Giraffe
Member
- Joined
- Jun 20, 2015
- Messages
- 3,730
There have been a couple of posts recently along the lines that "the Peat diet" was low in zinc and that high calcium intake would deplete zinc.
So I decided to check what information I could find about it. My conclusion:
A diet that contains adequate animal proteins from milk, eggs, and occasional liver and seafood provides adequate amounts of highly bio-available zinc. High dietary calcium intake does not interfere with zinc utilization.
++++
Bioavailability
"The amount of protein in the diet is a factor contributing to the efficiency of zinc absorption as zinc binds to protein. Small changes in protein digestion may produce significant changes in zinc absorption (Sandstrom & Lonnerdal 1989)."
"In general, zinc absorption from a diet high in animal protein will be greater than from a diet rich in plant derived proteins (King & Keen 1999). The requirement for dietary zinc may be as much as 50% greater for vegetarians, particularly strict vegetarians whose major staples are grains and legumes and whose dietary phytate:zinc ratio exceeds 15:1."
"Current data suggest that consumption of calcium-rich diets does not have a major effect on zinc absorption at an adequate intake level."
Nutrient Reference Values for Australia and New Zealand
"It is recognized that zinc is well absorbed from milk."
Effect of citrate on zinc bioavailability from milk, milk fractions and infant formulas
+++++
Now a few studies...
There have been several "animal studies that have shown that calcium interferes with the intestinal absorption of zinc. Some human studies have shown that increased calcium intake decreases zinc absorption (7, 8), others have been unable to confirm this (9, 10)."
"Wood and Hanssen (7) showed that milk and lactose-free milk reduced zinc absorption in lactose-tolerant and lactoseintolerant postmenopausal women significantly; however, 2 y later, in a subsequent study among postmenopausal women, they were not able to show any significant effect of the addition of milk or a calcium phosphate supplement on either zinc absorption or retention (10)."
I did not check the animal studies. It was mentioned in on of the humans studies that the calcium doses were very high. I am going to discuss reference 8 below.
Zinc balance in adolescent females consuming a low or high calcium diet
This is the most interesting study. It compared a low calcium diet (~ 670 mg) with a high calcium diet (~ 1670 mg). Zinc intake was below RDI.
"As part of the long-term supplementation trial, subjects consumed their normal, self-selected diets and were randomly assigned to receive either placebo tablets or 1000 mg Ca/d as calcium citrate malate."
"Average consumption of calcium was 667 ± 28 mg/d (range: 595-722 mg/d, depending on the amount of food eaten) and of zinc was 5.5 ± 0.6 mg/d (range: 4.4-6.3 mg/d)."
RDI zinc for adolescent females:
US: 9 mg
Australia: 7 mg
The cautious conclusion was that "long-term calcium supplementation with 1000 mg Ca as calcium citrate malate, in addition to dietary calcium, does not have detrimental effects on the zinc balance of adolescent females already consuming low amounts of zinc."
The authors write, "One girl in the supplemented group and four girls in the placebo group were in negative zinc balance. However, no significant difference was found between the placebo and supplemented groups for zinc balance (Table 2)."
However the data in table 2 suggest that calcium supplemented group had a much better zinc balance (0.8 vs 0.3).
The effect of calcium carbonate and calcium citrate on the absorption of zinc in healthy female subjects.
This study is the above mentioned reference 8.
Here the subjects drank water with "either 4.5 mg elemental zinc, zinc with 600 mg elemental calcium as calcium carbonate or zinc with 600 mg elemental calcium as calcium citrate."
If you check food databases, you will find that 600 mg is the average amount of calcium you get from food when you eat a mixed diet containing 4.5 mg zinc.
RESULTS:
"The area under the plasma zinc curve (AUC) (mean +/- SEM) following the coingestion of zinc with calcium carbonate (438.4 +/- 129.0 mumol Zn.min/100 g albumin) and calcium citrate (308.0 +/- 110.5) was significantly lower (P < 0.017) than when zinc was ingested alone (1561.7 +/- 240). Urinary excretion of calcium was significantly higher (P < 0.017) at 4 h after supplementation with calcium citrate (0.83 +/- 0.12 mumol Ca/mumol creatinine) compared with calcium carbonate (0.40 +/- 0.11)."
The authors come to the conclusion that the result "suggests that an antagonistic competition occurred between the minerals and that elemental calcium is the inhibiting factor."
So this is: zinc alone vs. zinc+calcium. I don't know of a food that does not contain calcium.
Comparisons of the effects of calcium carbonate and calcium acetate on zinc tolerance test in hemodialysis patients.
The effect of "calcium carbonate (CaCO3) and calcium acetate (CaAc), two other phosphate binders, on intestinal Zn absorption in nine patients on hemodialysis and in 11 controls by measuring 1- and 2-hour serum Zn levels after oral administration of 50 mg of elemental Zn as Zn gluconate with or without concomitant administration of 2 g CaCO3 (800 mg elemental Ca) or 3 g CaAc (750 mg elemental Ca)" was studied.
"The results demonstrate that intestinal Zn absorption after an oral Zn challenge decreased in patients on hemodialysis and concomitant administration of CaAc, but CaCO3 did not decrease intestinal Zn absorption in either group."
Unfortunately I could only find the abstract, which does not name numbers only a p-value (aka: plague in science), so we don't know how small or big the effect of CaAc was.
Effect of Dietary Calcium and Phosphorus Levels on the Utilization of Iron, Copper, and Zinc by Adult Males
"Iron, copper, and zinc utilization were examined in nine adult males fed a moderate calcium-moderate phosphorus diet (MCaMP), a moderate calcium-high phosphorus diet (MCaHP), and a high calcium-high phosphorus diets (HCaHP) during a 39-day balance study. The moderate and high calcium diets contained 780 mg and 2382 mg calcium daily, respectively. The moderate and high phosphorus diets contained 843 and 2442 mg phosphorus daily, respectively. The calcium supplements were fed as calcium gluconate, while the phosphorus supplements were fed as glycerol phosphate."
"Dietary treatments had no effect on subjects' fecal and urinary losses of zinc nor on their apparent retention of zinc. Plasma iron, zinc, copper, and transferrin levels and serum ferritin levels were not affected by the dietary treatment."
So I decided to check what information I could find about it. My conclusion:
A diet that contains adequate animal proteins from milk, eggs, and occasional liver and seafood provides adequate amounts of highly bio-available zinc. High dietary calcium intake does not interfere with zinc utilization.
++++
Bioavailability
"The amount of protein in the diet is a factor contributing to the efficiency of zinc absorption as zinc binds to protein. Small changes in protein digestion may produce significant changes in zinc absorption (Sandstrom & Lonnerdal 1989)."
"In general, zinc absorption from a diet high in animal protein will be greater than from a diet rich in plant derived proteins (King & Keen 1999). The requirement for dietary zinc may be as much as 50% greater for vegetarians, particularly strict vegetarians whose major staples are grains and legumes and whose dietary phytate:zinc ratio exceeds 15:1."
"Current data suggest that consumption of calcium-rich diets does not have a major effect on zinc absorption at an adequate intake level."
Nutrient Reference Values for Australia and New Zealand
"It is recognized that zinc is well absorbed from milk."
Effect of citrate on zinc bioavailability from milk, milk fractions and infant formulas
+++++
Now a few studies...
There have been several "animal studies that have shown that calcium interferes with the intestinal absorption of zinc. Some human studies have shown that increased calcium intake decreases zinc absorption (7, 8), others have been unable to confirm this (9, 10)."
"Wood and Hanssen (7) showed that milk and lactose-free milk reduced zinc absorption in lactose-tolerant and lactoseintolerant postmenopausal women significantly; however, 2 y later, in a subsequent study among postmenopausal women, they were not able to show any significant effect of the addition of milk or a calcium phosphate supplement on either zinc absorption or retention (10)."
I did not check the animal studies. It was mentioned in on of the humans studies that the calcium doses were very high. I am going to discuss reference 8 below.
Zinc balance in adolescent females consuming a low or high calcium diet
This is the most interesting study. It compared a low calcium diet (~ 670 mg) with a high calcium diet (~ 1670 mg). Zinc intake was below RDI.
"As part of the long-term supplementation trial, subjects consumed their normal, self-selected diets and were randomly assigned to receive either placebo tablets or 1000 mg Ca/d as calcium citrate malate."
"Average consumption of calcium was 667 ± 28 mg/d (range: 595-722 mg/d, depending on the amount of food eaten) and of zinc was 5.5 ± 0.6 mg/d (range: 4.4-6.3 mg/d)."
RDI zinc for adolescent females:
US: 9 mg
Australia: 7 mg
The cautious conclusion was that "long-term calcium supplementation with 1000 mg Ca as calcium citrate malate, in addition to dietary calcium, does not have detrimental effects on the zinc balance of adolescent females already consuming low amounts of zinc."
The authors write, "One girl in the supplemented group and four girls in the placebo group were in negative zinc balance. However, no significant difference was found between the placebo and supplemented groups for zinc balance (Table 2)."
However the data in table 2 suggest that calcium supplemented group had a much better zinc balance (0.8 vs 0.3).
The effect of calcium carbonate and calcium citrate on the absorption of zinc in healthy female subjects.
This study is the above mentioned reference 8.
Here the subjects drank water with "either 4.5 mg elemental zinc, zinc with 600 mg elemental calcium as calcium carbonate or zinc with 600 mg elemental calcium as calcium citrate."
If you check food databases, you will find that 600 mg is the average amount of calcium you get from food when you eat a mixed diet containing 4.5 mg zinc.
RESULTS:
"The area under the plasma zinc curve (AUC) (mean +/- SEM) following the coingestion of zinc with calcium carbonate (438.4 +/- 129.0 mumol Zn.min/100 g albumin) and calcium citrate (308.0 +/- 110.5) was significantly lower (P < 0.017) than when zinc was ingested alone (1561.7 +/- 240). Urinary excretion of calcium was significantly higher (P < 0.017) at 4 h after supplementation with calcium citrate (0.83 +/- 0.12 mumol Ca/mumol creatinine) compared with calcium carbonate (0.40 +/- 0.11)."
The authors come to the conclusion that the result "suggests that an antagonistic competition occurred between the minerals and that elemental calcium is the inhibiting factor."
So this is: zinc alone vs. zinc+calcium. I don't know of a food that does not contain calcium.
Comparisons of the effects of calcium carbonate and calcium acetate on zinc tolerance test in hemodialysis patients.
The effect of "calcium carbonate (CaCO3) and calcium acetate (CaAc), two other phosphate binders, on intestinal Zn absorption in nine patients on hemodialysis and in 11 controls by measuring 1- and 2-hour serum Zn levels after oral administration of 50 mg of elemental Zn as Zn gluconate with or without concomitant administration of 2 g CaCO3 (800 mg elemental Ca) or 3 g CaAc (750 mg elemental Ca)" was studied.
"The results demonstrate that intestinal Zn absorption after an oral Zn challenge decreased in patients on hemodialysis and concomitant administration of CaAc, but CaCO3 did not decrease intestinal Zn absorption in either group."
Unfortunately I could only find the abstract, which does not name numbers only a p-value (aka: plague in science), so we don't know how small or big the effect of CaAc was.
Effect of Dietary Calcium and Phosphorus Levels on the Utilization of Iron, Copper, and Zinc by Adult Males
"Iron, copper, and zinc utilization were examined in nine adult males fed a moderate calcium-moderate phosphorus diet (MCaMP), a moderate calcium-high phosphorus diet (MCaHP), and a high calcium-high phosphorus diets (HCaHP) during a 39-day balance study. The moderate and high calcium diets contained 780 mg and 2382 mg calcium daily, respectively. The moderate and high phosphorus diets contained 843 and 2442 mg phosphorus daily, respectively. The calcium supplements were fed as calcium gluconate, while the phosphorus supplements were fed as glycerol phosphate."
"Dietary treatments had no effect on subjects' fecal and urinary losses of zinc nor on their apparent retention of zinc. Plasma iron, zinc, copper, and transferrin levels and serum ferritin levels were not affected by the dietary treatment."
Last edited: