In most people with epilepsy, the condition is readily controlled, but 20-30% develop chronic epilepsy. An estimated 80,000 patients with epilepsy require ongoing specialist care in the United Kingdom. Nutrition may be a factor in the development of chronic epilepsy. Modern Western diets are thought to produce a low-grade chronic metabolic acidosis. The hydrogen ion, H+, is a potent modulator of NMDA-activated currents, and in cultured neurons, increased external [H+] strongly suppresses these currents. The effect of chronic metabolic acidosis in vivo has not been fully studied. It is possible that low-grade chronic metabolic acidosis chronically inhibits the NMDA-activated currents, and this may lead to upregulation of the NMDA receptor. This would result in a greater hyperexcitable state and may contribute to the development of chronic epilepsy.