Mustard oil is an excellent source of vitamin D. It helps maintain calcium and phosphorus levels. This vitamin increases immunity, improves the functioning of the thyroid gland, is able to prevent the development of cardiovascular and skin ailments. Of the fat-soluble vitamins in the oil, there is also vitamin E. Having anti-inflammatory, immuno-strengthening, rejuvenating and wound-healing properties, this vitamin lowers cholesterol, regulates blood clotting, strengthens the walls of capillaries and blood vessels.