Daily consumption of Indian spinach (Basella alba) or sweet potatoes has a positive effect on total-body vitamin A stores in Bangladeshi men

Background: Recent evidence suggests that the vitamin A equivalency of [beta]-carotene from plant sources is lower than previously estimated. Objective: We assessed the effect of 60 d of daily supplementation with 750 [micro]g retinol equivalents (RE) of either cooked, pureed sweet potatoes; cooked, pureed Indian spinach (Basella alba); or synthetic sources of vitamin A or [beta]-carotene on total-body vitamin A stores in Bangladeshi men. Design: Total-body vitamin A stores in Bangladeshi men (n = 14/group) were estimated by using the deuterated-retinol-dilution technique before and after 60 d of supplementation with either 0 [micro]g RE/d (white vegetables) or 750 [micro]g RE/d as sweet potatoes, Indian spinach, retinyl palmitate, or [beta]-carotene (RE = 1 [micro]g retinol or 6 [micro]g [beta]-carotene) in addition to a low-vitamin A diet providing [approximately equal to] 200 [micro]g RE/d. Mean changes in vitamin A stores in the vegetable and [beta]-carotene groups were compared with the mean change in the retinyl palmitate group to estimate the relative equivalency of these vitamin A sources. Results: Overall geometric mean ([+ or -] SD) initial vitamin A stores were 0.108 [+ or -] 0.067 mmol. Relative to the low-vitamin A control group, the estimated mean changes in vitamin A stores were 0.029 mmol for sweet potato (P = 0.21), 0.041 mmol for Indian spinach (P = 0.033), 0.065 mmol for retinyl palmitate (P < 0.001), and 0.062 mmol for [beta]-carotene (P < 0.002). Vitamin A equivalency factors ([beta]-carotene:retinol, wt:wt) were estimated as [approximately equal to] 13:1 for sweet potato, [approximately equal to]10:1 for Indian spinach, and [approximately equal to]6:1 for synthetic [beta]-carotene. Conclusion: Daily consumption of cooked, pureed green leafy vegetables or sweet potatoes has a positive effect on vitamin A stores in populations at risk of vitamin A deficiency. Am J Clin Nutr 2004;80:705-14. KEY WORDS Deuterated retinol dilution, stable isotope, bioavailability, vitamin A status, [beta]-carotene, vitamin A stores, green leafy vegetables, sweet potatoes, Bangladesh