Caffeine is an alkaloid derived from a variety of plant parts (fruits, leaves, seeds), widely present in coffee, tea, chocolate, cocoa and other drinks or food addition, because of the intake of the human body has the effect of improving physical endurance, reducing fatigue, improving mental alertness and concentration, etc., also known as the most legal, temperamental, and popular drug in history.
What are the main physiological mechanisms that caffeine affects the human body?
Caffeine is popular because of its exhilarating biological effects, which are related to its adenosine receptor antagonist mechanism, which controls nerve signaling and energy transmission, and thus has the effect of affecting sleep, cognition, learning, memory and a variety of physiological functions. Note 10
What are the proven benefits of caffeine?
1. Caffeine is beneficial for diabetes prevention
Diabetes is mainly caused by abnormal insulin secretion and function, regardless of gender or age, the prevalence rate of the population is about 10%, and the effect of long-term hyperglycemia is to increase the production of reactive oxygen species, glycosylated end products (AGE), causing large and small vascular lesions, increasing the risk of end-stage lesions such as eyes, nerves, kidneys and heart.
A meta-analysis (42 population observations, with about 1.8 million participants) noted that both coffee and caffeine consumption were associated with lower rates of diabetes (a 14% reduction in the risk for every 200 mg increase in caffeine intake). Note 1
The latter mechanism may increase metabolic rate and thermogenesis, and promote the utilization of fatty acids and muscle glycogen.
*Conclusion: Coffee intake may be associated with a lower incidence of diabetes, but more randomised controlled trials are needed to confirm causality
2. Caffeine is beneficial for chronic hepatitis C
Hepatitis C virus infection is the leading cause of chronic hepatitis, estimated by the World Health Organization to affect about 1 million people worldwide, 8% of whom develop chronic hepatitis, and 80%-20% of patients progress to cirrhosis or hepatocellular carcinoma if left untreated or poorly controlled.
A meta-analysis (5 observational studies with 1507 participants) showed that higher daily caffeine intake reduced the chance of progression to advanced fibrosis by 61% compared with the lower caffeine intake group. Note 3
The mechanism behind it may be related to the fact that caffeine inhibits hepatic stellate cell activation, reduces collagen matrix deposition, and thus reduces the progression of liver fibrosis.
*Conclusion: In patients with chronic hepatitis C, caffeine intake is associated with lower end-stage liver fibrosis events, but more experiments are needed to confirm the optimal dose and type of caffeinated beverage
3. Caffeine reduces the risk of depression
The main symptoms of depression include: extremely low psychological state, feeling guilty, lack of interest in all affairs, decreased thinking ability, etc., and often accompanied by insomnia, headache, dizziness and other abnormal physiological phenomena.
When the above physical and mental symptoms persist for more than two weeks, it is most likely depression.
A meta-analysis (11 observational studies with more than 300,000 participants) pointed out that both coffee and caffeine intake were associated with a lower risk of depression, and further dose-response analysis found that each additional cup of coffee consumed per day reduced the risk by 8%, while the daily intake of caffeine was between 68 mg and 509 mg. Note 4
*Conclusion: Coffee or caffeine consumption is associated with a lower incidence of depression, but more empirical confirmation is needed for the causal relationship
4. Caffeine boosts athletic performance
The use of doping or doping to improve sports performance in all sports competitions is a topic of constant discussion.
A meta-analysis (50 studies) showed that caffeine consumption had the effect of maximal voluntary contraction and muscle endurance, and was particularly pronounced in the need for knee stretching and open-end tests. Note 5
Another meta-analysis (6 studies, 246 participants) showed that caffeine consumption increased maximum strength and peak strength output results (measured by the Wingate test) during short periods of aerobic exercise. Note 6
*Conclusion: Caffeine has the effect of improving short-term/high-intensity aerobic exercise performance
5. Caffeine improves tension headaches
Tension-type headaches, also known as myocontractile headaches, are the most common form of headache, ranging from 12% to 78% in prevalence, often caused by tight jaws, lack of eating, stress, depression, anxiety, or too little sleep.
A meta-analysis (4 studies with 1,900 people with tension headache) showed that caffeine, acetaminophen, and aspirin produced more significant pain relief than acetamide alone or placebo, even in patients with more severe pain. Note 11
*Conclusion: For tension headache, caffeine combined with anti-inflammatory analgesics can improve the analgesic effect of drugs
Are there any side effects of consuming caffeine?
For most adults in good health, caffeine intake below 400 mg per day is safe, which translates to about 4 250 cc cups of brewed coffee, 10 cans of Coke, or 2 cans of energy supplemental drinks, but the true amount of each drink may vary.
Possible side effects of caffeine intake include: anxiety, irritability, insomnia, increased frequency of urination, stomach upset (gastroesophageal reflux), nausea, vomiting, heart rate and shortness of breath, related reactions may also vary according to individual tolerance, if the dose is too large may also cause arrhythmia, serious may be fatal.
Safety precautions (4 contraindications to use)
1. Pregnant women and nursing mothers should strictly control the daily intake of caffeine drinks (preferably not more than 200 mg, about 1 to 2 cups of coffee), because excessive amount may lead to complications such as miscarriage and low fetal weight. Notes 7-8
2. Although caffeine is not addictive, it will still produce symptoms of dependence for long-term regular intake of related drinks, and if it is stopped, symptoms such as headache, fatigue, and lack of concentration may occur
3. Some population observations suggest that coffee or caffeine intake may increase the risk of urinary incontinence, but a meta-literature analysis found no association. Note 9
4. People with bipolar disorder, anxiety disorder or irritable bowel disorder should use with caution, it may worsen symptoms