A caffeine diet can alter the mechanical properties of the bones of young ovariectomized rats

The general public widely consumes caffeine which is contained in various foods, beverages, and over-the-counter medications. The relationships between caffeine intake and bone fractures is controversial. Therefore, the aim of the current study was to determine what effects, if any, caffeine intake in early life exerts on mechanical properties and mineral contents of bone in growing ovariectomized rats. A total of 8 dams with pups were divided into two groups. Group 1 was fed a 20% protein diet. Group 2 was fed a 20% protein diet supplemented with caffeine (4 mg/100 g). The respective diets were fed to the dams during lactation and to the pups continuously after weaning on day 22 until the end of the experimental period. On day 32, offspring from both groups were ovariectomized. On day 52, the rats were sacrificed and the femora removed. The biomechanical properties of the femora were determined by three-point bend testing to failure at a rate of 2 mm/min, with continuous data sampling at 10 samples/s. The properties determined included the modulus of elasticity, yield load, yield stress, ultimate load, ultimate stress, and the second moment of area. The caffeine group exhibited a decrease in the various mechanical properties (ranging from approximately 7 to 20%), except for yield strain and moment of inertia. The decreases in maximum stress and elastic modulus values were significant. Calcium, magnesium, and phosphorous values for the caffeine group were significantly decreased. These results suggest that the bone in the caffeine group is weaker and less stiff, with greater deformation under applied loading. It could be concluded that caffeine intake during the early growing period affects the mechanical properties of bone.