Although vitamin U is not technically classified as a vitamin, it is commonly referred to as “vitamin U” due to its potential benefits in promoting a healthy upper gastrointestinal (GI) mucosal lining. Vitamin U is a compound called S-methylmethionine sulfonium (MMS), a derivative of the amino acid methionine found most abundantly in raw cabbage juice. The "U" portion in "vitamin U" comes from the word "ulcers”, as MMS may be clinically relevant to individuals with peptic ulcers.

Peptic ulcers are open sores that can develop on the inner lining of the stomach (gastric ulcers) or the duodenum (duodenal ulcers). The most common causes of peptic ulcers are H. Pylori infections and the long-term use of specific medications. Peptic ulcers can lead to various complaints, including stomach pain, a feeling of fullness, bloating, difficulty digesting fatty foods, heartburn, and nausea.

MMS offers various potential benefits to support the health of the GI mucosal lining. In rodent models, it has been shown to stimulate gastric mucus production and demonstrate antioxidant properties. MMS may also be a methyl donor for various chemical reactions. 

As early as the late 1940s, Dr. Garnett Cheney's research observed improved healing of peptic ulcers in individuals who consumed raw cabbage juice. During that period, MMS was not identified and was referred to as a "green plant substance contained in raw cabbage juice." The same researcher conducted two additional human clinical studies in 1952 and 1956, both supporting the potential clinical relevance of raw cabbage juice (likely due to vitamin U) in promoting healthy healing and pain responses for individuals with peptic ulcers.

In a 2023 article, researchers assessed the effects of MMS on the quality of life and dyspepsia in patients with chronic gastritis over six months. All 37 patients with chronic gastritis (aged 35 to 60) were administered 300 mg/day of MMS chloride. Clinical results were evaluated at three and six months using the Gastrointestinal Symptom Rating Scale (GSRS), totaling up to 15 points, and assessed the quality of life using the SF 36 questionnaire.

By the third month of the experiment, a statistically significant decrease in the total GSRS score was observed, with scores averaging 9 points (p < 0.05) among all patients. By the sixth month, the total GSRS score averaged 5.5 points (p < 0.05). Regarding quality of life, patients showed improvement in physical functioning, pain responses, and social functioning by the third month. By the end of the sixth month, other indicators, such as mental health, general perception of health, and viability, had also improved.

While raw cabbage is a rich source of vitamin U, this compound can also be found in various other foods, particularly cruciferous vegetables. Although more clinical research is required to fully understand the potential benefits of vitamin U on stomach and intestinal health, it holds promise in supporting upper GI health.

By Danielle Moyer Male, MS, CNS, LDN