J. Natn. Sci. Coun. S n Lanka 1985 13(2) : 187-196 VITAMIN A ANJl 0 -CAROTENE CONTENT OF SOME COMMON FOODS T. M . S. ATUKORALA Depamnent of l iocbemis ty , Faculsy of Medicine, Unbersity of Colombo, Colombo 8, Sri Lanka. (Date of receipt : 07 Mmch 1985) (Date of acceptance : 08 January 1986) Absamct I The content of vitamin A and its precursor, fl-carotene was determined in some commonly available foods in Sri Lanka. The edible pomon of the uncooked food samples werc used for analysis. The concentrations of vitamin A and O-carotene were determined by fluorescence and absorbance specuophotornetty by esrabliied metbods. Fish and ox liwr were the richest sources of vitamin A. The viramin A content in other animal foods except eggs and milk, was not sufficient to make a significant contribution to the daily vitamin A inrake in a Sri Lankan diet. The 0 -carotene content of dark green leafy vegetables ranged from 61.0 - 99.5 wg and wss two to three times higher than that of other wptables and fruits. A major roportion of the daily dietary requirement of vitamin A could be obtained as -caromtae from green leafy vegetables. 1. Introduction Vitamin A is required for growth, reproduction, vision and maintenance of the integrity of epithelial tissues. Its deficiency in the early stages leads to night bhdness and xerophthalmia, which may ultimately progress to blind- ness, if ~ n t r e a t e d . ~ ? ~ Deficiency of vitamin A is mainly due to inadequate dietary intake of the vitamin or its precursor, 0 -carotene. Therefore, it is of utmost importance to identify good sources of vitamin A and P -carotene among the foods commonly available in Sri Lanka. In fact, the identification of dietary sources of vitamin A, is listed as a research priority in the latest report published by the WHO expert committee on vitamin A deficiency.7 The onlyidata available at present is based on analyses carried out in 1ndia3 and on prCGminary studies by Atukorala et al.' in Sri Lanka. In this ,study, analyses for vitamin A and 6 -carotene have been carried out on some commonly available foods in Sri Lanka. 2. Methods 2.1 Sampling: The food samples were purchased from three different areas of Colombo to obtain a mean value for the foods commonly sold in Colombo. A weighed amount (0.2 - 0.5 g) of the edible portion of the raw, uncooked food was used for analysis. When analyses were carried out on plant foods, specimens (for replicate estimations) were taken from different leaves selected at random. Three different randomly seIected samples of each food item were malysed and the mean +- SEM taken. 2.2 The concentration of Vitamin A was determined b a modification of the fluorometric method of Thompson and co-workers Alcoholic KOH (30%) was used for saponification instead of (60%) aqueous KOH and the saponification time was increased to 3 0 minutes. Vitamin A was selectively extracted into hexane and the fluorescence was measured against a blank using a Perkin-Elmer LS3 fluorescence spectrophotorneter. Each sample of food was analysed in triplicate. Retinyl acetate (Sigma, U.S.A.) was used to prepare a standard solution. Vitamin A derivatives being labile compounds, the absorbance of the diluted standard was checked prior to use. The standard solutions were processed in the same manner as the food samples. The mean percentage recovery was 98.71 +- 1.30. 2.3 The concentration of 0 -carotene was detennhed by a spectrophoto- metric method. f 4 A standard solution was prepared by dissoIving all trans P -carotene (Sigma, U.S.A.) in absolute ethanol (Reiden de Haen, Germany). This stock solution ( I rnglrnl) was prepared every two weeks and stored in the dark at 4OC. Carotenoids were extracted into petroleum ether after saponification of food samples. The petroleum ether extract was washed twice with 9% methanol to remove x a n t h ~ ~ h ~ ~ s . ~ Its optical density was measured at 450 nm using a SP 6 - 450 UV visible spectrophotometer. Each estimation was carried out in duplicate. The mean percentage recovery was 97.5 k 2.1 0. 2.4 Statistical significance was assessed using the Student's t test. 3. Results and Discussion The vitamin A content 6E flesh foods is given in Table I. Both fish and ox liver had more vitamin A than meat or fish. Fish liver had the highest amount of vitamin A (95.03 * 17.79 pg/g) with slightly lower amounts in ox liver, but the differknce was not significant. The amount of vitamin A in chicken was significantly higher (p < 0.001 ) than that of other meats. Vitanzin A and fl -carotene content of some common foods 189 Table 1 Vitamin A content o f flesh foods Food Vitamin A (PgIg) Mean SEM Meat Beef, muscle Chicken, muscle Mutton, muscle Pork, muscle (lean) Fish Seer (Scomber sp . ) * Para (Carangids) * Kelawalla (Euthynnus sp.)* Thalapath (Istiophonis gladius)* Hurulla (Saydinella sirus) * Salay a (SawdineIla jussieu) Prawns Liver Ox liver Fish liver (Para) 0.404 0.338 trace 0 . 1 1 5 1 .413 1.395 1.196 Each value is rhe mean of 3 sampIes. The edihlc pottion of large fish usithour skin v.,r.ls used I ' tv :111:1lysis. Table 2. 0-Carotene and vitamin A content of Eggs and Milk Food j3-Carotene Vitamin A Mean SEM Mean SEM Egg, Hen @g/100 g) 3 64 72 195 2 3 Cow's milk (pg/100 ml) Pasteurised, bortled Pasteurised, packeted Sterilised, bottled Fresh, unboiled 71.0 12.5 52.2 18.5 115 17.0 60 14.9 trace - 40.5 7.2 120 8.6 87.6 19.6 Each value is rhe mean of 3 samples. Table 3. 0-Carotene content of cereals, starchy roots and pulses. Food B-carotene Wglg) Mean SEM Cereals Rice, parboiled Rice, Raw, milled Wheat flour Starchy roots* Potato (Solanum tuberosum) Sweet pocato (Zpomea batatas) 2.31 0.47 la nala (Coleus rotundifolius) 0.232 0.081. Kiriala (Habarala) (Colacasia esculenta ) 0.199 0.035 Pulses Mysoor Dhal (Cajanus cajan) 12.90 3.4 Cow pea (Vigna unguiculata) 2.50 . 0.31 Mung (Green gram) Pbaseolus aureus 7.22 0.52 - Each value is the mean of 3 samples. ' Starchy roots without peel were used for analysis. Vitamin A and 0 -carotene content ofsome co~nmon foods 191 Of the different varieties of fish studied, small fish .(Hurulla and Sdaya) had a significantly higher (P < 0.01) amount of vitamin A than large fish (Table 1). The B -carotene and vitamin A content of eggs and milk is given in Table 2. Eggs provide a rich source of both P -carotene (364 L 72 pg/100g) and vitamin A (195 * 23 pgJ100g). Fresh, unboiled cow's milk had the highest amount of 0 -carotene with sfghtly lower amounts in packeted pasteurised milk and significantly (p < 0.05) lower amounts in bottled pasteurised and ste&ed milk. Vitamin A content of milk also showed a simiIar variation, but the difference was not significant. Rice showed no detectable amounts of B -carotene, while wheat flour contained only traces (Table 3). Of the starchy roots studied, potato and sweet potato had a higher content (p < 0.01) of S -carotene than other starchy roots. The 0 -carotene content in pulses was higher than that in cereals or starchy roots, with Mysoor dhal and green gram having signifi- cantly (p < 0.05) higher amounts than cowpea. The f l -carotene content of vegetables anaIysed is given in Table 4. Dark green leafy vegetables had a significantly higher (p < 0.02) amounts of p -carotene compared to other vegetables except carrots. Moderate amounts of 0 -carotene were observed in spring onions, Iceks and legumes with levels decreasing in that order. Of the vegetable fruits studied, pumpkin had the most fl -carotene (Table 5). Coconut contained only traces of 0 -carotene. Among fruits, signifi- cantly higher (p < 0.001) amounts of fl -carotene were found in mango and papaw, with mango of the Karthakolumban variety having the highest amount (Table 6). 4. Conclusions The results obtained in the study are comparable to a similar study carried out on Indian foods3 The food sampIes were malysed in the fresh state as purchased and the effect of cooking or processing on the vitamin A and P -carotene content was not studied. Both fish and ox liver were rich sources of p~eformed vitamin A. Meat and fish, with a low content of vitamin A (0,2 - 2 p g l g ) do not make a signi- ficant contribution to the vitamin A supply in an average Sri Lankan diet. Eggs and milk form a richer source of preformed vitamin A and 0 -carotene. Table 4. 8-Carotene content of vegetables. 0-Carotene OlgJg) Mean SBM Dark-Green leafy vegetables M u k u n u w e ~ a (Alternantbera sessitis) Kankun (Ipomea aquatics) Gotukola (Centella asiatica) Kathurumurunga (Sesbania grandiflora) Spinach (Basella alba) Sarana (Sesuzkvm portulacastw m ) Other vegetables Leeks (Allium p o m m ) Cabbages (Brassica oleracea) Carrots* (Daucus carota) Spring onions (Allium cepa) Legumes Beans (Phaseolus vulgaris) . 18.60 0.99 Winged Beans (Pbaseolrrs lunatus) 17.69 1.05 String Beans Wignu cylindrica) 7.59 0.03 Each value is the mean of 3 samples. *Food withour peel was used for analysis. Vitamin A and p -carotene content ofsovie contmcrn foods Table 5. 0-Carotene content of vegetable fruits &-Carotene Food Mean SEM Vegetable fruits Brinjals (Solanurn melong&a) Pumpkinv (Cucurbita mixima) Snake gourd (Trichosanthes a~rguina) Bitter gourd (Mormordia charantia) Ladies fingers (Hibiscus esculenteus) Ribbed gourd (Luffa acutanpla) Each value is the mean of 3 samples. The edible pan of each food was used for analysis. *Food without peel was used for analysis. Table 6. &-Carotene content of fruits Food fl- Carotene W g ) Mean SEM Coconut (Cocos nucifem) rrace Orange (Citrus sinensis) Plantains (Ambul variety) - Musa sapienturn Plantains (Kolikuttu variety) - Musa sapientam Pineapple (Ananas comosus) Papaw CCan'ca papaya) Mango (Mangifera Indica) Mango (Kartbak olum ban vaarietyj- Mangifera Itldica ~uavas? (Psidistm guajrwa) Ripe Jak h i t (Artocarpus heterophyllus) Each value is the mean of 3 samples. The edible portion of each fruit without skin or seeds wasused for analysis. * The fruit was used with skm. Vitamin A and p -carotene content of some common foods 195 Most of the cornmonly available plant foods showed significant amounts of f l -carotene. The dark green leafy vegetables analysed (e.g Mukunuwenna, Gotukola) had a two to. three times higher content of 0 -carotene compared with other vegetables, and therefore constitute a very important dietary source, although the biological activity of 0 -carotene per unit weight is lower than that of vitamin A ( 1 International unit of vitamin A = 0.3 ~g vitamin A or 0.6 ~g 0 -carotene2). Other vegetables (carrots, leeks, spring onions and le