QualPharma December 2020

MEDICAL
the data used to develop the current
RDA came from a small number of
subjects, with the use of hematocrit
and mean corpuscular volume
(MCV) values as the only endpoints,
and did not take into account that
many patients with vitamin B-12 deficiency
only develop neurologic
symptoms.
The RDA of vitamin B-12 for adults in the
United States is 2.4 µg/d. In Western
diets, the dietary intake of vitamin
B12 is usually higher than the current
RDA of 2.4 µg/d.
10% to 30% of adults older than 50 years
often have vitamin B12 malabsorption
syndromes, driving absorption rates as low
as 1% of the ingested B12. Thus, those
adults who meet the RDA of 2.4 µg/d
would need to ingest 240 μg of vitamin
B12 to absorb at least 2.4 μg.
In another study, it was observed that for
healthy adults between the ages of 18 and
50 years, a dietary vitamin B 12 intake of 4
–7 µg/d is associated with normal
vitamin B 12 status as judged from
measurements of cobalamin, holotranscobalamin,
tHcy, and MMA. Thus,
the current RDA of 2.4 µg vitamin B-
12/d may be inadequate for optimal
biomarker status.
Data from the 1999–2000 National Health
and Nutrition Examination Survey
(NHANES) indicate that the median daily
intake of vitamin B12 for the U.S. population
is 3.4 mcg.
Various studies have indicated losses of 0.1
to 0.2 per cent/day of the vitamin B12 pool
regardless of the size of the pool. A loss of
0.2 per cent appears to be typical for individuals
who do not reabsorb biliary vitamin
B12 because of pernicious anaemia. A
person with a vitamin B12 pool of 1,000 μg
and a loss of 0.1 per cent would excrete 1
μg of vitamin B12 daily, and a person with
a 3,000-μg pool would excrete 3 μg daily.
If only 50 per cent of dietary vitamin
B12 is absorbed, the amounts required
daily to replenish the pools
are 2 and 6 μg of B12, respectively.
Information from the Boston Nutritional
Status Survey on supplement use of vitamin
B12 by a free-living elderly population
mentions that for those taking supplements,
the fiftieth percentile of supplemental
vitamin B12 intake was 5.0 μg for
men and 6.0 μg for women.
In Indian Population: India is one of
the countries with the lowest RDA
for vitamins.
When it comes to India, as discussed
above, Indian population lacks vitamin
B12 fortified food items as well
as does not get enough vitamin B12
from their daily diet too. Hence, there
is an increased need for vitamin B12
supplementation with higher RDA in
Indian population.
Vitamin B12 deficiency in India is further
alarming because at the time when
there are suggestions to increase the
RDA of vitamin B12 in Western
countries… back here in India, the
current RDA set by ICMR for vitamin
B12 is only 1.0 µg/d which is far
lesser than the current western RDA
for vitamin B12!!!
Thus, the call of the day is to
revise the RDA levels.
Against the backdrop of the extent of vitamin
B12 deficiency in India, researchers
and manufacturers have urged Food Safety
and Standards Authority of India (FSSAI)
to revise the RDA values.
Tolerable Upper Levels (TUL)
No adverse effects have been associated
with excess vitamin B12 intake from food
or supplements in healthy individuals.
Studies involving periodic parenteral administration
of vitamin B12 (1 to 5 mg) to
patients with pernicious anaemia provide
supportive evidence for the lack of adverse
effects at high doses. As indicated earlier,
when high doses are given orally
only a small percentage of vitamin
B12 can be absorbed from the gastrointestinal
tract, which may
QualPharma *Dec 2020* , Vol.3 ISSUE 12