u/LooperActual

Vitamin A is provided in the diet in two ways: animal-sourced foods like liver, eggs, dairy, and oily fish, in which it is absorbed and used almost perfectly, and in yellow, orange, and dark green leafy vegetables like carrots, sweet potatoes, and spinach which have to undergo conversion. For both carnivores and vegan/vegetarians alike, getting sufficient amounts of these foods could be unlikely, and to further complicate matters, approximately 45% of people carry a genetic mutation (a polymorphism) in the BCMO1 gene that significantly reduces their natural ability to convert plant-based carotenoids into vitamin A.

My proposal is that all TN sufferers try to either supplement with vitamin A or eat liverwurst (liver pate) or some other way, but don't overdo it as vitamin A is toxic in higher amounts.

https://www.healthline.com/nutrition/foods-high-in-vitamin-a

Edit: a few haters have already explained how Vitamin A can't possibly be a factor but I differ. No one can explain TN causes with any degree of certainty except for a few cases when the probable cause is visible on a scan. I got TN when I was 60 so its probably not an inborn defect. Genetics plays an important role along with diet and maybe even exposure to UV, and the older you get the more susceptible to illness we become. #TrigeminalCure who proposed that it could be psychosomatic might be half right because things that stress the body like (in my case) caffeine and calcium overload also stress the brain which is trying to subconsciously control all the autonomic and hormonal functions of the body. When the brain loses control it might be TN that is the alarm bell. So a person avoiding high vitamin A foods or simply unable to convert plant sources might have stress by being deficient. There are few foods high in Vitamin A and some (like dairy) can cause problems by being high in calcium and saturated fat, two alleged to promote TN.

Edit 2: Variances in BCM01 and other polymorphisms (see below) seem to imply genetic difference between vegetarian/vegan and carnivore persuasions and show that a person choosing one or the other may not thrive, especially if one has several of these polymorphisms.

• MTHFR (Methylenetetrahydrofolate reductase): Heavily studied for common SNPs (like C677T) that affect how the body processes folate and B-vitamins. [1, 2, 3]
• FADS1 and FADS2 (Fatty acid desaturase 1 and 2): These genes regulate the conversion of plant-based omega-3s into active DHA/EPA. Variations are widespread. [1, 2, 3, 4]
• VDR (Vitamin D receptor): Responsible for processing and using vitamin D in the body. Variations strongly affect vitamin D absorption and calcium metabolism. [1, 2, 3, 4, 5]
• FUT2 (Fucosyltransferase 2): Influences the absorption of certain vitamins and dictates a person's "secretor" status (whether they secrete blood group antigens into body fluids). [1, 2, 3]
• PPARG (Peroxisome proliferator-activated receptor gamma): Works alongside \(BCMO1\) to dictate how the body processes dietary fats and vitamin A. [1, 2]
• CD36: A fatty acid and scavenger receptor that, along with \(BCMO1\), has been heavily researched for genetic variants that alter how the body absorbs and stores beta-carotene. [1, 2, 3, 4].