While there certainly can be physical causes of sickness that can be addressed in the physical realm, we see continually throughout the history recorded in the Bible that sickness is often the result of a spiritual problem: our sin. If the cause is spiritual, the solution and the healing are spiritual also. Seeking physical remedies will not result in healing if the problem is a spiritual problem.
Physical illness is a reflection ultimately of a spiritual problem. To find optimal physical health, we need to understand the spiritual principles involved with our physical flesh which is marred by sin.