The LD50 (Lethal Dose 50%) of caffeine is 192 mg. The lower the LD50 number, the more lethal the substance is. For comparison, Vitamin C (ascorbic acid) has an LD50 of 11,900 mg/kg. Cyanide has an LD50 of 6.4 mg/kg.
Caffeine is mutagenic for mammalian somatic cells (meaning that is alters your DNA and is passed down genetically to offspring). Mutagenic for bacteria and/or yeast. May cause damage to the following organs: heart, gastrointestinal tract, central nervous system.
It has Chronic Effects on Humans: May cause adverse reproductive effects (fetotoxicity, maternal (parnutrition) and birth defects. May affect genetic material (mutagenic). May cause cancer (tumorgenic) based on animal data.
It may cause gastrointestinal (digestive) tract irritation with epigastric pain, abdominal cramps, nausea, vomiting and diarrhea.
It affects metabolism and cardiovascular system with symptoms including flushing, palpitations, rapid heart rate, dysrhythmias, hypotension, blood pressure elevation and weight loss, metabolic acidosis.
It may affect brain and behavior/central nervous system. Symptoms may include nervousness, anxiety, restlessness, insomnia, dizziness, tremor, seizures, convulsions, hallucinations,
somnolence, toxic psychosis, tremors, convulsions, ataxia.
May also affect blood, respiration (hyperventilation), and urinary system (mild increase in urinary volume and urinary sodium excretion), and may directly produce hypokalemia.
Chronic Potential Health Effects: May cause cancer (tumorigen) based on animal studies. May cause reproductive and fetal effects. May cause digestive tract disturbances (increased gastric acid, and pepsin secretion and a decrease in lower esophogeal sphincter pressure), cardiovascular disturbances.
Caffeine also fits the definition of an addictive substance, with withdrawal symptoms, an increase in tolerance over time, and physical cravings.
Caffeine is metabolized in the liver.
It increases lipolysis, leading to elevated glycerol and free fatty acid levels in the blood plasma.
It dilates blood vessels and increases urine volume.
Caffeine crosses the blood–brain barrier that separates the bloodstream from the interior of the brain.
Caffeine acts as a nonselective antagonist of adenosine receptors. The caffeine molecule is structurally similar to adenosine, and binds to adenosine receptors on the surface of cells without activating them (an “antagonist” mechanism of action). Therefore, caffeine acts as a competitive inhibitor.
Caffeine tolerance develops very quickly, especially among heavy coffee and energy drink consumers. Complete tolerance to sleep disruption effects of caffeine develops after consuming 400 mg of caffeine 3 times a day for 7 days. Full complete tolerance of caffeine was observed when subjects consumed 750–1200 mg per day.
Withdrawal symptoms — headache, irritability, an inability to concentrate, drowsiness, insomnia and pain in the stomach, upper body, and joints — may appear within 12 to 24 hours after discontinuation of caffeine intake. This peaks at roughly 48 hours, and usually last from one to five days, representing the time required for the number of adenosine receptors in the brain to revert to “normal” levels. Analgesics, such as aspirin, can relieve the pain symptoms.
The DOT Classification of caffeine: CLASS 6.1: Poisonous material!!
Caffeine can lead to a condition known as ”caffeinism.” Caffeinism combines caffeine dependency with a wide range of unpleasant physical and mental conditions including nervousness, irritability, anxiety, tremulousness, muscle twitching (hyperreflexia), insomnia, headaches, respiratory alkalosis, and heart palpitations. Furthermore, because caffeine increases the production of stomach acid, high usage over time can lead to peptic ulcers, erosive esophagitis, and gastroesophageal reflux disease.
There are four caffeine-induced psychiatric disorders recognized by the ”Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition”: caffeine intoxication, caffeine-induced anxiety disorder, caffeine-induced sleep disorder, and caffeine-related disorder.
Long-term consumption of caffeine could inhibit learning and memory partially through inhibition of hippocampal neurogenesis.
Caffeine binds to receptors on the surface of heart muscle cells, which leads to an increase in the level of cAMP inside the cells (by blocking the enzyme that degrades cAMP), mimicking the effects of epinephrine (which binds to receptors on the cell that activate cAMP production).
Despite its widespread use and the conventional view that it is a safe substance, a 2008 study suggested that pregnant women who consume 200 milligrams or more of caffeine per day have about twice the miscarriage risk as women who consume none.
5-6 cups of coffee a day may make you fat!
Caffeine can cause retention of fat within cells, glucose intolerance(a pre-diabetic condition), and increase resistance to insulin regulation.
LD50 LETHAL DOSE CHART:
High intakes of coffee are associated with raised concentrations of plasma homocysteine, a predictor of risk of cardiovascular disease. http://www.ncbi.nlm.nih.gov/pubmed/11237928
Personal note: I’ve been caffeine-free for about 8 months now. I’d given up caffeine a few years ago, but I went back to it after some stressful events. Caffeine just made me feel good/happy and I craved it when I felt bad or stressed.
The 1st time I gave it up was super-hard. I was consuming 8-16 cans of Coca-cola and energy drinks a day(insane, I know!). I switched that out to diet Coke and diet Pepsi, then I switched that out to strong tea. I gradually weakened the tea until I was just drinking water. I could not go cold-turkey because I have severe migraines. I had to slowly step it down.
This time, I went from energy drinks and soda straight to water. I had to use some Excedrin to get me through the 1st week. I naturally have 2-5 baaaaaad migraines every year (since I was about 2 years old). As long as I was consuming caffeine I wouldn’t have any, but if I was ever in a situation where I went without it for more than 6 hours – it would induce a monster migraine that would leave me crying in a fetal position. That could be several times a week. I much prefer to deal with my “regular” migraine episodes. I’ve only had 2 since I stopped consuming caffeine this last time. It’s also easier now for me to notice the signs of a migraine coming on – which means I have time to do a few things to take the edge off so that they don’t last as long and aren’t as severe.