Beta-D-ribofuranose and It’s Affects On Adenosine

Ribose – Supplement Profile

Many supplements have come and gone over the years. Some of them come with a lot of fanfare and others just sort of arrive on the scene taking people by surprise. Ribose is one of those supplements that has just sort of appeared on the scene. This has left a lot of people wondering, “What the heck is ribose and why should I take it?” If you don’t know what a supplement is, you certainly won’t be able to take advantage of it. Now, don’t get your shorts in a twist over ribose, Muscle Monthly is here to clear things up for you.

Ribose is a naturally occurring 5-carbon sugar called a “pentose”. It is active in many biological systems, usually in its D-form (the L- form is its mirror opposite). D-Ribose plays an important role as a structural component of high-energy phosphates such as adenosine triphosphate (ATP) as well as nucleic acids like DNA. As you can guess, ribose is a major player in maintaining every system and tissue in your body.

When we consider taking ribose as a dietary supplement, we are mainly focusing on its role as a substrate in ATP production. Before we get into that, let us first consider the importance of ATP in exercise and sport performance.

ATP is called a high-energy phosphate. ATP is used in all cells of the body and is often called the “energy currency” of living cells. It can be reversibly converted to ADP. This conversion releases energy that can be used by the cell to carry out any number of reactions including protein synthesis and muscle contraction.

ATP exists in “pools” within cells. This simply means that there is a ready-made supply floating around in the cell, ready to be utilized. The pool of ATP in cells is relatively small, yet stable. In many cells, ATP utilization is a slow process and those cells have no trouble keeping up with demand. However, muscle cells are quite different. During muscle activity like sprinting, ATP is utilized at an extremely fast rate. In fact, during a typical sprint, the entire intramuscular pool of ATP would be used up in as little as 2 seconds flat. If it weren?t for systems such as the creatine phosphate (CP) system in place to “regenerate” ATP in real time, you would literally stiffen up with rigor mortis shortly after stepping off the starting blocks.

We know that high intensity exercise puts a strain on your muscles? ability to meet ATP demands. In addition, there is some evidence that repeated bouts of high intensity exercise, such as the exercise that bodybuilders typically undertake, can lead to lower levels of ATP which can take days to return to baseline (Hellsten-Westing Y, Norman B, Balsom PD, Sjodin B. Decreased resting levels of adenine nucleotides in human skeletal muscle after high-intensity training. J Appl Physiol 1993 May;74(5):2523-8). In this study by Hellsten-Westing and colleagues, 11 male subjects (group A) performed high-intensity intermittent training on a cycle ergometer three times per week for 6 weeks, followed by 1 week of the same kind of training with two sessions per day. Nine males (group B) exclusively performed 1 week of training with two sessions per day. In group A, skeletal muscle high-energy phosphate levels decreased 12% over the 6-week period. In group B, the intensive week of training reduced high-energy phosphate levels by nearly 25%! These levels remained low after 3 days of rest. A similar study later performed by Stathis and colleagues confirmed these findings using sprinting as the form of exercise. (Stathis CG, Febbraio MA, Carey MF, Snow RJ. Influence of sprint training on human skeletal muscle purine nucleotide metabolism. J Appl Physiol 1994 Apr;76(4):1802-9)

As many of you may know, I’m a stickler for research when it comes to evaluating the value of a particular supplement. Until recently, there simply hasn?t been any relevant research relating to exercise and ribose supplementation. Previously, ribose has been shown to preserve ATP levels in heart muscle, protecting it from the devastating effects of ischemia (lack of oxygen), but there wasn’t anything specifically about exercise. Now the studies using healthy subjects are coming to light.

In a study by John Berardi and colleagues, 8 men were supplemented with 4, 8-gram doses of placebo or ribose over 3 days and performed 10-second cycle sprints in order to assess performance. Now the whole point of this study was to see whether ribose supplementation would affect anaerobic performance. Ribose appeared to increase peak and average power in the cycle sprints performed by these subjects, with a greater effect seen during repeated sprints. Berardi has indicated that they are currently trying to confirm these results with a larger group of subjects.

So, is ribose increasing ATP pools in healthy subjects? No one can really be sure at this point. Considering ribose’s effects on other tissues such as the heart, it is not unreasonable to speculate that ribose is indeed enhancing ATP levels during intense exercise.

If you choose to give ribose a try, keep in mind that although ribose has not been shown to cause any side effects, oral doses of more than 200 mg/kg/h caused diarrhea (Gross M, Reiter S, Zollner N. Metabolism of D-ribose administered continuously to healthy persons and to patients with myoadenylate deaminase deficiency. Klin Wochenschr 1989 Dec 4;67(23):1205-13). For a 220-pound guy, that?s 20 grams an hour. So if your going to use it, start with about 3-5 grams at a time and work up from there, if necessary.

Before I close, I must stay true to form and give you a little tidbit of information that you might not have thought about. There are some beneficial adaptations to exercise that actually seem to require a reduction in ATP levels. One of the most important ones is the increase in insulin sensitivity and/or glucose uptake into muscle cells after training. Studies have shown that if you artificially maintain ATP levels during the initiation of a high intensity exercise program, you don’t get the up-regulation of glucose transport into muscle cells. Let me qualify these statements by saying that these studies were done on animals, and that ATP levels were maintained by means other than ribose supplementation. Nevertheless, these studies should tell the discerning supplement consumer that ribose might be better for performance rather than muscle growth.