Caffeine is of much concern to many dieters. Some diets even prohibit caffeine-containing drinks, especially coffee, cola, cocoa and tea. For this reason we are printing some of the newest measurements of caffeine in popular drinks.

But first, a bit about caffeine.

The bottom line: It is a drug. Caffeine is an alkaline in the family of chemicals known as xanthines.

Caffeine drinks are used for their perking-up effect as well as for their flavor. They are stimulants; they provoke the heart and lungs to work at an abnormally fast rate.

Under the influence of caffeine, the kidneys excrete more fluid and the stomach excretes more acid. Individuals who consume lots of caffeine urinate more than normal and frequently have heartburn.

Caffeine also stimulates the body to dump sugar into the blood stream. When blood sugar climbs, appetite is depressed. But the effect is temporary. When the concentration of blood sugar falls, hunger begins again. Taking more caffeine (in coffee, for example) will increase blood sugar again, and so on.

Some diets prohibit caffeine drinks to prevent that roller-coaster of high-low-high blood sugar.

Amounts of caffeine in beverages are not consistent. Some coffees and teas are higher in caffeine than others. The method by which the beverage is prepared is a factor.

Recently, a premedical student at Columbia University in New York, Daniel S. Groisser, working for biochemist Randhir Dandhu, used a new laboratory technique to measure more accurately the amounts of caffeine in teas brewed different ways. In their report in The American Journal of Clinical Nutrition they wrote that tea made with loose leaves yields more caffeine than tea made in bags of paper or in metal containers (tea balls). Iced tea has more caffeine than hot tea.

The accompanying chart shows some of their data for tea and other beverages. All teas were made by steeping the leaves in hot water for four minutes, for a six-ounce cup.

For comparison with the statistics in the chart, a No-Doz or Vivarin "stay-awake" pill contains 100 milligrams of caffeine. Excedrin, Anacin, Dristan and Sinarest headache and cols preparations contain about 30 milligrams.

The morning cup of coffee, the afternoon cup of tea, the coke with lunch and cocoa when it it cold are part of our way of life. When the regular flow of caffeine from these beverages is interrupted-during a fast or crash diet, for example-we suffer withdrawal effects, such as headaches. Withdrawal symptoms are caused partially by decrease in surges of blood sugar.

If caffeine is a problem for you, taper off slowly. Switch from a high-caffeine beverage to a lower one and cut down on the number of cups of it per day.

CAFFEINE CONTENTS OF POPULAR BEVERAGES(TABLE) (COLUMN)(COLUMN)MG. of Brand(COLUMN)Method(COLUMN)Caffeine Red Rose(COLUMN)Bag(COLUMN)46 Salada(COLUMN)Bag(COLUMN)40 Lipton(COLUMN)Bag(COLUMN)38 Twinings Eng. Bkfst.(COLUMN)Bag(COLUMN)52 Twinings Eng. Bksft.(COLUMN)Metal Bag(COLUMN)58 Twinings Eng. Bkfst.(COLUMN)Loose(COLUMN)77 Twinings Darjeeling(COLUMN)Bag(COLUMN)65 Jackson Oolong(COLUMN)Metal Bag(COLUMN)42 Lipton Instant(COLUMN)62 Nestea(COLUMN)Instant(COLUMN)48 Coffee(COLUMN)Ground(COLUMN)85 Espresso(COLUMN)Ground(COLUMN)150 Coffee(COLUMN)Instant(COLUMN)60 Coca-Cola(COLUMN)(COLUMN)24 Tab(COLUMN)(COLUMN)24 Pepsi-Cola(COLUMN)(COLUMN)18 Diet Pepsi(COLUMN)(COLUMN)18 Diet Rite Cola(COLUMN)(COLUMN)21 Dr. Pepper(COLUMN)(COLUMN)32 Royal Crown Cola(COLUMN)(COLUMN)50 Cocoa(COLUMN)(COLUMN)50 Nestle Nescafe(COLUMN)(COLUMN)7 Sanka(COLUMN)(COLUMN)3.3 Nestle Decaf.(COLUMN)(COLUMN)0.18(END TABLE)