In postmenopausal Iranian women, a higher overall plant-based diet index (PDI), encompassing both healthy and unhealthy plant foods, is not significantly associated with bone mineral density at the femoral neck or lumbar spine after adjustment for age, BMI, physical activity, education, and calcium supplement use.

When people eat more healthy plant foods like fruits and vegetables, their bodies get more potassium and magnesium, which stop the loss of calcium through urine. This keeps more calcium available to build strong bones. When people eat more unhealthy plant foods like sugary snacks and refined grains, they get fewer of these helpful nutrients and more substances that increase acid in the body, which causes more calcium to be lost and weakens bones. Overall, when healthy and unhealthy plant foods are mixed together, their effects cancel out, so the total amount of plant foods eaten doesn’t change bone strength.