Side effects include: * Weight gain due to extra water retention to the muscle * Potential muscle cramps / strains / pulls * Upset stomach * Diarrhea * Dizziness One well-documented effect of<unk>  supplementation is weight gain within the first week of the supplement schedule, likely attributable to greater water retention due to the increased muscle<unk>  concentrations. A 2009 systematic review discredited concerns that<unk>  supplementation could affect hydration status and heat tolerance and lead to muscle cramping and diarrhea. Renal function A 2019 systematic review published by the National Kidney Foundation investigated whether<unk>  supplementation had adverse effects on renal function. They identified 15 studies from 1997–2013 that looked at standard<unk>  loading and maintenance protocols of 4–20 g/day of<unk>  versus placebo. They utilized serum<unk> ne,<unk> ne clearance, and serum urea levels as a measure of renal damage. While in general<unk>  supplementation resulted in slightly elevated<unk> ne levels that remained within normal limits, supplementation did not induce renal damage (P value< 0.001). Special populations included in the 2019 Systematic review included type 2 diabetic patients and post-menopausal women, bodybuilders, athletes, and resistance trained populations. The study also discussed 3 case studies where there were reports that<unk>  affected renal function. In a joint statement between the American College of Sports Medicine, Academy of Nutrition and Dietetics, and Dietitians in Canada on performance enhancing nutrition strategies,<unk>  was included in their list of ergogenic aids and they do not list renal function as a concern for use. The most recent position stand on<unk>  from the Journal of International Society of Sports Nutrition states that<unk>  is safe to take in healthy populations from infants to the elderly to performance athletes. They also state that long term (5 years) use of<unk>  has been considered safe. It is important to mention that kidneys themselves, for normal physiological function, need phosphocreatine and<unk>  and indeed kidneys express significant amounts of<unk>  kinases (BB-CK and u-mtCK isoenzymes). At the same time, the first of two steps for endogenous<unk>  synthesis takes place in the kidneys themselves. Patients with kidney disease and those undergoing dialysis treatment generally show significantly lower levels of<unk>  in their organs, since the pathological kidneys are both hampered in<unk>  synthesis capability and are in back-resorption of<unk>  from the urine in the distal tubules. In addition, dialysis patients lose<unk>  due to wash out by the dialysis treatment itself and thus become chronically<unk>  depleted. This situation is exacerbated by the fact that dialysis patients generally consume less meat and fish, the alimentary sources of<unk> . Therefore, to alleviate chronic<unk>  depletion in these patients and allow organs to replenish their stores of<unk> , it was recently proposed to supplement dialysis patients with extra<unk> , preferably by intra-dialytic administration. Such a supplementation with<unk>  in dialysis patients is expected to significantly improve the health and quality of the patients by improving muscle strength, coordination of movement, brain function and to alleviate depression and chronic fatigue that are common in these patients.
Creatine
Inositol
Beta-Hydroxy beta-methylbutyric acid
Phenylacetic acid
Choline
Phosphine
High-energy phosphate
Glycogen