Structural Effects of the Ketogenic Diet on the Heart and Aorta: A Light and Electron Microscopic Study in Rats

The purpose of this study was to investigate the effects of a ketogenic diet on heart muscle and aortic tissue in rats. The ketogenic diet is well known for its metabolic advantages, including weight loss and improved glycemic control. However, what it does to the heart and blood vessel tissues directly, particularly from a microscopic perspective, is not well understood. Adult male Sprague Dawley rats were randomly divided into two groups and were maintained on standard diet or ketogenic diet containing 78.8% fat for two months. Regular monitoring was done for body weight and food intake. At the end of two months, heart and aorta tissues were fixed for light microscopic and transmission electron microscopic studies. Body weight increased in both groups over the study period. Rats receiving the ketogenic diet exhibited distinct structural and ultrastructural alterations in both cardiac and aortic tissues compared with controls. In the myocardium, capillary dilation, erythrocyte stasis, endothelial swelling, cytoplasmic vacuolization, and focal myofibrillar degeneration were observed. Aortic examination revealed focal intimal thickening, fragmentation of elastic lamellae, endothelial alterations, and structural changes in smooth muscle cells, histologically consistent with early vascular remodeling. A ketogenic diet induces structural alterations in cardiac muscle and aortic tissue in rats, even in the absence of overt metabolic disease. These findings suggest that ketogenic feeding may elicit subclinical cardiovascular tissue stress or adaptive remodeling. Evaluation of ketogenic diets should therefore consider not only systemic metabolic outcomes but also organ-specific structural effects, particularly with prolonged high-fat exposure.