Brother Paul (whose letters constituted a large portion of New Testament of Bible) was brought up a Pharisee (a religious sect in Jesus' time). He was taught all the physical rules of hygiene in the Bible, e.g. touch no unclean thing, touch no dead-body/bones/graves, .... Later he became a Christian, because Jesus' love moved him. He became a preacher, but he taught none of these rules of hygiene to others.
I was brought up differently, with no religion. I became a Christian at 16 after reading Sermon on the Mount, and I love LOVE. I read brother Paul's letters, and all the more I was moved by LOVE. I still remember how I loved [1 Cor 13:4-7].
I read the Old Testament, and I thought the old rules of hygiene primitive : we have advanced medical knowledge and practices now ! and I forgot them after reading them.
I ate a lot of pork then (LORD : eat no fat nor blood. eat no unclean animal), which contain a lot of fat. Over the years, my brain function deteriorated, I simply couldn't use my brain as effectively as when I was young ! and my appetite got worse. In short, my vitality became very, very poor.
Once I sat on a dead man's grave (LORD : touch not dead body, dead man's bone, nor grave. If accidentally touched them, cleanse with water of impurity on the 3rd and 7th day), and became ill for a week.
Once I travelled abroad, and the first day I was there, I had a temperature (LORD : touch not unclean thing. After touching such, should take a bath before the sun goes down). I must have touched some unclean things (virus, bacteria, I was unaccustomed to ?) Then I quickly took a bath, and my temperature receded the next day.
I used to work very hard at youth and rarely took rest (LORD : rest one day every 7 days, rest one week every 6 months, rest one year every 6 years (simplified ! All LORD's words have been simplified here for brevity, please read the first 5 chapters of Old Testament for more details.). But my body would make me rest by making me ill, and I became sick often after a few weeks' hard work.
My attitude is changed now! I learned the value and simplicity of LORD's rule of hygiene, and my vitality returns to me. I have taken no medicine for the past 16 years ! and even though in these 16 years, I became sick on many occasions, but mostly I recovered without taking any medicine in a week (how wonderful it is usually one week, at worst 2 weeks, not one day, nor two days!), and even though I felt I had a temperature, my body vitality remained as usual and I could work as usual ! (except for very severe illnesses, I did not need to take rest.)
When I view TV and see how people suffer kidney failure (probably they have eaten those "unclean food" taught to us by LORD), and have to undergo transplant, or old people moving over the border from USA to Canada to buy cheap medicine, and have to take several pills a day, and poor body vitality, I feel sorry that no one would teach LORD's rules of hygiene to them.
The apostles told us that we do not have to obey those commandments now [Acts 15:29], except "eat no blood/strangled animal/food sacrificed to idols, plus no unchastity", but that doesn't mean all LORD's rules of hygiene are worthless. They only meant NOT to weary us ! Therefore we have much freedom in obeying them. e.g. in some urgent situations when I simply cannot take a bath, I take a towel and a bowl of water and clean myself.
It is always that people move from one extreme to another extreme, and rarely sit down and consider the values of both side. Before Jesus, those bodily rules were taught, after Jesus, none of them are taught.
I think we should care about both "spiritual" and "physical" aspects of LORD's words.
[1 Cor 13:4-7] : Love is patient and kind; love is not jealous or boastful; it is not arrogant or rude. Love does not insist on its own way; it is not irritable or resentful; it does not rejoice at wrong, but rejoices in the right. Love bears all things, believes all things, hopes all things, endures all things.