|From infancy to old age, it's
hard to avoid caffeine - especially if you love coffee and tea. It's present naturally or as an added
ingredient in so many foods, drinks and drugs that most Americans probably consume some caffeine every
day. But is it a serious health hazard? The answer is a qualified no, based on what many scientists
and public health experts now say. Are there still reasons to be concerned about caffeine consumption?
The answer is a qualified yes, although there is less concern about potential adverse health effects
today than previously.|
Less than 10 years ago, caffeine - which people have been consuming for centuries - was under a cloud because research had suggested it might be associated with birth defects, some forms of cancer, cardiovascular disease, behavioral problems, central nervous system disorders, reproductive problems, and nonmalignant breast lumps (fibrocystic disease) in women, just to name some of the concerns.
The concerns were enough to move the Food and Drug Administration in late 1980 to warn pregnant women to either avoid or moderate their consumption of caffeine. Pregnant women are of special concern because caffeine gets into the bloodstream and reaches the fetus through the placenta. Also a breast-fed child can obtain caffeine from its mother's milk.
Prompting the agency's advice was a 1980 teratology (birth defects) study with rats, conducted by FDA scientists. The study found that one of every five baby rats born to mothers that had been force-fed caffeine while they were pregnant had permanent birth defects - mainly missing or incomplete toes - and delayed development of bones, particularly of the breastbone. Not known at the time was whether the bone abnormality - called delayed ossification - was permanent or temporary. More recent studies showed that the condition was temporary and reversed itself.
|The agency readily admitted at the time that the scientific
community was uncertain about whether humans metabolized caffeine the say way that rats or other animals
did. And it acknowledged then that it had no evidence - and still doesn't - that caffeine ever caused
birth defects in humans. But the questions remained, and FDA coupled its advice for moderation with a
call for new studies to resolve many of the unanswered health issues surrounding caffeine.|
Many of these studies have now been completed and reviewed by FDA. And although they don't completely exonerate the substance, FDA's concerns over human consumption of caffeine have declined.
"I think it is quite fair to say that our concerns have been diminished quite significantly," said W. Gary Flamm, director of the Office of Toxicological Sciences at FDA's Center for Food Safety and Applied Nutrition. However, Flamm said that does not mean that pregnant women should start consuming large amounts of caffeine. "We are not prepared to rescind that warning (to pregnant women) because we have not reached the point where we have resolved all of the questions that impact on the issue of safe conditions of use of caffeine."
Its effects on individuals vary. Some people can consume substantial amounts without apparent ill effects. Others are quite sensitive to it. That's one reason why there will always be some uncertainty over the health effects of caffeine. No one knows for sure what the long-term effects may be on at least some segments of the population. Also, much of what is known about caffeine today is based mostly on animal studies. It is not always clear how such findings apply to humans.
"No one is anxious to give caffeine a clean bill of health," Flamm noted. For example, he said, "there are clearly people who have serious cardiac arrhythmias (irregular heartbeat) due to caffeine consumption. We have to say that, concerning cardiovascular health and cardiac arrhythmias, some people are sensitive to the effects of caffeine. If that is true of cardiac effects, it could be true of other things."
Human consumption of caffeine will probably be a matter of continuing interest to FDA as an enforcement agency because of the widespread presence of caffeine in food, especially in soft drinks and coffee. Tea, chocolate, baked goods, frozen dairy desserts, gelatin, puddings and pie fillings, and soft candy also contain caffeine.
Excluding the caffeine that is naturally present in coffee, tea, cocoa, and other products, "the predominant use of caffeine as an added ingredient is in soda water beverages (soft drinks), which accounts for the vast majority of the estimated 2 million pounds of caffeine added to food annually in the United States," according to a 1983 paper published by Sanford A. Miller, Ph.D., and Jane E. Harris, Ph.D. Miller was director of FDA's Center for Food Safety and Applied Nutrition until he resigned last July.
Since FDA's 1980 warning, a large number of caffeine studies have been reviewed by FDA toxicologists. Their review was contained in a September 1986 report.
Sipping vs Force-Feeding
Among its conclusions, the report said FDA had "significantly less concern" over caffeine's ability to cause birth defects in laboratory animals.
In a key study, completed in 1983, the baby rats whose mothers consumed caffeine while they were pregnant were born with no missing toes. Some of the rats ingested caffeine at even higher levels than those in the 1980 study in which birth defects did result.
The 1983 study was conducted by a team of FDA scientists headed by Thomas F.X. Collins, the same toxicologist who did the 1980 study. But there was a major difference in the way the two studies were conducted. For the 1980 study, a single daily dose of caffeine was force-fed through tubes into the stomachs of the pregnant rats. For the 1983 study, that daily caffeine dose was in the drinking water the pregnant rats sipped - more closely mimicking the way humans consume caffeine.
Although birth defects among off-spring were not observed in the sipping study, delayed bone development was. Whether the condition was permanent or temporary was not known until a follow-up study by Collins' team in 1986. The pregnant rats in that study were given caffeine in their water for the first 20 days of their 22-day gestation period. On the 20th day of gestation the unborn fetuses were examined and found to have delayed bone development. However, by the sixth day after birth, the condition had almost reversed itself. That finding lessened agency concerns about caffeine and pregnancy, according to Collins.
FDA also reviewed various epidemiological studies to determine whether caffeine could be implicated in adverse effects in infants born to women who consumed caffeine. The studies focused mainly on coffee-drinking and non-coffee-drinking mothers. One 1982 study of more than 12,000 women who gave birth between August 1977 and March 1980 suggested that low birth weight and premature birth occurred more often among the infants of mothers who drank four or more cups of coffee daily. But after considering the potential effects of smoking and other factors, no relationship was found between low birth weight and premature birth and heavy coffee consumption, FDA said.
No Increase In Birth Defects
In addition, the agency's science review cited two studies, published in 1982 and 1983, that found "no notable difference in the incidence of malformations" among babies of mothers who drank at least four cups of coffee daily with those who consumed none at all, the agency said.
In 1980, FDA was also confronted with the possibility that caffeine could cause testicular atrophy and other reproductive system effects in test animals. A 1984 study of male and female mice that were given caffeine in their drinking water indicated that the caffeine had no effect on the animals' fertility. Even continuous exposure to high doses of caffeine had "no significant effects on mating behavior, proportion of pups born alive, or live pup weight," the agency's scientists said.
The agency stated it still believes "there is insufficient evidence to conclude that caffeine adversely affects the reproduction function in humans."
Also in 1980, a widely publicized human study had suggested a link between pancreatic cancer and coffee consumption. But the methodology of the study was questioned, and several other epidemiology studies concluded that there was no proven association between coffee drinking and pancreatic cancer. Animal studies have also failed to provide any data "to indicate caffeine is carcinogenic in rats," the FDA reviewers said.
Caffeine And Benign Breast Lumps
Considerable publicity has also been given to the possibility that caffeine may be linked to the development of benign lumps in some women's breasts, a condition known as fibrocystic disease. However, the FDA review stated, more reliable studies since then have failed to show any relationship "between benign breast disease and coffee consumption."
Another widely voiced concern in past years focused on the possibility that caffeine could cause behavioral and developmental problems in young children. But in its 1986 review the agency said the findings of the various animal studies were inconsistent. "This lack of uniform effects in studies conducted in experimental animals...makes predictions of possible behavioral effects of caffeine in humans unreliable," it added.
Some studies, the agency said, have shown that high doses of caffeine given to adult laboratory animals and adult humans can have temporary effects. Other studies have indicated that children tend to be neither more nor less sensitive than adults to caffeine.
Since the early 1970's, there have been more than 20 studies on the possible link between caffeine and heart disease. Coffee drinking was implicated in a number of studies. The agency's 1986 report, however, states that "most of the evidence does not support a causal role" for coffee in coronary heart disease. FDA said the various studies are inconclusive because the adverse effects reported "may be related to substances other than caffeine," such as smoking and alcohol, that were not considered in the study.
What it all seems to boil down to is this: In 1980, FDA was confronted with various studies that aroused concern about the possible association of caffeine in the human diet with numerous health problems. Of immediate concern was the study that demonstrated caffeine's potential for causing birth defects in animals. Was there a danger to humans? The agency said that it didn't know. So, it chose to lean on the side of caution by warning pregnant women and, at the same time, asking industry and the scientific community to do more studies on caffeine's health effects. These have now been done, and they generally have produced less worrisome results. For that reason, and because FDA determined that some of the earlier studies were faulty, inconclusive, or contradicted by later findings, the concern about caffeine has lessened.
However, FDA is also saying that while there is a basis for being less concerned about caffeine's impact on health, some questions remain unanswered. The agency continues to stress that caffeine is a chemical stimulant that affects the central nervous system. It is a widely used food additive to which some people are more sensitive than others. It could have other, still unknown, effects. But determining what these effects are is not a simple matter, as some studies have indicated, since other factors - such as smoking, alcohol consumption, poor diet, and drug use - also can affect human health.
From a regulatory standpoint, FDA will continue to monitor caffeine use in foods and how much of it people consume. Meanwhile, consumers probably should adhere to some age-old advice: Moderation makes good sense.
Chris W. Lecos is a member of FDA's public affairs staff.
COFFEE DRINKERS IN DIFFERENT AGE GROUPSPercentage of Americans of Various Age Groups Who Are Coffee Drinkers (Source: International Coffee Organization, London, England).
10-19 Years 25.1% 5.3%
CAFFEINE CONTENT OF BEVERAGES AND FOODS(Source: FDA, Food Additive Chemistry Evaluation Branch, based on evaluations of existing literature on caffeine levels).
Milligrams Caffeine Average Range
Coffee (5-oz. cup)
Cocoa beverage (5-oz. cup) 4 2-20
Chocolate milk beverage (8 oz.) 5 2-7
Milk chocolate (1 oz.) 6 1-15
Dark chocolate, semi-sweet (1 oz.) 20 5-35
Baker's chocolate (1 oz.) 26 26
Chocolate-flavored syrup (1 oz.) 4 4
CONSUMPTION OF COFFEE AND OTHER BEVERAGES-Percentage of U.S. Population Who Drink Various Beverages (Source: International Coffee Organization, London, England.)
Coffee 74.7% 52.0%
CAFFEINE CONTENT OF SOFT DRINKS(Per 6-ounce serving) (Source: National Soft Drink Association, Washington, D.C. Amount of fruit juices added varies from 10 percent to 25 percent).
CAFFEINE CONTENT OF DRUGS(Source: FDA's Center for Drugs and Biologics)
Caffeine is an ingredient in many prescription and nonprescription drug products. It is often used in alertness or stay-awake tablets, headache and pain relief remedies, cold products, and diuretics. When caffeine is an ingredient, it is listed on the product label. Some examples of drugs that contain caffeine are:
Norgesic Forte (muscle relaxant) 60
Norgesic (muscle relaxant) 30
Fiorinal (tension headache) 40
Fioricet (headache pain relief) 40
Darvon compound (pain relief) 32.4
Synalgos-DC (pain relief) 30
Synalgos-DC-A (pain relief) 30
Alertness Tablets No Doz 100
Anacin, Maximum Strength Anacin 32
Coryban-D capsules 30
CAFFEINE DOESN'T MEAN JUST COFFEE ANYMORE
Mention the word caffeine, says George E. Boecklin, president of the National Coffee Association, and most people will think you are talking about coffee. "When a story breaks about caffeine, it's immediately translated in the consumer's mind to coffee." he declared. "He doesn't think about Coca-Cola, just coffee."
It's not surprising that caffeine and coffee are viewed as being almost synonymous. Coffee has been around for centuries. For years it has been America's most popular beverage and the largest single source of caffeine in the human diet.
But today, the soft drink industry is the biggest user of caffeine, and in 1985, soft drinks surpassed coffee for the first time as the favorite beverage of Americans.
Coffee's slide in popularity is part of a decline that has been almost continuous for the last 25 years, according to annual surveys by the International Coffee Organization, a London-based industry group.
Coffee consumption reached its peak in the United States in 1962, when nearly three out of four Americans were consuming the beverage. Today, slightly more than half the population drinks coffee. Twenty-five years ago, only about one of three persons consumed soft drinks. Today, according to the coffee industry survey, nearly six out every 10 persons (58 percent) include soft drinks in their daily diet.
In addition to the steady drop in the percentage of the U.S. population that drinks coffee, consumption among coffee drinkers has also dropped - from more than four cups a day per person in 1962 to 3.38 cups daily in 1987. Meanwhile, consumption of decaffeinated coffee rose from 4 percent of the population in 1962 to the current 17.5 percent.
Although such shifts suggest that at least some consumers are concerned about their caffeine intake, it is ironic that soft drinks with caffeine are today's biggest sellers, while sales of most caffeine-free beverages have declined.
According to Beverage Age magazine, soft drink consumption reached its highest lever ever in 1986 when Americans consumed nearly 6.8 billion cases. That's roughly 163 billion eight-ounce containers of soda. Cola drinks accounted for more than 4.5 billion cases, or 69 percent of the volume.
Under FDA's 1966 regulation of caffeine and cola, a soft drink cannot be called a cola or pepper type drink unless it has caffeine from kola nut extract or some other extract in which it is naturally present. Last May 20, however, FDA proposed eliminating that requirement to give manufacturers the option of using, or not using, caffeine in any soft drink. The regulation would also permit caffeine to be added to a carbonated beverage so long as the total caffeine content is no more than 0.02 percent by weight. In practice, around 95 percent of the caffeine in soft drinks is added.
If adopted, the proposed change would still require manufacturers who add caffeine to any soft drink to declare it on the label, as is required with any added ingredient.
Despite growing public awareness of caffeine, caffeine-free soft drinks made up only 4.1 percent of the market in 1986, a slight drop from the previous year.
"I think caffeine-free (soft drink) beverages are there, just as the decaffeinated coffees are there, to provide consumers with an alternative," says Boecklin. Coffee's popularity slid, in part, because the soft drink industry aggressively introduced a "vast array of new brands, new flavors, and new beverage forms, and spent millions and millions of dollars" to promote its offerings, he asserted.
Over the years, he continued, the coffee industry's share of the young adult market - those between 20 and 40 years of age - was dropping. The majority of the people in this group are now soft drink consumers. That's one reason, he said, why the coffee industry is now promoting coffee as a more "up-to-date, youthful product." Coffee for too long, he said, has suffered from the "Mrs. Olson" image of being "an old person's or the establishment's beverage."
Boecklin said that coffee drinking hit its peak popularity in 1962 because of the millions of young adults who became accustomed to coffee while in military service during World War II and the Korean War. "The two wars created, in my opinion, an artificially larger coffee-drinking population than we ever had before." he said. "Ten or 15 years later, those people matured to the age where coffee consumption is usually the greatest."
Meanwhile, other events were having their impact on coffee. At the same time the soft drink industry was introducing a greater variety of beverages, coffee was getting some bad press.
"There was a litany of things that caffeine was being accused of, or suspected of, that got publicity," Boecklin noted, adding that even the coffee industry's earlier promotion of decaffeinated coffees "seemed to reinforce the consumer's perception that maybe caffeine is not so good."
Food additives such as caffeine are regulated by FDA under provisions of the 1958 Food Additives Amendment to the Federal Food, Drug, and Cosmetic Act. The 1958 legislation requires industry to provide evidence of safety before marketing foods with new additives. The law, however, only applies to additives industry sought to use after its passage. Those in common use before the law's adoption were exempted and listed as being "generally recognized as safe," or GRAS. Caffeine was one of 700 substances placed on the so-called GRAS list.