Vitamins

Question

This piglix contains articles or sub-piglix about Vitamins

Answer 1

Pantetheine

Pantetheine

Pantetheine is the cysteamine amide analog of pantothenic acid (vitamin B₅). The dimer of this compound, pantethine is more commonly known, and is considered to be a more potent form of vitamin B₅ than pantothenic acid. Pantetheine is an intermediate in the production of coenzyme A by the body.

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Answer 2

Pantethine

Pantethine

Pantethine (bis-pantethine or co-enzyme pantethine) is a dimeric form of pantetheine, which is produced from pantothenic acid (vitamin B₅) by the addition of cysteamine. Pantethine is composed of two molecules of pantetheine linked by a bridging disulfide. Pantetheine is an intermediate in the production of Coenzyme A by the body. Most vitamin B₅ supplements are in the form of calcium pantothenate, a salt of pantothenic acid, with doses in the range of 5 to 10 mg/day. In contrast, pantethine is sold as a dietary supplement for lowering blood cholesterol and triglycerides at doses of 500 to 1200 mg/day

Pantethine is available in the United States as a dietary supplement because of evidence of its health benefits for lowering elevated LDL-cholesterol and triglycerides, and raising HDL-cholesterol (the 'good' cholesterol). In multiple clinical trials of patients with elevated cholesterol and triglycerides, total and LDL cholesterol were decreased by an average of 12%, triglycerides decreased by 19%, and HDL cholesterol was increased by 9%. These clinical trials were conducted with daily intakes ranging from 600 to 1200 mg/day. Within this dose range there is no evidence of a dose-effect relationship, i.e. changes in lipid concentrations overlapped across the range of doses. Direct dose-response evidence is not available because no trial tested more than one dose. A few trials conducted in Japan tested 300 mg/day and reported decreases in total cholesterol of about 4%, increases in HDL-cholesterol of 5% and inconsistent results for triglycerides. Most of the literature on pantethine and lipids is 20–30 years old, but recent carefully controlled trials of 600 and 900 mg/d doses have shown similar statistically significant lowering of LDL cholesterol in individuals with greatly or moderately elevated levels of blood lipids.

Although pantethine can serve as a precursor for generation of vitamin B₅ and consumption of therapeutic amounts of pantethine results in higher circulating concentrations of vitamin B₅, this is not thought to be the mechanism of action. Vitamin B₅ requirements are on the order of 5 mg/day. High doses of vitamin B₅ do not result in the lipid changes seen with pantethine.

Two mechanisms of action are proposed for pantethine. In the first, pantethine serves as the precursor for synthesis of coenzyme A. CoA is involved in the transfer of acetyl groups, in some instances to attach to proteins closely associated with activating and deactivating genes. By this theory, either the genes responsible for cholesterol and triglyceride synthesis are suppressed or the genes governing the catabolism of compounds are turned on. In the second theory, pantethine is converted to two pantetheine molecules which are in turn metabolized to form two pantethenic acid and two cysteamine molecules. Cysteamine is theorized to bind to and thus inactivate sulfur-containing amino acids in liver enzymes involved in the production of cholesterol and triglycerides. What is known is that high doses of the related vitamin - pantothenic acid - has no effect on lipids.

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Answer 3

Provitamin

A provitamin is a substance that may be converted within the body to a vitamin. The term "previtamin" is a synonym. For example, "Provitamin B5" is a name for panthenol, which may be converted in the body to vitamin B₅ (pantothenic acid).

The term "provitamin" is used when it is desirable to label a substance with little or no vitamin activity, but which can be converted to an active form by normal metabolic processes. For example, "provitamin A" is a name for β-carotene, which has only about 1/6 the biological activity of retinol (vitamin A); the body uses an enzyme to convert β-carotene to retinol. In other contexts, both β-carotene and retinol are simply considered to be different forms (vitamers) of vitamin A.

Provitamin D₂ is ergosterol, and provitamin D₃ is 7-dehydrocholesterol.Menadione is a synthetic provitamin of vitamin K.

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Answer 4

Pyridoxal

Pyridoxal

Gossypol

Pyridoxal is one form of vitamin B₆.

Some medically relevant bacteria, such as those in the genera Granulicatella and Abiotrophia, require pyridoxal for growth. This nutritional requirement can lead to the culture phenomenon of satellite growth. In in vitro culture, these pyridoxal-dependent bacteria may only grow in areas surrounding colonies of bacteria from other genera ("satellitism") that are capable of producing pyridoxal.

Pyridoxal is involved in what is believed to be the most ancient reaction of aerobic metabolism on Earth, about 2.9 billion years ago, a forerunner of the Great Oxidation Event

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Answer 5

Redoxon

Redoxon is the name of the first artificially synthesized ascorbic acid (Vitamin C). Redoxon was first marketed to the general public in 1934 – the first mass-manufactured synthetic vitamin in history. It is now a brand owned by German pharmaceutical company Bayer and is sold world-wide.

The product was developed by a team headed by chemist Tadeusz Reichstein, who discovered a method of synthesizing 30-40 g of vitamin C from 100 g of glucose. This used an intermediate step of creating sorbose using an ingenious bacterial fermentation method discovered by a French researcher, Gabriel Bertrand. In this method, fruit flies were attracted to a mixture of wine, vinegar, yeast bouillon, and sorbitol, a substance easily chemically prepared from glucose. Flies which fed upon sorbitol as a major food subtrate excreted bacteria which were able to synthesize sorbose from sorbitol. Using the bacteria, within a few days, it was possible to create 50 grams of sorbose using this method, and it was then easy to synthesise ascorbic acid from this.

Despite concern about using the wild strain of bacteria for fermentation-production of sorbose, the process was superior to a rival method of Szent-Györgyi which isolated Vitamin C from capsicum. After sale of the Reichstein process patent to Hoffmann-La Roche, this process became the basis of the corporation's large-scale production of vitamin C.

The commercial tablets are compounded from ascorbic acid and sodium bicarbonate. When these are added to water, they react to produce sodium ascorbate, water and carbon dioxide, thus producing a pleasant effervescence.

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Answer 6

Retinol

Retinol

Retinol, also known as Vitamin A₁, is a vitamin found in food and used as a dietary supplement. As a supplement it is used to treat and prevent vitamin A deficiency, especially that which is resulting in xerophthalmia. In areas where deficiency is common a single large dose is recommended to those at high risk a couple of times a year. It is also used to prevent further issues in those who have measles. It is used by mouth or injection into a muscle.

Retinol at normal doses is well tolerated. High doses may result in an enlarged liver, dry skin, or hypervitaminosis A. High doses during pregnancy may result in harm to the baby. Retinol is in the vitamin A family. It or other forms of vitamin A are needed for eye sight, maintenance of the skin, and human development. It is converted in the body to retinal and retinoic acid through which it acts. Dietary sources include fish, dairy products, and meat.

Retinol was discovered in 1909, isolated in 1931, and first made in 1947. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. Retinol is available as a generic medication and over the counter. The wholesale cost in the developing world is about 0.02 to 0.30 USD per 50,000 units. In the United States it is not very expensive.

Retinol is used to treat vitamin A deficiency.

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Answer 7

Reference Daily Intake

The Reference Daily Intake or Recommended Daily Intake (RDI) is the daily intake level of a nutrient that is considered to be sufficient to meet the requirements of 97–98% of healthy individuals in every demographic in the United States. While developed in USA it has been used in other countries though it is not universally accepted.

The RDI is used to determine the Daily Value (DV) of foods, which is printed on nutrition facts labels (as %DV) in the United States and Canada, and is regulated by the Food and Drug Administration (FDA) and Health Canada respectively.

The Recommended Dietary Allowances (RDAs) were a set of nutrition recommendations that evolved into both the Dietary Reference Intake (DRI) system of nutrition recommendations (which still defines RDA values) and the RDIs used for food labelling. The first regulations governing U.S. nutrition labels specified a % U.S. RDA declaration based on the current RDA values, which had been published in 1968. Later, the % U.S. RDA was renamed the %DV and the RDA values that the %DVs were based on became the RDIs.

The RDAs (and later the RDA values within the DRI) were regularly revised to reflect the latest scientific information, but although the nutrition labeling regulations were occasionally updated, the existing RDI values were not changed, so that until 2016 many of the DVs used on nutrition facts labels were still based on the outdated RDAs from 1968. In 2016 the Food and Drug Administration published changes to the regulations including updated RDIs and DVs based primarily on the RDAs in the current DRI. Larger manufacturers must start using the new labels by July 26, 2018 and all manufacturers must use the new values from July 26, 2019.

Daily Values used by the FDA for the following macronutrients are Daily Reference Values.

FDA issued a Final Rule on changes to facts panel in 2016. New values can be used on labels now, but companies have until July 28, 2018 to be in compliance. In the interim, products with old or new facts panel content will be on market shelves at same time.

The following table lists the old and new DVs based on a caloric intake of 2000 kcal (8400 kJ), for adults and children four or more years of age.

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Answer 8

Retinyl acetate

Retinyl acetate

Retinyl acetate (retinol acetate, vitamin A acetate) is a natural form of vitamin A which is the acetate ester of retinol. It has potential antineoplastic and chemopreventive activities.

In the United States, retinyl acetate is classified generally recognized as safe (GRAS) in the amounts used to fortify foods with vitamin A.

World Health Organization recommendation on Maternal Supplementation During Pregnancy states that "health benefits are expected for the mother and her developing fetus with little risk of detriment to either, from a daily supplement not exceeding 10,000IU [preformed] vitamin A (3000mcg RE) at any time during pregnancy." Preformed Vitamin A refers to retinyl palmitate and retinyl acetate.

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Answer 9

Retinyl palmitate

Retinyl palmitate

Retinyl palmitate, or vitamin A palmitate, is the ester of retinol (vitamin A) and palmitic acid, with formula C₃₆H₆₀O₂.

An alternate spelling, retinol palmitate, which violates the -yl organic chemical naming convention for esters, is also frequently seen.

Retinyl palmitate is a synthetic alternate for retinyl acetate in vitamin A supplements, and is available in oily or dry forms. It is a common vitamin supplement, available in both oral and injectable forms for treatment of vitamin A deficiency, under the brand names Aquasol A, Palmitate A and many others. It is a constituent of intra ocular treatment for dry eyes at a concentration of 138 µg/g (VitA-Pos) by Ursapharm. It is a pre-formed version of vitamin A; therefore, the intake should not exceed the Recommended Dietary Allowance (RDA). Overdosing preformed Vitamin A forms such as retinyl palmitate leads to adverse physiological reactions (hypervitaminosis A).

Retinyl palmitate is used as an antioxidant and a source of vitamin A added to low fat milk and other dairy products to replace the vitamin content lost through the removal of milk fat. Palmitate is attached to the alcohol form of vitamin A, retinol, in order to make vitamin A stable in milk.

Retinyl palmitate is also a constituent of some topically applied skin care products. After its absorption into the skin, retinyl palmitate is converted to retinol, and ultimately to retinoic acid (the active form of vitamin A present in Retin-A).

The Environmental Working Group (EWG) and New York Senator Chuck Schumer have called attention to the fact that high doses of topical retinyl palmitate were shown to accelerate cancer in lab animals, fueling the sunscreen controversy in the popular press. One toxicological analysis determined that "there is no convincing evidence to support the notion that [retinyl palmitate] in sunscreens is carcinogenic." EWG disputed the findings, calling the report "faulty" and "misleading." A technical report issued thereafter by the National Toxicology Program concluded that diisopropyl adipate increased incidence of skin tumors in mice, and the addition of either retinoic acid or retinyl palmitate both exacerbated the rate and frequency of tumors.

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Answer 10

Trolox

Trolox

Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) is a water-soluble analog of vitamin E sold by Hoffman-LaRoche. It is an antioxidant like vitamin E and it is used in biological or biochemical applications to reduce oxidative stress or damage.

Trolox equivalent antioxidant capacity (TEAC) is a measurement of antioxidant strength based on Trolox, measured in units called Trolox Equivalents (TE), e.g. micromolTE/100 g. Due to the difficulties in measuring individual antioxidant components of a complex mixture (such as blueberries or tomatoes), Trolox equivalency is used as a benchmark for the antioxidant capacity of such a mixture. Trolox equivalency is most often measured using the ABTS decolorization assay. The TEAC assay is used to measure antioxidant capacity of foods, beverages and supplements. Ferric reducing ability of plasma (FRAP) is an antioxidant capacity assays which uses Trolox as a standard.

Oxygen radical absorbance capacity (ORAC) used to be an alternative measurement, but the United States Department of Agriculture (USDA) withdrew these ratings in 2012 as biologically invalid, stating that "The data for antioxidant capacity of foods generated by in vitro (test-tube) methods cannot be extrapolated to in vivo (human) effects and the clinical trials to test benefits of dietary antioxidants have produced mixed results. We know now that antioxidant molecules in food have a wide range of functions, many of which are unrelated to the ability to absorb free radicals"

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