The Main Causes of Varicose Veins Lack of exercise,  being over-weight, high cholesterol,  poor nutrition which leads to constipation, lack of Vitamin C, E,  Calcium and Magnesium, and alcohol and tobacco use are  some of the main causes of varicose veins. Lack of exercise causes poor circulation, which can lead to varicose veins. Constipation puts pressure on the veins, especially those in the legs and in the groin area. Sometimes, an injury can predispose a person to getting varicose veins. Prevent Varicose Veins By Getting Enough Exercise. Walking, swimming, dancing, cycling, are all good for the legs and improve the circulaton. Such simple exercises as ...