If you are preparing to pursue a degree in public health, you may major in whatever you choose. Take courses across a range of disciplines that are relevant to your interests, and begin to explore programs in public health early in your college years to form a comprehensive academic plan. The individual programs will provide some guidance on how their applicants can be best prepared. All aspiring students of public health should build strong oral and written communication skills. A great list of health-related courses across the Five Colleges is available from the Five College Program in Culture, Health and Science.
More information about public health programs and their requirements is available on the ASPPH Program Finder. The ASPPH's page on All Areas of Study within public health is a good resource for learning more about public health academic and professional concentrations.
Biostatistics programs generally require college mathematics, including Calculus III and Linear Algebra. Programs may also expect some background in computer programming, statistics, and/or biological sciences. Prerequisite information from a small sampling of biostatistics programs is available here.
Environmental Health Sciences programs may require, at minimum, one year each of biology and chemistry. Physics, biochemistry, calculus and/or statistics may also be required.
Health Policy & Management programs may look for coursework in economics, accounting, business administration, or public policy.
Most programs in public health do not have set lists of prerequisite courses. Instead, they look for background in the areas most relevant to their particular area of focus.