now l carnitine powder FOODS L-Carnitine Pure 3 oz 100% Pure Acetyl L-Carnitine (ALCAR)

What we do NOT know The gaps here are large enough that unknown long-term safety should itself be treated as a risk, not a green light: No long-term human safety data

Chen K, Yu Y, Wang Y, Zhu Y, Qin C, Xu J, et al

I have had this before after a long period without B12 and then too much all at once in 2017, and I did go to the hospital and had an ECG

Other General Warnings You have existing medical conditions or are taking other medications, supplements, or complementary or integrative health approaches

For the complete picture of how all five key nutrients work together, see our guide: RunStrong Daily Supplement for Runners: A Complete Guide.