Sodium deficiency occurs when a person drinks too much water or sweats too much, leading to a condition called hyponatremia, according to About.com. Hyponatremia results from low levels of sodium in the blood.
Sodium is an important nutrient needed by the body, as it maintains balance in fluid levels by working with water, potassium and chloride, explains About.com. Becoming deficient in sodium is unlikely for people who eat enough food daily, even if they avoid salt and heavily processed foods. Small amounts of sodium are found naturally in meat, seafood, vegetables, breads, milk and cheese. When a person drinks too much water, the sodium levels in his blood are lowered to dangerous levels, causing hyponatremia. Symptoms of hyponatremia include vomiting, nausea, muscle cramps and dizziness. This condition leads to shock and coma if not treated.
It takes 6 gallons of water on a daily basis to affect a healthy young adult, notes About.com. People with heart or liver kidney problems have higher risks of hyponatremia and must consult a doctor to find out the right amounts of water to drink every day.
About.com adds that it is also possible to become deficient in sodium by sweating too much, like over-exerting the body on a really hot day. This can be prevented by drinking sports drinks that contain electrolytes.