Alcohol abuse or alcoholism can cause a decrease in a white blood cell (WBC) count, according to Dr. Sears. A reduction in white blood cells can affect the immune system because white blood cells help to defend the body against infections caused by different pathogens, such as bacteria and viruses.
Alcohol intake can rob the body of important nutrients needed for a healthy immune system, and it can also interfere with WBC production. Excess alcohol can also affect the specific white blood cells that fight cancer cells in the body.
Although excessive alcohol consumption is one factor that can lower the WBC count in the body, there are medical conditions that can also affect this count, such as lupus, cancer, infections caused by a virus or bacteria and cancer treatments, states the National Institutes of Health's MedlinePlus. A problem with the spleen can also cause a decrease in WBC count, reports eMedicineHealth.
There are different kinds of white blood cells, which are also known as leukocytes. Some leukocytes are basophils, neutrophils and eosinophils. A low WBC count is less than 4,500 per microliter. This medical condition is referred to as leukopenia.