The trial participants were given a steadily increasing dose of niacin, starting at 250 mg/day to 750-1000 mg/day over a 4-month period, then a 10-month follow-up treatment period. The participants were organized into a study group of individuals with mitochondrial myopathy and a control group of healthy age-matched people consisting of two healthy people for each patient with mitochondrial myopathy. All the study participants were placed on the same niacin supplementation regimen.
Source: https://www.lifespan.io/news/niacin-increases-nad-significantly-in-human-trial/The researchers report that niacin treatment increased muscle NAD+ levels by 1.3-fold at 4 months and 2.3-fold after 10 months in the study group. The control group saw no increase of NAD+, suggesting its levels are highly controlled in skeletal muscle tissue and will only increase in patients suffering from lower than normal levels of NAD+ experienced in conditions such as mitochondrial myopathy and potentially aging which also effects mitochondrial fuction. This is also important, as prior to this study, it was unknown if niacin supplementation improved NAD+ in muscle or if it is filtered out and simply elevated NAD+ in the liver.
The level of whole blood NAD+ was also increased by supplementation by 7.1-fold in the study group and 5.7 in the control group after 4 months compared to the participants’ baseline. At the 10-month mark, the increase was 8.2-fold compared to the baseline. This shows that niacin supplements are not simply filtered out by the liver; in fact, they reach the bloodstream in significant amounts to elevate NAD+ levels there.
Niacin supplementation also appears to improve body composition. Participants saw a decrease in whole-body fat percentage in controls and increased muscle mass in both the control and study group. After 10 months of niacin supplementation, the patients demonstrated improved muscle strength.
The researchers also observed that hepatic fat was halved and visceral fat was reduced by a quarter. These types of fat deposits are both linked to an increased risk of metabolic syndrome. So while the niacin had no effect on the surface fat around the body, it did impact significantly on the unhealthy fat surrounding the organs.
Finally, niacin has been linked to increasing blood glucose levels, a risk factor for developing conditions such as diabetes. The results of the study showed that niacin did increase fasting glucose levels in both study and control groups following 4 months of supplementation. However, glycosylated hemoglobin, which reflects long-term glucose levels, was not affected.