Soda Makers to Disclose Caffeine Content on Labels Soda drinkers are about to get an added jolt from their sodas: The big drinks makers now plan to disclose the caffeine content on the product label. The new information will allow consumers to compare the caffeine content of various soft drinks and comes as beverage companies are introducing new supercharged drinks. PepsiCo, for instance, in June plans to offer Diet Pepsi Max, touted as an "invigorating cola" with nearly twice the caffeine of regular Diet Pepsi. Coca-Cola, meanwhile, is offering Full Throttle, a citrus drink, and Tab Energy -- both of which contain more than three times the caffeine content of Coke Classic. Over the years, there has been a lot of confusion about caffeine because of studies linking coffee consumption with heart disease and high blood pressure, among other health worries. Most of the health risk shown in earlier studies probably was due to the fact that heavy coffee drinkers were often smokers. Later research has shown coffee is safe and may even have health benefits, possibly due to antioxidants and other compounds. Studies show coffee drinkers are less likely to develop diabetes, gallstones, Parkinson's disease and colon cancer. But the health effects of caffeine from sodas are less clear. Caffeine makes us feel alert by binding to brain receptors that make us sleepy and giving us a boost of adrenaline. The impact depends on the individual and how often he or she ingests caffeine. Too much can make you jittery or cause an upset stomach. Regular drinkers who miss a dose can experience withdrawal symptoms including headache, irritability and fatigue. While most caffeine drinkers feel they are getting a mental boost, it isn't clear if caffeine really improves alertness, according to the Harvard Mental Health Letter. People who aren't regular caffeine consumers say they feel more alert, but tests show caffeine doesn't boost performance. And studies suggest regular caffeine users develop a tolerance to caffeine's stimulating effects. So while regular drinkers may feel lifted by a midday caffeine dose, it's more likely they are avoiding the crash of caffeine withdrawal. Sodas typically have far less caffeine than coffee. Eight ounces of Pepsi, for instance, has about 25 milligrams of caffeine. Caffeine content of coffee varies by variety and brewing technique, but an eight-ounce cup may have from 100 to 200 milligrams of caffeine. The new Tab Energy drink from Coke has 72 milligrams per eight ounces. Most studies show people can drink about 300 milligrams of caffeine a day without any negative effects. However, studies at Johns Hopkins University show that as little as 100 milligrams of daily caffeine (about a cup of coffee or three cans of soda) over three days could trigger withdrawal symptoms when you stop the caffeine. The withdrawal symptoms become more severe after seven to 14 days of regular caffeine exposure. While the caffeine content of soft drinks isn't a huge issue for most adults, it can have a big impact on kids because of the differences in body weight. A child consuming a can of regular caffeinated soda receives a caffeine equivalent of about four cups of coffee. A big question about caffeine is its impact on blood pressure. A single cup of coffee can lead to a temporary jump in blood pressure. But a 2005 study in the Journal of the American Medical Association concluded that there's no link between coffee and chronic high blood pressure or hypertension. However, data from Harvard's Nurses Health Study show that while coffee-drinking nurses weren't at higher risk for hypertension, the women who drank four cans or more of regular or diet cola per day were at increased risk for high blood pressure. The culprit might be the caramel coloring used in colas, which contain unstable compounds called advanced glycation end products or AGEs, according to the study. The study authors noted far more data are needed. "I think the balance of health effects is much more positive for coffee than cola beverages,'' says Rob M. van Dam, assistant professor at the Harvard School of Public Health. The bottom line with caffeine is that moderation is the key. If you're jittery, suffering sleep problems and going to the bathroom more often than usual, chances are you're taking in too much caffeine.