1. Organic Acid
Ume contains organic acids such as rich citric acid, apple acid, amber acid and crude acid. The concept "Ume is good for your body" is related to how these organic acids function. Organic acids are effective for constipation and diarrhea because they normalize the function of the intestines by sterilizing only low-density lipoprotein, leaving high-density lipoprotein in place. Ume plums contain more citric acid than lemons and other food products. This allows the ume to powerfully activate metabolism and to lift fatigue and lactic acid from the body. Therefore, ume plums are recommended in summer because they can help prevent weariness from the heat of summer. The citric acid also helps with the fixing and absorption of calcium, which is often difficult for the body to absorb. The reason pregnant women often crave something sour early in pregnancy is because of an instinctive need for citric acid, which heightens the calcium fixing rate for forming the skeletal structure of an embryo. Citric acid also controls the secretion of gastric juice; it helps prevent stomach ulcers and helps stimulate the appetite of weak or elderly persons.

2. Sterilizing Effect

Normally the bacteria coming from the mouth are killed by the hydrochloric acid in the stomach. A healthy person's stomach is always acidic; therefore, the bacteria which cause food poisoning and other troubles are killed in the stomach. However, when the stomach is in a weak condition or secretion of gastric juice is not working smoothly due to overeating or drinking, the bacteria go through the stomach and reach the intestines alive. Umeboshi is known for its 功效 in such cases.

Organic acids in ume plums make the intestines temporarily acidic which prevents the live bacteria from increasing in number. After being absorbed through the wall of the intestines the organic acids become alkalized and enter the blood stream to maintain alkalized blood. With the help of this sterilizing effect, people have used Umeboshi as an ingredient inside rice balls and other foods for preservation.