Calcium phosphate supplement and blood calcium and phosphate
What it found
In nine men, bread enriched with calcium phosphate raised blood calcium slightly after four hours and did not raise blood phosphate.
The authors say it adds to calcium intake without pushing phosphate levels up.
What they found
Studies in people
Blood calcium after one dose
After a single dose, blood calcium was higher at 120 and 240 minutes than at the start. At 240 minutes it was higher than with the placebo.
Blood calcium after three weeks
After three weeks of daily calcium phosphate, blood calcium was higher at 60, 180 and 240 minutes than at the start. The total rise over four hours was larger than with the placebo.
Blood phosphate
Blood phosphate fell in the first 30 to 180 minutes after both the calcium phosphate and the placebo bread, then rose back towards the starting level. There was no difference between the two at 240 minutes.
Calcium-phosphorus product
The calcium-phosphorus product fell after both the calcium phosphate and the placebo bread at several time points. At the start it was higher after calcium phosphate than after the placebo.
Calcium absorption
The authors say the higher blood calcium at 240 minutes and the larger total rise after three weeks suggest that some calcium from the supplement was taken in.
What the authors conclude
“Our results show that CaP contributes to an adequate calcium supply, but without increasing the plasma concentration of phosphate.”
Also in their conclusions
- They conclude that calcium phosphate contributes to an adequate calcium supply without increasing the plasma concentration of phosphate.
- They say the major part of the phosphate from the supplement is precipitated as amorphous calcium phosphate in the human gut.
- They suggest isotopic tracer studies are needed to confirm these results.
How it was done
The authors wanted to see how well calcium phosphate is absorbed, because most studies look at its effects in the gut rather than in the blood. They also note that phosphate intake is debated because high blood phosphate is linked to heart and kidney problems.
Ten men aged 20 to 35 took part in a double-blind, placebo-controlled cross-over study. They ate bread with calcium phosphate (an extra 1 g calcium and 0.5 g phosphorus per day) or a placebo bread for three weeks, then switched after a two-week break. Blood was drawn over four hours after a single dose and again after three weeks; nine men finished.
What it can’t tell you
- The study was small, with nine men aged 20 to 35, so the results may not apply to other groups.
- It only measured blood calcium and phosphate over four hours after a meal and after three weeks of daily bread, not longer-term health outcomes.
- It cannot show whether calcium phosphate affects the risk of heart or kidney problems.
Who paid
- Authors work at
- Friedrich Schiller University of Jena, Germany
The paper
- Title
- Postprandial effects of calcium phosphate supplementation on plasma concentration-double-blind, placebo-controlled cross-over human study
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Trautvetter U, Kiehntopf M, Jahreis G (2013). Postprandial effects of calcium phosphate supplementation on plasma concentration-double-blind, placebo-controlled cross-over human study. Nutrition journal. doi:10.1186/1475-2891-12-30Free full textPubMed 23510513DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error