Uridine, a nucleoside, contains an uracil attached to a ribose ring (known as a ribofuranose) via a β-N1-glycosidic bond. If uracil is attached to a deoxyribose ring, it is known as a deoxyuridine.

Uridine(CAS.NO:58-96-8) is a crystalline pyrimidine nucleoside C9H12N2O6 that is composed of uracil attached to ribose, that is derived by hydrolysis from nucleic acids, and that in the form of phosphate derivatives plays an important role in carbohydrate metabolism.

Uridine is one of the four basic components of ribonucleic acid (RNA); the other three are adenosine, guanosine, and cytidine. Some foods that contain uridine in the form of RNA are listed below. However virtually none of the uridine in this form is bioavailable, since – as shown by Handschumacher’s Laboratory at Yale Medical School in 1981  – it is destroyed in the liver and gastrointestinal tract, and no food, when consumed, has ever been reliably shown to elevate blood uridine levels. In infants consuming mothers’milk or commercial infant formulas, uridine is present as its monophosphate, UMP, and this source of uridine is indeed bioavailable  and enters the blood.

*Sugarcane extract

*Tomatoes (0.5 to 1.0 g uridine per kilogram dry weight)

*Brewer’s yeast (1.7% uridine by dry weight)

*Beer

*Broccoli

*Offal (liver, pancreas, etc.)

Consumption of RNA-rich foods may lead to high levels of purines (adenosine and guanosine) in blood. High levels of purines are known to increase uric acid production and may aggravate or lead to conditions such as gout. Moderate consumption of yeast, about 5 grams per day, should provide adequate uridine for improved health with minimal side effects.

Note: It has been suggested that the RNA content of yeast products should be chemically reduced if these products are to be consumed in high amounts (50 grams or more per day) as a source of protein. However, such processing is expensive and, as of 2008, commonly available brewer’s yeast products were not RNA-reduced.

Beer seems to be a great source of uridine, relatively speaking,

Whereas a significant DNA and RNA content (possibly indicative of some Uridine content) has been noted in.

Liver (Pig and Beef) at 2.12-2.3% for beef and 3.1-3.5% for pig (RNA) and 1.7-2% for beef and 1.4-1.8% for pig (DNA); all dry weight

Pancreas, the largest source of RNA at 6.4-7.8% (pig) and 7.4-10.2% (beef)

Lymph Nodes, the largest source of DNA at 6.7-7.0% (pig) and 6.7-11.5% (beef)

Fish at 0.17-0.47% (RNA) and 0.03-0.1% (DNA), with Herring having the highest RNA at 1.53%

Baker’s Yeast (6.62% RNA, 0.6% DNA)

Mushrooms; Boletus at 1.9-2.4% RNA, Champignon at 2.05% RNA, and Chestnut at 2.1% RNA all with minute (0.06-0.1%) DNA

Broccoli at 2.06% RNA and 0.51% DNA

Oats at 0.3% RNA with no detectable DNA

Chinese Cabbage, Spinach, and Cauliflower with similar levels at 1.5% RNA and 0.2-0.3% DNA

Parsley at 0.81% RNA and 0.27% DNA

Organ meats and, surprisingly, Cruciferous vegetables appear to generally have a high RNA and DHA content which insinuates they have a Uridine content

Ingestion of beer at 10mL/kg can increase serum Uridine levels 1.8-fold, which is similar levels at supplemental intake of the same uridine dosage (0.05mg/kg); Alcohol content does not influence absorption and urinary levels of Uridine increased by similar degrees. Uridine in beer does not appear to be causative of the increases seen in Uric Acid after beer consumption,and inhibiting Uric Acid synthesis with Allopurinol does not appear to influence the serum levels of Uridine achieved via beer.

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