With regards to supplements or nutrition that you have experienced(preferred) or observed in others.
Ill start; I was using a hair conditioner that I think was making my forehead breakout so I stopped using it and started taking fish oil again after quite a while of not using it(about a TBSP a night of which is about 3-4 grams of DHA+EPA with a 3:2 EPA to DHA ratio which was also vitamin D fortified) and the next day my forehead significantly cleared up and skin in general looked more moisturized.
I have a feeling that a low fat vegetarian/vegan diet contributes to gallbladder problems especially among women(rational for this are the women at my church who follow such a diet).