. Very few foods contain vitamin D; synthesis of vitamin D (specifically cholecalciferol) in the skin is the major natural source of the vitamin. Dermal synthesis of vitamin D from cholesterol is dependent on sun exposure (specifically UVB radiation).

Vitamin D from the diet or dermal synthesis from sunlight is biologically inactive; activation requires enzymatic conversion (hydroxylation) in the liver and kidney. Evidence indicates the synthesis of vitamin D from sun exposure is regulated by a negative feedback loop that prevents toxicity, but because of uncertainty about the cancer risk from sunlight, no recommendations are issued by the Institute of Medicine (US) for the amount of sun exposure required to reach vitamin D requirements. Accordingly, the Dietary Reference Intake for vitamin D assumes no synthesis occurs and all of a person's vitamin D is from food intake. As vitamin D is synthesized in adequate amounts by most mammals exposed to sunlight, it is not strictly a vitamin, and may be considered a hormone as its synthesis and activity occur in different locations. Vitamin D has a significant role in calcium homeostasis and metabolism. Its discovery was due to effort to find the dietary substance lacking in rickets (the childhood form of osteomalacia).

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Answer 6

Vitamin D and Omega-3 Trial

Vitamin D and Omega-3 Trial (VITAL) (VITamin D and OmegA-3 TriaL) is a 5 year trial to run from 2010 to determine the benefits of vitamin D and Omega-3 supplements on elderly Americans.

It aims to enroll 20,000 participants (women 55 or over, men 50 or over) who will be randomized to one of four groups:

Participants will answer annual questionnaires to determine effects on risk of cancer, heart disease, stroke, osteoporosis, diabetes, memory loss and depression.

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Answer 7

Vitamin E

Vitamin E refers to a group of compounds that include both and . Of the many different forms of vitamin E, is the most common form found in the North American diet. γ-Tocopherol can be found in corn oil, soybean oil, margarine, and dressings., the most biologically active form of vitamin E, is the second-most common form of vitamin E in the diet. This variant can be found most abundantly in wheat germ oil, sunflower, and safflower oils. As a fat-soluble antioxidant, it interrupts the propagation of reactive oxygen species that spread through biological membranes or through a fat when its lipid content undergoes oxidation by reacting with more-reactive lipid radicals to form more stable products. Regular consumption of more than 1,000 mg (1,500 IU) of tocopherols per day may be expected to cause hypervitaminosis E, with an associated risk of vitamin K deficiency and consequently of bleeding problems.

The nutritional content of vitamin E is defined by α-tocopherol activity. The molecules that contribute α-tocopherol activity are four and four , identified by the prefixes alpha- (α-), beta- (β-), gamma- (γ-), and delta- (δ-). Natural tocopherols occur in the RRR-configuration only. The synthetic form contains eight different stereoisomers and is called 'all-rac'-α-tocopherol. Water-soluble forms such as d-alpha-tocopheryl succinate are used as food additive.

is an important lipid-soluble antioxidant. It performs its functions as antioxidant in the glutathione peroxidase pathway, and it protects cell membranes from oxidation by reacting with lipid radicals produced in the lipid peroxidation chain reaction. This removes the free radical intermediates and prevents the oxidation reaction from continuing. The oxidized α-tocopheroxyl radicals produced in this process may be recycled back to the active reduced form through reduction by other antioxidants, such as ascorbate, retinol or ubiquinol. Other forms of vitamin E have their own unique properties; for example, γ-tocopherol is a nucleophile that can react with electrophilic mutagens.

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Answer 8

Vitamin K

Vitamin K is a group of structurally similar, fat-soluble vitamins the human body requires for complete synthesis of certain proteins that are prerequisites for blood coagulation and which the body also needs for controlling binding of calcium in bones and other tissues. The vitamin K-related modification of the proteins allows them to bind calcium ions, which they cannot do otherwise. Without vitamin K, blood coagulation is seriously impaired, and uncontrolled bleeding occurs. Low levels of vitamin K also weaken bones and promote calcification of arteries and other soft tissues.

Chemically, the vitamin K family comprises 2-methyl-1,4-naphthoquinone (3-) derivatives. Vitamin K includes two natural vitamers: vitamin K₁ and vitamin K₂. Vitamin K₂, in turn, consists of a number of related chemical subtypes, with differing lengths of carbon side chains made of isoprenoid groups of atoms.

Vitamin K₁, also known as phylloquinone, is made by plants, and is found in highest amounts in green leafy vegetables because it is directly involved in photosynthesis. It may be thought of as the "plant" form of vitamin K. It is active as a vitamin in animals and performs the classic functions of vitamin K, including its activity in the production of blood-clotting proteins. Animals may also convert it to vitamin K₂.

Bacteria in the gut flora can also convert K₁ into vitamin K₂. In addition, bacteria typically lengthen the isoprenoid side chain of vitamin K₂ to produce a range of vitamin K₂ forms, most notably the MK-7 to MK-11 homologues of vitamin K₂. All forms of K₂ other than MK-4 can only be produced by bacteria, which use these forms in anaerobic respiration. The MK-7 and other bacterially derived forms of vitamin K₂ exhibit vitamin K activity in animals, but MK-7's extra utility over MK-4, if any, is unclear and is a matter of investigation.

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