Spirulina as a source of vitamin A.

Experiments were carried out to assess spirulina fusiformis-a blue green algae as a source of vitamin A in rats. In one experiment, the control rats were fed synthetic vitamin A and the experimental rats spirulina as the sole source of vitamin A. The liver vitamin A concentration of spirulina-fed rats of both sexes was found to be significantly higher than that of the control rats. In another experiment the absorption of carotenes from the solvent extract of spirulina and their availability (vitamin A value) as judged by the levels of vitamin A and carotene in plasma and liver were compared with those of synthetic beta-carotene or vitamin A in male rats. The absorption of beta-carotene from spirulina extract tended to be lower than that of crystalline beta-carotene at doses of 550 and 1100 micrograms of beta-carotene. The difference became insignificant at lower beta-carotene dose of 275 micrograms. Spirulina carotene-fed rats did not show a strict dose related increase in the liver or serum vitamin A concentration. The liver vitamin A storage and plasma levels of vitamin A of spirulina carotene-fed rats was much higher than expected. The results of the two studies reported suggest that the algae spirulina can be a valuable source of vitamin A.

In vitro availability of iron and zinc in white and coloured ragi (Eleusine coracana): role of tannin and phytate.

White and brown ragi (Eleusine coracana) varieties were analysed for tannin, phytate phosphorus, total phosphorus, iron, ionisable iron, zinc and soluble zinc content. White ragi had no detectable tannin while in brown varieties it ranged from 351 to 2392 mg per 100 g. Germination brought about a progressive decrease in tannin and phytate phosphorus and an increase in ionisable iron and soluble zinc content of grain ragi. Both in raw and germinated grain, ionizable iron was significantly higher in white than in brown varieties. While ionisable iron was inversely correlated with the level of tannin and phytate phosphorus, soluble zinc was negatively correlated with phytate phosphorus. After extraction of tannin, ionisable iron of brown ragi rose by 85%. On the other hand, in white varieties, addition of tannin extracted from brown ragi, resulted in a 52-65% decrease in ionisable iron content. These studies indicated that poor iron availability in ragi as judged by its low ionisable iron content was due to the presence of tannin in the grain.