DEAR DR. BLONZ: My question is about coffee and antioxidants. I had thought that because coffee beans are roasted, they lost their antioxidants in the process. Also, could you explain a bit about the effects of caffeine on the body and how long those effects are felt? -- M.Q., Tucson, Arizona
DEAR M.Q.: Plants produce seeds and package them with enough nourishment to keep them viable until they can begin to grow and gather nutrients on their own. Along with sustenance comes an army of substances (phytochemicals) designed to protect against attacks, whether from insects, animals or the oxidizing rays of the sun. (Interestingly, many “antioxidant” substances have bitter tastes, and this helps to discourage nibbling.)
The coffee plant is no exception to this theme. The ripe, red coffee cherry is the seed for the coffee plant, and it typically contains two green coffee beans. The coffee plant grows in tropical climates, and it contains an array of antioxidant substances for its seeds. Green coffee beans are a rich source of antioxidants. The roasting process darkens the color of the bean and develops the flavor and aroma we associate with coffee. You would think that a high-heat process would be destructive to antioxidants, and roasting does indeed affect the level and type of antioxidants in coffee. What’s been discovered, though, is that the roasting process creates a novel type of antioxidants in coffee beans known as melanoidins, which are not present in the unroasted beans. A study in the June 2002 issue of the Journal of Agricultural and Food Chemistry found that a medium-roasted coffee bean contained more antioxidants than either a light-roasted or a dark-roasted bean.
Regarding caffeine, it won’t surprise you to hear that it stimulates the brain. Its other effects include an increase in heart rate, increased acid release by the stomach, quicker transport of food through the digestive system and a relaxation of the smooth muscles, such as those found in the lungs. Caffeine is also a diuretic, which means it increases the volume of urine the body produces.
Once in the body, caffeine goes just about everywhere. In a pregnant or nursing woman, this may mean it makes its way to a developing fetus or into breast milk.
Because caffeine is a foreign substance, the body starts breaking it down as soon as it appears. The half-life of caffeine can vary. Those who break down caffeine fastest are smokers and, strangely enough, children. It takes them about three hours to eliminate half their body’s caffeine.
The half-life for the average nonsmoking adult is five to seven hours. For women taking birth control pills, it’s up to 13 hours. The half-life in pregnant women is 18 to 20 hours, but returns to normal within a month after delivery. A newborn does not gain any real ability to metabolize caffeine until several days old. Any caffeine received through breast milk during this period has a half-life of about three to four days -- important to consider while pregnant or nursing.
Abrupt withdrawal by a regular caffeine user can lead to symptoms ranging from a simple headache to nausea, drowsiness, depression and reduced attention span. People who drink as little as two cups of coffee a day may experience these withdrawal effects. According to a study in the October 1992 New England Journal of Medicine, half of the 62 coffee drinkers studied experienced moderate to severe headaches when they stopped drinking coffee, and about 1 in 10 reported depression and anxiety.
The symptoms were connected to the caffeine, in that those who discontinued coffee but received caffeine (not placebo) capsules did not report the same problems. However, these symptoms tend to be short-lived, and most can be avoided by cutting back gradually.
Send questions to: “On Nutrition,” Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to email@example.com. Due to the volume of mail, personal replies cannot be provided.