research Determination of Vitamin B3 Vitamer (Nicotinamide) and Vitamin B6 Vitamers in Human Hair Using LC-MS/MS 7 citations, July 2021 in “Molecules/Molecules online/Molecules annual” The method can measure vitamin B3 levels in human hair accurately.
research A Non-Invasive Hair Test to Determine Vitamin D3 Levels 4 citations, May 2021 in “Molecules” The hair test for vitamin D could be a useful alternative to blood tests, providing a longer-term vitamin D status, but more research is needed.