Retinol

Cosmetic ingredients (Retinol) -> CIR (Cosmetic Ingredient Review)

Skin conditioning

log Kow = 5.68

5.68

5.68

Practically insoluble (NTP, 1992)

Practically insoluble in water or glycerol; soluble in absolute alcohol, methanol, chloroform, ether, fats and oils

Sol in ethanol and acetone and benzene

Breast Feeding; Lactation; Milk, Human; Vitamins

FDA approved drugs -> Active ingredient

Vitamins and minerals

279 to 280 °F at 1e-06 mmHg (NTP, 1992)

137-138 °C at 1X10-6 mm Hg

This chemical does not meet GHS hazard criteria for 0.3% (1 of 311) of reports.

Danger

H302 (15.8%): Harmful if swallowed [Warning Acute toxicity, oral]

P203, P261, P264, P264+P265, P270, P272, P273, P280, P301+P317, P302+P352, P305+P351+P338, P318, P321, P330, P333+P317, P337+P317, P362+P364, P405, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 311 reports by companies from 14 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

This chemical does not meet GHS hazard criteria for 1% (1 of 105) of reports.

Chemical: Retinol

Chemical: Vitamin A

Status: Active Update: 13-10-2010 https://echa.europa.eu/registration-dossier/-/registered-dossier/11075

Vitamin A: Does not have an individual approval but may be used as a component in a product covered by a group standard. It is not approved for use as a chemical in its own right.

Retinol: Does not have an individual approval but may be used under an appropriate group standard

SYMPTOMS: Symptoms of chronic overdose include fatigue, malaise, lethargy, abdominal discomfort, anorexia and vomiting. Skeletal effects include slow growth, hard tender cortical thickening over the radius and tibia, migratory arthralgia and premature closing of the epiphysis. Central nervous system effects include irritability, headache and increased intracranial pressure as manifested by bulging fontanels, papilledema and exophthalmos. Dermatologic effects include fissures of the lips, drying and cracking of the skin, alopecia, scaling, massive desquamation and increased pigmentation. Systemic effects include hypomenorrhea, hepatosplenomegaly, jaundice, leukopenia and vitamin A plasma level over 1200 units. Other effects include painful nodular periosteal swelling, osteoporosis, itching, skin eruptions, ulcerations, drowsiness, alopecia, liver enlargement, diplopia and papilledema.

Oral administration of high doses in adults causes cirrhosis, hemorrhage, anorexia, jaundice, and dermatitis; [RTECS] Contraindicated in pregnancy at doses > FDA RDA; May be toxic if more than 25,000 IU/d consumed for longer that 2-3 weeks; Toxic effects include liver injury and increased intracranial pressure (blurred vision, headaches, and altered mental status); Serum levels may be useful in diagnosis; [Olson, p. 69, 446] An irritant; Harmful by ingestion; Teratogenic effects observed in experimental animals; [Sigma-Aldrich MSDS]

Substance added directly to human food affirmed as generally recognized as safe (GRAS).

Vitamin A used as a nutrient and/or dietary supplement in animal drugs, feeds, and related products is generally recognized as safe when used in accordance with good manufacturing or feeding practice.

Vitamin A acetate used as a nutrient and/or dietary supplement in animal drugs, feeds, and related products is generally recognized as safe when used in accordance with good manufacturing or feeding practice. /Vitamin A Acetate/

Vitamin A palmitate used as a nutrient and/or dietary supplement in animal drugs, feeds, and related products is generally recognized as safe when used in accordance with good manufacturing or feeding practice. /Vitamin A Palmitate/

Acute Tox. 4 (15.8%)

Skin Sens. 1 (99%)

EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. If symptoms (such as redness or irritation) develop, immediately transport the victim to a hospital.

Vitamin A is unstable in, and should be protected from, air and light. Vitamin A preparations should be stored at a temperature less than 40 °C, preferably between 15-30 °C. Oral vitamin A preparations should be stored in tight, light-resistant containers and the injection should be protected from light and freezing.

SMALL SPILLS AND LEAKAGE: Should a spill occur while you are handling this chemical, FIRST REMOVE ALL SOURCES OF IGNITION, then you should dampen the solid spill material with 60-70% ethanol and transfer the dampened material to a suitable container. Use absorbent paper dampened with 60-70% ethanol to pick up any remaining material. Seal the absorbent paper, and any of your clothes, which may be contaminated, in a vapor-tight plastic bag for eventual disposal. Solvent wash all contaminated surfaces with 60-70% ethanol followed by washing with a soap and water solution. Do not reenter the contaminated area until the Safety Officer (or other responsible person) has verified that the area has been properly cleaned.

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.

RECOMMENDED RESPIRATOR: Where the neat test chemical is weighed and diluted, wear a NIOSH-approved half face respirator equipped with an organic vapor/acid gas cartridge (specific for organic vapors, HCl, acid gas and SO2) with a dust/mist filter. (NTP, 1992)

Insulin antagonizes the /teratogenic/ effects /of vitamin A/.

The antithyroid compound methylthiouracil increases teratogenic effect /of vitamin A/.

Thyroxine antagonizes the teratogenic action of vitamin A.

In rats, the incidence of congenital abnormalities in the head due to hypervitaminosis A was increased greatly by appropriate administration of cortisone to the dams.

For more Interactions (Complete) data for VITAMIN A (19 total), please visit the HSDB record page.

Occupational hepatotoxin - Secondary hepatotoxins: the potential for toxic effect in the occupational setting is based on cases of poisoning by human ingestion or animal experimentation.

Excessive levels of natural or synthetic vitamin A can lead to various adverse effects. Vitamin A toxicity, also known as hypervitaminosis A, is more commonly associated with the misuse of vitamin A supplements than with health intervention programs. Toxic reactions can also result from consuming liver products rich in vitamin A or from the overuse of vitamin A preparations. The amount of vitamin A required to cause toxicity varies among individuals, depending on factors such as age and hepatic function.

Safe in the present practices of use and concentration. Ingredient, concentration, and use information are available in documents discoverable at https://cir-reports.cir-safety.org

Signs and Symptoms of Overdose

Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.

Acute toxicity (single ingestion of 7 500 RE or 25 000 IU per kg or more): Signs and symptoms may be delayed for 8 to 24 hours and include: increased intracranial pressure, headache, irritability, drowsiness, dizziness, lethargy, vomiting, diarrhea, bulging of fontanels in infants, diplopia, papilledema. Peeling of skin around mouth may be observed from 1 to several days after ingestion and may spread to the rest of the body.

VITAMIN A ... IS FOUND ONLY IN THE ANIMAL KINGDOM. ... /IT/ OCCURS IN MARINE FISH LIVER OILS AND IN THE LIVER OF MOST LAND VERTEBRATES AS WELL AS IN BUTTER FAT AND EGGS.

Occurs preformed only in animals; metabolized from carotenoids, such as beta-carotene

/HUMAN EXPOSURE STUDIES/ The tolerance to two alternative large dosage strengths of vitamin A preparation was determined in a double blind study involving 2471 children in two municipalities in the Philippines. Each child, aged 1-6 yr, not suffering from active zerophthalmia or from nausea and/or vomiting, headache, diarrhea, and fever, was randomly given 1 ml of a syrupy suspension later identified to contain, 0, 30, or 60 mg vitaminA. Clinical evaluation of subjects was done by physicians 24 hr and 1 wk after dosing. Nausea and/or vomiting and headache were twice as common among children given 60 mg than those given 30 mg. Severe vomiting (1.2%) was confined to those given 60 mg. Almost all experienced their symptoms within 24 hr after dosing; symptoms lasted for no more than 12-24 hr. The incidence of diarrhea and fever for vitamin A recipients was not significantly different from that of those receiving placebo.

/HUMAN EXPOSURE STUDIES/ Studies of hypervitaminosis A in animals and anecdotal reports of accidental vitamin A poisoning in humans suggest impairment of bone remodeling and increased numbers of fractures. Because of the widespread use of high dose vitamin A supplements which may produce subclinical hypervitaminosis associated with decreased bone mass and increased risk of fracture, the relationship between current vitamin A supplement use, serum retinol levels, radial bone mass and fracture history was studied in a geographically defined population of 246 postmenopausal women, 55-80 years of age. More than 36% of this population used a vitamin A supplement with 8% of these consuming an amount in excess of 2000 retinol equivalents/day. Serum retinol was measured using high pressure liquid chromatography and radial bone mass was measured using single photon absorptiometry. After controlling for age, current estrogen replacement, and current thiazide antihypertensive use, no statistically significant relationship between vitamin A supplement use or serum retinol with radial bone mass or fractures was observed.

/SIGNS AND SYMPTOMS/ Early signs and symptoms of chronic vitamin A intoxication include irritability, vomiting, loss of appetite, headache, dry and pruritic skin, skin desquamation, and erythematous dermatitis.

/SIGNS AND SYMPTOMS/ In addition to hepatosplenomegaly, pathological changes /after chronic vitamin A intoxication/ in the liver include hypertrophy of fat-storing cells, fibrosis, sclerosis of central veins, and cirrhosis, with resultant portal hypertension and ascites.

For more Human Toxicity Excerpts (Complete) data for VITAMIN A (22 total), please visit the HSDB record page.

Drug-Induced Liver Injury Severity and Toxicity (DILIst)

vitamin a

DILI Positive

Intramuscular

DOI:10.1016/j.drudis.2019.09.022

/LABORATORY ANIMALS: Acute Exposure/ ... Repeated applications of large amounts of vitamin A in ointment to rabbit eyes ... /resulted in/ Blepharoconjunctivitis, with loss of hair from the lids.

/LABORATORY ANIMALS: Acute Exposure/ /In hypervitaminotic animals/ lesions occur in the bones and result from accelerated resorption of bone and cartilage and formation of new bone. ... Other manifestations ... are anorexia, cutaneous lesions, temporary thickening of skin, exophthalmos, hypoprothrombinemia, and eventually death.

/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ Weanling cross bred pigs (36 or 48) were caged individually and fed diets containing a supplement of vitamin A (experiment 1) or vitamin D3 (experiment 2) at levels representing 1, 5, 10, 25, 50 and 100 times the NRC (1988) estimated requirements, for 4 wk. Growth rate, feed intake and feed/gain ratio were not influenced significantly. In experiment 1 the plasma retinol concentrations were at 4 weeks, respectively, 31.7, 39.4, 43.2, 42.9, 44.4, and 46.3 ug/dL (P < 0.05). In experiment 2, the plasma 25(OH)D3 concentrations were at 2 weeks, respectively, 22.5, 29.5, 35.7, 46.2, 79.9, 135.3 ng/mL (P < 0.001). Histological examination of lung, stomach, kidney, liver and heart indicated no abnormalities, but focal microscopic lesions consistent with osteochondrosis were found in pigs receiving vitamin A at levels over 10 times the requirement. The incidence of osteochondrosis at 2 weeks was, respectively, 0/8, 0/8, 0/8, 0/8, 0/8, and 1/8, and at 4 weeks was, respectively, 0/8, 0/8, 0/8, 2/8, 2/8 and 2/8.

/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ Feeding of vitamin A deficient diet to male weanling rats for 10 wk caused significant reduction in the hepatic cytochrome p450, cytochrome b5, aminopyrine N-demethylase and arylhydrocarbon hydroxylase activities. Contrary to this, the levels of these Phase I enzymes were found to be significantly elevated in all the 3 portions (proximal, middle and distal) of the intestine in deficient animals as compared to corresponding pair fed controls. Of the Phase II enzymes studied, uridine diphosphate-glucuronyltransferase showed a significant decrease whereas glutathione S-transferase showed a significant increase in vitamin A deficient rat liver and small intestine.

For more Non-Human Toxicity Excerpts (Complete) data for VITAMIN A (20 total), please visit the HSDB record page.

Substance added directly to human food affirmed as generally recognized as safe (GRAS).

Vitamin A used as a nutrient and/or dietary supplement in animal drugs, feeds, and related products is generally recognized as safe when used in accordance with good manufacturing or feeding practice.

Vitamin A acetate used as a nutrient and/or dietary supplement in animal drugs, feeds, and related products is generally recognized as safe when used in accordance with good manufacturing or feeding practice. /Vitamin A Acetate/

Vitamin A palmitate used as a nutrient and/or dietary supplement in animal drugs, feeds, and related products is generally recognized as safe when used in accordance with good manufacturing or feeding practice. /Vitamin A Palmitate/

D - Dermatologicals

A - Alimentary tract and metabolism

R - Respiratory system

S - Sensory organs

QR - Respiratory system

QD - Dermatologicals

Vitamin A deficiency leads to xerophthalmia, Bitot's spots, keratomalacia, night blindness (nyctalopia), hyperkeratosis of the skin, epithelial metaplasia of mucous membranes, and decreased resistance to infections. Administration of vitamin A completely reverses signs of vitamin deficiency unless keratomalacia has resulted in irreversible ocular damage.

Changes in the bronchorespiratory epithelium from mucus secretion to keratinization lead to increased incidence of respiratory infections ... there is also a decrease in elasticity of the lung and other tissues.

State of Deficiency: Urinary calculi are frequent concomitants of vitamin A deficiency. ... Abnormalities of reproduction include impairment of spermatogenesis, degeneration of testes, abortion, resorption of fetuses, and production of malformed offspring.

Often both taste and smell are impaired in Vitamin A deficient individual. Hearing may also become impaired. ... Deficiency can interfere with erythropoiesis. ... Nerve lesions, increased cerebrospinal fluid pressure, and hydrocephalus have been reported.

For more Bionecessity (Complete) data for VITAMIN A (9 total), please visit the HSDB record page.

Less than 5% of circulating vitamin A is bound to lipoproteins in blood in normal condition, but may be up to 65% when hepatic stores are saturated because of excessive intake. When released from liver, vitamin A is bound to retinol-binding protein (RBP). Most vitamin A circulates in the form of retinol bound to RBP.

Vitamin A is effective for the treatment of Vitamin A deficiency. Vitamin A refers to a group of fat-soluble substances that are structurally related to and possess the biological activity of the parent substance of the group called all-<i>trans</i> retinol or retinol. Vitamin A plays vital roles in vision, epithelial differentiation, growth, reproduction, pattern formation during embryogenesis, bone development, hematopoiesis and brain development. It is also important for the maintenance of the proper functioning of the immune system.

Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.

Topical vitamin A can reverse the impairment of wound healing seen in patients receiving corticosteroids, perhaps by restoring the normal inflammatory reaction in the wound. The possibility has been suggested that systemic vitamin A could inhibit the anti-inflammatory effect of systemic corticosteroids.

Retinol arrested proliferation of cultured neuroblastoma cells at concentrations of 50 um. A correlation existed between inhibition of growth and inhibition of ornithine decarboxylase in both neuroblastoma cells and glioma cells with retinol.

In rats exptl-hypervitaminosis A has been shown ... to produce severe damage of the retina, mainly in the pigment epithelium according to electron microscopy. Alcohol dehydrogenase activity was shown to disappear in the pigment epithelium and visual cells ... .

/The authors/ have shown that in an experimental cell culture system consisting of carcinogen-treated 10T1/2 cells, both retinoids and all dietary carotenoids examined can reversibly inhibit neoplastic transformation in the post-initiation phase of carcinogenesis. This activity strongly correlates with their ability to increase gap junctional intercellular communication by up-regulating the expression of the gene CX43 (connexin43). Connexins comprise the structural unit of gap junctions, organelles which allow direct transfer of signals, nutrients and waste products between contacting cells. CX43 is the most widely expressed member of the gap junction family of genes, and we have demonstrated that its expression is strongly down-regulated in human cancers and in several premalignant conditions. When several human tumour cell lines were genetically engineered to conditionally express CX43 under the influence of a tetracycline promoter, their neoplastic phenotype was strongly attenuated. Specifically, induced cells were inhibited from growing in an anchorage-independent manner and, additionally, growth as xenografts in immunocompromised animals was also strongly attenuated. Growth inhibition in suspension was associated both with increased G(1) cell-cycle arrest and with increased apoptosis. /The authors/ propose a model whereby junctional communication allows the transfer of growth inhibitory signals from normal to neoplastic cells and that retinoids and carotenoids, by increasing signal transfer, act to prevent cancer.

1.9 hours

Hepatic reserves of vitamin A decrease with a half-life of about 50 days in animals ...

Hepatic. Retinol is conjugated with glucuronic acid; the B-glucuronide undergoes enterohepatic circulation and oxidation to retinol and retinoic acid. Retinoic acid undergoes decarboxylation and conjugation with glucuronic acid.

Retinol is converted to retinyl phosphate in epithelial tissues, and this intermediate is in turn metabolized to mannosylretinylphosphate in a reaction that is catalyzed by a microsomal enzyme and requires guanosine diphosphomannose as a glycosyl donor. ... /the vitamin A/ mediates transfer of mannose to specific glycoproteins.

Retinol is in part conjugated to form a beta-glucuronide, which undergoes enterohepatic circulation and is oxidized to retinal and retinoic acid.

Within the retina, all-trans-retinol is oxidized to retinal by alcohol dehydrogenases, and is then Isomerized to the 11-cis-isomer which combines with opsin in the rod to yield rhodopsin, and with different opsins in human cones to yield three different iodopsin pigments.

Retinoic acid (RA) is the bioactive metabolite of vitamin A (retinol) which acts on cells to establish or change the pattern of gene activity. Retinol is converted to RA by the action of two types of enzyme, retinol dehydrogenases and retinal dehydrogenases. In the nucleus RA acts as a ligand to activate two families of transcription factors, the RA receptors (RAR) and the retinoid X receptors (RXR) which heterodimerize and bind to the upstream sequences of RA-responsive genes.

Retinol has known human metabolites that include 4-Hydroxyretinol and retinal.

81G40H8B0T

VITAMIN A

Chemical Structure [CS] - Vitamin A

Established Pharmacologic Class [EPC] - Vitamin A

Vitamin a is a Vitamin A.

VITAMIN A

Readily absorbed from the normal gastrointestinal tract

Vitamin A is distributed into breast milk ... .

Less than 5% of circulating vitamin A is bound to lipoproteins in blood (normal), but may be up to 65% when hepatic stores are saturated because of excessive intake. The amount of vitamin A bound to lipoproteins may be increased in hyperlipoproteinemia. When released from liver, vitamin A is bound to retinol-binding protein (RBP). Most vitamin A circulates in the form of retinol bound to RBP.

Storage: Hepatic (approximately 2 years' adult requirements), with small amounts stored in kidney and lung tissues. Zinc is required for mobilization of vitamin A reserves in the liver.

More than 90% of the intake of preformed vitamin A is in the form of retinol esters, usually as retinyl palmitate. ... When a large excess is ingested, some of the vitamin escapes in the feces. ... Absorption ... is related to that of lipid and is enhanced by bile. ... Aqueous dispersions ... are absorbed more rapidly than are oily solution.

For more Absorption, Distribution and Excretion (Complete) data for VITAMIN A (9 total), please visit the HSDB record page.

CIR ingredient: Retinol

Essential micronutrient found in animals; [Merck Index] Used as a nutritional supplement for foods; [FDA] Permitted for use as an inert ingredient in non-food pesticide products; [EPA]

Vitamin (antixerophthalmic)

MEDICATION

MEDICATION (VET)

For the treatment of vitamin A deficiency. Vitamin A helps regulate the immune system, which helps prevent or fight off infections by making white blood cells that destroy harmful bacteria and viruses.

(1972) 8.12X10+8 GRAMS

(1975) 1.30X10+8 GRAMS

(1984) 9.62X10+8 g /Vitamin A and Provitamin A, Synthetic/

(1972) 4.71X10+8 GRAMS

(1975) PROBABLY GREATER THAN 4.54X10+5 GRAMS

(1985) In the United States, commercial production of synthetic retinol is about 1000 tons /9.08X10+8 g/ per year

... Vitamin A is isolated by liquid-liquid extraction, molecular distillation, and HPLC. Commercial isolation of retinol from natural raw materials starts with fish oils and is conducted in six steps: (1) accumulation of crude vitamin A by the Solexol countercurrent extraction process, (2) short-path distillation of the retinyl esters (200 °C, 400 Pa), (3) ester saponification (KOH, 60 -70 °C, 30 minutes, N2), (4) extraction of retinol with ether, (5) short-path distillation of retinol (120 °C, 400 Pa), and (6) final purification by crystallization from ethyl formate (-35 °C. With the development of efficient processes for the synthesis of vitamin A on a commercial scale, isolation from natural raw materials has lost importance.

REACTION OF BETA-IONONE AND A PROPARGYL HALIDE

AQUEOUS SOLN (DISPERSIONS) OF OIL-SOLUBLE VIT ARE PREPARED BY THE USE OF AN EMULSIFYING AGENT SUCH AS POLYSORBATE 80.

There are many types of preparations that contain retinol. These include solutions of pure synthetic retinol and concentrates that contain both retinol and vitamin D in various proportions. Vitamin A capsules contain 3 to 15 mg of retinol (10,000 to 50,000 USP vitamin A units) per capsule: tablets are also available. A water-miscible preparation (15 mg/ml; 50,000 USP units/ml) can be given intramuscularly. Tretinoin (all-trans-retinoic acid; RETIN-A) is available for topical use as a solution (0.05%), a cream (0.05 and 0.1%), and a gel (0.025 and 0.01%). Isotretinoin (13-cis-retinoic acid; ACCUTANE) is available for oral use as 10, 20, and 40 mg capsules.

Retinol: ACTIVE

Vitamin A: ACTIVE

Retinol is sold almost exclusively in the form of the more stable esters (mainly as retinyl acetate, also as retinyl palmitate and propionate). About 80% of the production is used in animal feed, the remainder in the food and pharmaceutical sectors.

... THE NOMENCLATURE /FOR VIT A UNITAGE/ IS IN TERMS OF RETINOL EQUIV, WHICH REPRESENTS 1 UG OF ALL-TRANS-RETINOL, 6 UG OF DIETARY BETA-CAROTENE, OR 12 UG OF OTHER PROVITAMIN A CAROTENOIDS. THUS, 1 RETINOL EQUIV EQUALS 3.3 IU UNITS OF VIT A ACTIVITY AS SUPPLIED BY RETINOL OR 10 UNITS ... AS SUPPLIED BY BETA-CAROTENE.