Antioxidants are used in food to protect it from deleterious effects of oxidation and are also employed as dietary supplements to neutralize the adverse effects of oxidative stress. Many of the natural antioxidants of interest are of plant origin and belong to the phenolic and polyphenolic class of compounds as well as carotenoids and antioxidant vitamins, among others. The activity of antioxidants and their mechanism of action is dictated by the structural features of the molecules involved, the system in which they are present as well as processing and storage conditions, among others.

1. Assessment of Vitamin
Status and Antioxidants
Submitted by:
KOMAL OJHA
PH.D STUDENT

2. Assessment of vitamin A status
Liver vitamin A concentration
Serum Vitamin A
Conjunctival Impression cytology
Dark Adaptation test
Metabolic indicator
Functional tests
Breast milk retinol
Tear fluid retinol

3. Evaluation of Vitamin D Status
• The half – life of 25 – hydroxy vitamin D in plasma
is 3 to 7 weeks, and the plasma concentration of
this metabolite of vitamin D appears to be a reliable
indicator of the amount of vitamin D stored in the
liver. Thus, the plasma 25 – hydroxy vitamin D
concentration is a good indicator of overall vitamin
D status, and it is a nutritional biomarker of
vitamin D Sufficiency.
• Normal levels of 25 –hydroxy vitamin D for
infants is 10 – 40 ng / ml. In infants with rickets
the level is less than 9 ng / ml.

4. Evaluation of Vitamin E status
• Serum Vitamin E: Serum
level below 0.6 mg /dl suggest a
state of vitamin E deficiency
whereas levels above 3.5 mg / dl
may be associated with
symptoms of vitamin E toxicity.
• Erythrocyte haemolysis
test: Vitamin E offers
protection against the peroxide
induced erythrocyte membrane
damage responsible for
haemolysis. Hence the
resistance of erythrocytes to
haemolysis provides an indirect
but useful indication of vitamin
E status.

5. Evaluation of Vitamin K status
The measurement of
phylloquinone (K1) in serum is
the most commonly used
marker of vitamin K status and
reflects abundance of the
vitamin.
Concentrations <0.15 µg/L
are indicative of deficiency.

6. Evaluation of Thiamine Status
• Specific test to know the
deficiency of thiamine is the
measurement of transketolase
activity in the red blood
corpuscles with and without
the addition of TPP in vitro. If
TPP increases activity by more
than 25 per cent indicates
thiamine deficiency. Normal
individuals have an
erythrocyte transketalase
activity of 850 – 1000 µg
hexose / ml hydrolysate / hr.

7. Evaluation of Riboflavin Status
Riboflavin status is determined
by measuring the increase in
activity of the enzyme
glutathione reductase in red
blood cells in response to the
addition of FAD which is
required for the enzyme
activity. The activity of
glutathione reductase in red
blood cells of people with
normal riboflavin status rises
by less than 20 per cent in
response to the addition of
FAD. In riboflavin deficiency
an activation of more than 40
per cent is observed.

8. Evaluation of Niacin Status
Measurement of two urinary
metabolites, methyl –
carboxamido pyridone and
methyl nictoinamide and their
ratio have been used to
measure niacin status. Urinary
excretion of less than 0.8 mg /
day of methyl nicotinamide is
indicative of niacin deficiency.
A ratio of less than 1 suggests
latent niacin deficiency.
Clinical symptoms, however,
do not appear until the
pyridone has been absent from
the urine for several weeks.

9. Evaluation of Folate Status
The following criteria are used
to evaluate folate status
provided there is no vitamin
B12 deficiency.
 Positive megaloblatic anaemia
 Plasma Folates < 3 ng / ml
 Red Blood Cell folate < 160 ng
/ ml
 Elevated formimino glutamic
acid (FIGLU) excretion after
histidine load.
 Elevated plasma homocysteine

10. Evaluation of Vitamin B 6 Status
Methods for assessment of
vitamin B6 status include
measurement of urinary
pyridoxic acid, blood pyridoxal
phosphate levels, in vitro
activation of erythrocyte
aspartate amino transferase or
alamine amino transferase
with pyridoxal phosphate and
urinary excretion of
xanthurenic acid after oral
load of tryptophan. Plasma
pyridoxal phosphate is the best
indicator as it reflects tissue
stores.

11. Evaluation of Vitamin C status
Measurements of vitamin C
levels in blood plasma is a
poor indicator of ascorbic acid
status. Concentration of the
vitamin in circulating
leukocytes is currently used to
evaluate vitamin C status in
humans.

30. How antioxidant works

31. Antioxidant and ageing

34. Antioxidants and Metabolic Disorders

36. Antioxidant action in our body

40. https://nutritionfacts.org/video/food-antioxidants-
and-cancer/