What is the halakhic response regarding the need to protect one’s health? For example, some foods, including non-organic foods, animal foods and dairy products with hormones and antibiotics in them, and genetically-engineered foods, may be considered to be unhealthful. Is there an obligation not to eat these foods, or to avoid unhealthful environmental practices that may cause damage to our health?
According to the majority of later halakhic authorities and some early halakhic authorities the following two verses in the Torah, “Only take heed and watch yourself very carefully…” (Deuteronomy 4:9) and “Watch yourselves very carefully…” (Deuteronomy 4:15) are the source for a negative Torah commandment regarding the protection of one’s life from life-threatening circumstances, things and people. According to one such early authority, the [medieval] Sefer Hahinukh, this commandment extends not only to the obligation to protect oneself from things that can end one’s life but as well to things that can damage one’s life and body.
We will now examine two different Talmudic precedents as further expressions of the Torah law to protect oneself from damage to one’s life and body:
“Our Rabbis taught: there was an incident with a pious Jew, that he was praying on the road. A ruler came and greeted him and he did not respond to his greeting. The ruler waited till he finished praying, and after he finished praying, he said to him, “Empty one! Is it not written in your Torah, ‘Only take heed and watch yourself very carefully?’ Is it not further written, ‘Watch yourselves very carefully?’ When I greeted you why did you not respond to my greeting? If I would have chopped off your head with a sword, who would demand an accounting of your life from me?'” (Talmud Bavli Berakhot 32B)
In [the Talmud] Shavout 36A we have a source that confirms that we can rely on this ruler’s quotations and understanding of Torah verses. “Rabbi Yannai says, all agree [that if a person curses himself he transgresses a negative Torah commandment] as it is written, ‘Only take heed and watch yourselves very carefully.'” The sages thus had a tradition that these verses quoted by the ruler applied to the law of protecting one’s life.