Whether it is a domestic or foreign film and television drama, there are always protagonists who will enter gracefully with coffee, which also shows from the side that coffee is one of the most popular drinks in the world, but people's attitude towards it is contradictory. There is a lot of caffeine in coffee, and regular drinking may help refresh the mind, but many people are worried that the coffee in it will increase the risk of cardiovascular disease and cancer.
On the other hand, relevant data show that by 2045, the global risk of diabetes may exceed 700 million, and dietary intervention plays an important role in blood sugar control in adults with type 2 diabetes. Because depending on the content of sugar and other ingredients, different types of drinks may have different effects on health. Let's take a look at the specific disease of type 2 diabetes, what role does coffee play in it, and whether caffeine can inhibit the total amount of body fat and reduce the risk of type 2 diabetes?
First, coffee is harmful to the body but not beneficial? BMJ Medicine and Scientific Reports two studies tell you the answer
For people who need to stay up late and work overtime every day, coffee is like a "life-saving straw" that can survive the sleepy night, but in fact, many people in life are resistant to drinking coffee, they feel that no matter how much coffee is not good, it is harmful to the body and not beneficial. A study published in the journal BMJ Medicine suggests that the potential role of zero-calorie caffeinated beverages in reducing the risk of type 2 diabetes and obesity may be worth studying.
The main purpose of this study is to explore the potential causal effects of long-term plasma caffeine concentration on type 2 diabetes, obesity and major cardiovascular diseases, which is manifested in the researchers designing two Mendelian randomized studies, which correlated two single nucleotide polymorphisms associated with plasma caffeine at genome-wide significant thresholds, and set the association of the results as genome-wide association study summary data.
But why do researchers use Mendelian randomization methods?
In fact, previous studies have shown that drinking 3~5 cups of coffee a day containing a lot of caffeine (an average of about 70mg~150mg of caffeine per cup) is associated with a lower risk of cardiovascular disease, type 2 diabetes and other diseases, but these studies also have limitations. For example, most studies focus on observational studies, ignoring other potential influencing factors and not reliably determining causation.
Mendelian randomization is a way to use genetic variation as a substitute for a certain risk factor in order to obtain genetic evidence that supports a particular outcome. In this way, researchers can find out how high levels of caffeine in the blood affect type 2 diabetes and stroke, heart failure, coronary heart disease and other major cardiovascular diseases, irregular heart rhythms, and long-term risk of body fat.
Specifically, the researchers conducted six long-term studies on nearly 10,000 people of mainly European ancestry, and also studied two genes related to the rate of caffeine metabolism in the body: AHR and CYP1A2 genes. It was found that participants with genetic variants associated with slower caffeine metabolism, even though they drank less coffee on average, had higher levels of caffeine in their blood than those whose rapid metabolism maintained (or reached) the level required for coffee excitability.
After detailed analysis, the researchers found that the higher the genetically predicted blood caffeine level, the lower the body fat and BMI, and the genetically predicted higher blood caffeine level was associated with a reduced risk of type 2 diabetes. To conduct further research, the researchers analyzed the extent to which caffeine's effect on type 2 diabetes risk was due to concurrent weight loss.
Subsequently, it was found that genetically predicted blood caffeine levels did not show a strong association with cardiovascular disease risk. That said, high levels of caffeine in the blood may actually inhibit body fat levels, thereby reducing the risk of type 2 diabetes to some extent.
Although researchers say that caffeine can increase fat burning, etc. is well established, and the daily intake of appropriate caffeine can increase a lot of energy expenditure, or reduce the possibility of obesity, but this study does have many limitations.
For example, only people of European ancestry were studied, and only two genetic variants were used. Further clinical studies are needed on the translational potential of these findings in reducing the burden of metabolic diseases, and it is necessary to evaluate whether zero-calorie caffeinated beverages reduce the risk of type 2 diabetes and obesity through randomized controlled trials.
In another study, caffeine also showed that it can promote calorie consumption, which may play a role in the treatment of type 2 diabetes and obesity. Researchers say that nowadays there are more and more diabetics, obesity and type 2 diabetes have become a health challenge, and the function of specific components on brown fat may regulate the body's fat and glucose in the future, thus becoming a treatment for diabetes and obesity.
The brown fat mentioned here is actually one of the two types of fat in humans or other mammals, which can promote the consumption of fat and sugar to heat up. The other is white fat that can store excess energy. It is worth noting that brown fat tends to be activated in a cold environment, not only improving the control of blood lipids and blood sugar levels, but also burning additional calories, which is important for weight loss.
However, previous studies have shown that no specific way to activate brown fat has been found. In response to this situation, scientists at the University of Nottingham in the United Kingdom have made a bold conjecture, can caffeine in coffee directly activate brown fat? In order to solve the mystery, the researchers carried out a series of studies and published the results in Scientific Reports.
The researchers first started from the perspective of stem cell research, and the results deduced that caffeine can indeed stimulate brown fat. Because the researchers found that fat cells exposed to caffeine increased the abundance of uncoupling protein-1 (UCP1) in the mitochondria in the cell, the corresponding rate of cellular metabolism accelerated as oxygen consumption increased. Moreover, the expression of UCP1 protein-related genes and some biomarkers with brown fat selectivity also showed an increasing trend.
However, stem cell studies alone are not enough, and further validation in human trials is needed. The researchers then used 5 women and 4 healthy men as the study subjects to track the brown fat in the participants with the help of non-invasive thermal imaging technology. It was found that after drinking coffee, the temperature of the neck area above the human collarbone (the main distribution area of brown fat in the human body) increased significantly. That is to say, after drinking coffee, brown fat plays a thermogenic role.
Researchers said that by activating brown fat in the human body, coffee components can play a role in promoting calorie consumption, and may provide new solutions for diabetes and obesity in the future. It can be seen that coffee is also a double-edged sword, it is not beneficial to the body, the important thing is how people use it or drink it in moderation. But we should note that there is a group of people who want to reduce the amount of coffee they drink.
Second, don't drink coffee blindly! Ophthalmology study: Such people who drink less may increase the risk of blindness
A study published in Ophthalmology looked at the correlation between habitual caffeine intake and intraocular pressure and glaucoma, and whether genetic predisposition to high intraocular pressure changed the correlation. It was found that for the participants with the strongest genetic predisposition to high intraocular pressure, the higher the caffeine intake, the higher the intraocular pressure and the corresponding prevalence of glaucoma.
Specifically, coffee is not suitable for everyone to drink more, and for some people, excessive caffeine intake may increase the risk of blindness. For example, in people with a genetic predisposition to high intraocular pressure, a high daily intake of caffeine increases the risk of glaucoma by more than 3 times.
Many people do not know about glaucoma, it ranks second in the world among the main blinding eye diseases, is a progressive and irreversible vision loss, an eye disease characterized by optic nerve damage, and in most cases the disease has no symptoms, but can bring irreversible damage to the patient's vision. It is worth noting that there is a close connection between intraocular pressure and glaucoma.
A major risk factor for glaucoma is increased intraocular pressure, which is often controlled for life, and even surgery in severe cases. The researchers of this study mainly used the large biomedical database BioBank as the research object, and analyzed more than 120,000 people aged 39~73 years old, mainly including dietary questionnaires, DNA samples, health records, etc.
Participants were given targeted questionnaires such as how much caffeinated foods they ate each day, how many caffeinated drinks they drank, and of course vision-related problems such as whether they had glaucoma or a family history of glaucoma. The entire study period was 3 years, and when the follow-up time was over, participants also needed to undergo eye tests and intraocular pressure tests.
The researchers found no correlation between high caffeine intake and an overall increased risk of glaucoma or high intraocular pressure, but there was a correlation between high caffeine intake and a higher prevalence of glaucoma and high intraocular pressure in the first 25% of participants with the strongest genetic predisposition to increased intraocular pressure. That is, participants who drank about 4 cups per day (caffeine intake of more than 480 g) had a 0.35 mmHg higher intraocular pressure.
And compared with people with the lowest risk score who rarely or never consume caffeine, people with the highest genetic risk score who drink about 3 cups of coffee a day (caffeine intake more than 321mg) increase the risk of glaucoma by 3.9 times.
Therefore, for people with a high genetic risk of increased intraocular pressure, it is best to drink less coffee, after all, this study shows that only in this type of population, the negative relationship between caffeine intake and glaucoma risk is obvious.
Bibliography:
[1] Susanna C Larsson, Benjamin Woolf.Appraisal of the causal effect of plasma caffeine on adiposity, type 2 diabetes, and cardiovascular disease: two sample mendelian randomisation study.2023.03.30.
[2] Marleen A.H. Lentjes.Intraocular Pressure, Glaucoma, and Dietary Caffeine Consumption: A Gene–Diet Interaction Study from the UK Biobank2020.12.14.
[3] Hilda Anaid Lugo Leija, Ian Bloor.Caffeine exposure induces browning features in adipose tissue in vitro and in vivo.2019.06.24.