A recently published study in Science Advances shows benefits of long-term NR supplementation, but also its potential undesired effects highlighting the benefits of measuring NADs. While the researchers found out that NR improved systemic NAD+ metabolism and muscle mitochondrial number, they also concluded NR did not ameliorate adiposity or metabolic health. During the study body weight and fat percentage of the subjects increased and insulin sensitivity decreased.
The study involved 20 twin pairs who were offered NR for five months. You can find the study here.