Ill Effects

The ill effects of excessive tea drinking - the "tea habit " - are referable to its action on the digestive and nervous systems and are cumulative. If taken in large quantities with meals, tea precipitates the digestive ferments, retards the activity of digestion, and may even occasion gastric irritation and catarrh. Constipation usually results, though there is sometimes diarrhoea, and more or less flatulency. The latter may itself cause insomnia. The effect of the "tea habit " on the nervous system is to overstimulate and then depress it, first producing restlessness, worry, and insomnia, and finally muscular tremors, sensory disturbances, and palpitation. Persons who are subjected to some unusual strain or anxiety find that tea for the time being disagrees with them, whereas they are able to drink it regularly when in ordinary health. Cheap teas are always much more apt to produce ill effects than the more expensive varieties. In many persons five cups of strong tea per diem produce symptoms of the "tea habit".

Indian teas contain a larger proportion of tannin than do those from China. For this reason they are more likely to produce disorders of digestion and constipation. They also occasion nervousness and sleeplessness to a marked degree when drunk in excess.

The ill effects of poor tea and of tea rich in tannin can be overcome in some degree, as suggested by Roberts, by the addition of carbonate of sodium in the proportion of ten grains to the ounce of dried tea leaves; this does not materially interfere with the taste.

When tea taken with milk and sugar is found to disagree, substitution of the juice of a slice or two of lemon makes it acceptable and beneficial to many persons. Tea which is "steeped " is more unwholesome on account of the extra tannin, etc., which is extracted.

Tea must be avoided in dyspepsia, gastric irritability from any cause, constipation, anaemia, insomnia, and "nervousness," and usually in gastric catarrh, although Bauer recommends weak tea as less likely than coffee to induce heartburn or aggravate diarrhoea. The ill effects of the "tea habit" are even more pronounced in children and youth than in adults.

A case of multiple neuritis caused by drinking between two and three pints daily of strong tea has been reported by Spratling, and several similar cases are recorded.

In a recent report upon insanity in Ireland tea is mentioned as a contributing factor. A very poor quality is there used, and it is often stewed nearly all day, water being added from time to time. This report continues: "Undoubtedly the method of preparation adopted and the excessive use of this article of diet, now so general among our poorer population, tends to the production of dyspepsia, which in its turn leads to states of mental depression highly favourable to the production of various forms of neurotic disturbance." Exceptionally the "tea habit" has been acquired through chewing the leaves.

Adulteration Of Tea

The adulteration of tea is extensively practised, but it can rarely be said to be injurious to the digestion, for the adulterants are either added in very minute proportion, as in the case of plumbago, indigo, or Prussian blue, for the purpose of colouring or "facing" the tea, or foreign leaves are mixed with the tea, which simply dilute it without necessarily making it injurious. Green tea is more likely than black to be adulterated. Catechu as well as salts of iron are sometimes added to increase the astringency.

Quantity Consumed

It is interesting to make a comparison between the consumption of tea and coffee in the United States. The quantity of tea consumed in 1890 was 83,494,956 pounds, while the consumption of coffee during the same period was 490,181,755 pounds. On the other hand, London consumed per annum 25,000,-000 pounds of tea (or 1.38 pound per capita) as against 2,740,000 pounds of coffee (1898). The amount of tea consumed per capita in the United States is 1.33 pound, while the amount of coffee consumed is 7.8 pounds. Slightly more than half of the tea drunk in the United States comes from China, and a large part of the remainder from Japan. The India teas are nearly twice as strong as the others, but they are much less commonly drunk in this country excepting in mixtures where they have been added to Chinese or Japanese teas to improve their flavour and strength.