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.
There are related points of what people believe and their consumption of certain items. Core traditionalists with herbal practices detests some certain modern foods. Most traditionalists hates indomie noodles and other junk foods and prefer the native foods.
I know about people who don't take minerals because of their chemical, acidic and gastric contents, they prefer water . Christains does not have such belief systems that coordinates what they consume.
A good example is the herbal method of healing which Christains believe to be fetish so, they resort to consuming chemical and acidic medicines that affects their being.