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OBJECTIVES |
To
study the absorption of beta carotene from Indian traditional vegetarian
meals differingin levels of fat, fibre and other dietary factors
.
To identify the prominent factors affecting the beta carotene absorption
in Indians and develop a model
Report of the work done : |
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OBJECTIVE
1 |
Experiments
using ileostomy subjects as model for micronutrient absorption
 |
From
Dr. Puntambekar’s clinic, 25 individuals with well-established
ileostomy have been listed who were likely to participate in the
study. Subjects taking radiotherapy or other medicines have been
excluded. In all, 11 subjects were observed for their intakes
and ileostomy fluids on adlibitum food intakes as described in
Table 1. In this trial, subjects were asked to take a night meal
and to give a sample equivalent to 50% of the ingested food for
analysis. The entire ileostomy fluid representing the meal was
collected in the next morning. The samples of both food and fluid
were brought to the laboratory for further analysis. Levels of
beta carotene and ascorbic acid in the meals and ileostomy bags
were estimated using spectrophotometry and those of riboflavin
and thiamine by photofluorometry and trace element analysis by
atomic absorption spectrophotometry. Tables 2 and 3 give the mean
and SD of the intakes, output and % absorption for the meals.
% absorptionof these four micronutrients have a coefficient of
variation around 10-20%. Chapati-based meals with inclusion of
papaya showed highest % absorption of beta carotene while sorghum
roti meal showed the lowest % absorption. |
The levels of five important trace elements in dried food and ileostomy
samples were assessed for all the subjects. Table 4 gives the levels
of trace elements in the meals (intake), ileostomy fluid (output) and
% absorption for this data. The range of % absorption for zinc, iron
and copper is comparable to the reported levels for soy protein-based
and high phytate diets.4
Present data showed associations of beta carotene absorption with intakes
of riboflavin (r=0.84, p = 0.018) and iron
(r=0.67, p = 0.1). Data on more number of subjects would be required
to confirm interactive effects of these factors on beta carotene absorption.
 
Area
under the curve of plasma beta carotene for two meals differing in beta
carotene sources
An alternative approach to study absorption of beta carotene is to study
area under the curve for plasma after feeding the experimental meals.
A small trial was undertaken to compare the absorption of commercial
beta carotene and water soluble vitamin supplements (meal 1) with food-based
beta carotene (meal 2). For this purpose eight young healthy volunteers
were observed in fasting condition and for 1,2,3,4 hours after the meal
for their plasma levels of beta carotene. They were informed about the
experimental protocol and written consent was taken before the experiment.
At each time point, 2 ml blood was drawn in EDTA coated bulbs and stored
at 4oC. Plasma levels of beta carotene were measured for all the samples.
The methods of estimation were as set in our laboratory during previous
studies. The composition of experimental meals
is given in Table 5. The mean levels of beta carotene at five
time points are shown in Fig. 1. The total increase of beta carotene
per unit intake of beta carotene were comparable in both the meals indicating
natural sources of beta carotene to be equally competent in bioavailability
of beta carotene.
 |
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OBJECTIVE
2 |
Validation
of in vitro model for beta carotene absorption |
During
the recent years, considering the practical difficulties in collecting
data on ileostomised patients, in vitro models are being set as an alternative
approach.1 This is based on in vitro stimulation of gastro-intestinal
digestion process and estimation of the available micronutrient from
the soluble/emulsifiable/dialyzable fraction or using in vitro uptakes
by everted/non-everted intestinal loops of either goat or pig or mice.
Earlier we have used in vitro models for estimation of iron and zinc
availability from a variety of Indian foods and meals.5,6
During the current report an attempt was made to develop and set the
in vitro model for assessment of beta carotene availability. The first
step was to validate the in vitro model using the ileostomy data as
true values. For this purpose, the meals consumed by the ileostomy subjects
(reported earlier) were prepared and subjected to GI tract digestion
(using pepsin-HCl treatment followed by bile acid (1.2 g) and pancreatin
(0.1 g) mixture in 20 ml of 0.1 M NaHCO3, made to pH 7 and volume 25
ml). The levels of beta carotene in total meal, water miscible fraction
was estimated. The in vitro uptake by everted intestinal loops was also
studied by incubating with gentle shaking for one hour. The estimates
were compared with the % absorption of the same meals as observed in
ileostomy subjects. The data though collected on small number of meals
shows a significant association (r-0.82, p < 0.01) for the % miscibility
and a weak association with % intestinal uptake (r=0.38). |
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Experiments
using in vitro model for beta carotene absorption |
Using this in vitro model, we have assessed the effect of different
types of oils consumed in India and also the effect of increasing the
level of oil on beta carotene availability. Miscible fraction of beta
carotene was estimated in presence of different oils; viz; sunflower,
gingely (til), safflower, groundnut, mustard and soyabean. This was
assessed using a meal made up of wheat chapati and fenugreek vegetable.
The levels of total beta carotene in the meal, miscible fraction were
estimated. The response to increasing levels of oil is shown in Fig.
2. It was seen that oils in general enhanced the miscibility of beta
carotene. The highest value for enhancement was for the soyabean oil.
Levels of beta carotene in the medium after in vitro intestinal uptake
were also estimated. The beta carotene uptakes were higher for sunflower
and safflower oils than the other oils
(Table 6).
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Beta
carotene bioavailability from green leafy vegetables using plasma responses
in young adults |
Indian traditional meals have a variety of foods which can be subdivided
into beta carotene rich, medium and poor sources based on their gross
contents.3 However, there are limited reports about the extent to which
it is bioavailability to humans. The levels of total and bioavailable
beta carotene are also likely to be affected by the dietary factors
like amount of oil used during cooking of the foods and due to interactive
effects of other micronutrients.
Among the several approaches for study of beta carotene availability,
study of long term plasma response after multiple doses of experimental
foods to achieve constant elevated level is of promise to estimate relative
bioavailability of different sources.2
The reported literature by NIN3 and our earlier data7 indicates GLV
to be the richest source of beta carotene. It was of interest to study
the efficacy of GLV’s improving the plasma beta carotene levels
through supplementation of GLV for 3 weeks. Secondly, we also wished
to study the effect of the amount of oil used in cooking and effect
of vitamin C and E supplementation on plasma responses.
A study was planned on a five groups of healthy men (5) and women (5)
in each group (18-45 years). They were observed for their status and
b-carotene, vitamin A, iron and other micronutrients through blood analysis
and habitual food intake information by 24 hour recall and food frequency
questionnaire (FFQ). After the initial period of 2 weeks for the baseline
observations, subjects were allocated to five groups such that the groups
have comparable weight and age. Study design was :
Group 1 : GLV with normal oil (100 g/day)
Group 2 : GLV (100 g/day) + oil (extra oil added in GLV : 5
g/100 g GLV/day)
Group 3 : GLV (100 g/day) + vitamin C (Celin tablets of 100
mg/day)
Group 4 : GLV (100 g/day) + vitamin E (tablets of 100 µg/day)
Control group : normal diet without GLV + Parry’s beta
carotene from spirulina (10 mg) thrice/week
Types of GLV : Fenugreek leaves (methi)/Amaranth g. tricolor
(lal math) / Amaranthus v. (chavlai) / Amaranathus p (rajgira) / Spinach
(Palak)
Common additive to the diet : Coriander/curry leaves/Mint (pudina)
Blood sample collection : at the start, without GLV for 2 weeks,
with GLV for 2 weeks. No history of chronic metabolic diseases like
diabetes, hypertension, obesity, absence of gynaecological problems
like excessive blood loss for women were the criteria for inclusion
of subjects in the study. All the subjects were observed for changes
in plasma levels of beta carotene, zinc, vitamin C and haemoglobin.
Participation in the study was voluntary with informed written consent
taken prior to the experiments.
Effect of green leafy vegetable (GLV) supplementation, and micronutrients
on plasma b-carotene levels (µg/dl) in 42 healthy individuals
is shown in Fig. 3. The relative bioavailability of beta-carotene from
GLV based meals is expressed as per cent of the bioavailability of beta
carotene tablets. It was seen that the addition of extra oil or vitamin
C and E enhanced the bioavailability.
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Highlights
of the results |
| • |
Chapati
based meals with inclusion of papaya showed highest % absorption
of beta carotene while sorghum roti meal
showed the lowest % absorption. |
| • |
In
vitro model for bioavailability of beta carotene was developed
and validated. |
| • |
Oils
in general enhanced the miscibility of beta carotene. The highest
value for enhancement was for the soyabean oil. |
| • |
The
in vitro beta carotene uptakes were higher for sunflower and
safflower oil than other oils. |
| • |
Bioavailability
of beta carotene from green leafy vegetables was increased with
addition of oil as well as antioxidant vitamins viz.; vitamin
C and E. |
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REFERENCES |
| 1 |
Southon
Bioavailability of carotenoids food and nutrition for better
health June 2001. |
| 2 |
Jackson
MJ, Fairweather - Tait SJ, Berg Henk van den, Cohn W. Assessment
of the bioavailability of micronutrients. Proceedings of ILSI
Europe Workshop. Eur J Clin Nutr 1997; 54 : Suppl, S70.. |
| 3 |
Gopalan
C, Ramasastri BV, Balasubramanian SG. Revised and updated by
Rao BSN, Deosthale YB, Pant KC. Nutritive value of Indian foods,
(Published by National Institute of Nutrition, Hyderabad, India),
2000. |
| 4 |
WHO
Trace elements in human nutrition and health, Geneva, 1996. |
| 5 |
Agte
VV, Khot S, Paknikar KM, Chiplonkar SA. Comparative performance
of pearl millet and sorghum based diets vs wheat and rice based
diets for trace metal bioavailability. J of Trace Elements in
Medicine and Biology 1999; 13 : 215-19. |
| 6 |
Agte
VV, Tarwadi KW, Chiplonkar SA. The influence of various food
ingredients and their combinations on in vitro availability
of iron and zinc in cereal-based vegetarian meals. In : Trace
Elements in Man and Animals 10,2000, Plenum Publishers, New
York, 261-66. |
| 7 |
Agte
VV, Tarwadi KV, Mengale SS, Chiplonkar SA. Potential of traditionally
cooked green leafy vegetables as natural sources for supplementation
of eight micronutrients in vegetarian diets. J Food Comp Analysis
2000; 13 : 885-91. |
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LIMITED
HAEMORRHOIDECTOMY IS THE MOST EFFECTIVE TREATMENT FOR INTRACTABLE
DISEASE
Haemorrhoidopexy is a new treatment that is less painful and
allows a shorter convalescence than open haemorrhoidectomy,
but it requires further long term evaluation. In their clinical
review, Nisar and Scholefield discuss the evidence comparing
these two procedures and explain conservative methods of managing
haemorrhoids. The traditional treatment for prolapsing haemorrhoids
not responding to band ligation has been formal haemorrhoidectomy,
but the authors say that current practice favours a limited
approach, conserving continence mechanisms and decreasing pain.
BMJ 2003; 327 : 847 |
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