Vitamin B9 - Folate
Folate (vitamin B9) is a key B vitamin that is essential for making DNA, for repairing DNA, for detoxification, for making red blood cells, for mental health, for histamine metabolism, for muscle growth, and for prevention of neural tube defects. Not getting enough can lead to depression and obsessive thinking (deficiency is quite common in depression), recurrent allergies, or unexplained cardiovascular disease. Good sources of folate are liver, legumes (preferably sprouted), and leafy greens. The RDA for folate is 400 mcg DFE per day; there is some concern that doses over 1000 mcg DFE per day can cause problems. You need just the right amount!
Vitamin B1 - Thiamin
Thiamine, or vitamin B1, is the first of eight B vitamins. It is involved in burning carbohydrates (more so than any other vitamin), making ATP, supporting mitochondria, and supporting the heart and nervous system. Deficiency may be more common than we think. Thiamin can be found in high concentrations in nutritional yeast, legumes, and whole grains, and can be safely supplemented (usually in doses between 10 and 100 mg).