Increased calcium bioavailability in mice fed genetically engineered plants lacking calcium oxalate.

Area of Science:

• Plant genetics and nutrition
• Calcium metabolism and bioavailability
• Food science and crop improvement

Background:

• Bioavailable calcium is crucial for bone health, influencing bone formation and calcification.
• The model forage crop Medicago truncatula is used to study calcium partitioning.
• A previously identified mutant, cod5, lacks oxalate crystals but has similar calcium concentrations to wild-type.

Purpose of the Study:

• To investigate the effect of a single gene mutation altering calcium partitioning on calcium bioavailability in Medicago truncatula.
• To determine the nutritional impact of removing oxalate crystals from the diet.
• To provide the first genetic evidence for the role of oxalate crystals in calcium absorption.

Main Methods:

• Mice were fed diets containing 45Ca-labeled Medicago truncatula or its cod5 mutant.
• Diets were either extrinsically or intrinsically labeled to track calcium absorption.
• Calcium absorption was measured in mouse legs one day post-consumption.

Main Results:

• Extrinsically labeled diets showed similar calcium absorption between wild-type and cod5 groups.
• Intrinsically labeled diets revealed a 22.87% higher calcium absorption (P < 0.001) in mice fed the cod5 mutant.
• This indicates that the absence of oxalate crystals significantly improves calcium bioavailability.

Conclusions:

• The genetic removal of oxalate crystals from Medicago truncatula enhances dietary calcium absorption.
• Oxalate crystals negatively impact calcium bioavailability, a finding supported by this genetic evidence.
• This research highlights a novel strategy for improving the nutritional value of food crops through genetic modification.