I will not agree with your points and the topic "herbalists live longer than Christians" people life and health doesn't depend on their believe neither their religion, Christians no longer get fooled with certain believe like this and taking good care of your health that's what really matters.
Same herbalist can depend on natural herbs and will still die so religion  doesn't give full guarantee over a person lifespan.
You made mention of science and man made food but food and medicine are meant for good purpose like preservative etc, just imagine a world without science. Christians do live long and sometimes live longer compared to heberlist.