Citation
Loh, Su Peng
(2004)
Iron Bioavailability From Spirulina (Arthrospira Platensis) And Its Interactions With Other Dietary Factors In Vitro And In Vivo.
Doctoral thesis, Universiti Putra Malaysia.
Abstract
Deficiency of iron is common worldwide. Various approaches have been
used to improve iron intake and absorption. These include the use of
spirulina, a microalage that is already popular in many Asian countries as a
functional food supplement. The main objective of this study was to
determine the iron bioavailability from spirulina and its interactions with other
dietary factors both in vitro and in vivo.
In vitro digestion/Caco-2 cell culture system accompanied by either
centrifugation or dialysis step was used to assess the availability of iron from
spirulina. Using the centrifugation method, the cultured and commercial
spirulina yielded significantly higher results (P< 0.05) than then dialysis
method, both in the form of iron available for uptake and the actual amount
of iron being transported across the Caco-2 cells. The amount of available
iron and iron being transported from ferrous sulphate (FeS04) did not differ
significantly for both the dialysis and centrifugation method. The effects of different molar ratios of nutrients (calcium, ascorbic acid, zinc, tannic acid
and caffeine) to iron on the availability of iron from cultured spirulina differs
in comparison with FeS04. In the presence of lower concentrations of
calcium (1:5, 1:10, 1:15 and 1:20 Fe:Ca molar ratios), iron from spirulina
was not significantly inhibited compared to FeS04 but at higher
concentrations (1 :37.34, 1:74.67 and 1:149.34 Fe:Ca molar ratios) iron from
both spirulina and FeS04 was significantly inhibited. The availability of iron
from spirulina in the presence of ascorbic acid were not significantly
enhanced at all the molar ratios tested (1:0.5, 1:1, 1:1.5 and 1:2 Fe:AA
molar ratios) whereas iron availability from FeS04 were significantly higher
for all the molar ratios. Both zinc and tannic acid were more inhibiting on
iron availability from spirulina in comparison to FeS04. As for caffeine, it did
not show any significant inhibitory effects on both iron availability from
spirulina and FeS04. Two iron pools could coexist in the spirulina, one
containing organic iron and another comprising inorganic iron. Organic iron
is known to be more bioavailable and less affected by the presence of other
nutrients. This could be one of the explanations why the iron from this algae
is highly available and its bioavailability is not significantly affected by other
nutrients as in FeS04.
Haemoglobin repletion assay was used to further investigate the effect of
calcium on absorption of iron in spirulina and it comparison with FeS04. In
this study, haemoglobin and haematocrit levels of male Sprague-Dawley
rats fed both spirulina and FeS04 were found similar although the dose of
FeS04 used had twice the amount of iron compared to that in spirulina. The presence of calcium did not significantly reduced the haematological value in
rats fed spirulina and FeS04. The percentage of haemoglobin regeneration
efficiency (HRE) obtained was significantly higher in rats fed spirulina
compared with rats fed FeS04 indicated that the absorption efficiency were
better from iron in spirulina compared to iron in FeS04.
The distribution study of iron from spirulina and FeS04 in the presence of
calcium was done using iron deficient and iron normal male ICR mice fed
either spirulina or FeS04 tagged extrinsically with 59Fe. The amount of 59Fe
being absorbed by the iron deficient mice fed spirulina was comparable with
those fed FeS04 at 6 hand 24 h. However at 7 d, the FeS04 group showed
better absorption than the spirulina group. In the iron normal mice, a
significantly lower percentage of 59Fe was observed in mice fed spirulina
compared to mice fed FeS04 at 6 hand 24 h indicating that iron from
spirulina were not readily absorbed in iron normal states, which could
prevent iron overload and toxicity. The presence of calcium did not
significantly inhibit iron absorption in spirulina as shown in the in vitro study.
This study indicated that spirulina is a concentrated source of iron for both
supplementation and fortification. Iron from spirulina is highly bioavailable
and easily absorbed by the body especially in the iron deficient state.
Beside providing the necessary iron, it could also prevent iron overload and
toxicity in normal iron status and thus making spirulina suitable for both the
iron deficient and normal iron status.
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