Vitamins- final

Vitamins
Introduction
The word "vitamin" comes from the Latin word vita, means "life".
Vitamins are organic compounds of low molecule weight.
They are necessary for keeping natural physiological function, especially for intracellular specific metabolism.
They can’t be synthesized in the body.
They are not the material of the tissue.
They exist in natural food in different form.
They can’t supply energy.
History
From about 1500 BC it was known that various diseases could be treated with specific foods.
Frederick Hopkins reported in 1906 that foods contain a small amount of "growth factors" neede
d to sustain growth and lif
e itself.
The general category of "vitamins" was defined as (1) substances found to be absolutely necessa ry for life (i.e., vital) and which (2) the body cannot synthesize on its own.
In 1912 Cashmir Funk named these growth factors “vitamines”because they were required for l ife ("vita") and because he found that thiamine isolated from rice husks contained nitrogen (call ed an "amine" - i.e., containing a nitrogen bound to three hydrogen atoms -NH3).
Funk's original term "vitamine" was changed to "vitamin" when many scientists identified, purifi ed, and synthesized all of the vitamins and discovered they did not all contain nitrogen.
In the 1930s a scientific discovery demonstrated the biochemical functions of the vitamins and e stablished the body's requirements for them. From then on, they have been commercially produc ed.
Classification of Vitamins
According to their solubility, they are classified into fat soluble vtamin and water soluble vitamin. FAT SOLUBLE A D E K
W ATER SOLUBLE B1- Thiamine B2 –Riboflavin B3 –Niacin B5 –pantothenic acid B6 –Pyridoxi ne B8 –biotin B 9-Folic acid B12 -CyanoCobalamin C vitamin (ascorbic acid)
Water soluble Vitamins
Water soluble(hydrophilic): B vitamins and vitamin C
o found in watery compartments of food
o moves directly into the blood after being absorbed
o can travel freely in the blood
o freely circulate in watery compartments of the body's cells
O regulated and excreted when in excess by the liver easily –are less likely to have toxic effects when ingested in large amounts.
Fat soluble Vitamins
Fat soluble (hydrophobic) Vitamins A, D, E, and K
o found in fats and oils of food
O need fat for their absorption
o carried through the lymph to the blood
o many times require proteins for transportation
in the blood
o trapped in cells associated with fat
o less readily excreted - tend to stay in fat storage sites –can build up to toxic levels with seriou
s and potentially fatal results.
Digestion, Absorption and Transportation of Vitamins
一、VITAMIN A
VITAMIN A :- Is widely distributed in animal and plant foods
From animals –pre-formed –Retinal,
retinol, retinoic acid
From plants –pro-formed –Carotenoids
Must be converted to retinoid form
Intestinal cells can split carotene in two (molecules of retinoids)
Found in plant products
在体内β - 胡萝卜素-15，15′-双氧酶（双加氧酶）催化下，可将β - 胡萝卜素转变为两分子的视黄醛（ratinal），视黄醛在视黄醛还原酶的作用下还原为视黄醇。

但β - 胡萝卜素也可能合成astaxant
hin即虾青素的强抗氧化剂，
Terminal Ends of Retinoids Retinol,retinal,retinoic acid,
and related compounds are
known as retinoids （类维生
素A ）.15，15′-dioxygenase
reductase
在体内β - 胡萝卜素-15，15′-双氧酶（双加氧酶）催化下，可将β-胡萝卜素转变为两分子的视黄醛（ratinal ），视黄醛在视黄醛还原酶的作用下还原为视黄醇。

但β - 胡萝卜素也可能合成astaxanthin 即虾青素的强抗氧化剂
Conversion of Carotenoids to Retinoids
•
Enzymatic conversion of carotenoids occurs in liver or intestinal cells, forming retinal and retin oic acid • Provitamin A carotenoids
– Beta-carotene
– Alpha carotene
– Beta-cryptoxanthin 隐黄素 [ˌkript əu ˌzæn θin]
• Other carotenoids
– Lutein 叶黄素
– Lycopene
– Zeaxanthin 玉米黄质 [zi əˌzæn θin]
Absorption of Vitamin A
• Retinoids
– Retinyl esters broken down to free retinol in small intestine - requires bile, digestive e
nzymes, integration into micelles
– Once absorbed, retinyl esters reformed in intestinal cells
– 90% of retinoids can be absorbed
• Carotenoids
– Absorbed intact, absorption rate much lower
– Intestinal cells can convert carotenoids to retinoids
• Approximately 80% is absorbed.
• It is passed along with fat through the lymphatic system into blood stream.
• absorption is poor in case
of diarrhea, jaundice 黄疸病 [ˌd ʒɔnd ɪs] and abdominal 腹部的
[æbˌdɑmənəl] disorder.
•absorption increases if taken with fat.
•vitamin A which is not absorbed is excreted within 1 or 2 days in feces .
STORAGE
The liver has enoromous capacity to store –in the form of retinol palmitate.
under normal conditions a well-fed person has sufficient Vitamin A reserves to meet his need fo r 6 to 9 months or more.
Free retinol is highly active but toxic & therefore transported in blood stream in combination with retinol binding protein (liver)
Physiological Functions of Vitamin A
Vision
Regulation of gene expression
Immunity function
Growth and Development
Red blood cell production
1.Vision
The retina视网膜is located at the back of the eye. When light passes through the lens, it is sensed by t he retina and converted to a nerve impulse for interpretation by the brain.
Retinol is transported to the retina via the circulation, where it moves into retinal pigment epithelial cells. There, retinol is esterified to form a retinyl ester, which can be stored. When needed, retinyl esters are broken apart (hydrolyzed) and isomerized to form 11-cis retinol, which can be oxidized to form 11-cis r etinal. 11-cis Retinal can be shuttled across the interphotoreceptor matrix to the rod (杆状) cell, where it binds to a protein called opsin（视蛋白）to form the visual pigment, rhodopsin(visual purple 视紫红质). Rod cells with rhodopsin can detect very small amounts of light, making them important for night v ision. Absorption of a photon of light catalyzes the isomerization of 11-cis retinal to all-trans retinal an d results in its release. This isomerization triggers a cascade of events, leading to the generation of an el ectrical signal to the optic nerve. The nerve impulse generated by the optic nerve is conveyed（转达）t o the brain where it can be interpreted as vision. Once released all-trans retinal is converted to all-trans retinol, which can be transported across the interphotoreceptor matrix to the retinal epithelial cell to comp lete the visual cycle. Inadequate retinol available to the retina results in impaired dark adaptation, known as "night blindness."
眼的光感受器是视网膜中的杆状细胞和锥状细胞。

这两种细胞都存在有感光色素，即感弱光的视紫红质和感强光的视紫蓝质。

视紫红质与视紫蓝质都是由视蛋白与视黄醛所构成的。

视紫红质经光照射后，11-顺视黄醛异构成反视黄醛，并与视蛋白分离而失色，此过程称“漂白”。

若进入暗处，则因对弱光不敏感的视紫红质消失，故不能见物。

分离后的视黄醛被还原为全反式视黄醛，进一步转变为反式视黄酯（或异构为顺式）并储存于色素上皮中。

由视网膜中视黄酯水解酶，将视黄酯转变为反式视黄醇，经氧化和异构化，形成11-顺视黄醛。

再与蛋白重新结合为视紫红质，恢复对弱光的敏感性，从而能在一定照度的暗处见物，此过程称暗适应（DarkAd aptation）。

由肝脏释放的视黄醇与视黄醇结合蛋白（RBP）结合，在血浆中再与前白蛋白结合，运送至视网膜，参与视网膜的光化学反应，若维生素A充足，则视紫红质的再生快而完全，故暗适应恢复时间短；若维生素A不足，则视紫红质再生慢而不完全，故暗适应恢复时间延长，严重时可产生夜盲症（NightBlindne ss）。

2) Regulation of gene expression
Retinoic acid (RA) and its isomers act as hormones to affect gene expression and thereby influence numerous physiological processes
All-trans RA and 9-cis RA are transported to the nucleus of the cell bound to cytoplasmic retinoic acid-binding proteins. Within the nucleus, all-trans RA binds to retinoic acid receptors (RAR) and 9 -cis RA binds to retinoid receptors (RXR). RAR and RXR form RAR/RXR heterodimers(异质二聚体), which bind to regulatory regions of the chromosome called retinoic acid response elements (RA RE). Binding of all-trans RA and 9-cis RA to RAR and RXR respectively allows the complex to reg ulate the rate of gene transcription.
3) Immunity
Vitamin A is commonly known as the anti-infective vitamin, because it is required for n ormal functioning of the immune system . The skin and mucosal cells function as a barrier and f orm the body's first line of defense against infection. Retinol and its metabolites are required to maintain the integrity and function of these cells .
4) Growth and Development
Both vitamin A excess and deficiency are known to cause birth defects. Retinol and retinoic ac
id (RA) are essential for embryonic development. During fetal development, RA functions in l imb development and formation of the heart, eyes, and ears . Additionally, RA has been found
to regulate expression of the gene for growth hormone
5) Red blood cell production
Red blood cells, like all blood cells, are derived from precursor cells called stem cells. Thes e stem cells are dependent on retinoids for normal differentiation into red blood cells. Additionally, vita min A appears to facilitate the mobilization of iron from storage sites to the developing red blood cell for incorporation into hemoglobin, the oxygen carrier in red blood cells .
Deficiency symptoms
The signs of vitamin A deficiency
Ocular 眼睛的[ˈɑkjəlɚ]
Night blindness. Conjunctival xerosis 结膜干燥病[zɪˈrosɪs] bitot’s spot 毕特氏斑
Corneal xerosis 眼角膜keratomalacia 角膜软化
Extra ocular
Retarded growth Skin disorders Effect on reproductive organs. Effect on bone
Night blindness
Lack of vitamin A causes night blindness or inability to see in dim light.
night blindness occurs as a result of inadequate pigment in the retina.
It also called tunnel vision.
Night blindness is also found in pregnant women in some instances, especially during the l ast trimester 三个月of pregnancy when the vitamin A needs are increased.
对弱光敏感度下降，暗适应*时间延长的重症表现。

多因V A缺乏所致，也有先天夜盲者。

主要症状为白天视觉几乎正常，黄昏时光线渐暗则视物不清。

因麻雀等某些鸟类系先天夜盲，故又名“雀目”、“雀盲”、“雀目眼”。

V A 缺乏引起夜盲的主要机理如下：视网膜上有在强光下产生颜色感觉的视圆锥细胞和在弱光下产生暗视觉的视杆状细胞。

而决定暗视觉好坏和暗适应快慢的主要因素之一，是视紫红质（视杆细胞色素）在血中的浓度。

视紫红质的合成与分解受光调节；强光下分解多于合成，弱光下合成多于分解，使其浓度逐渐达到一定的光敏感度所需水平，达到这一水平所用的时间即是暗适应的时间。

因为V A是视紫红质的“原料”，所以当V A缺乏时，则视紫红质得不到足够的补充，从而血中浓度下降，导致视杆状细胞功能不全，对弱光敏感度下降，暗适应时间延长等，出现夜盲症状。

适量补充V A可以有效地治疗因V A 缺乏引起的夜盲症。

我国早在唐代便已应用猪肝等富含V A的食物治疗“雀目”。

Bitot's spots毕特氏斑
These are foamy and whitish cheese-like tissue spots that develop around the eye ball, causing sever e dryness in the eyes. These spots do not affect eye sight in the day light.
Conjunctival xerosis 结膜
Conjunctiva becomes dry and non wettable.
Instead of looking smooth object, it appears muddy & wrinkled.起皱
keratomalacia角膜软化
One of the major cause for blindness in India. cornea becomes soft and may burst open .
The process is rapid If the eye collapses，vision is lost.
Increased risk of mortality from infectious disease
it has been best studied in malnourished children, but also is seen in animals. In such cases, supple mentation with vitamin A has been shown to substantially reduce mortality from diseases such as d iarrhea, measles and gastrointestinal infections.
Toxicity
The condition caused by vitamin A toxicity is called hypervitaminosis A. It is caused by overconsumptio n of preformed vitamin A, not carotenoids. Preformed vitamin A is rapidly absorbed and slowly cleared f rom the body, so toxicity may result acutely from high-dose exposure over a short period of time, or chr onically from much lower intake.
Acute –short-term megadose (100 x RDA); symptoms disappear when intake stops
GI effects gastrointestinal Headaches Blurred vision Poor muscle coordination
Chronic –long-term megadose; possible permanent damage
Bone and muscle pain Loss of appetite Skin disorders Headache Dry skin Hair loss Increased liver s ize V omiting
Teratogenic 畸形的[ˌtɛrətəˌdʒɛnɪk] (may occur with as little as 3 x RDA of preformed vitamin A) Tends to produce physical defect on developing fetus as a result of excess vitamin A intake Spontaneous abortion Birth defects
Health Effects of Vitamin A
Tolerable Upper Level of Intake (UL) for Preformed Vitamin A (Retinol)
Carotenemia胡萝卜素血症
A condition in which conversion of carotene to vitamin A is impaired by inborn metabolic erro r or hepatic diseases
generalized yellowish skin and mucosa.
excessive deposition of carotene which is result of high intake of foods containing car
otene.
TREATMENT
vitamin deficiency should be treated urgently .
depending upon deficiency symptoms it is given in the dose of 7,500 to 15,000 mcg p er day for one month
nearly all of the early stages of xerophthalmia can be reversed by administration of a massive dose –2,00000 IU or 110mg orally on two successive days (30).
If Hypervitaminosis restriction of diet
RDA
SOURCES
Everyday your body needs about 500-600 mg of vitamin A.
Sources of vitamin A can be divided in two groups, vegetable and animal foods. In a nimal foods the vitamin A is present in a form called retinol, which is the active for
m of vitamin A, and in vegetables it is present as provitamin A. You have to eat six
times as much provitamin A to get the same amount of vitamin A as in retinol.
It is easier for the body to take up vitamin A if the food is cooked and eaten togeth er with some fat or oil.
Animal food sources
Liver.
Fish liver oil.
Egg yolk.
Milk and milk products for example cheese.
Food with milk fat for examples margarine and butter.
Breast milk.
Small fish, with liver for example sardines .
Vegetable food sources
Dark green leaves for example spinach, cassava （木薯）and mustard.
Yellow and orange vegetables for example carrot, coloured yams, yellow squash (南瓜) and sweet potatoes.
Yellow and orange fruits for example papaya番木瓜果, apricots杏and mangoes (but no t citrus fruits).
Red palm oil.
vitamin D
it is also called SUNSHINE VITAMIN.
it is available in 2 forms
D3 –cholecalciferol
D2 - calciferol
Cholecalciferol (vitamin D3)
is made from 7-dehydrocholesterol in the skin of animals and humans.
calciferol - D2
obtained artificially by irradiation of ergo- sterol and is called ergocalciferol
chemical origins of vitamin D
Precursors of vitamin D are found in both yeast and animal tissues. In yeast, a sterol prec ursor (ergosterol) is converted to vitamin D2 (ergocalciferol). Ergocalciferol is the compou
nd most commonly found as the additive to fortify milk.
In the dermal tissue of animals, the precursor is 7-dehydrocholesterol which is converted fi rst to a pre-vitamin D3, then to vitamin D3 (cholecalciferol).
Vitamin D2 and vitamin D3 are both converted to similar active compounds (calcidiol and calcitriol) in the liver and kidney.
Status
A "vitamin" by definition is a substance regularly required by the body in small amounts but
which the body cannot make. Therefore, It required to be supplied in the daily diet. Technicall y the molecular species classified as vitamin D is not really a vitamin because it can be produ ced by exposure of the skin to sunlight .
vitamin D endocrine system include the following
•The parathyroid glands sense the serum calcium level, a nd secrete parathyroid hormone (PTH) if it becomes too low, fo r example, when dietary calcium intake is inadequate. PTH stim ulates the activity of the 1-hydroxylase enzyme in the kidney, re sulting in increased production of calcitriol, the biologically activ
e form o
f vitamin D3. Increased calcitriol production restores no
rmal serum calcium levels in three different ways: 1) by activati ng the vitamin D-dependent transport system in the small intesti ne, increasing the absorption of dietary calcium; 2) by increasin
g the mobilization of calcium from bone into the circulation; an
d 3) by increasing th
e reabsorption o
f calcium by the kidneys.
PTH is also required to increase calcium mobilization from bone and calcium reabsorption by the kidneys. However, PTH is not required for the effect of calcitriol on the intestinal absorption of calcium.
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liver
skin
blood
7-dehydrocholesterol
Inactive compounds
Previtamin D 3D 3(Cholecalciferol)
DBP (vit. D binding protein)
DBP-D 3
24, 25-OH D
3(inactive)
1, 25-OH D 3(active)
(calcitriol)
kidney
Ca ++transport (intestine)
Ca ++resorption (bone)
D 3
(calcidiol)
25-OH D 3
25-OH D 3
DBP-calcidiol (tight binding)
Physiological Action
Promote calcium be absorbed in small intestine. Accelerate calcium and phosphor’ absorb in kidney
Boost the absorb of calcium and phosphor in bone, strong the teeth. Adjust the transcription. Keep the balance of calcemia.
Prevent the loss of amino acid in kidney
Promote calcium be absorbed in small intestine.
• 1α,25-(OH)-D 3 induce the synthesize of calcium binding protein. It’s the carrier of calcium. • This protein can make calcium easily enter small intestine. • The calcium is transported to blood circle.
Accelerate calcium and phosphor’ absorb in kidney
• 25-(OH)2D 3 has direct effect on kidney. it enlarge the absorption of calcium and phosphor • Reduce the probability of rachitis 佝偻病 • Boost calcification of bones tissues
Adjust the gene transcription.
• The regulation of gene transcription by 1a,25(OH)2D 3 is known to be mediated by interacti on of this ligand with a nuclear receptor protein, termed the VDR.
• The tissue distribution of the VDR is known to occur in over 30 different cell types. • In addition ,1a,25(OH)2D 3 and the VDR are known to regulate the independent transcriptio n of numerous proteins.
Keep the balance of calcemia. 钙血(症)
• There is vitamin D internal secretion system in our body.
•
1α,25-(OH)-D 3 is the main adjust factor ，it can adjust the calcemia level.
•Regulating blood calcium levels is important. When there is too little calcium in the blood, soft-tissue cells--especially nerves and muscle--shut down, sending the body into convulsio
ns;
•when there is too much calcium in the blood, organs calcify and eventually cease to wor k.
•For human patients who had lost their parathyroid glands (甲状旁腺) or their kidneys and could no longer regulate the level of calcium in their blood.
•the newly synthesized vitamin D hormone, when given with plenty of calcium, had a dra matic effect, curing them of convulsions and chronic bone disease.
vitamin D - deficiency
Rrickets 佝偻病→Children's
Osteomalacia 软骨病→Adults
Increase the risk of Osteoporosis骨质疏松症
Cause of V D deficiency
•Short of sun.
•Deficiency of outdoor activity.
•Lack of V D in dietary.
•Some babies grow too quick.
•The illness in stomach, intestines, will affect the incorporation and utilization of calcium and V D.
•Some medicines have negative effect on V D absorption
•prednisone泼尼松and gabapentin加巴喷丁(抗焦虑药) (Neurontin) alter vitamin D activity。

Rickets
Rickets was once considered an extremely common disorder of childhood. The term itself is derived from the old English word for "twist," or "wrick,“
Rickets is caused by a deficiency in vitamin D. During growth, human bone is made and maintained by the interaction of calcium, phosphorus, and vitamin D. Calcium is deposit
ed in immature bone (osteoid) in a process called calcification, which transforms immature
bone into its mature and familiar form.
in order to absorb and use the calcium available in food, the body needs vitamin D. In ri ckets, the lack of this important vitamin leads to low calcium, poor calcification, and defo
rmed bones.
59
DEFICIENCY
RICKETS
Osteomalacia
it is also known as adult rickets and flat bones
it is most commonly seen in post menopause female with history of low dietary calcium i
ntake.
The majority of patient have bone pain &muscle weakness.
Excess of V D
• Too much V D will cause toxicosis
• Large dose V D may lead to ill reaction. Including anorexia 厌食, fatigue, spew(喷涌), even insanity 精神错乱.
• It can also cause impair to sight. • Too much V D is harmful for kidney. • It will destroy vein.
• Others include anemia, weight loosing, etc
The cause of toxicosis
• Inject too much V D , especially after being taken orally
• Long time of V D taking, because of the ignorance of the toxicosis of V D • Too much lead to calcium’ decompensate 代谢失调.
The treatment of toxicosis of V D
• Stop the take of V D and calcium. • Avoid the sun
• Have low calcium dietary. • If worse, you must see doctor
Daily recommendation
vitamin k
VITAMIN K (PHYLOQUINONE 叶绿醌) 醌 [ˌfil əukwi ˌn əun]
It is essential for production of a type of protein called prothrombin & other factor involve in blood clotting mechanism. Hence it is known as anti – hemorrhagic vitamin.
long term administration of antibiotic doses for more than a week may temporarily
suppress the normal intestinal flora, thus may cause deficiency of vitimin k it is also known as PHYLOQUINONE
67
Forms
It is available in 2 forms
K1–it is the form occurs in plant origin .
K2 -is synthesized by intestinal bacteria.
FUNCTIONS
it is essential for the hepatic synthesis of coagulation factor II, V , VII, IX, X.
Clotting – it prevents hemorrhage only in cases when there is defective production of
prothrombin
Oxidative Phosporylation – it acts
as a co- factor in oxidative phosphorylation associa
ted with lipid
Bone metabolism
85
DEFICIENCY
Causes
Increase clotting time
Prolong bleeding
Hemorrhagic conditions
After antibacterial therapy,
Surgical operations-Cholecystectomy Conditions like
→Malabsorption →Obstructive jaundice
cholecystectomy 胆囊切除术[ˌkol ɪs ɪˌst ɛkt əmi] jaundice 黄疸病
VITAMIN E
It is also called anti-aging factor.
The word tocopherol is derived from the word toco meaning child birth and pheros meaning to bear.
It is yellow oily liquid freely soluble in fat solvent.
Tocopherol alpha,beta, gamma, delta have been obtained from the natural sources
These vitamers can be put into 2 classes: tocopherols (saturated phytyl side chain)
tocotrienols (unsaturated phytyl side chain with 3 double bonds) • antioxidant property is due to the presence of the chrome ring.
Structure of a-tocopherol
SOURCES
DAILY RECOMMENDED DOSE
Vitamin E & Vitamin K absorption
Transport of chylomicrons
•Inside the enterocyte, tocopherols are incorporated
into “chylomicrons” and transported via the lymph and thoracic duct 胸导管into s ystemic circulation.
•Any problem in the pancreas that decreases pancreatic enzyme concentration e.g. cy stic fibrosis can result in vitamin E malabsorption.
•Any disease that reduces the surface area of intestinal cells (e.g. celiac disease) or th
e total length o
f the intestine can result in vitamin E malabsorption.
•Tocopherol is distributed to tissues primarily by LDLs and may play a role in protec ting LDLs from oxidation.
FUNCTIONS
Reproductive function–it has got protective effect on reproduction and prevention of sterility.
Anti-oxidation activity in vivo
Anti-atherosclerosis
Anti-inflammation
Anti-Oxidant:
•Vitamin E protects cell membranes, especially in the lungs and red blood cells. It par ticularly protects fatty acids against oxidative damage caused by various pollutants, pe
roxides, and free radicals formed during metabolic processes. It aids in the prevention
of lipofuscin脂褐质, an oxidized fat that has been implicated in the aging process.
•Vitamin E works synergistically with other antioxidant nutrients including selenium, vitamin C, B-carotene and others to quench free radicals, peroxides and other potentially harmful substances. Vitamin E can spare other antioxidants and vice versa反之亦然. Red blood cel ls are particularly susceptible to oxidative damage because of their high oxygen tension. Sic kle cell镰状细胞anemia has been successfully treated with vitamin E.
Anti-atherosclerosis
Cholesterol peroxidation can occur when vitamin E is deficient. In particular, LDL c holesterol yields epoxy- cholesterols环氧的which have been implicated in cardiovascular dis ease.
•Anti-inflammatory effects:
vitamin E inhibits the enzyme lypoxygenase脂肪氧化酶, an enzyme responsible for the
formation of leukotrienes白三烯which cause inflammation. This can be useful in the treat ment of asthma哮喘and other inflammatory conditions such as arthritis关节炎.
Oxidation of LDL
ROS/RNS
pro-atherogenic
ROS:reactive oxygen species RNS:reactive nitrogen species
Oxd LDL
LDL
Needed for normal reproduction
• Some unproven theories about the powers of vitamin E to improve sexual performance, pr event aging.
• In the experimental animals, it is needed for normal reproduction.
Vitamin E deficiency
• There are 3 categories of patients who are susceptible to vitamin E deficiency: • 1) premature infants
• 2) patients with G .I. diseases leading to malabsorption (e.g. cystic fibrosis) • 3) individuals with abetalipoproteinemia
• Abetalipoproteinemia 无β脂蛋白血症
•
无β-脂蛋白血症因微粒体甘油三酯转移蛋白基因突变所致,脂肪的吸收功能被显著削弱,既无乳糜微粒亦无极低密度(前-β)脂蛋白(VLDL)形成,所有的血浆脂质皆显著降低,无饭后脂血症.无特殊的治疗,大量运用肠外或口服维生素E,A 能延缓或阻滞神经系统发病. • REPRODUCTIVE – abortion of fetus in females & atrophy of spermatogenic structure in males leading to permanent sterility.
• HEART - there is necrosis & fibrosis of heart muscle.
•
BLOOD CAPILLARIES – may lead to degenerative changes in the blood capillaries
Toxicity and Treatment
• Vitamin E appears to be one of the least toxic of the vitamin. • Large intakes of vitamin E > 1200 mg /day.
Water soluble vitamins
Water soluble vitamins are found in yeast,grain,rice,vegetables, fish, and meat. These are essential co-enzymes required in energy releasing mechanisms. They also act as co-enzymes for metabolism of proteins, carbohydrates and fats. They do not store in body and excrete easily B complex vitamins
B1- Thiamine 硫胺素 B2 – Riboflavin 核黄素 B3 – Niacin 烟酸
B5 – pantothenic acid 泛酸 B6 –Pyridoxine 吡哆醇 B8 – biotin 生物素 B 9-Folic acid 叶酸
B12 –CyanoCobalamin 氰钴胺素 C vitamin (ascorbic acid) 抗坏血酸
THIAMINE (VIT B1)
It is also called Anti Beri-Beri factor, Anti Neuritic 神经炎的factor, and also Aneurin.
Active form in body : thiamin pyrophosphate (焦磷酸硫胺素TPP)
N
N C
H 3CH 2
NH 2S
C
H N
+
CH 3
CH 2
CH 2
O
P OH
O O P O OH
OH
焦磷酸硫胺素(TPP)
Functions
Act as co-enzyme Acted as co-enzyme
thiamin pyrophosphate焦磷酸盐, or cocarboxylase焦磷酸硫胺素TPP as coenzyme for oxid ative decarboxylation of α–keto acetic acids丙酮酸的氧化脱羧in the oxidation of glucose.
Essential for maintaining nerves in normal condition
it plays important role in the normal functioning of the entire nervous system.
Essential for maintaining nerves in normal condition
丙酮酸脱氢酶复合体的组成
酶
E1：丙酮酸脱氢酶
E2：二氢硫辛酰胺转乙酰酶E3：二氢硫辛酰胺脱氢酶
HSCoA
NAD+辅酶
TPP
硫辛酸（) HSCoA
FAD, NAD+
S
S
L
Deficiency
BERI BERI脚气病
. Wernicke-Korsakoff syndrome魏尼凯氏脑病
BERI BERI脚气病
The most important use of thiamine is in the treatment of beriberi, a condition caused by a de
ficiency of thiamine in the diet. Symptoms include swelling, tingling麻刺感or burning sensatio
n in the hands and feet, confusion, difficulty breathing (from fluid in the lungs), and uncontroll
ed eye movements (called nystagmus眼球震颤).
Wernicke-Korsakoff syndrome
•Wernicke-Korsakoff syndrome is a brain disorder caused by thiamine deficiency. Replacing thiamine alleviates the symptoms of this syndrome. Wernicke-Korsakoff is actually two dis
orders in one:
•(1) Wernicke's disease involves damage to nerves in the central and peripheral nervous sys tems and is generally caused by malnutrition (particularly a lack of thiamine) associated w
ith habitual alcohol abuse.
•(2)Korsakoff syndrome is characterized by memory impairment with various symptoms of nerve damage. High doses of thiamine can improve muscle in coordination and confusion
associated with this disease, but only rarely improves the memory loss.
Wernicke-Korsakoff Syndrome，又称魏尼凯氏脑病（Wernicke's encephalopathy）。

是一种神经脑病综合征，是由于酒精中毒引起硫胺素缺乏所致。

呈急性或亚急性发病，主要累及中脑上部灰质及下丘脑包括乳头体。

主要表现为精神意识障碍、共济失调及眼外肌麻痹。

periphera 周围的；外围的；外部的pyruvic acid 丙酮酸...dilation 扩张。