Do my philosophical beliefs affect my health?

Absolutely, as all treatments have a placebo effect, all beliefs and expectations have a placebo effect. A placebo effect is a result of a belief or expectation. Philosophical beliefs are core beliefs or core expectations and are therefore particularly influential. They have a strong placebo effect.

If you believe you or your body are in any way tainted, that has a broad detrimental effect. If you think you are an accidental product of savage evolution that also hurts you across the board. Those beliefs have a placebo effect in the body. Those beliefs manifest physically in your body and in your life.