In theory, you can apply to medical school with almost any major, as long as you meet the minimum requirements. However, medical schools do expect applicants to perform extremely well in science courses. The smaller the number of science courses, the more weight that each individual science course carries.
Most students interested in medicine major in the sciences because their natural interest lies in this area and the course requirements for medical school and a biology or chemistry major strongly overlap. Nationwide, approximately 60% of people in medical schools have biology degrees, 25-30% have chemistry or engineering degrees, and the remaining 10-15% have humanities and social sciences degrees.