Iron is essential for the formation of haemoglobin in red blood cells and hence, it's deficiency leads to anaemia. The deficiency of vitamin B1 causes a disease called beriberi, a condition in which muscles get weakened and can even lead to paralysis. Scurvy is a disease caused due to lack of vitamin C. Some of the symptoms of scurvy include bleeding gums and weakness. Deficiency of iodine causes goitre (enlargement of thyroid gland).