Gerson therapy was developed by Max Gerson, a German who emigrated to the United States. He initially treated tuberculosis through a low-salt diet and then modified his recommendations for treatment of more chronic conditions, especially cancer. He believed that his regimes reversed the conditions that were necessary to support the growth of malignant cells. He promoted the elimination of toxins, protected and supported the liver and paid special attention to the balance of sodium and potassium in the body. Gerson therapy also encourages the use of thyroid supplements containing iodine and potassium but is principally a set dietary regime.

The diet proposes fresh, raw juices of vegetables and fruits taken regularly, in conjunction with a restricted fat and salt intake, a high intake of complex carbohydrates and a low proportion of protein foods. Coffee enemas are part of the treatment and, if organic liver is available, raw liver juice is prescribed. The diet is a strict one, and the regime, which also involves counselling, demands commitment on the part of the client.

The guidelines on diet now officially recommended by governments for optimum health follow the Gerson principles, and the therapy has been shown to enhance mood and well-being, promote faster healing of wounds and relieve pain. Research supports the Gerson concept as an anti-cancer therapy, but because there is no element within it that would create profits for a pharmaceutical company, little money goes into further studies .