300 mg per day
We have painstakingly sifted through all those comments, compiling the top 20 caffeine allergic reactions in order from most common to least common. Advertisement. In most cases these symptoms were reported after only having a little to moderate amount of caffeine through coffee, tea, soda and/or energy drinks.  The amount of caffeine considered to be an overdose varies by a person’s size, age and gender, but in general, doses of greater than 10 grams can be fatal in adults. A typical cup of coffee has about 115 mg of caffeine, so you’d need to drink more than 85 cups to consume 10 grams. Caffeine's effects last long after you finish that cup of java. It takes 5 to 6 hours for your body to eliminate just half the caffeine in a cup of coffee, which is why having a cup in the afternoon can affect your sleep. This means that if your parents seem to get strong effects of caffeine on a small amount-a half cup, say-you are likely to have the same kind of response. Look to your family tree, to get a clue of how much caffeine might work for you in a health promoting way. This does vary! 7. The response is much less. This is call attenuation. Same dose of caffeine, less effect. With this knowledge, the best way to have optimal effect of caffeine is to limit consumption to about 300 mg per day, and consume it ONCE a day – at the time you want to be most alert, and want the maximal effect. The FDA limits the caffeine content in soft drinks to 71 mg per 12 oz serving, but there is no limit on the amount of caffeine “energy drinks” can contain. Several energy drinks have more than 100 mg of caffeine per serving, and some have more than 200 mg. Caffeine's effects last long after you finish that cup of java. It takes 5 to 6 hours for your body to eliminate just half the caffeine in a cup of coffee, which is why having a cup in the afternoon can affect your sleep. Studies suggest that moderate amounts of caffeine are not harmful. How much is moderate? One hundred to 200 mg (one to two 5-ounce cups of coffee) each day is the limit that some doctors suggest, but each person is a little different. How caffeine affects people varies with their size, their sex, and how sensitive they are to caffeine’s effects. Medicines in my Home: Caffeine and Your Body Caffeine occurs naturally in more than 60 plants including coffee beans, tea leaves, kola nuts used to flavor soft drink colas, and cacao pods used to make chocolate products. Man-made caffeine is sometimes added to foods, drinks, and medicines. Science. A safe caffeine limit is the amount of caffeine a person can consume without experiencing any negative caffeine overdose symptoms. It’s difficult assign an exact amount for everyone because people can have different sensitivities or reactions to caffeine based on age, medical history, and tolerance. Those Ultra-Sensitive to Caffeine. For those ultra-sensitive to caffeine it is hard to determine an exact caffeine safe limit. Some people can have one cup of coffee (100mg-120mg) in the morning and still fail to get to sleep that evening. This is well after the caffeine’s effects should have worn off as it does for “normal” caffeine consumers If you're susceptible to the effects of caffeine, just small amounts — even one cup of coffee or tea — may prompt unwanted effects, such as restlessness and sleep problems. How you react to caffeine may be determined in part by how much caffeine you're used to drinking. And adolescents should limit themselves to no more than 100 mg of caffeine a day. Even among adults, heavy caffeine use can cause unpleasant side effects. Between 200 mg and 300 mg of caffeine, the amount in two to three cups of coffee, is considered a moderate amount and is generally considered safe for most adults. Caffeine's effects last long after you finish that cup of java. It takes 5 to 6 hours for your body to eliminate just half the caffeine in a cup of coffee, which is why having a cup in the afternoon can affect your sleep. That's roughly the amount of caffeine in four cups of brewed coffee, 10 cans of cola or two energy shot drinks. Although caffeine use may be safe for adults, it's not a good idea for children. And adolescents should limit themselves to no more than 100 mg of caffeine a day. Even among adults, heavy caffeine use can cause unpleasant side effects. And caffeine may not be a good choice for people who are highly sensitive to its effects or who take certain medications
http://www.caffeineinformer.com/caffeine-allergy-top-20-symptoms http://www.webmd.com/diet/rm-quiz-caffeine-myths http://www.today.com/health/7-things-you-didnt-know-about-caffeine-1B6013380 http://www.webmd.com/diet/rm-quiz-caffeine-myths http://www.fda.gov/downloads/UCM200805.pdf http://www.caffeineinformer.com/caffeine-safe-limits http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/caffeine/art-20045678 http://www.webmd.com/diet/rm-quiz-caffeine-myths http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/caffeine/art-20045678
how do i know what amount of caffeine is right for me