The use of malt (including rice malt) for indigestion is primarily rooted in traditional medicine, particularly in East Asian practices like Traditional Chinese Medicine (TCM). In TCM, "Mai Ya" (barley malt) and sometimes rice malt are used to aid digestion, especially for starchy foods. The rationale is that malt contains natural enzymes, notably amylase, which can help break down carbohydrates, thus easing digestive discomfort. Rice malt, produced by fermenting rice with specific molds and enzymes, similarly contains digestive enzymes and has been used as a mild digestive tonic in some folk traditions.

However, the scientific evidence supporting the use of rice malt specifically for indigestion is limited. While the presence of enzymes like amylase in malted grains is well-established, clinical trials or robust scientific studies directly examining rice malt's effectiveness for treating human indigestion are lacking. Most of the available evidence is either extrapolated from laboratory enzyme activity data or from broader studies on malted barley or enzyme supplements in general, not rice malt in particular.

In summary, rice malt's use for indigestion is mostly justified by tradition, especially in Asian cultures, with some plausible biochemical basis but little direct clinical validation. The evidence supporting its effectiveness is best described as low to moderate (level 2 out of 5), mainly due to the absence of direct clinical research.