Vitamin B group

A group of water-soluble vitamins that characteristically serve as components of coenzymes.

Plants and many microorganisms can manufacture B vitamins but dietary sources are essential for most animals.

Heat and light tend to destroy B vitamins.The vitamin B complex consists of 12

related substances. Eight are considered essential vitamins

because they need to be included in the diet. Four are not essential because the body can synthesize them.

They include thiamin (B1), riboflavin(B2), niacin, vitamin B6, pantothenic acid, folic acid, biotin and vitamin B12 (cobalamin); some authorities also include choline, lipoic acid, inositol, and para-aminobenzoic acid.

Although these vitamins are chemically distinct, they are grouped together because they are found with one another in the same foods.

B1; or Thiamin Function

It is an organic compound of two parts contains sulphur and nitrogen.

Antineuritic vitaminDestroyed by

alkaline and heat

Precursor of the coenzyme thiamine pyrophosphate (TPP), which functions in carbohydrate metabolism.

is essential to normal nerve function and the utilization of carbohydrates

Stimulate" the appetite Prevent and "cure" beriberi,

or multiple neuritis, characterized by inflammation and degeneration of the peripheral nerves, intense pain, resulting, finally, in paralysis and wasting of the muscles.

• first symptoms of B1 deficiency is loss of appetite.

• Beriberi (which can cause weakness, leg spasms, poor appetite, and loss of coordination.) muscle spasm include heart

• In alcoholic result in Wernicke-Korsakoff syndrome( mental confusion, staggering, rapid eye movement or paralysis of eye muscle.)

• Deficiency Wheat germ, beans,

peas, and green vegetablesMeat Sunflower seeds

RDAMen: 1.2 mgWomen: 1.1 mgRequirement increases with energy expenditure

Toxicity: none known

• Sources:

B2 or riboflavin Functions

composed of a single type of sugar (ribose) and a yellow pigment (flavin)

first discovered in milk and also been called lactoflavin.

It is a constituent of the coenzymes FAD and FMN, which have an important role in the metabolism of all major nutrients as well as in the oxidative phosphorylation reactions of the electron transport chain.(Kreb’s cycle

Flavin mononucleotide (FMN)Flavin adenine dinucleotide

(FAD)

RDAMen: 1.3 mgWomen: 1.1 mgToxicity: none known

Deficiency-Skin lesions, especially cheliosis, or fissures in the corners of the mouth and tongue -Bloodshot eyes

Sources: Milk/productsEnriched grainsLiverMushroms green vegatbles Brewer’s yeast-Sensitive to uv radiation (sunlight)

B3; Niacin Functions

Nicotinic acidOther forms of

vitamin B3 nicotinamide

Can be made from the essential amino acid tryptophan

precursor to NADH, NAD+, NADP+ and NADPH, which play essential metabolic roles in living cells.

In larger doses, niacin can reverse atherosclerosis by lowering low density lipoprotein (LDL)

Nicotinamide adenine dinucleotide (NAD)Nicotinamide adenine dinucleotide phosphate (NADP)

Deficiency Pellagra is characterized by diarrhea, dermatitis and dementia as well as “necklace” lesions on the lower neck, hyperpigmentation, thickening of the skin, inflammation of the mouth and tongue, digestive disturbances, amnesia, delirium, and eventually death, if left untreated[ Dietary niacin deficiency tends to occur in areas where people eat maize("corn") as a staple food. Maize is the only grain low in niacin( nixtamalization is needed)

Sources:MushroomsEnriched grainsBeef, chicken, turkey, fishHeat stable; little cooking loss

skin flushing and itching

Gastrointestinal complaints

such as dyspepsia (indigestion) and liver toxicity

RDAMen: 16 mg equivalentsWomen: 14 mg equivalentsBody can make niacin from tryptophan

Toxicity

B5; Pantothenic acid

needed to form coenzyme-A (CoA

and is critical in the metabolism and synthesis of carbohydrates, proteins, and fats.

PantothenicGreek word meaning "from everywhere: widely distributed

Deficiency: rare.

Biotin functions

described as the most powerful of all the vitamins

Names: vitamin H, a second called it biotin and a third called it "coenzyme R,"

Necessary for cell growth, the production of fatty acids, and the metabolism of fats and amino acids.

Need for carboxylation reactions

Recommended for strengthening hair and nails

Need to make glycogen

Adequate Intake is 30 ug/day for adultsThis may overestimate the amount needed for adultsNo Upper Limit for biotin

Deficiency: Rare DepressionNumbness/tingling in arms and legsskin rash, hair loss, convulsion, neurological disorders, impaired growth in children

Sources: Widespread in food

Cheese, egg yolk, liver, peanut butter, soybeans, fish

Synthesized by GI bacteria

Vitamin B6 or pyridoxine Functions

It is a constituent of a coenzyme (pyridoxal phosphate) involved in amino acid metabolism.

assists in the balancing of sodium and potassium.

promote red blood cell production

Synthesize sertonin, histamine, epinephrine and norepinephrine

Conversion of tryptophan to niacin

Other names• Pyridoxine• Pyridoxal• PyridoxamineDestroyed by heat

• Deficiency :• Microcytic

anemia• causes retarded

growth.• dermatitis.

Convulsions RDA– 1.3 mg/day for adults– 1.7 mg/day for men over 50– 1.5 mg/day for women over 50• Athletes may need more• Alcohol increases vitamin B-6 destruction

• Irreversable nerve damage, numbness in hands feet

• Difficult of work, Convulsion, Restlessness and

• Insomnia.

• Sources:• Meat, fish

legume• Seeds and

nuts• Liver• Noncitrus fruit

Toxicity

Folic acidB9 or folacin

Function

folate (the naturally occurring form),

Folic acid is itself not biologically active, but its biological importance is due to tetrahydrofolate and other derivatives after its conversion to dihydrofolic acid in the liver

Essential for synthesis of DNA, repair DNA, and methylate DNA

Important during periods of rapid cell division and growth.

Breakdown homocysteine

May reduce risk of some cancer as breast and pancreatic cancers.

Deficiency Neural tube in

developing embryos.DNA synthesis and

repair are impaired and this could lead to cancer development

Megaloblastic anemia

400 ug/day for adults

Sources:LiverFortified breakfast cerealsGrains, legumesFoliage vegetablesSusceptible to heat, oxidation, ultraviolet light

B12 ; (cyanocobalamin; cobalamin)

It is structurally the most complicated vitamin and it contains the biochemically rare element cobalt

Biosynthesis of the basic structure of the vitamin can only be accomplished by bacteria, but conversion between different forms of the vitamin can be accomplished in the human body.

A common synthetic form of the vitamin, cyanocobalamin, does not occur in nature, but is used in many pharmaceuticals and supplements, and as a food additive

Vitamin B12 is normally involved in the metabolism of every cell of the body, especially affecting the DNA synthesis and regulation , fatty acid synthesis and energy production. many (though not all) of the effects of functions of B12 can be replaced by sufficient quantities of folic acid, since B12 is used to regenerate folate in the body.

Helps maintain myelin sheath around nerve cell.

Pernicious anemia which include: Megaloblastic anaemia, nerve damage,

creeping analysis, sore red tongue and fatigue.

This can be masked by folate intake.

Deficiency

Food SourcesAlmost exclusively animal productsMeat, fish, poultry, milk, cheese, eggsFortified soy milk, fortified cerealsEasily destroyed by microwave cooking and oxygen.

RDA2.4 mg for adultsToxicity: none known

Figure 10-12Page 342

Normal and Anemic Blood Cells

Normal blood cells. The size, shape, andcolor of the red blood cells show that

they are normal.

Blood cells in pernicious anemia (mega-loblastic). Megaloblastic blood cells are

slightly larger than normal red bloodcells, and their shapes are irregular.