All about Niacin. Starting from Ingestion to Excretion. Includes disorders also.

2. • Introduction.
• History.
• Chemistry.
• Co-enzyme forms.
• Synthesis, Absorption, Transportation, Excretion
• Sources
• Useful Functions, NAD & NADP dependent
enzymes.
• Recommended Daily allowance (RDA).
• Deficiency Manifestations and Causes.
• Hypervitaminosis

3. Niacin is a water- soluble
vit amin, also known as
vitamin B3.
Niacinamide is t he
active form of vit amin.

4. Warburg elucidat ed st ruct ure of
NAD+
and won noble pr ize in 1931.
Alexander Todd demonst rat ed
f unct ion of NAD+
and won noble prize
in 1957.
NAD+
was originally called as Co-
Enzyme-1.

5. Niacin is pyridine-3-carboxylic
acid. Niacinamide is t he acid
amide. I n NAD+
and NADP+
, t he
react ive sit e is t he 4t h
carbon
at om and t he nit rogen at om of
t he nicot inamide ring

6. There are t wo co-enzyme f orms of
niacin:
1. NAD+
- Nicot inamide adenine
dinucleot ide.
…continued

7. 2. NADP+
-Nicot inamide adenine
dinucleot ide phosphat e

8. The liver can synt hesize niacin f rom t he
essent ial amino acid t rypt ophan, requiring
60 mg of t rypt ophan t o make one mg of
niacin. Ribof lavin, vit amin B6 and iron are
required in some of t he react ions involved
in t he conversion of t rypt ophan t o NAD.

9. Absorpt ion of nicot inic acid and
nicot inamide f rom t he st omach and
t he int est ine is rapid and at low
concent rat ions is mediat ed by sodium
ion-dependent f acilit at ed dif f usion.
At higher concent rat ions, passive
dif f usion predominat es.

10. Nicot inamide is t ransport ed t o
t issues t o be used in synt hesis of
NAD when needed. Bot h f orms of
t he vit amin ent er cells by simple
dif f usion; however, bot h nicot inic
acid and nicot inamide also ent er
eryt hrocyt es by f acilit at ed
t ransport .

11. Excess niacin is met hylat ed in t he liver t o
N1
-met hyl-nicot inamide, which is excret ed
in t he urine along wit h t he 2- and 4-
pyridone oxidat ion product s of N1
-met hyl-
nicot inamide. The t wo maj or excret ion
product s are N1
-met hyl-nicot inamide and
it s pyridone derivat ive. The proport ions
dif f er somewhat depending on t he
amount and f orm of niacin ingest ed and
t he niacin st at us of t he individual.

12. Animal
products:
Chicken-
(6.5 mg)
beef (5 –
6 mg)
f ish (2.5 –
13 mg)
eggs
(0.1 mg)
Fruits and
vegetables:
Avocados (1 mg)
Dat es (2 mg)
Tomat oes (0.7 mg)
leaf veget ables (0.3
0.4 mg)
Broccoli (0.6 mg)
Carrot s (0.3 - 0.6 mg
Sweet pot at oes
(0.5mg)…continued

13. Ot her Sources:
Red Bull Energy Drink
(28 mg per 12 ounces)
Peanut but t er (15 mg)
Mushrooms (3.5 – 4 mg)
Soy sauce (0.4 mg)
nut s (2 mg)

14. •NIACIN THE CRAB CONVERTOR: A maj or
f unct ion is t hat it assist s ot her t ypes of B
vit amins in convert ing carbohydrat es t o glucose
(a source of energy f or t he body) and in
met abolizing f at s.
• One of t he most import ant f unct ion of niacin
is t hat it helps in maint aining good
cardiovascular healt h. I t can regulat e
cholest erol and serum t riglyceride
concent rat ions in syst em. I t can also increase…continued

15. •Niacin shows great pot ent ial in cure f or
Alzheimer’s disease.
•Healt hy eyesight can also be a benef it of
niacin
•NAD+
may also be added ont o cellular RNA as
a base modif icat ion t o f orm poly(ADP-ribose)
st ruct ure, which is involved in t he regulat ion
of several cellular event s and is most
import ant in t he cell nucleus, in processes
such as DNA repair and t elomere

16. •Lact at e dehydrogenase.
•Glyceraldehyde-3-phosphat e
dehydrogenase.
•Pyruvat e dehydrogenase.[Pyruvat e
Acet yl CoA]
•α ket oglut arat e dehydrogenase.
[alpha ket oglut arat e Succinyl
CoA]

17. •Glucose-6-Phosphat e dehydrogenase.
[Glucose-6-Phospaht e 6-Phospho-
glucono lact one].
•6-phospho gluconat e dehydrogenase.
[6-phospho gluconat e 3-ket o-6-
phospho gluconat e].
•Cyt oplasmic isocit rat e dehydrogenase.
•Malic [malat e pyruvat e]

18. Children: Adult s:
Lact at ing st age:
0-3mont hs-(3mg) Males: 19-50yrs-(17mg)
+2mg
1-3yrs-(8mg) Females: 19-50yrs(13mg)
7-10yrs(12mg)

19. Pellagra is a clinical condit ion caused by
def iciency of Niacin as well as
Trypt ophan. Pellagra means Rough Skin.
Pellagra is charact erized by a
photosensitive dermatitis. As t he condit ion
get s worse t here is dementia as
well as diarrhea. Unt reat ed pellagra is fatal.
Alt hough t he nut rit ional et iology
of pellagra is well est ablished, and t rypt ophan
or niacin prevent s or cures t he

20. A number of genet ic diseases t hat result in
def ect s of t rypt ophan met abolism are
associat ed wit h t he development of pellagra,
despit e an apparent ly adequat e int ake of bot h
t rypt ophan and niacin are:
• Hartnup Disease: Trypt ophan absorpt ion
f rom int est ine is def ect ive in t his congenit al
disease. Moreover, t rypt ophan is excret ed in
urine in large quant it ies. This leads t o lack of…continued

21. • Carcinoid Syndrome: The t umor ut ilises
maj or port ion of available t rypt ophan f or t he
synt hesis of serot onin, so t rypt ophan is
unavailable.
•Isoniazid (INH): I t is an ant it uberculous
drug, which inhibit s pyridoxal phosphat e
f ormat ion. Hence, t here is block in conversion
of t rypt ophan t o NAD+.

22. Nicot inic acid when given orally or
parent erally produces a t ransient
vasodilat at ion of t he cut aneous vessels
and Histamine release. The react ion is
accompanied by itching, burning, and
tingling. I nt ake of nicot inic acid in
excess of 50mg/ day may lead t o liver
damage.