Under normal circumstances, almost no body (except perhaps people in India) makes coffee this light. If it is an -instant coffee, we have been adding only 1/8th of a teaspoon for a mug full of drink.
If you watched the coffee makers in restaurants, you could have seen them adding one and a half (1 1/2) teaspoon of the coffee powder.
Thus, anything (in this case, the coffee) in excess becomes poisonous.
Caffeine in small doses does good, but in large doses does bad to us.
Take rice for example, which is considered harmless, that we give porridge to people even when they suffer from small pox.
If you overfill your stomach with rice, you are bound to vomit. Vomiting is sickness - it is brain's way of communication - it is body language - it is a demonstration of agitation.
In this case, the vomiting is not caused by rice as such, but is caused by the excessive quantity. The same could occur even if it is tapioca or corn, or anything else for that matter. Coffee in mild dose (taken hot) in a diluted manner is very, very good.
This resembles hen's egg. If the egg is laid by a home-raised hen (which lays without any hormone treatment), and if that is eaten INTACT (i.e., white + yolk), it is very good.
One should not seperate the yolk away and eat only the white. In Nature, you would find ALL things occur in a BALANCED state.
Egg is no exception. (Before, I have eaten 60 eggs a month, and nowadays, it varies between 8 and 20 or so a month.
I purchase the "D" or "E" grade eggs in a supermarket. These are the smallest eggs laid by hens.
The "D" or "E" grade eggs are those that are hatched by a hen soon after reaching maturity, and just before being treated growth hormones.
Once the hens in the farm are treated with growth boosters, within 2 or 3 days, the eggs start becoming bigger in their sizes - C, B, or A grade.
A grade is the biggest, and they are not that good! However, in my opinion, the home-grown hen's A-grade egg may not pose any problem.
Often, people ask me if they could consume decaffeinated coffee.
The answer is: decaffeinated coffee may not be good. Removal of caffein, in my opinion again, should mean that it is a manupulated unnatural product.
Natural coffee in dilution is good. The little caffeine, in fact, may help the body to build "immunity' against whatever its overdose would do!
This is similar to Bitter Gourd (Pavakkai, Suddakkai, Agathi Keerai, etc.). All these are mildly poisonous.
If such mild and natural poisons are taken once in 10 days or so, they would build up 'immunity' to tolerate poisons.
If taken daily, the bitter-tasting Agathi keerai (Sesbania grandiflora) for instance, would definitely give you the skin disease psoriasis - no doubt about that at all!
In Siddha / Ayurvedic medicine, they suggest that this should be eaten only once in 25 days or so.
Referring to tannin that is present in tea, it is known as "iron scavenger". In other words, it spoils the iron content that may enter into our body from the food (i.e., green leafy vegetables) from getting absorbed.
As a result, a regular tea drinker would end up developing iron deficiency anemia, grey hair, erratic menses in women, headaches, forgetfulness, energylessness, indigestion, loss of appetite, slow reflex, and the like.
If a person has white skin (depigmented skin, called vitiligo or leucoderma), and if he were to take tea nonstop, it would spread rapidly, due to the loss of iron and also due to the enhanced retention of calcium.
The moral of the story appears to be that (a) nothing should be taken in excess, and (b) coffee is harmless if taken in a diluted form.
I have been drinking 3 cups of hot, diluted coffee (using instant coffee powder) daily, since 40 years or so, without any problem.