Uridine is used in the synthesis of RNA. When taken as a supplement it provides a range of nootropic benefits and enjoys strong synergy with Choline.
What Is Uridine?
Uridine is an important building block used to create RNA. It can be found in many dietary sources such as Broccoli, Beer, and Tomatoes. Recently, studies have revealed that Uridine does, in fact, carry nootropic properties. Studies have shown that it works in synergy with Choline to help improve memory, improve fluid intelligence, and fight forms of dementia.  Other studies show that it can work in synergy with EPA/DHA omega-3 fatty acids to act as an anti-depressant.
Uridine Dosage Information
Regretfully, there is little information on a standard dosage for Uridine. Most studies have been conducted on animals, and the scaled dosage to humans is hard to pinpoint. I would suggest following the instructions on the specific supplement you purchase.
However, I know many of you will be buying in bulk. Brewers yeast is a dietary source of Uridine at a 3% concentration. The recommended dose for this supplement is 20g. If you were to do the math, that’s 3% of 20,000mg or 600mg. My suggestion would be to start at 300mg per day and work your way up. It’s also important to note that the supplement you purchase may be a different percentage of Uridine, so you will have to adjust accordingly.
How Does Uridine Work?
Uridine increases the synthesis of brain phosphatidylcholine (PC). In fact, one study concluded that administration of Uridine and Choline may increase PC levels by up to 45%  This is important because PC is a very important part of your cell membranes. If your brain runs out of choline it begins to eat away at the PC component of your cell membranes. This can be problematic because the PC plays a crucial role in your cells ability to govern its basic activities and regulate enzymes.  In other words, if a cell loses its PC, it can’t function properly.
Uridine is converted to CDP Choline in the brain. . This increases the synthesis of Acetylcholine (ACh). ACh is a key neurotransmitter involved in synaptic plasticity. Synaptic plasticity refers to your brain’s ability to form, strengthen, weaken, or destroy connections between neurons. To be stated simply, the more synaptic your brain is, the greater your working memory is. The greater your working memory is, the greater your fluid intelligence is. 
Increases production of neurites.  A neurite is any projection of from the cell body. These “projections” can be either axons or dendrites. Axons are where signals leave your neurons and dendrites receive those signals.(Though it has recently been discovered that dendrites may release signals as well.) In other words, more neurites mean your brain can make more connections. More connections lead to improved cognitive abilities.
Increases levels dopamine in the brain.  Dopamine is the key neurotransmitter involved in the reward and pleasure center of the brain. Higher levels of dopamine improve your motivation and give you more energy. Simply stated, it is easier to sustain attention on a particular task. This could also be one of the causes for Uridine’s anti-depressant properties. 
Safety and Side Effects of Uridine
Uridine is considered a relatively safe nootropic and shouldn’t present any problems if taken properly. In one study conducted to view the effects of uridine treatment on HIV lipoatrophy, 165 participants were given supplementation the contained uridine for 48 weeks. Only three of the participants dropped out of the trial due to diarrhea. The study stated that “Uridine was well tolerated”.  Thus far diarrhea is the only reported side effect, and this side effect did not persist when doses were stopped.
There is also evidence to suggest Uridine may lower levels of Vitamine B12.  This can easily be avoided by taking vitamin B12 supplements and B9 supplements.
Below are some of the most commonly asked questions about Uridine.
4. Kanno K, Wu MK, Agate DA, Fanelli BK, Wagle N, Scapa EF, Ukomadu C, Cohen DE (October 2007). “Interacting proteins dictate function of the minimal START domain phosphatidylcholine transfer protein/StarD2.”. J. Biol. Chem. 282 (42)
6. Dietary supplementation with uridine-5′-monophosphate (UMP), a membrane phosphatide precursor, increases acetylcholine level and release in striatum of aged rat. Brain Research. Volume 1133, Issue 1, 16 January 2007, Pages 42-48.
10. Chronic administration of docosahexaenoic acid or eicosapentaenoic acid, but not arachidonic acid, alone or in combination with uridine, increases brain phosphatide and synaptic protein levels in gerbils. Neuroscience 148 (2007) 421–431