3 days, 9 hours ago

 how many health benefits does coffee have? The impact of NEJM review on a variety of diseases

Coffee, tea and caffeinated soda and energy drinks are all popular drinks. There are different opinions about the effects of coffee or caffeine on health, and there are constantly emerging evidences. In the latest review published today in the New England Journal of Medicine (NEJM), the National University of Singapore and Harvard Medical School Team elaborated on the metabolism, physiology, toxicity of coffee and its association with a variety of chronic diseases. We share the main points with readers. 


 
 source: New England Journal of medicine 
 
 
 based on a large amount of evidence review, the author's team believes that 
 coffee intake does not increase the risk of cardiovascular disease and cancer, and drinking 3-5 standard cups per day 
 (standard cup is defined as 8 oz, 235 Coffee was also associated with reducing the risk of several chronic diseases. However, excessive caffeine intake still has adverse effects. Due to metabolic differences, everyone's sensitivity to caffeine is different. 
 suggestions for reference are as follows: the daily intake limit of caffeine for ordinary adults is 400mg, and that for pregnant or lactating women is 200mg. 



 
 metabolism, physiological and toxic effects of caffeine

Absorption and metabolism of caffeine in human body

In general, 
 after ingestion of caffeine, the body will fully absorb it within 45 minutes, and the concentration of caffeine in the blood reaches its peak in 15 minutes to 2 hours. 
 caffeine is absorbed throughout the body and reaches the brain through the blood-brain barrier. 

Under the action of cytochrome oxidase P450 (CYP), especially CYP1A2, caffeine is metabolized in the liver, and finally is metabolized into uric acid, which is excreted in urine. 
 in adults, the half-life of caffeine is usually 2.5-4.5 hours, but individual differences are large, and metabolic enzyme activities are affected by genetic factors. 


In addition, 
 smoking can double caffeine metabolism, while pregnancy can significantly slow down caffeine metabolism. 
 in late pregnancy, caffeine half-life can be as long as 15 hours. 
 some drugs can also slow down the clearance of caffeine, 
 including oral contraceptives, quinolones, cardiovascular drugs, bronchodilators and antidepressants, usually because the metabolism of these drugs and caffeine requires the same enzymes. 
 on the contrary, caffeine can affect the effects of various drugs. 



 2. How does caffeine refresh

For people who don't sleep enough in a fast-paced life, coffee is a must-have. Coffee is refreshing because its molecular structure is similar to adenosine. It can block and inhibit the binding of adenosine and receptor by competitive binding to adenosine receptor, and the combination of adenosine and receptor will increase drowsiness. 
 although moderate doses of caffeine 
 (40-300mg) 
 can help reduce fatigue and improve responsiveness in the moment, it should be noted that caffeine can not make up for the performance decline after long-term sleep deprivation. 



 
} take a cup every day and give yourself a lift (photo source: pixabay) 
 
 
 
 antagonizing this effect of adenosine is also a double-edged sword. 
 if you eat too late, caffeine can also affect sleep quality and even cause anxiety. Withdrawal symptoms, including headache, fatigue, decreased alertness and depression, and even flu like symptoms, may occur after forming the habit of drinking caffeine. 
 abstinence symptoms are usually the most serious 1-2 days after cessation of intake, lasting for 2-9 days. These symptoms can be alleviated by slowly reducing the dosage. 


In addition, there is evidence that caffeine combined with analgesics can moderate pain relief. 


 3. Excessive intake is fatal

Excessive caffeine intake can cause anxiety, restlessness, nervousness, irritability, insomnia, excessive excitement, psychomotor agitation, and poor thinking or language expression. According to research estimates, 
 caffeine intake of more than 1.2g will produce toxic effects, 10-14g intake is more likely to be fatal. 


It is worth noting that caffeine in 
 energy drinks may have more adverse effects than other caffeine beverages. 
 the underlying reasons are as follows: 
 did not realize that it contains caffeine 
; daily intake of large amounts of caffeine led to decreased caffeine tolerance; children and adolescents who drink energy drinks more often are also more vulnerable to caffeine; interact with other components of energy drinks; 
 at the same time, strenuous exercise 
 or drinking. Heavy consumption of caffeine containing energy drinks, especially when mixed with alcohol, may also be associated with cardiovascular, psychological or neurological events, and sometimes even fatal. 


 
} excessive caffeine intake can also cause toxic effects (photo source: pixabay) 
 
 
 
 the impact of coffee on chronic diseases

Need to worry about cardiovascular problems? 


Some individuals will have discomfort such as rapid heartbeat after drinking coffee, so they are worried about the impact of coffee on cardiovascular health. However, the comprehensive evidence shows that coffee does not increase the risk of cardiovascular disease at the population level. 

Although caffeine intake can raise blood pressure in the short term, it can be tolerated within a week. 
 in clinical trials and prospective cohort studies, no substantial effect of coffee on blood pressure was found, even in patients with hypertension 
, it may be that other components in caffeine offset the effect of caffeine on blood pressure. 


 caffeinol in coffee can increase cholesterol, but its content is affected by different preparation methods. 
 in unfiltered coffees (e.g. pressed and brewed coffee), the caffeinol concentration is relatively high, and the concentration is moderate in espresso and mocha pot, while it is insignificant in drip, instant and percolated coffee. In a randomized trial, drinking 6 cups of unfiltered coffee per day was associated with increased low-density lipoprotein cholesterol (LDL-C) and an 11% increased risk of major cardiovascular events compared with filtered coffee. 
 drinking less unfiltered coffee helps to control blood lipids. 



 people who drink 3-5 cups of coffee a day have the lowest risk of cardiovascular disease. 



 2. Improve obesity and type 2 diabetes 
 2

Studies suggest that caffeine may improve energy balance and help weight management. In metabolic studies, repeated daytime intake of caffeine (6 × 100mg) resulted in a 5% increase in 24-hour energy consumption. In cohort studies, increased caffeine intake was associated with a slight decrease in long-term weight gain. Limited evidence from randomized trials also supports the moderate beneficial effect of caffeine intake on body fat. 

In blood glucose studies, 
 caffeine intake can reduce insulin sensitivity in the short term, but long-term data show no significant effect 
, which is tolerated by the human body, or the adverse effect can be offset by the long-term beneficial effects of other components in coffee on blood glucose metabolism. In cohort studies, 
 coffee intake was also associated with reduced risk of type 2 diabetes. 



 3. Carcinogenesis or cancer prevention? 


Whether coffee can prevent cancer is also a hot topic. The results of many prospective cohort studies provide strong evidence that coffee intake is not associated with an increased risk of cancer onset or death. 
 among melanoma, other skin cancer, breast cancer, prostate cancer, endometrial cancer, hepatocellular carcinoma and gallbladder cancer, coffee intake was also associated with reduced risk. 
 (related reading: 
 does coffee cause cancer or prevent cancer? Take a look at 300000 people and find out what 
)


 4. Potential benefits for liver disease, stones and Parkinson's disease 
 4

Also through competitive binding to adenosine receptors, 
 caffeine helps prevent liver fibrosis and cirrhosis 
, because adenosine promotes tissue remodeling. Coffee polyphenols can also prevent hepatic steatosis and fibrosis by improving fat homeostasis and reducing oxidative stress. 

Studies have also shown that coffee intake 
 is associated with reduced risk of gallstones and kidney stones. 
 prospective cohort studies conducted in the United States, Europe and Asia have shown that caffeine intake 
 is significantly associated with a reduced risk of Parkinson's disease 
; consistent results have been observed in animal experiments. (related reading: 
 this cup is not only coffee, but also a" compound decoction "to prevent Parkinson's disease

Can you prolong your life? 


Studies in many places around the world and in European populations, African Americans and Asians have shown that 
 drinking 2-5 standard cups of coffee a day is associated with a reduction in the overall risk of death. 
 after excluding people with abnormal health status, the conclusion is still consistent, and this result is not affected by the speed of caffeine metabolism. 


 
 source: pexels 
 
 
 
 
 the special effect of caffeine on pregnancy

Caffeine is easy to pass through the placenta, and slow metabolism of caffeine during pregnancy can lead to an increase in blood caffeine levels. Caffeine may cause placental vasoconstriction and hypoxia by increasing catecholamine levels in pregnant women and fetuses. 

In prospective studies, 
 higher caffeine intake was associated with lower birth weight and higher risk of miscarriage. 
 among them, studies have shown that the more caffeine intake, the more obvious the risk of low birth weight, and there is no clear safety threshold, especially in tea drinkers. However, in a randomized trial, moderate reduction of caffeine intake in late pregnancy did not significantly affect fetal birth weight; 
 however, low dose caffeine intake did not significantly affect fetal birth weight

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