Serum L Carnitine Levels Are Associated With First Stroke in Chinese Adults With Hypertension Stroke If you are like a lot of people, you may have never heard of carnitine but this important nutrient is critical for our body's ability to optimally burn fat required for energy. The adverse effects of long term l carnitine supplementation on liver and kidney function in rats L Liu, D M Zhang, M X Wang, C Y Fan, F Zhou, S J Wang, L D Kong, 2015 L carnitine levels decrease with age, contributing to aging and a decline in mitochondrial function. The list doesn't stop there. L carnitine supports: Joint health L carnitine has been shown to support joint comfort