When looking specifically at human studies, there has been a failure of creatine supplementation to induce or exacerbate kidney damage in people with amyotrophic lateral sclerosis (ALS). Subjects do not experience kidney damage for up to or over a year’s worth of supplementation in the 5-10g range. Postmenopausal women, people with type II diabetes, people on hemodialysis, otherwise healthy elderly, young people, and athletes do not experience kidney damage either. Moreover, numerous scientific reviews on both the long- and short-term safety of supplemental creatine have consistently found no adverse effects on kidney function in a wide range of doses. However, while doses >10 g/day have been found not to impair kidney function, there are fewer long-term trials using such high chronic daily intakes.
There you have it — our five favorite creatine products on the market. But when you’ve tried as many creatines as we have, there were a lot of others that we loved but didn’t make the very top of our list for the previous categories. That’s why we’ve also come up with a list of the best creatines for men, best creatines for women, best creatines for muscle growth, for bulking, for the brain, and the best micronized creatine. Keep reading for our favorite picks!
It is known that intracellular energy depletion (assessed by a depletion of ATP) stimulates AMPK activity in order to normalize the AMP:ATP ratio, and when activated AMPK (active in states of low cellular energy and colocalizes with creatine kinase in muscle tissue) appears to inhibit creatine kinase via phosphorylation (preserving phosphocreatine stores but attenuating the rate that creatine buffers ATP). While phosphocreatine technically inhibits AMPK, this does not occur in the presence of creatine at a 2:1 ratio. It seems that if the ratio of phosphocreatine:creatine increases (indicative of excess cellular energy status) that AMPK activity is then attenuated, since when a cell is in a high energy status, there is less AMP to directly activate AMPK.