The time it takes for nicotinamide adenine dinucleotide supplements to work can vary depending on several factors, including individual metabolism, dosage, and the specific health goals. Some people may notice improvements in energy levels, mental clarity, or athletic performance relatively quickly after starting supplementation, while others may require more time to experience noticeable effects. In general, it's recommended to give any supplement at least a few weeks to a few months to assess its effectiveness fully. However, it's essential to remember that the effects of nicotinamide adenine dinucleotide supplements may be subtle and may not be immediately apparent. Long-term supplementation may be necessary to support cellular health and achieve desired health outcomes.