Some individuals have a genetic mutation which prohibits the proper absorption of Vitamin B. This leads to a general lack of energy, premature aging, and eventually chronic disease. Some people complain of cognitive issues including inability to focus and even depression or anxiety. Intracellular MTHFR is designed specifically for this individual who is heterozygous or homozygous for the C677T or A1298C and is under-methylating (has little or no COMT or MAO) and needs more methylation support. Dr. Crozier recommends this supplement for his patients whose DNA has been tested and who have this specific glitch in their DNA, and also for patients who take a Vitamin B but with no positive health benefits.