Food/ Health Put a limit on your daily caffeine dose

Press, 12 July 1980, Page 10

Food/ Health Put a limit on your daily caffeine dose

COFFEE — it’s pleasurable, but is it good or £ bad for our health? j We are consuming in- . creasing amounts of in- t stant coffee. Tea drinking E has fallen off in New Zea- ’ ’ land, especially amongst [ young women. 1 What are the possible health effects of high < coffee intake in New Zea- ; land? ‘ Is coffee more harmful < than tea? Mormons feel i that both beverages are ] harmful and forbid them. < As such views are based ■ on religious dogma and ■ not on reason, what is the - ; best scientific evidence : available?

CAFFEINE Coffee does contain more caffeine than tea. Caffeine is also a biologically active substance known as an alkaloid. Some of these alkaloids such as caffeine, them from tea, and theophylline stimulate cellular systems in the human body. Other alkaloid substances such as morphine and heroin depress cells in the body. These alkaloid or plant substances are similar to basic structural proteins in normal body cells called purines and xanthines. Such purine and xanthine derivatives are widely found in animal cells and plants. They are found in

coffee and cocoa beans, in the young leaves of tea plants, and in kola nuts. Caffeine is a natural xanthine. and once the beans have been broken down, it can be readily extracted by boiling water. CAFFEINE INTAKE A CUP Dr D. M. Graham, a research biochemist from Walnut Creek, California, has reported on the caffeine content of common beverages. Strength or brew affects content, but on average, a large cup contains: — CAFFEINE PER CUP Coffee: Roasted and ground — 85 mgm Instant — 60 mgm Decaffeinated — 3 mgm Instant Tea — 30 mgm Brewed tea — 40 mgm Cocoa — 20 mgm. DAILY CAFFEINE INTAKE No reliable research studies have been carried out in New Zealand. The results from several recent United States studies are available. Even infants under one year there consume 42 mgm per day. The figures for young people are startling as set out in a table for age. AGE GROUP MGM/DAY 12-23 months 49 mgm/day. 2-5 years (pre-school) 70 mgm/day. Primary school, 100 mgm/day Adults (all), 227 mgm/day. Pregnant women, 193 mgm/day. WHAT DOES CAFFEINE DO? The coffee consumed passes into the stomach where caffeine is rapidly absorbed. It passes into all cells in the body within one hour and is almost all gone after six hours. Only' 5 per cent comes out

unchanged in the urine. The '’caffeine acts on brain cells as a stimulant to increase activity or excitement. It also opens up very slightly the coronary arteries, 'although a cup of tea does this better. Tea should be preferred by angina patients. Coffee increases urine flow, as is well known by older people drinking coffee late at night. Unlike morphine, caffeine is not adaptive — that is. regular consumption does not reduce the pleasurable effect. Withdrawal can and does occur. After ■ a heavy' co f f e e-drinking bout, sudden cessation can produce real withdrawal headaches. Despite some sense of alertness, caffeine has not been shown to improve intellectual performance or thought processes. High levels of caffeine are 'toxic to man. They may cause nausea or even vomiting. Excess . coffee., may stimulate stomach acid leading to indigestion and even gastric ulcers. A SENSIBLE POLICY You should not take caffeine in tablet form. Impurities may damage other organs. As coffee, you can safely take several large cups daily without harm. As it acts for up to six hours, evening coffee may stop you dropping off to sleep. In pregnancy it is best to limit any heavy' intake of coffee, tea or cocoa, although evidence for harmful effects on the foetus is minimal. Coffee drinking is a recent dietary' phenomenon. Excess may eventually be shown to be related to health, because caffeine is a biologically active substance shown to have chemical effects on many body systems.