N-acetylcysteine (NAC), L-arginine, and acetyl L-carnitine are often taken as dietary supplements for various health benefits, but their absorption and effectiveness can depend on how they are consumed:

1. N-acetylcysteine (NAC): NAC is typically well-absorbed, but taking it on an empty stomach can sometimes lead to gastrointestinal discomfort for some people. It's generally recommended to take it with a small amount of food if stomach upset occurs¹.

2. L-arginine: L-arginine is an amino acid that is important in the synthesis of nitric oxide, a vasodilator. Absorption of L-arginine is typically effective whether taken on an empty stomach or with food, although taking amino acids on an empty stomach may sometimes enhance absorption due to reduced competition with other dietary amino acids².

3. Acetyl L-carnitine: This compound is known for its role in energy production. Similar to other amino acid derivatives, acetyl L-carnitine is often absorbed well when taken on an empty stomach, although individual experiences can vary, and some people may experience gastrointestinal side effects³.

In general, all three supplements can be taken together and may be absorbed adequately on an empty stomach, but gastrointestinal tolerance varies from person to person. If you experience any discomfort, it might be helpful to take them with a small amount of food. As always, it’s advisable to consult with a healthcare professional before starting any new supplement regimen, especially if you have underlying health conditions or are taking other medications.

Footnotes

1. Office of Dietary Supplements - NAC Information ↩

2. Office of Dietary Supplements - Arginine Information ↩

3. Office of Dietary Supplements - Carnitine Information ↩