Philosophy in the strict sense means love of wisdom. Wisdom is classically taken to mean the knowledge of the highest causes, by which a wise person can judge and measure inferior causes. That can't possibly be bad for you as a whole, as this definition entails that you need wisdom to choose what's good for you. Without a standard by which you can choose wisely, the best you can do is choose good by accident, and you'll probably not even recognize it as good (indeed, you may think instead that an evil was actually a good and vice-versa).
And, of course, it depends on what you mean by health. Just like the human body can destroy parts of itself for the sake of the whole (e.g. apoptosis, which when failing can cause cancer), if there are aspects of humanity over and above the body - the soul - then choosing good doesn't always guarantee your bodily health. For example, it could be that starving is better than acquiring food immorally. Your body won't be very well off and for that reason such a choice could be said to be "unhealthy", but the "health" of your soul will be guaranteed, and if the latter truly is more important then you can be said to be better off this way, which is not too dissimilar from undergoing chemotherapy or amputating a gangrenous limb. This is why Socrates preferred to die than betray his principles by escaping from prison.
Much of modern "philosophy", if not almost the entirety of it, has been more like anti-philosophy than philosophy per se. When you effectively deny that wisdom is possible (for example, by arguing that "good" or "truth" are illusions or that human reason itself is never justified) you're undermining the whole point of the philosophical enterprise. If you try learning philosophy only from authors of the past 500 years it's likely you'll only end up further from wisdom than when you started - as you yourself seem to be noticing from the hesitance in taking them seriously enough.
Since the modern world began in the sixteenth century, nobody’s system of philosophy has really corresponded to everybody’s sense of reality; to what, if left to themselves, common men would call common sense. Each started with a paradox; a peculiar point of view demanding the sacrifice of what they would call a sane point of view. That is the one thing common to Hobbes and Hegel, to Kant and Bergson, to Berkeley and William James. A man had to believe something that no normal man would believe, if it were suddenly propounded to his simplicity; as that law is above right, or right is outside reason, or things are only as we think them, or everything is relative to a reality that is not there. The modern philosopher claims, like a sort of confidence man, that if once we will grant him this, the rest will be easy; he will straighten out the world, if once he is allowed to give this one twist to the mind.
-- G.K. Chesterton, "Saint Thomas Aquinas"
The examples of "philosophy" which you provided will surely be bad for you one way or another, even if only by making you a little insaner. Good philosophy, however, can only make you better, even if at the expense of lower goods. If you truly want to learn what philosophy has in store for you, I recommend The Consolation of Philosophy by Boethius.