l carnitine choose potency L-Carnitine (500mg) Stability enhancement and formulation development

The duration of 7 weeks was chosen based on a prior human study in CFS patients showing that the greatest improvement against fatigue took place between 4 and 8 weeks (35), resulting in exclusion of 7 hypothyroidism and 2 CFS patients

So the limit seems to be about two weeks of regular use before you'd want to take a break of about two weeks

Extremely halophilic strains of Halobacterium salinarum as a potential starter culture for fish sauce fermentation

Subsequently, its oncogenic role was extended to human lymphoid and myeloid malignancies [6, 7], and to bladder [8] and pancreatic cancer [9], basal-like breast cancer [10], gliomas [11] and prostate cancer [12]

However, the dose makes the difference as a form of hormetic stress (a stressor that can be beneficial in small doses)