What is caffeine?

There are few people who are not aware of the stimulating effect that caffeine provides. We have a choice and choose caffeinated beverages for a reason. Caffeine is considered the most commonly used psychoactive drug in the world. Approximately 80% of the world's population consumes it on a daily basis, and continuous research is being done on its health benefits and consequences.

Caffeine is the common name for 1,3,7-trimethylxanthine. When purified, caffeine produces an intensely bitter white powder that provides a distinctive taste in soft drinks. The word "caffeine" came from the German word kaffee and the French word café, each meaning coffee. After ingesting caffeine, it is completely absorbed within 30 to 45 minutes, and its effects substantially diminish within about three hours. It is eventually excreted so there is no accumulation in the body. Caffeine has been shown to affect mood, stamina, the cerebral vascular system, and gastric and colonic activity. But caffeine may not be for everyone. This article will discuss the health benefits and consequences of caffeine.

What are the sources of caffeine?

Caffeine is naturally found in certain leaves, seeds, and fruits of over 60 plants worldwide. The most common sources in our diet are coffee, tea leaves, cocoa beans, cola, and energy drinks. Caffeine can also be produced synthetically and added to food, beverages, supplements, and medications. Product labels are required to list caffeine in the ingredients but are not required to list the actual amounts of the substance. A low to moderate intake is 130 to 300 mg of caffeine per day, while heavy caffeine consumption corresponds to more than 6,000 mg/day. It is estimated that the average daily caffeine consumption among Americans is about 280 mg/day, while 20% to 30% consume more than 600 mg daily. The caffeine content in some common sources of caffeine are listed below:

Sources of Caffeine	Caffeine Content
Coffee
Plain, brewed 8 oz	135 mg
Instant 8 oz	95 mg
Espresso 1 oz	30-50 mg
Plain, decaffeinated 8 oz	5 mg
Tea
Green tea 8 oz	25-40 mg
Black tea 8 oz	40-70 mg
Soft Drinks
Coca-Cola Classic 12 oz	34.5 mg
Diet Coke 12 oz	46.5 mg
Dr. Pepper 12 oz	42 mg
Mountain Dew 12 oz	55.5 mg
Pepsi-Cola 12 oz	37.5 mg
Sunkist Orange 12 oz	42 mg
Energy Drink
Full Throttle, 16 oz	144 mg
Red Bull, 8.5 oz	80 mg
SoBe No Fear	158 mg
Chocolates or Candies
Candy, milk chocolate 1 bar (1.5 oz)	9 mg
Candy, sweet chocolate 1 bar (1.45 oz)	27 mg
Cocoa mix, powder 3 tsp	5 mg
Puddings, chocolate, ready-to-eat 4 oz	9 mg
Medicine: Over the Counter
Excedrin	65 mg
Bayer Select Maximum Strength	65.4 mg
Midol Menstrual Maximum Strength	60 mg
NoDoz 100 mg	32.4 mg
Pain Reliever Tablets	65 mg
Vivarin	200 mg

There are many products that may contain caffeine without your awareness. Be sure to read the label to see if caffeine is listed among the ingredients.

Caffeine (cont.)

Is caffeine addictive?

Have you ever said that you can't function until your morning cup of coffee? Do you find yourself reaching for caffeinated coffee, tea, or soda when you are feeling lethargic? Could it be that you are addicted to caffeine? That all depends on who you ask. Whether we consume caffeine for pleasure or purpose is a controversial topic. Those opposed to caffeine being addictive claim that we consume it for the pleasure of the product, while those who believe that it is addictive claim that we consume it for the purpose of satisfying our craving for it.

Psychiatric diagnoses are categorized by a manual published by the American Psychiatric Association called the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV). This manual covers all mental-health disorders for both children and adults. The DSM-IV has a proposed diagnosis of caffeine withdrawal, instead of an official diagnosis, to encourage further research on the range and specificity of caffeine-withdrawal symptoms. A review and analysis of the effects of caffeine abstinence in humans claims that the withdrawal symptoms experienced are proof of physical dependence. These symptoms includeheadache, tiredness/fatigue, decreased energy/activeness, decreased alertness/attentiveness, drowsiness/sleepiness, decreased contentedness/well-being, depressed mood, difficulty concentrating, irritability, and felling muzzy/foggy/not clearheaded. The study also found that the onset of withdrawal symptoms typically begins 12 to 24 hours after abstinence, with the peak intensity occurring at 20 to 51 hours. The duration of withdrawal symptoms ranged from two to nine days. This is a considerable amount of time that makes it easy to understand why people would have a hard time omitting caffeine from their diet. It was recommended that further research be done to determine how vulnerability to caffeine withdrawal is affected by gender, genetics, personality, behavioral conditioning, drug abuse histories, and other factors.

As compelling as the research in favor of caffeine being addictive is, there is equally compelling evidence that it is not addictive. It is argued that the pleasurable aroma, taste, and social aspects of coffee are the reasons for consumption. Research has shown that the desire to repeatedly use caffeine is primarily found in heavy caffeine consumers who also had histories of alcohol or drug abuse, and not in moderate consumers. While there is some agreement about the occurrence of withdrawal symptoms, there is disagreement about any form of addiction to caffeine. An addiction can be demonstrated by the irresistibility of regular consumption and problems created from its consumption. Caffeinated products are said to be consumed by habit, not need, and do not pose any harm to society.

The definitive answer to the question of whether caffeine is addictive is still unknown. Research is under way to clarify the issue. For anyone looking to decrease or cut out caffeine, experts all recommend doing so slowly. Stopping abruptly can result in unpleasant side effects.

Is caffeine a diuretic?

Caffeine has been considered a diuretic by experts and consumers for years. Some people believe that drinking caffeinated beverages will cause them to lose fluids so they can't be counted as part of their daily intake. Others say that caffeinated beverages do not increase fluid losses. The best way to flush out the truth is to examine the research.

Each day our body has a need for water. We lose water through respiration, skin, renal, and gastrointestinal tract losses. Our intake of water comes from liquids and foods. We need to maintain an adequate water balance for our bodies to function properly. Factors such as age, activity level, health, diet, and environment can affect our water balance.

Some research has shown that caffeine intake can also affect our fluid balance. In one study, 12 caffeine consumers were told to abstain from caffeine for five days and were then given 642 mg of caffeine in the form of coffee. Their urine output increased when given the caffeine. Another study done on eight men tested the effect of 45, 90, 180, or 360 mg of caffeine on urine volume. An increase in urine volume was seen only at the 360-mg dose of caffeine. One limitation to these studies is that they did not evaluate the impact of caffeine when consumed on a regular basis. A onetime dose may affect the body differently than daily consumption.

Back in 1928, caffeine was shown to have no significant impact on urinary output. Subsequent studies have shown that caffeine-containing beverages did not impact urinary output any differently than other beverages. Based on this, the Institute of Medicine recommends that "unless additional evidence becomes available indicating cumulative total water deficits in individuals with habitual intakes of significant amounts of caffeine, caffeinated beverages appear to contribute to the daily total water intake similar to that contributed by noncaffeinated beverages."

This doesn't mean that caffeine does not increase your need to urinate. Your reaction can depend on the amount that you consume, the type of product, and your tolerance level. If you have urinary incontinence, you may experience a greater "urgency" to urinate after consuming a caffeinated beverage. You will need to monitor your reaction and tolerance to caffeine to determine how you are affected. Water is still the recommended choice for optimal hydration, so be sure to include it as part of your daily fluid consumption.

Does caffeine cause heart disease?

With the high prevalence of heart disease, links between lifestyle factors, such as diet and physical activity, are undergoing extensive research. The original research into caffeine's role in this epidemic resulted in conflicting answers. Some evidence suggests an elevation in stress hormones from caffeine consumption that could pose a cardiovascular risk, but recent research has shown no relationship between caffeine ingestion and heart disease. In fact, studies have actually shown a protective effect against heart disease with habitual intake of caffeinated beverages in the elderlypopulation. The reason for the discrepancy may be due to the kind of beverage being consumed. Studies have shown that coffee and tea were not associated with increases in blood pressure or arrhythmias, while soft drinks were. Research also showed that decaffeinated coffee and tea did not provide the same benefits as the caffeinated versions. The well-respected Framingham Heart Study examined all potential links between caffeine intake and cardiovascular disease and found no harmful effects from drinking coffee. There can, however, be exceptions to this. People react differently to caffeine, and some may experience elevations in blood pressure or arrhythmias. The blood pressure elevations are said to be short-lived, lasting no more than several hours and are comparable to modest elevations experienced climbing a flight of stairs. It's always best to check with your physician if you are experiencing any side effects.

Does caffeine cause bone loss?

Too much of a good thing could be a problem for caffeine consumers. Evidence suggests that high caffeine intake may accelerate bone loss. One study found that elderly postmenopausal women who consumed more than 300 mg per day of caffeine lost more bone in the spine than women who consumed less than 300 mg per day. However, coffee and tea drinkers may be able to counteract this negative effect by adding milk to their beverage. The consumption of cola has also been shown to be associated with lower bone mineral density. While these studies were compelling, more evidence is needed to make a definitive decision about the role of caffeine and osteoporosis.

Does caffeine help with weight loss?

The weight-loss industry is estimated to be a $50 billion a year industry. Many people are looking for a way to get their piece of the money-making pie without a lot of credibility behind what they are promoting. The supplement industry is constantly promoting a new product to enhance weight loss by increasing satiety or burning fat. The claims are convincing, but the research backing many products is often lacking. To make matters worse, supplements often contain combinations of ingredients in the hopes of enhancing each one's effect without safety or efficacy tests. Caffeine is one of the ingredients now being included in many of the weight-loss supplements. It's added for its energy enhancement, appetite suppressant, and "fat-burning" properties.

The scientific evidence about caffeine as a weight-control agent is mixed. In a study done to monitor the impact of a green tea-caffeine combination on weight loss and maintenance, participants were divided into those who consume low levels of caffeine (<300 mg/day) and high-caffeine consumers (>300 mg/day). Weight loss was significantly higher in the high-caffeine consumption group, but weight maintenance was higher in the low-caffeine consumption group. The conclusion was that the caffeine was related to greater weight loss, higher thermogenesis, and fat oxidation, while the tea was responsible for the greater weight maintenance. Other studies have stated that caffeine actually contributes to weight gain by increasing stress hormones. It appears that caffeine's role in weight loss is as inconclusive as the efficacy of the majority of weight-loss supplements on the market.

Is caffeine safe during pregnancy?

There is no disputing the importance of proper nutrition during pregnancy. There is some dispute about the safety of caffeine during this time. One concern is that caffeine may lead to miscarriages. In a study following 431 pregnant women, no relationship between caffeine consumption up to 300 mg/day and adverse pregnancy outcomes was found. Another study examined the relationship between caffeine consumption and spontaneous abortions in over 5,000 women and found no association.

Research has also shown no clear relationship between caffeine intake and fertility andbirth defects. While the evidence appears to show no risk for pregnant women, the recommendations are to limit caffeine intake. It is difficult to accurately test the effects of very high intakes of caffeine without risking the health of the mother and child. The majority of the subjects in the studies were consuming small to moderate amounts of caffeine. The American College of Obstetricians and Gynecologists recommends a caffeine limit of the equivalent of 1 to 2 cups of coffee per day during pregnancy.

Should caffeine be consumed by children?

With the increased popularity of coffee shops, a new generation of caffeine consumers was born. Children are being exposed to caffeine from soft drinks, coffee, tea, energy drinks, ice cream, caffeinated water, chocolate, and medications on a daily basis. Could this trend be harming children?

The Center for Science in the Public Interest (CSPI), a consumer advocacy group, wants the FDA to require labels on caffeine-containing products that list the number of grams of caffeine they contain along with the warning that caffeine is a mild stimulant and not appropriate for children. A great deal of the problem with caffeine is the fact that caffeinated soft drinks often replace more nutritious drinks like milk. The trend is that milk consumption clearly shows a decline over time, while soft drink consumption has risen. Vending machines were added to some schools which exposed children of all ages to soft drinks.

The Centers for Disease Control and Prevention's School Health Policies and Programs Study (SHPPS) 2000 survey concluded that 43% of elementary schools, 89.4% of middle/junior high, and 98.2% of senior high schools had either a vending machine or a school store, canteen, or snack bar where students could purchase foods or beverages. A study done by CSPI found that of the drinks sold in the 13,650 vending-machine slots surveyed, 70% were sugary drinks such as soda, juice drinks with less than 50% juice, iced tea, and "sports" drinks. Of the sodas, only 14% were diet, and only 12% of the drinks available were water. Just 5% of drink options were milk but of those, most (57%) were high-fat, whole, or 2% milk. Fortunately, this problem has gained a great deal of recognition and some states have now enacted legislation to replace existing food and drinks of minimal nutritional value for healthier options or to restrict student access to the machines.

The effect of caffeine on children's moods and behavior is another concern. In a studydone by the National Institute of Mental Health, 8- to 13-year-olds who regularly consumed high doses of caffeine were judged to be more restless by teachers, and one-third were hyperactive enough to meet the criteria for attention deficit disorder with hyperactivity (ADHD). A Stanford study of fifth- and sixth-graders deprived of daily caffeine reported having symptoms including trouble thinking clearly, not feeling energetic, and getting angry. These symptoms were even reported by children who typically consume 28 mg of caffeine a day. The research in this area is somewhat limited, but the studies that have been conducted are compelling enough to warrant restricting caffeine intake in children to as little as possible. If there is no need for caffeine, why take the risk and allow children to consume it?

How much fluid do we need?

Anyone who has ever been on a diet will tell you that you are supposed to drink at least 8 cups of water a day. Everyone knows this, but finding the evidence to support it is another story. In 2004, the Food and Nutrition Board established recommendations on the intake of water. The recommendations were set based on the necessary amount needed to maintain health and reduce chronic disease risk:

• The vast majority of healthy people adequately meet their daily hydration needs by letting thirst be their guide.
• The report did not specify exact requirements for water, but set general recommendations for women at approximately 2.7 L (91 oz) of total water-from all beverages and foods-each day, and men an average of approximately 3.7 L (125 oz daily) of total water.
• The panel did not set an upper level for water.
• About 80% of people's total water intake comes from drinking water and beverages—including caffeinated beverages—and the other 20% is derived from food.
• Prolonged physical activity and heat exposure will increase water losses and therefore may raise daily fluid needs, although it is important to note that excessive amounts of fluid can be life-threatening. Acute water toxicity has been reported due to rapid consumption of large quantities of fluids that greatly exceeded the kidney's maximal excretion rate of approximately 0.7 to 1.0 L/hour.

The report allows all fluids to be counted into your total intake, so people began eliminating water from their diet in favor of other liquids. However, the recommendations were not intended to reduce water consumption. Water should be your primary source of fluid. Our bodies are made up of over 60% water, not coffee, tea, juice, or soda. Caffeine is a treat that will have health consequences when consumed in excessive amounts and is not safe for everyone. Set limits on the treats that you allow yourself, and be sure to give your body what it needs in adequate amounts. It's the only body that you have.