EDIT: scroll down towards the bottom towards the bottom for my answer. Its thoracic outlet syndrome. If I do certain stretches it goes away. Its an issue related to my bad posture and nerves getting pinched (from sitting in front of a computer the whole day)
OLD
I have mild Raynauds, which means the tips of my fingers are usually the same temperature as the atmosphere of the room/outside. (unrelated: I don't have any autoimmune disease, but I think this is from typing my whole life)
Anyways, I started to notice that when I chew this gum called "NeuroGum" found on Amazon, my fingers warm up. I'm very curious, what ingredient(s) could be causing my hands (finger tips) to warm up. Here is the list of core ingredients, (copy+pasted from amazon)
Ingredients Sorbitol, gum base, L-theanine, Natural Flavors (Vanilla and Mint), Natural caffeine, Calcium Stearate, Steviol Glycosides, Acesulfame K, Vitamin B6 (as Pyridoxine), Vitamin B12 (as Cyanocobalamin) note:its "Vitamin B12 (as Methylcobalamin)" on my gum
The only other thing that has similar effects is alcohol. I've tried buying the (same form of) b12 and b6 and l-theanin supplements and trying those separately/individually. This has not shown any success, (although I'll keep trying)
EDIT: one more ingredient that i've noticed ALWAYS makes my hands warm is melatonin, (sleeping aid). Specifically this brand of mouth dis-solvable ones. "NATROL® MELATONIN ADVANCED SLEEP MAXIMUM STRENGTH 10 MG." I've also tried chewing caffeinated gum without any success