I have not seen this but a veteran physician treating very ill insomnia patients has one woman who has been on 30,000 units of Vitamin D for four years. Her basic lab level is always in the 60's (the simple range is 30–100).
She reports that a very low level of Vitamin D will lower Vitamin B levels. And vitamin D receptors are in brainstem which controls sleep.
She also feels low vitamin D lowers the microbiome.
She reports that her full Vitamin D treatment eventually caused patients to experience body troubles. B vitamins are one solution for usually under 12 months. I would add that almost all my patients
Vitamin B treatment requires all eight B vitamins, much like playing the piano requires all fingers. However, having extra high B12 is useful.
She reports that giving only D and all Bs provided significant benefit for multiple health problems.
CoA or Coenzyme A, is highly critical to function.
Acetylcholine is only similar to nicotine and has helped Parkinsons if they smoked. And acetylcholione helps cognition,
Food is not an "optimal source of Bs," since B illnesses can exist with a traditional unchanged diet. She reports B's from the microbiome are the key. And many bacteria need certain growth factors. And not one thing.
Prebiotics == "FEED BACTERIA so they feed you." She doubts probiotics are as powerful as prebiotics. I feel both matter, and probiotics have prevented antibiotic troubles like C. diff. diff constant diarrhea, or IBS, UC, and other problems I believe.
Curiously, she suggests that if you improve, and then feel poorly, ask yourself "What is my body asking for?" I would merely add: "What is being missed?" And "What do good doctors get little training in?"
In past torture marches they were given unhulled rice, rice, rice or pure carbs. And if you only have "corn gruel," you will also need intervention. Replacing them with meat and vegetables slowly healed many of thier diseases.