Is Coffee Good For You?

so I drink around four cups of coffee every day and I've often wondered is this a good thing or a bad thing that I'm doing with my life so in this video the very first episode of journal club we are taking a break from the deluge of coronavirus related content and we're looking at the scientific evidence behind whether drinking coffee is good for you let's dive into it so firstly what does coffee actually do well as you might know coffee contains caffeine and caffeine is a natural stimulant which blocks one of the neurotransmitters in the brain called adenosine now adenosine is very special because it's an inhibitory neurotransmitter and so it's main action is to dampen down brain activity and so when caffeine blocks adenosine that actually increases overall neuronal firing in the brain and that increases the activity of other neurotransmitters like dopamine which ultimately stimulates changes in our energy mood and attention and coffees got a few other bits in it other than just caffeine but because it's mostly caffeine that causes the positive and negative effects that's what we're going to be focusing on in this video and caffeine and therefore coffees most famous effect is that it enhances our mental performance and it does that in three main ways so firstly studies have shown that coffee improves our cognitive function in terms of alertness and vigilance so for example we've got this study from 1987 why they gave 20 healthy male volunteers different doses of caffeine and they showed that just 32 milligrams of caffeine which is less than half a cup of coffee that was enough to increase their auditory vigilance ie they were more aware of the auditory stimuli around them and also increased their visual reaction times ie they were able to respond to stuff quicker secondly we've got this paper from the European Food Safety Authority and they reviewed 22 studies that were randomized double-blind placebo-controlled trials on the effect of caffeine and attention and they said that overall there was a cause-and-effect relationship between a 75 milligrams serving of caffeine which is approximately one regular cup of coffee and increased attention and alertness and interesting ly they concluded that caffeine increases both selective attention and sustained attention so selective attention is kind of focusing on one thing at a time and sustained attention is kind of being able to focus for extended periods of time which is obviously very useful when we're studying or trying to be productive in any kind of way and on top of that we've got this review from 2013 and they looked at 66 double-blind placebo-controlled trials and they said that both simple and complex attention tasks were consistently affected by caffeine consumption caffeine affected both reaction times and the accuracy on a variety of simple tar but also had the potential to enhance higher-order processes involved in active monitoring and coordination of behavior such as task switching response inhibition and interference and overall they concluded that caffeine has clear beneficial effect on attention and that the effects are even more widespread than previously assumed so we've got all this evidence that says caffeine and therefore coffee improves our alertness and I can certainly attest to that anecdotally speaking like whenever I have my cup of coffee I feel like I'm what alert and I can actually focus more on the thing that I'm doing secondly there is a fair amount of evidence in the literature that suggests that coffee improves our memory and recall so for example we've got this study from 2009 where they gave loads of college students 6 lists of 15 words each to memorize and in some tests they gave them caffeine beforehand and in others they gave them a placebo and overall they found that the students who had caffeine were more able to recall the words in the list than the students had been given the placebo although to be honest this study was quite interesting because the students who had caffeine were also able to recall the wrong like wrong words like words that weren't on the list had been asked to memorize but that could be sort of related to the words there so this wasn't a fully conclusive 100 percent study but the authors did conclude that caffeine appears to intensify the strength of connections amongst list words and critical those thereby enhancing both true and false memory there is also some evidence that caffeine enhances the consolidation of memories so for example we've got this study from Johns Hopkins University in 2014 and this study was interesting because normally studies give people caffeine before they get asked to learn words and then get tested on them but what this study did is that it gave them caffeine or placebo after they got asked to learn the words and it was a pretty good study because they used 160 students it was double-blind placebo-controlled and randomized and they tested the performance of the groups the caffeine group and the placebo group 24 hours after they were asked to learn the words and they concluded that caffeine enhanced performance 24 hours after administration according to an inverted u-shaped dose-response curve this effect was specific to consolidation and not to retrieval we conclude that caffeine enhanced consolidation of long term memories in humans but then it also say that we conclude that a dose of at least 200 milligrams is required to observe the enhancing effect of caffeine on consolidation of memory which is about two regular cups of coffee so two cups of coffee a day saves John Hopkins University is pretty legit from Korea for improving the consolidation of memories and thirdly the scientific evidence suggests that coffee can actually improve our mood on top of all the other things that it does for example this was a study from 2011 done by Harvard that used 50,000 volunteers and it was a long attitudinal study over a 10-year period which is really hard to do and initially at baseline these women in the study didn't have any kind of severe symptoms of depression or clinical depression but the study looked at what the correlation was between their coffee consumption and the subsequent risk of developing depression and they said that the risk of depression decreased in a dose-dependent manner with increasing consumption of caffeinated coffee and that basically led them to conclude that the more coffee you drink the less likely you are to be depressed the actual causation aspect of that is probably a little bit dubious but it's an interesting study nonetheless and then in 2016 we had a meta-analysis of 12 studies that looked at 346,000 913 different people and there showed that 300 milligrams of caffeine which is about 3 or 4 cups of coffee that could be helpful for those suffering with depression with a protective effect of coffee and partially of tea and caffeine on the risk of depression and that's quoted from the study and for me personally what I've noticed is that when I'm drinking caffeine that really gives me a mental boost and it helps me get out of the slump that I'm in at the moment and I find that that mental boost is similar to what I get when I do online courses on brilliant who are very kindly sponsoring this video brilliant is a fantastic online platform for boosting our cognitive abilities and they've got courses on maths science and computer science and these are all firstly really interesting but secondly they're also challenging enough in a way that really makes your brain work when you go through them like it's not just spoon-feeding information it's really kind of giving you a concept and then giving you a problem that helps you run with the concept to try and solve it for yourself the course that I'm working through these days is called introduction to neural networks and this is a topic that I've been curious about for a few years especially because in medicine we've got all this talk about neural networks AI machine learning and all this stuff being used to interpret medical imaging like x-ray CT scans and ECGs and so this course I'm brilliant has really given me a good starting point to how this whole neural network thing works and and the nice thing about it is that it doesn't like drill down into the nitty-gritty of the maths but they use these clever it's kind of problems that you have to solve for yourself to help you understand like the potentially complicated math behind it all and they've also got this really cool day challenges feature which everyday gives you one or two different problems to solve and these can take between 5 minutes and 15 minutes depending on how much effort you want to put in and actually do find that sometimes what I do like study with me videos I will drink my cup of coffee and then if I'm still feeling in a slump I would do an online course or like a daily challenge and brilliant and I find that that mental workout really gets me into the mood to start studying again so if you happen to be stuck at home for whatever reason or you just want to improve your cognitive abilities head over to brilliant dog /le and the first 200 people to visit that link will get 20% off an annual premium subscription so those are some of the effects of coffee on a mental performance we've talked about how increases alertness vigilance memory recall than even mood let's not talk about the effects of coffee on physical performance and the way this works is that as we said coffee contains caffeine and caffeine is an adenosine antagonist it blocks the actions of the inhe between your transmitter adenosine overall causing more neuronal firing in the brain but when there's more neuronal firing in the brain the brain thinks oh crap you know we must be doing something serious and it increases the amount of adrenaline in our body so then we produce more adrenaline and adrenaline increases blood flow to our muscles increases a heart rate it makes us kind of more pumped and more like exercising if that makes sense so firstly we've got some evidence that caffeine consumption can increase the amount of time you can do exercise until you become exhausted so for example we've got this study from 1978 and they got nine competitive cyclists to basically cycle as much as they could until they were physically exhausted them couldn't cycle anymore and in one of the tests they gave them coffee with caffeine before hand and the other one they gave them decaffeinated coffee and they found that in the caffeine group the caffeinated coffee group they were able to exercise for 90. 2 minutes before collapsing of exhaustion but the decaffeinated coffee group could only exercise for seventy five point five minutes before they collapsed of exhaustion and so the fact that they drank coffee that contained caffeine versus coffee that didn't contain caffeine that increased their performance time by run about 20% which is pretty good going secondly there's some research that suggests that coffee can reduce our perception of tiredness during exercise so for example in 2015 the European Food Safety Authority published their official scientific opinion on the safety of caffeine and that was a meta-analysis of 23 randomized control trials looking at caffeine and sports performance and they concluded that a cause and effect relationship has been established between the consumption of caffeine at an increase in endurance capacity and thirdly we've got some evidence that coffee can actually help our recovery from exercise as well so for example we've got this study from the University of Illinois which showed that caffeine consumption can reduce Dom's so delayed onset muscle soreness which is that kind of pump the kind of pain thing that you get in your muscles a day or two after exercising and what they did is that they got 18 men split them up into two groups one was a caffeine group one was a placebo group and they got them to do loads of bicep curls at the gym and then they sort of assess how sore the muscles were like a day two days three days five days after doing the bicep curls and they found that the group that had caffeine before hand had significantly less sore muscles on day two and day three which is when Dom's committee kicks in those who had caffeine had less sore muscles than those who didn't have caffeine and actually the group that had caffeine when they did a final kind of test set where they did as many reps of bicep curls as they could until failure they managed to get more reps in than the group that had the placebo and overall they said that the decreased perception of soreness in the days after a strenuous resistance training workout may allow individuals to increase the number of training sessions in a given time period so yeah overall that suggests and loads of all the studies of Bagger sub that caffeine might help our recovery from physical exercise and interestingly between 1984 and 2004 the world anti-doping Authority said that caffeine had such an effect on physical performance they banned high quantities of caffeine from Olympic events but then in 2004 for some reason they said that caffeine actually didn't meet the criteria that they had set out for being an unfair perform with an answer and so now everyone probably has coffee before because they know the caffeine is improves your physical performance and stuff and that's like a good thing alright so so far we've seen that the studies generally sure that coffee has a positive effect on our mental alertness and mental performance but also on our physical performance but actually and quite surprisingly for me I didn't know this was the case there are some studies that show a link between coffee consumption or caffeine consumption and a reduction in long-term health problems so firstly we've got the fact that coffee contains some key micronutrients like vitamins B 2 B 3 and B 5 which are naturally found in coffee beans and on top of that coffee contains natural antioxidants as well antioxidants are useful chemicals that help fight the reactive oxygen species that form when a mitochondria respire and produce energy and we've got this one study from the Journal of nutrition that showed that coffee was the single biggest source of antioxidant intake in the body when come paired with a lot of other stuff including fruits vegetables and cereal so yeah drinking coffee increases antioxidants in your body and that is generally a good thing but also secondly and I think more interestingly coffee consumption is negatively correlated with a bunch of long-term health problems so firstly coffee consumption is inversely correlated with the development of some neurodegenerative conditions so for example we've got this systematic review and meta-analysis of 26 studies that was done in 2010 and they found that 300 milligrams of coffee per day which is three or four cups of coffee that reduced the risk of developing Parkinson's disease by 32% and that's quite a large number although you know there is the caveat that all of this stuff is correlational rather than causational but even so the authors said that this study confirmed an inverse association between caffeine intake and the risk of Parkinson's disease which can hardly be explained by bias or uncontrolled confounding and in relation to Alzheimer's disease we've got this study from 2010 that looked at 1409 individuals aged between 65 and 79 and that examined them over a 21-year period which is a really long period of time and they showed that coffee consumption in the midlife reduced the risk of developing Alzheimer's disease and dementia in the elderly with the lowest risk which was a 65 percent decrease found in the groups that had between three and five cups of coffee per day secondly we've got the negative correlation between coffee intake and type-2 diabetes so for example we've got this meta-analysis from 2018 that had over 1 million people or Dineen total analyzed and they showed a statistically significant inverse correlation between coffee consumption and the development of type 2 diabetes and to quote from study they said that the risk of type 2 diabetes decreased by 6 percent for each cup per day increase in coffee consumption and those consuming 5 cups of coffee per day could reduce their risk by 29% and the data suggested that those who consumed 5 or more cups of coffee per day could potentially again correlational Lee could reduce their risk of developing type 2 diabetes by up to 29% thirdly we've got some evidence that moderate coffee consumption can help reduce cardiovascular disease so for example we've got this review in 2017 that says in healthy people in comparison to not consuming coffee habitual consumption of 3 to 5 cups of coffee per day is associated with a 15% reduction in the risk of cardiovascular disease and higher coffee consumption has not been linked to elevated cardiovascular disease risk so what they're saying is that the more coffee you drink the lower your risk for cardiovascular diseases but they've not shown link between drinking too much coffee and getting more cardiovascular disease so yeah that seems pretty legit for now fourthly we've got some evidence that coffee could even reduce your risk of stroke so for example we've got this meta-analysis from 2011 and they looked at 11 prospective studies that had over 10,000 cases of stroke and over 450,000 participants across the studies and they showed the correlation that drinking two cups of coffee per day reduced your risk of stroke by 14% and drinking three cups of coffee per day reduced your risk of stroke by 17 percent and again purely correlational not necessarily causational but still the data does sort of add up to the fact that coffee is kind of good for you and finally we've also got some evidence that drinking coffee might even reduce your risk of certain types of cancer in 2016 for example the International Agency for research on cancer which I didn't realize was the thing they published a review of over a thousand studies looking at the links between coffee and cancer and firstly they found that there was no direct correlation between drinking coffee and you developing cancer but in fact they found an inverse relationship between drinking coffee and developing certain types of cancer so for example there was some evidence that coffee is linked to reduced risks of liver cancer they said that dose-response analysis revealed a significant linear dose-response relationship between coffee consumption and liver cancer risk subgroup analyses stratified by pre specified variables like gender geographic region and ingested factors indicated similar results within individual sub groups are meta analysis suggested that coffee consumption is inversely associated with liver cancer risk so that's kind of interesting we've got this review of a thousand studies that says that there's no link between drinking coffee and causing cancer but in fact there is a negative correlation ie the more coffee you drink the less likely you are to develop liver cancer again with the caveat that all of this is correlational and it's really quite hard to test this in a positional fashion but still there's a lot of data out there that supports the fact that coffee seems to be on the surface to be good for you but we probably shouldn't get carried away and start drinking absolutely gallons of coffee because there are a few caveats that we have to keep in mind firstly although we know that coffee can increase alertness and vigilance we've got some evidence that says that too much coffee can cause anxiety restlessness and agitation for example we've got this review from 2010 that concluded at low doses caffeine improves hedonic tone and reduces anxiety while at high doses there is an increase intense arousal including anxiety nervousness and jitteriness so yeah as we all know too much coffee you get quite jittery which could potentially be bad but interestingly the author of this study also said that caffeine has also been reported to prevent cognitive decline in healthy subjects so basically what we've just talked about that coffee can reduce your risk of developing Alzheimer's and dementia and stuff if you look at the correlational data but the author of this study says that the result of the studies are heterogeneous some finding no age-related effects while others reported effects only in one sex and mainly in the oldest population so what she's saying is that we really shouldn't take this whole caffeine reduces your risk of dementia we shouldn't take that at face value because there is a lot of variation between the studies and it kind of depends on how old the patient is because different age groups have been studied in different ways secondly there is a lot of evidence that when we have caffeine especially later in the day that can really negatively impact our sleep so for example we've got this study from 2013 and they gave different people a 400 milligram dose of caffeine so about 4 and a bit cups of coffee either 0 3 or 6 hours before bedtime compared to a placebo group who had well a placebo pill and they showed that this moderate dose of caffeine whether you had it just before or three hours before or even six hours before bedtime that had a significant negative impact on quality of sleep and overall we know that caffeine can remain in our system for up to nine hours and so like people generally suggest and I started following this advice that you shouldn't drink any coffee after 2:00 p. m.

because that like if you sleep at 9:00 10:00 11:00 p. m.