In the body, inosine supports oxygen transportation into both cardiac and skeletal muscle cells and aids the synthesis of ATP, our main energy fuel, while also supporting blood flow. While there was a lot of hype for this nutrient in the 1990's and it continues to be studied for its energy-boosting effects, research has found it to have little if any positive effects.
Where to find Inosine
Sources of inosine include brewer's yeast and organ meats, such as heart and liver. It's also formed naturally in all human tissues, primarily in cardiac and skeletal muscle.
Why athletes use Inosine
Resistance-trained athletes sometimes supplement with inosine to boost performance, believing claims that it may improve protein use, oxygen to muscle tissues, and blood flow. Endurance athletes have also tried supplementing with inosine to potentially fight fatigue during competitions. Unfortunately, while inosine does have a key role in our bodies' ability to produce energy, there appears to be a lot more hype than hope for this nutrient. There are likely a number of more effective nutrients than this one for enhancing energy or muscle growth.
- Supposedly aid in protein synthesis to support muscle recovery
- Theoretically support energy production by regenerating the primary fuel used by muscles
- Might help encourage blood flow and transport increased oxygen to muscle cells
More about Inosine
In the early 1990's, inosine gained popularity with active individuals because it's a precursor to adenosine and thus an ATP supporter, so proponents claimed it could aid oxygen metabolism, insulin release, muscle-building capacity, as well as increasing energy and endurance for workouts. Unfortunately, much of the research on orally supplemented inosine revealed that this nutrient falls far short of its expected effects.
Inosine in the body
Inosine, a nucleoside, does play a role in the production of something known as "2,3 DPG," which is essential for oxygen transportation to muscle cells. Oxygen is, of course, necessary for energy during workouts, allowing muscles to work harder, improving strength, and promoting growth.
Inosine also supports the regeneration of ATP, which is the primary fuel our muscles use for energy. Without sufficient ATP regeneration, we become fatigued easily, and our muscles work far below optimum levels.
While inosine is an important player in our bodies' energy-producing ability, research has revealed orally supplementing with inosine doesn't improve performance for either endurance or resistance-trained athletes, but it may dangerously raise levels of uric acid, which can be especially harmful to people with gout or kidney stones.
Highly preliminary evidence has suggested that inosine may be helpful in fighting some forms of heart disease, such as heart attracts and irregular heartbeats. Some research has also suggested it may be helpful for people with the neurological disorder Tourette's syndrome. But the research in these areas is still very new, and scientists are unsure of its real potential in these cases.
There was a lot of hope for this nutrient because it is such a necessary part of our bodies' ability to produce energy. But alas, sometimes the hype is far greater than the hope, and it appears that inosine is not as effective as once suggested. Yet, more research is needed to explore its possible benefits, real applications, and even forms to discover if this nutrient has some as yet unrevealed performance potential. Still, this isn't one we're following too closely — it appears to quite simply be a dog.
Between 5,000 and 6,000 mg is reportedly typical. Some experts have recommended 5 to 10 mg per pound of lean body mass.
One dose 45 to 60 minutes before exercising, with food, is common.
Some experts suggest the most effective form appears to be inosine hypoxanthine riboside (inosine HXR).
Synergists of Inosine
Creatine monohydrate appears to increase the effectiveness of inosine.
Used with PABA, inosine may better help boost immune functioning.
Safety of Inosine
Unused or excess amounts of inosine convert to uric acid, so inosine supplementation should be avoided by those with gout or kidney disorders.
Toxicity of Inosine
No known toxicity.
Bans and restrictions
- McNaughton, L., et al., "Inosine Supplementation Has No Effect on Aerobic or Anaerobic Cycling Performance," Int J Sport Nutr 9.4 (1999) : 333-44.
- Starling, R.D., et al., "Effect of Inosine Supplementation on Aerobic and Anaerobic Cycling Performance," Med Sci Sports Exerc 28.9 (1996) : 1193-8.
- Williams, M.H., et al., "Effect of Inosine Supplementation on 3-Mile Treadmill Run Performance and VO2 Peak," Med Sci Sports Exerc 22.4 (1990) : 517-22.