Thanks for writing this up, I just looked back at the results of a generic blood test measuring many different things I did earlier in the year and I had a creatinine value of 0.82 (the reference range was given as 0.7-1.3). I haven’t looked through the literature you cited, do you happen to know if I am already in the healthy range whether it is still helpful to be supplementing, or if it is bad to go over 1.3 if I do supplement?
Thanks, Oscar. I do not know how much creatinine one should have in the blood to maximise the cognitive benefits. From the meta-analysis of Xu et al. (2024), it looks like the optimal supplementation is an open question (emphasis mine):
Despite these limitations, the results of this study provide promising evidence for creatine as a cognitive enhancer, particularly in improving memory and information processing speed. Notably, these findings specifically support creatine monohydrate as an effective form of supplementation. This evidence offers a scientific basis for the application of creatine in cognitive enhancement and provides direction for future research. Future studies should aim to optimize creatine supplementation strategies, including exploring the optimal dosage, supplementation duration, and long-term effects, to maximize its cognitive benefits. Additionally, further research is needed to elucidate the mechanisms by which creatine affects cognitive function and to investigate its interactions with other cognitive interventions, such as cognitive training and other nutritional supplements.
It is still very early days. It is not even clear whether creatine supplementation improves overall cognitive function. Below is the forest plot of the 6 studies meta-analysed in Xu et al. (2024).
Below is a scatter plot with the effect size and daily dosage of the above studies. A positive value favours creatine. I think the legend of the horizontal axis above should have [Con] on the left, and [Cre] (creatine) on the right.
In terms of how much creatine one can take, from the systemic review of Kreider et al. (2017):
[...] There is no compelling scientific evidence that the short- or long-term use of creatine monohydrate (up to 30 g/day for 5 years) has any detrimental effects on otherwise healthy individuals or among clinical populations who may benefit from creatine supplementation.
So I assume it is fine for one to experiment with daily dosages higher than the conventional 5 g/d.
One can determine the optimal daily dosage speculating about the function describing the benefits. For my assumption that the benefits are proportional to the logarithm of 1 plus the daily dosage in g/d, the benefits in $/year are 10.6*10^3/ln(1 + 3)*ln(1 + “daily dosage in g/d”) = 7.65*10^3*ln(1 + “daily dosage in g/d”). The cost in $/year is “cost in $/year/(g/d)”*”daily dosagr in g/d”. So the net benefits in $/year are 7.65*10^3*ln(1 + “daily dosage in g/d”) - “cost in $/year/(g/d)”*”daily dosage in g/d”. The derivative of this with respect to the daily dosage is 7.65*10^3/(1 + “daily dosage in g/d”) - “cost in $/year/(g/d)”, which is 0 for a daily dosage in g/d of 7.65*10^3/”cost in $/year/(g/d)” − 1. This is the dosage for which the net benefits are maximum because their 2nd derivative with respect to the daily dosage, −7.65*10^3/(1 + “daily dosage in g/d”)^2, is always negative. For my cost of 31.7 $/year/(g/d) (= 95.2/3), the optimum daily dosage is 240 g/d (= 7.65*10^3/31.7 − 1). I think this is way too high because I am underestimating the diminishing returns of the benefits. My function implies they grow indefinitely with ln(1 + “daily dosage in g/d”), but they will eventually stagnate, decrease and become negative (harmful) for sufficiently large daily dosages, even if my assumption is a good approximation for small dosages.
Thanks for writing this up, I just looked back at the results of a generic blood test measuring many different things I did earlier in the year and I had a creatinine value of 0.82 (the reference range was given as 0.7-1.3).
I haven’t looked through the literature you cited, do you happen to know if I am already in the healthy range whether it is still helpful to be supplementing, or if it is bad to go over 1.3 if I do supplement?
Thanks, Oscar. I do not know how much creatinine one should have in the blood to maximise the cognitive benefits. From the meta-analysis of Xu et al. (2024), it looks like the optimal supplementation is an open question (emphasis mine):
It is still very early days. It is not even clear whether creatine supplementation improves overall cognitive function. Below is the forest plot of the 6 studies meta-analysed in Xu et al. (2024).
Below is a scatter plot with the effect size and daily dosage of the above studies. A positive value favours creatine. I think the legend of the horizontal axis above should have [Con] on the left, and [Cre] (creatine) on the right.
There is basically no correlation. The coefficient of determination is 0.961 % (and the slope is negligibly negative, −0.00906 d/g).
In terms of how much creatine one can take, from the systemic review of Kreider et al. (2017):
So I assume it is fine for one to experiment with daily dosages higher than the conventional 5 g/d.
One can determine the optimal daily dosage speculating about the function describing the benefits. For my assumption that the benefits are proportional to the logarithm of 1 plus the daily dosage in g/d, the benefits in $/year are 10.6*10^3/ln(1 + 3)*ln(1 + “daily dosage in g/d”) = 7.65*10^3*ln(1 + “daily dosage in g/d”). The cost in $/year is “cost in $/year/(g/d)”*”daily dosagr in g/d”. So the net benefits in $/year are 7.65*10^3*ln(1 + “daily dosage in g/d”) - “cost in $/year/(g/d)”*”daily dosage in g/d”. The derivative of this with respect to the daily dosage is 7.65*10^3/(1 + “daily dosage in g/d”) - “cost in $/year/(g/d)”, which is 0 for a daily dosage in g/d of 7.65*10^3/”cost in $/year/(g/d)” − 1. This is the dosage for which the net benefits are maximum because their 2nd derivative with respect to the daily dosage, −7.65*10^3/(1 + “daily dosage in g/d”)^2, is always negative. For my cost of 31.7 $/year/(g/d) (= 95.2/3), the optimum daily dosage is 240 g/d (= 7.65*10^3/31.7 − 1). I think this is way too high because I am underestimating the diminishing returns of the benefits. My function implies they grow indefinitely with ln(1 + “daily dosage in g/d”), but they will eventually stagnate, decrease and become negative (harmful) for sufficiently large daily dosages, even if my assumption is a good approximation for small dosages.