Unfortunately, many problems can arise in the blood, including: 1) Inability to carry oxygen 2) Inability to circulate oxygen and food to needed areas 3) Inability to fight off bacteria, virus, fungi, parasites, and abnormal cancer cells 4) Inability to clear or purify toxins, chemicals, and drugs Bloods inability to carry oxygen occurs commonly with certain mineral and vitamin deficiencies, especially iron and Vitamin B12.