Lady May Mellanby, a pioneering British medical researcher, alongside her husband, Sir Edward Mellanby, conducted groundbreaking research throughout the 1920s and 1930s proving that tooth decay is heavily linked to nutrition and can be halted or even reversed through diet. In a series of controlled trials published by the Medical Research Council, Mellanby demonstrated that teeth are dynamic, living organs capable of healing themselves from within. She discovered that a diet rich in fat-soluble vitamins (specifically Vitamin D & A) and calcium stimulated the dental pulp to produce “secondary dentin”. This new layer of calcified tissue essentially builds a barrier from the inside out to arrest and seal off a cavity. She also proved that diets high in cereals and grains—specifically those containing phytic acid (like oatmeal)—could block calcium absorption and trigger rapid tooth decay if not offset by enough Vitamin D. In 1932, researchers documented the islanders of Tristan da Cunha, who had practically flawless teeth despite never using toothbrushes or practicing oral hygiene. Their diet consisted almost entirely of fish, milk, and potatoes—foods dense in the exact vitamins Mellanby championed. Mellanby’s findings sparked a massive feud with the mainstream dental establishment of her time. The dominant theory was that “a clean tooth never decays”, which placed all blame on surface bacteria and hygiene. Because drilling and filling became highly profitable, and the subsequent discovery of topical fluoride offered a simpler public health fix, Mellanby’s focus on systemic, fat-soluble nutrition fell out of the broader public consciousness. It is important to note that while Mellanby proved that early-stage decay can be successfully remineralized and arrested naturally, once a cavity breaks all the way through the enamel and creates a structural hole in the tooth, the physical structure cannot grow back to fill the empty void. Check out the comment section for the holistic protocol for early demineralization.