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Niacin (B3)
it is also known as nicotinic acid
it is essential for metabolism of carbohydrate,
protein & fat.

4. • Niacin used to be called vitamin B3 or
vitamin PP (pellagra preventive). Today,
the term “Niacin” is used to denominate
nicotinic acid and nicotinamide (A). In their
biological activity they are quantitative and
qualitative equivalents since the body can
convert them into one another (B).

6. Niacin structure

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SOURCES
• Plant :
 Rice
 Pulses- soybeans
 Vegetables –
Carrot leaves,
potato
 Ground nuts
 Fruits- apple
• Animals:-
 liver of sheep
 eggs
 Mutton
 Prawn
 milk

8. VITAMIN B3 (NIACIN/NICOTONIC ACID)
SOURCES:
 Liver
 Kidney
 Meat
 fish
 Legumes(pea,beans,lentil)
 Nuts
 Green vegetables
 Coffee
 Tea
 Synthesize from A. acid Tryptophan
RDA: 17-21 mg/day in adults

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Absorption & excretion
It is readily absorbed from stomach & intestine
It is stored in all the tissue’
Excretion – urine

10. Niacin equivalent
• The term (niacin equivalent, NE) is
used to express the combined values
of dietary sources of this vitamin and
that converted from dietary tryptophan
• 60 mg tryptophan = 1 mg niacin

11. • Daily recommended intake of niacin are
16 –18 mg for men ,and 13 – 15 mg for
women .
• Richest sources of niacin are yeast ,
liver , meats , & beans .

12. NIACIN
NAD+
and NADH are coenzymes of niacin:
A- NAD+
containing dehydrogenases are:
1. Isocitrate dehydrogenase of mitochondrial
origin.
2. Alcohol dehydrogenase
3. Lactate dehydrogenase
4. Malate dehydrogenase of citric acid cycle.
Malate Oxaloacetate

13. 5. Glyceraldehyde-3-P dehyrogenase of
glycolysis
6. Pyrurate dehydrogenase complex
7. α-ketoglutarate dehydrogenase of citric
acid cycle.
8. β-hydroxy fatty acyl-coA dehydrogenase of
β-oxidation of fatty acids

14. B- NADP+
containing dehydrogenases are:
1. Isocitrate dehydrogenase of extra
mitochondrial origin.
2. Glucose-6-phosphate dehydrogenase of
HMP-shunt

15. 3. β-ketoacyl reductase in the fatty acid
synthesis
4. HMG-CoA reductase in cholesterol
synthesis
HMG-CoA → Mevalonate

16. 5. Enoyl reductase of fatty acid synthase
complex

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Daily requirement
Men – 17mg
women – 13 mg
Pregnancy and lactation – 12 to15 mg .
Children – 15mg.

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FUNCTIONS
nervous system- it is important for proper
functioning of nervous system
blood vessels :- It dilates the blood vessel &
increases the flow of blood to the peripheral
capillary system
hormones - it is essential for production of
estrogen progesterone & testosterone

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DEFICIENCY
 its deficiency results in pellagra.
 it is called disease of 3 ds
DERMATITIS
DIARRHOEA
DEMENTIA
 skin - in acute cases, skin lesions may
produce vesiculation, cracking, exudation,
crusting with ulceration & secondary
infection
 Chronic cases – dermatitis occurs as
roughening & thickening of skin .

20. Pellagra

26. Pellagra

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Oral manifestation
Oral mucosa – becomes fiery red & painful &
salivation is profuse.
Tongue – epithelium of entire tongue is
desquamated.
The tongue becomes red swollen & beefy
In advanced cases, the tongue loses all the
papillae & reddening becomes intense.

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Management
Niacin 10mg or 10,000mcg per day
Vitamin B complex
Alcohol should be stopped

30. SUMMARY
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31. FUNCTIONS:
It has two active forms NAD+
,NADP+
serves as co-enzymes in various oxido-
reductive reactions in ETC
DEFICIENCY
 PELLEGRA (pelle-skin; agra- rough)
“3D” Disease: Dermatitis, Dementia, Diarrhoea
 Gingivitis and stomatis
 Achlorhydria
 Fatty liver
 Effect on plasma
lipids

32. IMPORTANCE OF NIACIN OR
VITAMIN B 3

33. Niacin (B3)
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