G. S. RANHOTRA and J. A. GELROTH
American Institute of Baking, Nutrition Research, Manhattan, KS 66502
Under the curren levels of phytate
which may possibly i n h i b i t zinc absorption, are not a source of undue concern for the majority of the population. However, as our awareness of the con- cepts of nutrient economics and nutrient density, and of matters of health as they might relate to foods of plant o r i g i n increases, more of the zinc i n our diet could originate from cereal-based and other plant foods. Consequently, the t o t a l and b i o - available zinc content of our diet may become com- promised. This may have serious health implications especially when a steady decline i n our c a l o r i c in- take i s being witnessed. Health measures encompass- ing f o r t i f i c a t i o n of foods with z i n c , the process- ing of foods to control the levels of suspected i n h i b i t o r s of zinc absorption, and long-term studies to examine the effect of "adaptation" (to changed dietary regimens) are some of the areas which demand our immediate attention.
Zinc deficiency i n man was f i r s t recognized i n the early I960
1s (1). Since that time, research concerning the role of zinc i n health and disease has been intense. Evidence that a sizable segment of the U.S. population may be deficient i n z i n c , at least marginally (2), has contributed to the interest i n zinc research.
Although the major sources of zinc i n the diet are foods of animal o r i g i n , p a r t i c u l a r l y meats, shellfishes and cheese (3,b), cereal-based foods also make important contributions.
Cereal-Based Food Products Zinc content.
Table I l i s t s the zinc content of some cereal-based food pro- ducts 03*4·). Substantial zinc loss occurs during refinement of ce- real grains, e . g . , m i l l i n g of wheat to produce white flour. There- fore, products which are less refined or which contain the bran
0097-6156/83/0210-0185$06.00/0
© 1983 American Chemical Society
In Nutritional Bioavailability of Zinc; Inglett, G.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1983.
and germ f r a c t i o n s of g r a i n s are p a r t i c u l a r l y good sources of z i n c .
Table I . Z i n c content of some c e r e a l - b a s e d f o o d sa
Product mg/100 g
Cake, white 0.2
Sweet corn, b o i l e d 0.4
Hamburger r o l l 0.6
White bread 0.6
Oatmeal bread 1.0
Graham c r a c k e r s 1.1
Oatmeal c o o k i e s 1.3
Cake, c h o c o l a t e 1.3
White r i c e dr 1.3
Brown r i c e Macaroni
wholewheat bread 1.8
B r e a k f a s t c e r e a l s
shredded wheat 2.8
bran f l a k e s , 40% 3.6
germ, t o a s t e d 15.4
a Murphy et a l . (3) and F r e e l a n d and Cousins (4)
Z i n c f o r t i f i c a t i o n .
The c u r r e n t c e r e a l f o r t i f i c a t i o n (enrichment) p r a c t i c e r e - s t o r e s some of the n u t r i e n t s ( z i n c not i n c l u d e d ) l o s t d u r i n g m i l l - i n g . In 1974, however, the Food and N u t r i t i o n Board (5) proposed an expansion of the c u r r e n t program to i n c l u d e a t o t a l of 10 m i c r o - n u t r i e n t s ( z i n c i n c l u d e d ) . The proposed l e v e l of z i n c (Table I I ) would almost completely r e s t o r e z i n c to the l e v e l present i n whole g r a i n s .
Although great changes i n d i e t a r y h a b i t s are c u r r e n t l y being witnessed, r e f i n e d products are l i k e l y to remain the mainstay of our d i e t . T h i s and the f a c t that our c a l o r i c i n t a k e has been de- c l i n i n g i n r e c e n t y e a r s , n e c e s s i t a t e s t h a t the d i e t a r y adequacy of c e r t a i n n u t r i t i o n a l l y c r i t i c a l n u t r i e n t s such as z i n c be ensur- ed. F o r t i f i c a t i o n p r o v i d e s a mean to accomplish t h i s .
Z i n c f o r t i f i c a t i o n sources.
Should the n u t r i t i o n a l and other c o n s i d e r a t i o n s permit f o r t i - f i c a t i o n , a number of z i n c sources can be used to f o r t i f y g r a i n p r o d u c t s . These sources, u n l i k e p o t e n t i a l i r o n sources, appear not to d i f f e r a p p r e c i a b l y i n t h e i r r e l a t i v e b i o l o g i c a l v a l u e ( 6 ) . T h i s was observed i n r a t s f e d submarginal (9.5 ppm) z i n c d i e t s (Table I I I ) . Femur z i n c content was used to assess b i o l o g i c a l v a l u e s
(BVs). I n d i r e c t l y , t h i s means that product c o m p a t i b i l i t y and c o s t are l i k e l v to be more important than n u t r i t i o n a l c o n s i d e r a t i o n s i n choosing the z i n c source to be used i n c e r e a l f o r t i f i c a t i o n .
13. R A N H O T R A A N D G E L R O T H Zinc Bioavailability from Cereal Foods 187
T a b l e I I . Expanded c e r e a l f o r t i f i c a t i o n p r o g r a m3'b
F o r t i f i c a t i o n ( e n r i c h m e n t )
Current Expanded(1974) (mg/100 g) (mg/100 g)
V i t a m i n A ( r e t . e q . )
-
0.29Thiamin 0.64 0.64
R i b o f l a v i n 0.40 0.40
N i a c i n 5.29 5.29
V i t a m i n B-6
-
0.44F o l i c a c i d
-
0.07I r o nc 2 .86-3.63 8.81
Calcium 211 ( o p t i o n a l ) 198.20
Magnesium
-
44.04Z i n c
a Food and N u t r i t i o
b Wheat f l o u r , corn g r i t s , corn meal and r i c e
c L e v e l proposed (FDA) i n 1981: 4.41 mg/ 100 g ( l e v e l proposed i n 1974 was d i s a l l o w e d ) Z i n c B i o a v a i l a b i l i t y
D i e t a r y adequacy of z i n c i s s t r o n g l y l i n k e d t o z i n c b i o a - v a i l a b i l i t y , p a r t i c u l a r l y i n foods r e p r e s e n t i n g the bread and c e - r e a l group. C e r e a l products c u r r e n t l y p r o v i d e about o n e - f i f t h of our energy need ( 7 ) . V a r i o u s d i e t a r y g u i d e l i n e s proposed i n r e c e n t years t o improve h e a l t h have recommended t h a t we i n c r e a s e our con- sumption o f c e r e a l foods t o i n c l u d e more complex carbohydrates i n the d i e t . These and o t h e r c o n s i d e r a t i o n s have l e d t o an i m p r e s s i v e i n c r e a s e i n our consumption of some g r a i n products such as v a r i e t y breads ( 8 ) . T h i s means more and more o f the z i n c i n our d i e t o r i g - i n a t e s from foods which a l s o c o n t a i n n a t u r a l l y o c c u r r i n g o r added components suspected t o i n h i b i t the a b s o r p t i o n o f z i n c . The com- ponents most w i d e l y i n v e s t i g a t e d and which w i l l be d i s c u s s e d i n - clude (a) p h y t a t e s , (b) f i b e r , (c) p r o t e i n and (d) c e r t a i n m i c r o - n u t r i e n t s . Other f a c t o r s (Table IV) a r e a l s o important but w i l l not be d i s c u s s e d .
E f f e c t o f p h y t a t e s .
A number of s t u d i e s have shown t h a t z i n c , as compared t o o t h e r m i n e r a l s , i s p o o r l y u t i l i z e d from p h y t a t e - c o n t a i n i n g foods.
The r e l a t i v e BV o f z i n c i n a number of p h y t a t e - c o n t a i n i n g foods was r e c e n t l y examined by Franz et_ a l ( 9 ) . Each product was p r e p a r - ed as f o r human consumption and i n c o r p o r a t e d i n t o a s e m i - p u r i f i e d d i e t f e d t o r a t s . Whole c o r n and brown r i c e had a low r e l a t i v e BV
(0.58 o r l e s s compared t o 1.00 f o r z i n c i n z i n c s u l f a t e ) w h i l e wholewheat f l o u r and unleavened wholewheat bread had medium v a l u e s
(0.63-0.74). R e f i n e d c e r e a l products such as w h i t e f l o u r , leavened and unleavened w h i t e bread and w h i t e r i c e ( a l l low i n phytate) had h i g h r e l a t i v e BV (0.89-1.08) as d i d leavened wholewheat bread
In Nutritional Bioavailability of Zinc; Inglett, G.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1983.
Table III. Bioavailability of zinc in potential fortification sources Source (diet) Carbonate Chloride Oxide Sulfate Stéarate Acetate Elementa Zinc content source (%) 53.8 44.7 79.5 36.1 11.2 30.0 100.0 diet (ppm) 9.5 9.5 9.5 9.5 9.5 9.5 9.5 Serum zinc (μ%/ά1) 167+18 154+12 165+19 140+24 144+20 144+18 161+11 Femur zinc (pg) 31.8+2.5 29.6+3.5 34.4+4.1 34.2+2.8 35.0+2.9 35.8+3.4 33.0+2. Zinc intake (ug) 694+92 766+36 775+58 730+43 751+57 729+58 698+97 Zinc absorbed (%) 76+5 89+3 87+4 87+4 89+2 87+5 88+4 RBV of zinc
b 93 87 101 100 102 105 95 a Ranhotra et al. (6) Relative (zinc in zinc sulfate = 100%) biological value based on femur zinc. Table IV. Factors affecting the bioavailability of zinc in food -Form and chemical nature of zinc -Dietary interactions (zinc vs. protein, lipids, carbohydrates such as fiber, other minerals, vitamins and chelators such as phytates) -Food processing conditions (leavening, etc.) -Digestibility of food -Body
1 s need for zinc/effect of "adaptation" -Health status of the individual -Intestinal microflora -Effect of age, sex, medication, etc. -Environmental and other factors
13. R A N H O T R A A N D G E L R O T H Zinc Bioavailability from Cereal Foods 189
( 1 . 0 4 ) . The authors conclude that r e l a t i v e BV appeared to be i n v e r s e l y r e l a t e d to phytate contents of the foods. Another study
( 1 0 ) t e s t e d c o o k i e s made w i t h egg albumin w i t h phytate added or not. The a d d i t i o n of phytate (Table V) s i g n i f i c a n t l y reduced the b i o a v a i l a b i l i t y of z i n c as determined based on the z i n c content of femur (Table V I ) . The reduced BV was comparable to BVs obtained w i t h c o o k i e s made w i t h the soy p r o t e i n p r o d u c t s . In these s t u d i e s ,
the l e v e l of p r o t e i n and z i n c i n a l l t e s t products was e q u a l i z e d . In the albumin-based c o o k i e s , however, the z i n c o r i g i n a t e d almost e n t i r e l y from the added source ( z i n c c h l o r i d e ) , w h i l e i n the soy- based c o o k i e s the added source made o n l y a p a r t i a l c o n t r i b u t i o n . In these s t u d i e s , v e r y l i t t l e phytate was h y d r o l y z e d d u r i n g the
Table V. Cookie f o r m u l a3
Cake f l o u r (g) 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 Other i n g r e d i e n t s ( g ) 5 8 5 8 5 8 5 8 5 8 P r o t e i n source*3(g)
egg albumin 3 3 3 3 - - -
soy f l o u r (def.) - - 5 0 - -
soy c o n c e n t r a t e - - - 3 9 . ,9 -
soy i s o l a t e - - - - 3 0 . 9
Z i n c (mg)
added (as c h l o . ) 4 . 4 9 4 . 4 9 2 . , 2 0 3 . , 4 0 2 . 2 4 i n p r o t e i n source 0 . 0 7 0 . 0 7 2 . , 3 6 1, . 1 6 2 . 3 2 Phytate (mg)
added (as Na s a l t ) - 1 1 0 7 - 6 6 4 4 8
i n p r o t e i n source - - 1 1 0 7 1 0 4 1 6 5 9 Phyt. h y d r o l y z e dc( % ) 1 0 0 1 9 . 6 7 , . 3 9 , . 8 1 8 . 4
a Ranhotra et a l . ( 1 0 )
D Amount added p r o v i d e d 2 6 g p r o t e i n
c In cookie-making
cookie-making process (Table V ) . In c e r e a l - b a s e d products where a p p r e c i a b l e phytate h y d r o l y s i s occurs d u r i n g p r o c e s s i n g , b i o a v a i l a b i l i t y of z i n c seems to improve. T h i s was observed i n a study ( 1 1 ) where breads, made w i t h or without soy (Table V I I ) , c o n t a i n e d added p h y t a t e . In these breads, phytate was almost completely hy
d r o l y z e d d u r i n g p r o c e s s i n g . The breadmaking process a l s o s i g n i f i c a n t l y improved the apparent a b s o r p t i o n of z i n c (Table V I I ) . R e i n h o l d et_ a l . ( 1 2 ) s t u d i e d the a v a i l a b i l i t y of z i n c i n leavened and unleavened wholemeal wheaten breads and concluded t h a t l e a v e n i n g
( h y d r o l y z e s phytate) markedly i n c r e a s e d the b i o u t i l i z a t i o n of z i n c i n bread. M o r r i s and E l l i s ( 1 3 ) examined the e f f e c t of d e p h y t i n i z - i n g wheat bran on z i n c u t i l i z a t i o n by r a t s and demonstrated that i t i s f e a s i b l e to g r e a t l y overcome the phytate e f f e c t through de- p h y t i n i z a t i o n (Table V I I I ) . In humans, Sandstrom et a l . ( 1 4 ) r e ported r e d u c t i o n i n the a v a i l a b i l i t y of z i n c added to wholemeal
In Nutritional Bioavailability of Zinc; Inglett, G.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1983.
Table VI. Tissue concentration and absorption of zinc in rats fed cookies
3 Cookies (Table V) A Β C D Ε Dietary zinc (ppm) 9.0 9.0 9.0 9.0 9.0 Body weight gain (g) 163+10 160+9 165+9 166+14 165+12 Serum zinc (pg/dl) 98+14 90+14 100+11 87+15 86+13 Femur zinc (pg) 45.5+2.8 33.6+2.9 34.2+2.7 33.4+3.0 32.4+4. Zinc intake fag) 3197+162 2995+296 3188+182 3204+258 3132+296 Zinc absorbed (%) 89+2 85+2 83+3 83+3 81+3 RBVb 100 76 77 77 73 a Ranhotra et al. (10) D Relative (zinc in cookie A=100%) biological value based on femur zinc content. Table VII. Tissue concentration and absorption of zinc in rats fed bread
3 >
b Phytate added^ No soy Soy added (12%) Ingredients Bread Ingredients Bread Dietary zinc (ppm) 9.5 9.5 9.5 9.5 Body weight gain (g) 188+12 185+11 190+11 189+11 Serum zinc (pg/dl) 106+32 105+10 109+43 174+26 Femur zinc fag) 53.4+6.3 57.6+4.9 50.1+5.9 55.7+6.5 Zinc intake (Mg) 1168+64 1168+87 1242+64 1234+84 Zinc absorbed (%) 61+9 82+3 65+6 80+3 Phytate hydrolyzed (%) — 100 — 92.2 3 Ranhotra et al. (11) D Flour contained 2.2 mg added zinc/100 g; zinc addition adjusted for zinc in soy- c As sodium salt. Phytate added to provide 77 mg Ρ (phytate in soy considered).
13. R A N H O T R A A N D G E L R O T H Zinc Bioavailability from Cereal Foods 191
bread compared w i t h w h i t e bread. But they a l s o found t h a t the
" a b s o l u t e " a b s o r p t i o n of z i n c n a t u r a l l y - o c c u r r i n g i n wholemeal bread i s h i g h . T h i s may a l s o be t r u e f o r a l l g r a i n products which are good sources of z i n c , u n l e s s these products have " i n h i b i t o r y "
(on z i n c a b s o r p t i o n ) i n f l u e n c e s too g r e a t to be overcome d u r i n g d i g e s t i o n and/or a b s o r p t i o n p r o c e s s e s .
Added and n a t u r a l l y - o c c u r r i n g p h y t a t e s may a f f e c t z i n c absorp
t i o n d i f f e r e n t l y a l t h o u g h M o r r i s and E l l i s (13) r e p o r t t h a t phy
t a t e i n wheat bran a f f e c t s z i n c u t i l i z a t i o n i n r a t s i n n e a r l y the same manner as does p h y t a t e added at a s i m i l a r p h y t a t e : z i n c molar r a t i o . One can a r r i v e at a s i m i l a r c o n c l u s i o n i n examining the d a t a i n Table VI where c o o k i e Β c o n t a i n i n g added p h y t a t e compared w e l l w i t h c o o k i e C which c o n t a i n e d n a t u r a l l y - o c c u r r i n g p h y t a t e .
P h y t a t e : z i n c molar r a t i o s i n food products can be used to e s t i m a t e the r e l a t i v e
Oberleas and H a r l a n d (2
r a t i o of 10 or l e s s i s a c c e p t a b l e i n p r o v i d i n g adequate z i n c and t h a t d a i l y r a t i o s above 20 may j e o p a r d i z e z i n c s t a t u s .
E f f e c t of f i b e r .
U n l i k e p h y t a t e s , the e f f e c t of f i b e r on z i n c a b s o r p t i o n r e mains more u n c e r t a i n . The i n f o r m a t i o n r e c e n t l y compiled (Table IX) by K e l s a y (15) underscores t h i s . The u n c e r t a i n t y may, i n p a r t , be a t t r i b u t e d to (a) d i f f e r e n c e s i n p r e e x p e r i m e n t a l d i e t a r y regimen of t e s t s u b j e c t s , (b) d i f f e r e n c e s i n the l e v e l of f i b e r i n t a k e ,
(c) d i f f e r e n c e s i n the type of f i b e r t e s t e d , (d) d i f f e r e n c e s i n the time span of the study ( e f f e c t of " a d a p t a t i o n " ) , and most c r i t i c a l l y (e) the e x p e r i m e n t a l d i f f i c u l t i e s i n d i s a s s o c i a t i n g the e f f e c t of o t h e r suspected i n h i b i t o r s from e f f e c t due to f i b e r . C o n c e i v a b l y , the n a t u r e of the z i n c complex ( i n v o l v i n g f i b e r , phy
t a t e , p r o t e i n , e t c . ) e x i s t e n t at the s i t e of z i n c a b s o r p t i o n may be more c r i t i c a l than the mere l e v e l s of p o t e n t i a l i n h i b i t o r s .
The e f f e c t of " a d a p t a t i o n " may be p a r t i c u l a r l y s i g n i f i c a n t . Anderson et_ a l . (16) s t u d i e d the z i n c s t a t u s of long-term v e g e t a r i a n women who o b t a i n e d 77% of the t o t a l d i e t a r y z i n c from p l a n t p r o d u c t s . Three-day d i e t a r y r e c o r d s showed t h a t these s u b j e c t s consumed 9.2 + 2.5 mg z i n c and 30.9 + 11.0 g d i e t a r y f i b e r o r i g i n a t i n g from f i v e d i f f e r e n t food groups. T h e i r z i n c s t a t u s (serum z i n c ( p g / d l ) : 98.3 + 23.9; h a i r z i n c fag/g)i 187 + 44) appeared w i t h i n the normal range d e s p i t e t h e i r h i g h i n t a k e of l e s s r a p i d l y absorbed z i n c and t h e i r h i g h i n t a k e of t o t a l f i b e r and p h y t a t e .
Table V I I I . Femur z i n c c o n c e n t r a t i o n i n r a t sa
D i e t a r y z i n c source Femur z i n c (ppm)
Z i n c s u l f a t e 177+10
Raw wheat bran 69+3
Low-phytate bran 136+6
a M o r r i s and E l l i s (13). D i e t a r y z i n c : 12 ppm E f f e c t of p r o t e i n .
Many e a r l i e r s t u d i e s have shown t h a t z i n c i s l e s s e f f i c i e n t l y
In Nutritional Bioavailability of Zinc; Inglett, G.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1983.
Table IX. Effect of fiber on zinc balance3 Investigator Fiber source Zinc balance Reinhold et al. Unleavened wholemeal bread Became negative with wholemea (1973) (350 g/day for 32 days) bread Reinhold et al. Leavened wholemeal bread Became negative with wholemea (1976) (60% of calories) for 20 days bread Ismail-Beigi et al. Cellulose (10 g) in apple Negative with addition of (1977) compote for 20 days cellulose Sandstead et al. Soft white wheat bran (26 Not significantly affected b (1978) g) or corn bran (26 g) for bran 28-30 days Guthrie and Robinson Wheat bran (14 g) for four Not significantly affected b (1978) weeks bran Drews et al. Cellulose, hemicellulose Significantly lowered by (1979) or pectin (14.2 g) for four hemicellulose days Papakyrikos et al. Cellulose, hemicellulose or Tendency of all sources to (1979) wheat bran (10 or 20 g) for increase fecal zinc loss seven days Kies et al. Hemicellulose (4.2, 14.2, or Decreased as fiber intake (1979) 24.4 g) for 14 days increased; negative with highest level of fiber Kelsay et al. Fruits and vegetables (24 g Negative with fruits and (1979) of neutral-detergent fiber) vegetables for 26 days Kelsay et al. Fruits and vegetables (10, 18, Significantly lower on 25 g (1979) or 25 g of NDF) for 21 days of NDF than on low fiber die or on 10 g of NDF 3 Kelsay (L5)
13. R A N H O T R A A N D G E L R O T H Zinc Bioavailability from Cereal Foods 193 absorbed i n animals f e d p l a n t p r o t e i n r a t h e r than a n i m a l p r o t e i n
(17). T h i s may be a t t r i b u t a b l e to d i f f e r e n c e s i n the makeup of the two p r o t e i n s and/or to the e f f e c t due to a s s o c i a t e d components such as f i b e r and p h y t a t e . I n s t u d i e s w i t h préadolescent g i r l s , P r i c e e£^ a l . (18) observed t h a t the a b s o r p t i o n of z i n c from mixed d i e t ( p l a n t and animal foods) was somewhat h i g h e r than t h a t from p l a n t foods (Table X ) . The r e s u l t s may be somewhat confounded by the d i f f e r e n c e s i n d i e t a r y p r o t e i n l e v e l s . I n a r e c e n t study, Sandstrom et^ a l . (14) showed a p o s i t i v e c o r r e l a t i o n between z i n c a b s o r p t i o n and the p r o t e i n content i n meals c o n t a i n i n g m i l k , cheese, beef and egg i n v a r i o u s combinations w i t h wholemeal bread.
I n another study, Sandstrom eit a l . (19) compared the e f f e c t of ham- b u r g e r , the bun and the combination of the two on changes i n p l a s - ma z i n c i n human s u b j e c t s . They found t h a t meat alone d i d not ap- pear to i n h i b i t z i n c a b s o r p t i o but th bu ( w i t h w i t h o u t meat) caused a r e d u c t i o n i n plasm
q u i t e low i n f i b e r and phytat p r o t e i n
E f f e c t of c e r t a i n m i c r o n u t r i e n t s .
The e f f e c t of m i c r o n u t r i e n t s on z i n c u t i l i z a t i o n has r e c e i v e d l i t t l e a t t e n t i o n . Van Campen (20) demonstrated i n v i t r o t h a t z i n c and copper are m u t u a l l y a n t a g o n i s t i c d u r i n g the a b s o r p t i v e p r o c e s s . C a l c i u m a l s o aggrevates z i n c d e f i c i e n c y when added to d i e t s based on p l a n t products t h a t might a l s o c o n t a i n a p p r e c i a b l e amount of p h y t a t e . For example, the r e l a t i v e BV of z i n c i n a l k a l i - t r e a t e d corn ( c a l c i u m h y d r o x i d e ) i s r e p o r t e d to be low compared to b o i l e d or raw corn ( 9 ) . When the d i e t i s f r e e of or low i n p h y t a t e s , z i n c a b s o r p t i o n i n humans consuming h i g h or low c a l c i u m l e v e l s appears not to be a f f e c t e d (21). Solomons (22) r e p o r t s a s i g n i f i c a n t reduc-
t i o n i n z i n c a b s o r p t i o n i n humans i n the presence of nonheme ( i n - o r g a n i c ) i r o n (Table X I ) ; heme i r o n seems to have no such e f f e c t . Duncan and H u r l e y (23) s t u d i e d the i n t e r a c t i o n between z i n c and v i t a m i n A i n pregnant and f e t a l r a t s and found t h a t plasma v i t a m i n A i n both animals was s i g n i f i c a n t l y reduced by low i n t a k e s of e i -
t h e r z i n c or v i t a m i n A. Over the range of doses commonly consumed by man, a s c o r b i c a c i d was shown (24) to have no demonstratable e f - f e c t , u n l i k e t h a t on i r o n , on the a b s o r p t i o n of i n o r g a n i c z i n c i n man.
Table X. E f f e c t of p r o t e i n on z i n c a b s o r p t i o n i n a d o l e s c e n t g i r l sa
D i e t a r y p r o t e i n Z i n c
Source Amount I n t a k e F e c a l and Absorbed
(g/day) (mg) u r i n a r y losses(mg)
(%)
P l a n t 25 4.83 4.29 11.2
P l a n t 25 4.53 3.72 17.9
Mixed 46 6.93 4.94 28.7
Mixed 46 6.83 5.09 26.0
a P r i c e et a l . (18)
In Nutritional Bioavailability of Zinc; Inglett, G.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1983.
T a b l e X I . Z i n c and i r o n ( i n o r g a n i c ) i n t e r a c t i o n i n humansa
Fe : Zn Plasma Zn Qug/dl) Treatment r a t i o 1 h r 2 h r 3 h r 4 h r
a. 25 mg Z n ^ h 0 56+11 85+18 72+16 48+12
b. a + 25 mg Fe*4" 1:1 18+8 40+9 47+8 36+9
c. a + 50 mg F e ^ 2:1 23+2 44+4 38+8 27+8
d. a 4- 75 mg F e ^ 3:1 16+3 27+5 21+4 19+4
a Solomons (22)
R i s e above f a s t i n g plasma l e v e l s
Literature Cited 1. Prasad, A.S. "Zinc
Lab. S c i . : Boca Raton, , ; p
2. Oberleas, D.; Harland, B.F. J. Am. Diet. Assoc. 1981, 79, 433 3. Murphy, E.W.; W i l l i s , B.W.; Watt, B.K. J. Am. Diet. Assoc.
1975, 66, 345
4. Freeland, J.H.; Cousins, R.J. J. Am. Diet. Assoc. 1976, 68, 526
5. Food and Nutrition Board. "Proposed Fortification Policy for Cereal-Grain Products"; National Res. Council/National Acad.
S c i . : Washington, DC, 1974; p. 2
6. Ranhotra, G.S.; Loewe, R . J . ; Puyat, L.V. Cereal Chem. 1977, 54, 496
7. Marston, R.M.; Peterkin, B.B. Natl. Food Rev. 1980, NFR-9, 21 8. Ranhotra, G.S.; Winterringer, G.L. "The Consumption Pattern of
Variety Breads in the U.S. in Variety Breads in the United States (Miller, B. ed.); Am. Assoc. Cereal Chem.: St. Paul, 1981, p. 37
9. Franz, K.B. ; Kennedy, B.M.; Fellers, D.A. J. Nutr. 1980, 110, 2272
10. Ranhotra, G.S.; Lee, C.; Gelroth, J.A. Cereal Chem. 1979, 56, 552
11. Ranhotra, G.S.; Lee, C.; Gelroth, J.A. Nutr. Rep. I n t l . 1978, 18, 487
12. Reinhold, J.G.; Parsa, Α.; Karimian, N . ; Hammick, J.W.: Ismail
-Beigi, F. J. Nutr. 1974, 104, 976
13. Morris, E.R.; Ellis, R. J. Nutr. 1980, 110, 2000
14. Sandstrom, B.B.; Arvidsson, Α.; Cederbald, Α.; Bjorn-Rasmussen, E. Am. J. Clin. Nutr. 1980, 33, 739
15. Kelsay, J.L. Cereal Chem. 1981, 58, 2
16. Anderson, B.M.; Gibson, R.S.; Sabry, J.H. Am. J. Clin. Nutr.
1981, 34, 1042
17. O'Dell, B.L. Am. J. Clin. Nutr. 1969, 22, 1315
18. Price, N.O.; Bunce, G.E.; Engel, R.W. Am. J. Clin. Nutr. 1970,
23, 258
13. R A N H O T R A AND GELROTH Zinc Bioavailability from Cereal Foods 195
19. Sandstrom, B . ; Arvidsson, Α.; Bjorn-Rasmussen, E . ; Cederbald, A. "Zinc Absorption from Bread Meals in Trace Elements Metabo
lism in Man and Animals (Kirchgessner, M. ed.) III." Proc.
Third I n t l . Sym. Arpeitskeirs Fuhr Tierernahrungs Forschung:
Weihenstephan, 1978; p. 129
20. Van Campen, D.R. J. Nutr. 1970, 97, 104
21. Spencer, H . ; Vankinscott, V . ; Lavin, I . ; Samachon, J. J. Nutr.
1965, 86, 169
22. Solomons, N.W.J. Am. Diet. Assoc. 1982, 80, 115 23. Duncan, R . J . ; Hurley, L.S. J. Nutr. 1978, 108, 1431
24. Solomons, N.W.; Jacob, R.A.; Pineda, O.; V i t e r i , F.E. Am. J.
Clin, Nutr. 1979, 32, 2495
RECEIVED
October
5,1982In Nutritional Bioavailability of Zinc; Inglett, G.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1983.