Everyone is obsessed with vitamin D, but it is only one of the essential vitamins your body needs in a day to function optimally and boost immunity. Even if you eat a perfect diet full of healthy plant-based protein, complex carbs from fruits and vegetables, legumes, and whole grains, and heart-healthy fats from nuts, seeds, and a small amount of oil, you may have a hard time getting all essential daily vitamins and nutrients your body needs to function at its optimally healthy level, says Mastaneh Sharafi Ph.D., a nutrition scientist and Registered Dietician. Follow the "Food First" approa...