Ann Nutr Metab 1990:34:32-36
© I990S. Karger A G . Basel 0250-6807/90/034I-0032S2.75/0
Effect of Ascorbic Acid Supplementation on Haematological Response and Ascorbic Acid Status of Young Female Adults Olufunmike Alalade Ajayi, Ugochi R. Nnaji Department of Human Nutrition, College o f Medicine, University o f Ibadan. Nigeria
Key Words. Ascorbic acid supplementation • Haematological response • Leucocyte ascorbate • Young female adults
Introduction The unique role o f ascorbic acid (AA, vitamin C) in intermediary metabolism is well established [1], It is evident that A A is also involved in oxidation reduction pro cesses. maintenance o f tissue integrity, wound healing, collagen and D N A synthesis [2], AA also plays a dual role in haemopoie sis by enhancing iron absorption [3, 4] and by maintaining folic acid (a haemopoietic
factor) in the reduced form [ 1]. Existing data indicate that vitamin C deficiency may pre cipitate microcytic hypochromic anaemia [1]. Seshadri et al. [5] reported improved haematological response in anaemic chil dren given A A supplementation. Although AA supplementation improves AA and iron status, the amount needed to elicit response has not been defined. The susceptibility of infants and women of reproductive age to anaemia which may
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Abstract. Haematological response and ascorbic acid (AA) status were evaluated in 32 young adult females (age 20-34 years) 8 weeks after supplementation with two levels o f A A (50 and 100 mg). Both levels o f AA intake produced a similar response marked by significant elevation (p < 0 .0 1 ) in Hb concentration, Hct level. R B C count, serum and leucocyte ascor bate concentrations. Ten weeks after withdrawal o f the supplements, values for all parame ters evaluated decreased significantly (p < 0.01) to prcsupplementation levels. Haemoglobin concentration and leucocyte ascorbate remained relatively higher (p < 0.01) than initial values in subjects who received 100 mg A A . This study showed that AA supplementation improved erythropoietic activity and AA status of our female population. However, the higher dose o f AA (100 mg) sustained Hb concentration and tissue ascorbate longer after withdrawal o f supplementation.
Ascorbic Acid Status of Nigerians
Materials and Methods Experimental Design Thirty-two apparently healthy female volunteers, aged 20-34 years, drawn from school o f Nursing, Eleyele and University o f Ibadan, participated in the study. The subjects were randomly divided into three groups. Subjects in group A received a daily dietary supplement o f 100 mg A A . group B subjects received 50 mg AA while group C subjects served as the con trol (unsupplemented). Venous blood (10 ml) was col lected from each subject before (presupplementation), after 8 weeks o f supplementation and 10 weeks after withdrawal o f the supplement. An aliquot (2 ml) of blood collected in bottles containing ED TA as anti coagulant was used for haemoglobin (Hb) and haematocrit (Hct) determination, using standard methods. Erythrocyte concentration was counted manually and independently by trained technicians after diluting the blood with formalin-trisodium citrate solution [6]. Blood for white cell count was diluted with aqueous solution o f acetic acid-gentian violet and counted. Serum extracted from coagulated blood was sta bilised with 5 % T CA and stored frozen until analysed for serum ascorbate [7], Leucocyte ascorbate was de termined by a modified procedure o f Denson and Bowers [7], The modification consisted o f increasing the incubation temperature from 37 to 60 °C . Incuba tion time was also reduced from 4 to I It. The diluent solution utilised for leucocyte ascorbate contained 2,000 ml physiological saline. 50 ml of 60% dextran and 20 ml of 10% sequeslrene. All data were expressed as means ± SD . Student's t test was used for comparison between the groups. Paired t test was used to compare haematological and A A levels before and after supplementation. Correla tion between various parameters was calculated to indicate metabolic interrelationships.
Results The relative changes in haematological measurement and A A status after supple mentation with 2 doses of A A (50 and 100 mg) are presented in table 1. Only 22 of the 32 subjects who started the study com pleted it. For all parameters evaluated, pre supplementation values were similar for all groups. Eight weeks' supplementation pro duced a significant (p < 0.01) elevation in Hb, Hct and erythrocyte (RBC) count. The mean increase in Hb and R B C was similar for supplemented subjects, being 17.9 versus 18.4 g/1, and 0.34 versus 0.42 X 10 12/1 for the subjects who received 50 and 100 mg A A , respectively. Four subjects who initially had a low Hb concentration showed a mean rise of 20.8 ± 3.2 g/1 (from I 14.8 ± 3.2 to 135.5 ± 6.4 g/1) after A A supplementation. Ten weeks after the withdrawal o f supple ments, Hct value and R B C count decreased significantly (p < 0.02) to values slightly higher than presupplementation levels. However, Hb concentration remained signif icantly higher (p < 0.05) than initial (pre supplementation) values for subjects who re ceived a higher A A intake (100 mg AA). Both serum and leucocyte ascorbate in creased significantly (p < 0.01) after supple mentation with either 50 or 100 mg AA. On withdrawal of supplements, serum ascorbate decreased significantly (p < 0.01) to presup plementation level for both groups. On the other hand, leucocyte ascorbate was consis tently higher (p < 0.025) than initial values (presupplementation) in subjects who re ceived a daily dietary supplement o f 100 mg A A . Serum ascorbate correlated significantly with leucocyte ascorbate only in subjects who received a higher vitamin dose (r = 0.8794. p < 0.002).
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coexist with AA deficiency necessitated this study aimed at assessing the haematological response to AA supplementation in young adult women. The changes in A A status sub sequent to supplementation or withdrawal will also be evaluated.
33
Ajayi/Nnaji
34
Table 1. Haematologic and AA status o f AA-supplemented subjects AA supplement
Hb. g/l
1
Hct, %
2
3
1
R B C count X 10'-/l
2
3
1
2
3
100 mg AA (n = 9)
126.9 ±11.2
146.5 ±11.1
139.8 ±11.6
40.1 ±2.9
44.8 ±1.9
40.8 ±2.8
4.5 ±0.4
5.6 ±0.5
5.0 ±0.8
50 mg AA (n = 7)
125.0 ±9.8
142.9 ±8.9
134.3 ±6.8
38.9 ±2.3
43.2 ±1.7
39.9 ± 2.8
4.4 ±0.4
5.3 ±0.2
4.7 ±0.5
None (control) (n = 6)
126.3 ±6.9
122.0 ±5.9
123.5 ±6.3
39.0 ±2.4
37.2 ±2.8
38.0 ± 3.0
4.3 ±0.6
4.1 ±0.3
4.2 ± 0.5
Discussion Biochemical data obtained from the present study indicate that the A A status of the subjects was within acceptable range [8], The mean basal AA value (6.1 ± 0.6 mg/1) obtained for these subjects was lower than mean values observed for a similar age group [Ajayi, unpubl. observation], A criti cal evaluation of data available on the AA status o f Nigerians suggests that the AA sta tus of most population groups has declined considerably in recent times. Keshinro [9] observed that high A A losses accompanied cooking o f vegetables in Nigeria. Hence fruit constitutes the major source o f A A in the diet, and the poor A A status o f Nigerians may be due to low consumption o f fruit. The desirable AA status observed for these subjects may not be unconnected with ade quate exposure to improved dietary habits and nutrition information since the subjects
were predominantly nurses and university students. This study also demonstrates that short term supplementation with A A improved erythropoietic activity. The dramatic in crease in haematological values after A A supplementation (50 or 100 mg daily) is con sistent with the reports of other investigators [5, 10], Layrisse et al. [11] earlier demon strated that AA facilitates iron utilisation and Smith [10] also indicated that iron ab sorption is enhanced in the presence o f AA. The mobilization of certain haemopoietic factors into erylhroid marrow for Hb synthe sis is also AA-dependent [1], The present study was undertaken at a time when green vegetables which are good sources o f folic acid were abundant. The improved ervthropoiesis observed in the AA-supplemented group may be ascribed in part to the mobili zation and utilization o f iron and folic acid consequent to A A availability. Studies in
Downloaded by: Thomas Jefferson University Scott Library 147.140.27.100 - 8/23/2018 8:29:36 AM
Values are means ± SD , 1 = Basal value before supplementation: 2 = after 8 weeks o f supplementation: 3 = 1 0 weeks after supplementation was withdraw n.
Ascorbic Acid Status o f Nigerians
Serum ascorbate, mg/l
1
2
3
1
6.2 ±1.7
6.0 ±1.3
5.9 ± 2.0
6.13 ±0.5
6.3 ±1.8
6.2 ±2.0
6.1 ± 1.5
5.80 ±0.9
6.1 ±1.4
6.3 ±1.8
6.5 ± 1.5
6.27 ± 1.1
Leucocyte ascorbate pg/IOs cells 3
1
2
3
5.18 ±0.5
25.6 ± 10.4
66.4 ±12.7
38.5 ±10.1
8.31 ±2.2
5.0 ±0.4
28.3 ± 10.5
53.3 ± 10.7
31.4 ± 6.4
5.22 ±0.7
5.20 ±0.5
23.3 ±7.7
28.0 ±9.8
27.3 ±6.1
2 10.13 ±2.8
anaemic children have demonstrated the beneficial effect of iron-folic acid supple mentation on Hb concentration [12]. Other investigators [13] have indicated that AA supplementation maintained rather than enhanced erythropoiesis in nonanaemic populations. However, data from this study have shown that AA supplementa tion was beneficial to all subjects whether they had low or acceptable haemoglobin ini tially. Nevertheless, the increment in Hb concentration after supplementation was slightly higher for subjects with initially low Hb ( < 120 g/1). The observed improvement in AA status subsequent to supplementation is in agreement with previous findings [2]. It is evident that plasma and leucocyte ascorbate concentrations are reliable indices in assessing A A status [1]. The significant association between plasma and leucocyte AA in the present study confirms the well established metabolic shuttle existing be
tween plasma and tissue ascorbate [14], The data from this study further indicate that tis sue saturation of AA can be maintained on a daily supplement of 50 mg AA . However, raising the daily dose to 100 mg sustained Hb concentration and tissue ascorbate for a long er period after withdrawal of supplement. In essence, a daily dietary A A intake be low 50 mg may not adequately meet physio logical demands especially in an environ ment where chronic infection is common. Hence, the presently adopted recommended dietary allowance of 30 mg for A A [ 15] mayneed re-evaluation. A comparative study is therefore needed to ascertain A A needs of both rural and urban population in Nigeria.
Acknowledgement The authors extend deep appreciation to the staff o f Eleyele School o f Nursing and to all the students who participated to the study.
Downloaded by: Thomas Jefferson University Scott Library 147.140.27.100 - 8/23/2018 8:29:36 AM
Leucocytes X I09/I
35
Ajayi/Nnaji
.36
1 Schorah C J: The level o f vitamin C reserve re quired in man: Towards a solution to the contro versy. Proc Nutr Soc 1981:40:147-154. 2 Ludvigson J. Hansson L O . Stendhal O: The effect of large doses of vitamin C on leucocyte function and some laboratory parameters. Int J Vitam Nutr Res 1979:49:161-165. 3 Roeser HP, Halliday JW , Sizemore D J, et al: Serum ferritin in ascorbic acid deficiency. Br J Haematol 1980:45:457-466. 4 Roeser HP: The role o f ascorbic acid in the turn over of storage iron. Semin Haematol 1983:2:91-
.
100
5 Seshadri S, Shah A, Bhade S: Haematologic re sponse o f anaemic preschool children to ascorbic acid supplementation. Hum Nutr Appl Nutr 1985;39A: 151 —154. 6 Dacie JK . Lewis SM : Practical Haematology. Edinburgh, Churchill Livingstone. 1984. pp 2834. 7 Denson K.W. Bowers EF: Determinations o f as corbic acid in the white blood cells. Clin Sci 1961: 21:157-162. 8 International Research National Institute of Health: Nutrition Survey: Republic o f Nigeria. Washington. United States Department o f Health Education and Welfare. 1967. 9 Keshinro O O : The effect o f cooking on the ascor bic acid content o f some Nigerian foodstuffs and their contribution to vitamin C status o f the con sumers: PhD thesis Ibadan (1980)
10 Smith R: Ascorbic acid: More than just a vitamin. Food Sci Ncwslett 1986:12:1-6. 11 Layrisse M, Martinez-Torres C . Gonzales M: Measurement o f the daily dietary iron absorption by the extrinsic tag model. Am J Clin Nutr 1974: 27:152-162. 12 Seshadri S. Hirode K , Naik P. et al: An effective intervention to reduce the prevalence o f anaemia in children, lnd J Med Res 1984:80:164—173. 13 Suboticanec-Buzina K . Buzina R. Brubacher G . et al: Vitamin C status and physical working capac ity in adolescents. Int J Vitam Nutr Res 1984:54: 55-60. 14 Loh HS. Wilson CW : Relationship between leuco cyte and plasma ascorbic acid concentrations. Br Med J 1971 :ii:733—735. 15 Passmore R: Handbook on Human Nutritional Requirements. W H O Monograph Ser. No 61. ed 6. Rome. World Health Organization, 1974.
Received: March 20, 1989 Accepted: July 25. 1989 Olufunmike Alalade Ajayi Department o f Human Nutrition College o f Medicine University o f Ibadan Ibadan (Nigeria)
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References
© I990S. Karger A G . Basel 0250-6807/90/034I-0032S2.75/0
Effect of Ascorbic Acid Supplementation on Haematological Response and Ascorbic Acid Status of Young Female Adults Olufunmike Alalade Ajayi, Ugochi R. Nnaji Department of Human Nutrition, College o f Medicine, University o f Ibadan. Nigeria
Key Words. Ascorbic acid supplementation • Haematological response • Leucocyte ascorbate • Young female adults
Introduction The unique role o f ascorbic acid (AA, vitamin C) in intermediary metabolism is well established [1], It is evident that A A is also involved in oxidation reduction pro cesses. maintenance o f tissue integrity, wound healing, collagen and D N A synthesis [2], AA also plays a dual role in haemopoie sis by enhancing iron absorption [3, 4] and by maintaining folic acid (a haemopoietic
factor) in the reduced form [ 1]. Existing data indicate that vitamin C deficiency may pre cipitate microcytic hypochromic anaemia [1]. Seshadri et al. [5] reported improved haematological response in anaemic chil dren given A A supplementation. Although AA supplementation improves AA and iron status, the amount needed to elicit response has not been defined. The susceptibility of infants and women of reproductive age to anaemia which may
Downloaded by: Thomas Jefferson University Scott Library 147.140.27.100 - 8/23/2018 8:29:36 AM
Abstract. Haematological response and ascorbic acid (AA) status were evaluated in 32 young adult females (age 20-34 years) 8 weeks after supplementation with two levels o f A A (50 and 100 mg). Both levels o f AA intake produced a similar response marked by significant elevation (p < 0 .0 1 ) in Hb concentration, Hct level. R B C count, serum and leucocyte ascor bate concentrations. Ten weeks after withdrawal o f the supplements, values for all parame ters evaluated decreased significantly (p < 0.01) to prcsupplementation levels. Haemoglobin concentration and leucocyte ascorbate remained relatively higher (p < 0.01) than initial values in subjects who received 100 mg A A . This study showed that AA supplementation improved erythropoietic activity and AA status of our female population. However, the higher dose o f AA (100 mg) sustained Hb concentration and tissue ascorbate longer after withdrawal o f supplementation.
Ascorbic Acid Status of Nigerians
Materials and Methods Experimental Design Thirty-two apparently healthy female volunteers, aged 20-34 years, drawn from school o f Nursing, Eleyele and University o f Ibadan, participated in the study. The subjects were randomly divided into three groups. Subjects in group A received a daily dietary supplement o f 100 mg A A . group B subjects received 50 mg AA while group C subjects served as the con trol (unsupplemented). Venous blood (10 ml) was col lected from each subject before (presupplementation), after 8 weeks o f supplementation and 10 weeks after withdrawal o f the supplement. An aliquot (2 ml) of blood collected in bottles containing ED TA as anti coagulant was used for haemoglobin (Hb) and haematocrit (Hct) determination, using standard methods. Erythrocyte concentration was counted manually and independently by trained technicians after diluting the blood with formalin-trisodium citrate solution [6]. Blood for white cell count was diluted with aqueous solution o f acetic acid-gentian violet and counted. Serum extracted from coagulated blood was sta bilised with 5 % T CA and stored frozen until analysed for serum ascorbate [7], Leucocyte ascorbate was de termined by a modified procedure o f Denson and Bowers [7], The modification consisted o f increasing the incubation temperature from 37 to 60 °C . Incuba tion time was also reduced from 4 to I It. The diluent solution utilised for leucocyte ascorbate contained 2,000 ml physiological saline. 50 ml of 60% dextran and 20 ml of 10% sequeslrene. All data were expressed as means ± SD . Student's t test was used for comparison between the groups. Paired t test was used to compare haematological and A A levels before and after supplementation. Correla tion between various parameters was calculated to indicate metabolic interrelationships.
Results The relative changes in haematological measurement and A A status after supple mentation with 2 doses of A A (50 and 100 mg) are presented in table 1. Only 22 of the 32 subjects who started the study com pleted it. For all parameters evaluated, pre supplementation values were similar for all groups. Eight weeks' supplementation pro duced a significant (p < 0.01) elevation in Hb, Hct and erythrocyte (RBC) count. The mean increase in Hb and R B C was similar for supplemented subjects, being 17.9 versus 18.4 g/1, and 0.34 versus 0.42 X 10 12/1 for the subjects who received 50 and 100 mg A A , respectively. Four subjects who initially had a low Hb concentration showed a mean rise of 20.8 ± 3.2 g/1 (from I 14.8 ± 3.2 to 135.5 ± 6.4 g/1) after A A supplementation. Ten weeks after the withdrawal o f supple ments, Hct value and R B C count decreased significantly (p < 0.02) to values slightly higher than presupplementation levels. However, Hb concentration remained signif icantly higher (p < 0.05) than initial (pre supplementation) values for subjects who re ceived a higher A A intake (100 mg AA). Both serum and leucocyte ascorbate in creased significantly (p < 0.01) after supple mentation with either 50 or 100 mg AA. On withdrawal of supplements, serum ascorbate decreased significantly (p < 0.01) to presup plementation level for both groups. On the other hand, leucocyte ascorbate was consis tently higher (p < 0.025) than initial values (presupplementation) in subjects who re ceived a daily dietary supplement o f 100 mg A A . Serum ascorbate correlated significantly with leucocyte ascorbate only in subjects who received a higher vitamin dose (r = 0.8794. p < 0.002).
Downloaded by: Thomas Jefferson University Scott Library 147.140.27.100 - 8/23/2018 8:29:36 AM
coexist with AA deficiency necessitated this study aimed at assessing the haematological response to AA supplementation in young adult women. The changes in A A status sub sequent to supplementation or withdrawal will also be evaluated.
33
Ajayi/Nnaji
34
Table 1. Haematologic and AA status o f AA-supplemented subjects AA supplement
Hb. g/l
1
Hct, %
2
3
1
R B C count X 10'-/l
2
3
1
2
3
100 mg AA (n = 9)
126.9 ±11.2
146.5 ±11.1
139.8 ±11.6
40.1 ±2.9
44.8 ±1.9
40.8 ±2.8
4.5 ±0.4
5.6 ±0.5
5.0 ±0.8
50 mg AA (n = 7)
125.0 ±9.8
142.9 ±8.9
134.3 ±6.8
38.9 ±2.3
43.2 ±1.7
39.9 ± 2.8
4.4 ±0.4
5.3 ±0.2
4.7 ±0.5
None (control) (n = 6)
126.3 ±6.9
122.0 ±5.9
123.5 ±6.3
39.0 ±2.4
37.2 ±2.8
38.0 ± 3.0
4.3 ±0.6
4.1 ±0.3
4.2 ± 0.5
Discussion Biochemical data obtained from the present study indicate that the A A status of the subjects was within acceptable range [8], The mean basal AA value (6.1 ± 0.6 mg/1) obtained for these subjects was lower than mean values observed for a similar age group [Ajayi, unpubl. observation], A criti cal evaluation of data available on the AA status o f Nigerians suggests that the AA sta tus of most population groups has declined considerably in recent times. Keshinro [9] observed that high A A losses accompanied cooking o f vegetables in Nigeria. Hence fruit constitutes the major source o f A A in the diet, and the poor A A status o f Nigerians may be due to low consumption o f fruit. The desirable AA status observed for these subjects may not be unconnected with ade quate exposure to improved dietary habits and nutrition information since the subjects
were predominantly nurses and university students. This study also demonstrates that short term supplementation with A A improved erythropoietic activity. The dramatic in crease in haematological values after A A supplementation (50 or 100 mg daily) is con sistent with the reports of other investigators [5, 10], Layrisse et al. [11] earlier demon strated that AA facilitates iron utilisation and Smith [10] also indicated that iron ab sorption is enhanced in the presence o f AA. The mobilization of certain haemopoietic factors into erylhroid marrow for Hb synthe sis is also AA-dependent [1], The present study was undertaken at a time when green vegetables which are good sources o f folic acid were abundant. The improved ervthropoiesis observed in the AA-supplemented group may be ascribed in part to the mobili zation and utilization o f iron and folic acid consequent to A A availability. Studies in
Downloaded by: Thomas Jefferson University Scott Library 147.140.27.100 - 8/23/2018 8:29:36 AM
Values are means ± SD , 1 = Basal value before supplementation: 2 = after 8 weeks o f supplementation: 3 = 1 0 weeks after supplementation was withdraw n.
Ascorbic Acid Status o f Nigerians
Serum ascorbate, mg/l
1
2
3
1
6.2 ±1.7
6.0 ±1.3
5.9 ± 2.0
6.13 ±0.5
6.3 ±1.8
6.2 ±2.0
6.1 ± 1.5
5.80 ±0.9
6.1 ±1.4
6.3 ±1.8
6.5 ± 1.5
6.27 ± 1.1
Leucocyte ascorbate pg/IOs cells 3
1
2
3
5.18 ±0.5
25.6 ± 10.4
66.4 ±12.7
38.5 ±10.1
8.31 ±2.2
5.0 ±0.4
28.3 ± 10.5
53.3 ± 10.7
31.4 ± 6.4
5.22 ±0.7
5.20 ±0.5
23.3 ±7.7
28.0 ±9.8
27.3 ±6.1
2 10.13 ±2.8
anaemic children have demonstrated the beneficial effect of iron-folic acid supple mentation on Hb concentration [12]. Other investigators [13] have indicated that AA supplementation maintained rather than enhanced erythropoiesis in nonanaemic populations. However, data from this study have shown that AA supplementa tion was beneficial to all subjects whether they had low or acceptable haemoglobin ini tially. Nevertheless, the increment in Hb concentration after supplementation was slightly higher for subjects with initially low Hb ( < 120 g/1). The observed improvement in AA status subsequent to supplementation is in agreement with previous findings [2]. It is evident that plasma and leucocyte ascorbate concentrations are reliable indices in assessing A A status [1]. The significant association between plasma and leucocyte AA in the present study confirms the well established metabolic shuttle existing be
tween plasma and tissue ascorbate [14], The data from this study further indicate that tis sue saturation of AA can be maintained on a daily supplement of 50 mg AA . However, raising the daily dose to 100 mg sustained Hb concentration and tissue ascorbate for a long er period after withdrawal of supplement. In essence, a daily dietary A A intake be low 50 mg may not adequately meet physio logical demands especially in an environ ment where chronic infection is common. Hence, the presently adopted recommended dietary allowance of 30 mg for A A [ 15] mayneed re-evaluation. A comparative study is therefore needed to ascertain A A needs of both rural and urban population in Nigeria.
Acknowledgement The authors extend deep appreciation to the staff o f Eleyele School o f Nursing and to all the students who participated to the study.
Downloaded by: Thomas Jefferson University Scott Library 147.140.27.100 - 8/23/2018 8:29:36 AM
Leucocytes X I09/I
35
Ajayi/Nnaji
.36
1 Schorah C J: The level o f vitamin C reserve re quired in man: Towards a solution to the contro versy. Proc Nutr Soc 1981:40:147-154. 2 Ludvigson J. Hansson L O . Stendhal O: The effect of large doses of vitamin C on leucocyte function and some laboratory parameters. Int J Vitam Nutr Res 1979:49:161-165. 3 Roeser HP, Halliday JW , Sizemore D J, et al: Serum ferritin in ascorbic acid deficiency. Br J Haematol 1980:45:457-466. 4 Roeser HP: The role o f ascorbic acid in the turn over of storage iron. Semin Haematol 1983:2:91-
.
100
5 Seshadri S, Shah A, Bhade S: Haematologic re sponse o f anaemic preschool children to ascorbic acid supplementation. Hum Nutr Appl Nutr 1985;39A: 151 —154. 6 Dacie JK . Lewis SM : Practical Haematology. Edinburgh, Churchill Livingstone. 1984. pp 2834. 7 Denson K.W. Bowers EF: Determinations o f as corbic acid in the white blood cells. Clin Sci 1961: 21:157-162. 8 International Research National Institute of Health: Nutrition Survey: Republic o f Nigeria. Washington. United States Department o f Health Education and Welfare. 1967. 9 Keshinro O O : The effect o f cooking on the ascor bic acid content o f some Nigerian foodstuffs and their contribution to vitamin C status o f the con sumers: PhD thesis Ibadan (1980)
10 Smith R: Ascorbic acid: More than just a vitamin. Food Sci Ncwslett 1986:12:1-6. 11 Layrisse M, Martinez-Torres C . Gonzales M: Measurement o f the daily dietary iron absorption by the extrinsic tag model. Am J Clin Nutr 1974: 27:152-162. 12 Seshadri S. Hirode K , Naik P. et al: An effective intervention to reduce the prevalence o f anaemia in children, lnd J Med Res 1984:80:164—173. 13 Suboticanec-Buzina K . Buzina R. Brubacher G . et al: Vitamin C status and physical working capac ity in adolescents. Int J Vitam Nutr Res 1984:54: 55-60. 14 Loh HS. Wilson CW : Relationship between leuco cyte and plasma ascorbic acid concentrations. Br Med J 1971 :ii:733—735. 15 Passmore R: Handbook on Human Nutritional Requirements. W H O Monograph Ser. No 61. ed 6. Rome. World Health Organization, 1974.
Received: March 20, 1989 Accepted: July 25. 1989 Olufunmike Alalade Ajayi Department o f Human Nutrition College o f Medicine University o f Ibadan Ibadan (Nigeria)
Downloaded by: Thomas Jefferson University Scott Library 147.140.27.100 - 8/23/2018 8:29:36 AM
References
