Is Tea Actually Good for Health & Weight Loss? Green vs Black Tea

Common wisdom is that tea is the healthy source of caffeine because it has benefits for health and weight loss, but does the science actually support that? Today I'm going over scientific studies on how drinking tea affects your weight, blood pressure, cholesterol, cancer risk, diabetes risk, and insulin resistance. Hey there, I'm Mish, and I am a full-time research scientist running and publishing studies of my own, and as a hobby on the side, I make videos here on all sorts of scientific studies to help you reach your weight loss, fitness, health, and nutrition goals. And as a reminder, I've got bonus videos over on the Patreon, and for March the bonus video was a Q&A where I answered 19 of your questions, and for April the bonus video is going to be on ways to improve insulin resistance slash insulin sensitivity using lifestyle changes like diet in addition to just weight loss. And I'm going to try to include some stuff on PCOS as well, assuming there's solid research on that. So if you're interested in any of that, the link will be in the description below. And back to today's video, which is a highly requested topic, so that is why I'm filming it, and I will be focusing on green tea and black tea because that is what the vast majority of the research has been done on. And most of the studies I will be sharing will be randomized controlled trials, especially meta-analyses of randomized controlled trials, which means we are getting at cause and effect because these researchers are running experiments and looking at how making people drink tea influences various things in terms of health and weight. And for the cancer risk and diabetes risk, these studies will be epidemiological because that's just the nature of the beast, but I will specify what type of study I'm talking about for each category. And doing the research for this video was a bit frustrating because tea is more of an industry-funded minefield than I would have expected, where most of the studies on black tea are funded by industry. So as always, I am focusing on studies that are not funded by industry, and at the end I'll tell you about some implications of the fact that so many of these studies are funded by industry, but not the ones I'm talking about. So first I'm going to talk about weight loss, and all of these studies are randomized controlled trials that establish cause and effect. And the reason I specify this now is because the gurus out there are causing a lot of confusion among the public in terms of what can get at cause and effect. So I'm specifying clearly now. And first for green tea, green tea has been found to be helpful for weight loss and weight maintenance, and in particular it's the catechins in green tea, you may have heard of ECGC, that is particularly helpful for weight loss. For example, a meta-analysis found that giving people catechins improved both weight loss and weight maintenance after weight loss, such that after 12 weeks, people who were given catechins ended up three pounds lower than people who were not given catechins. And another study suggests that green tea is particularly beneficial for abdominal fat. And the quantities of catechins across these studies differs, but in general I'm seeing numbers around or that are equivalent to around two to four cups of green tea. And these studies typically use a mixture of catechins and caffeine that mimics green tea. And one of the reasons they do that is to establish what it is in particular about green tea that causes weight loss. So they isolate it down to the ECGC and the caffeine. And if you want to get more catechins, studies suggest that matcha has about 130 times more catechins than green tea. And I have matcha, most days I put it in my smoothies or have it as a matcha latte, which now you can also get at most cafes. And if you're curious about the type of matcha I use, I'm linking it in the description below. It's organic and independently tested for heavy metals, which is why I picked it. I am not an affiliate, I am not sponsored or anything, I just like it. And for black tea, there's hardly any research that is not funded by industry, but one non-funded study found that drinking black tea helped prevent weight gain over the course of three months, but this effect went away when looking over the course of six months. So it's possible that black tea has some slight short-term benefits for not gaining weight, but it doesn't seem nearly as strong as green tea. Next for blood pressure, a meta-analysis of randomized controlled trials find that green tea extract, so catechins in particular, or decaffeinated green tea helps reduce both diastolic and systolic blood pressure. But perhaps unsurprisingly, caffeinated green tea doesn't seem to have much of a benefit. As for black tea, I could not find solid non-funded research on randomized controlled trials of black tea affecting blood pressure, so I'll keep an eye out for that, but kind of inconclusive at the moment with black tea. As for cholesterol, another meta-analysis of randomized controlled trials finds that green tea reduces total cholesterol and more importantly LDL cholesterol. And there are a few studies suggesting that black tea might lower LDL cholesterol, especially in people who already have a high risk of cardiovascular disease. So for blood pressure and cholesterol, green tea seems to have really good effects, and black tea might have a helpful effect too. And next for cancer risk, as a reminder these studies are epidemiological or correlational, which is the case for almost all cancer research, and it's found that in general green tea has slight benefits or no effect on various types of cancer. So green tea probably on average has a slight benefit. On the other hand, black tea is typically found to have a weaker benefit or no benefit for different types of cancer. So overall what I'm seeing so far from the literature is that green tea probably has a weak benefit across different types of cancers, whereas black tea probably doesn't really affect things either way. And next for diabetes risk, for whatever reason these studies generally treat tea as a single category, largely in comparison to coffee, rather than breaking it down by green or black tea, but overall drinking more tea epidemiologically correlationally predicts a lower chance of getting type 2 diabetes. And next for insulin resistance, this time we're getting back to cause and effect with a meta-analysis of randomized controlled trials finding that green tea consumption causes people to have lower fasting blood glucose, lower fasting insulin, and lower A1c, which is pretty exciting. I'll put the specific numbers slash effect sizes up on the screen so you can see for the various units and whatnot how drinking green tea is affecting these different insulin resistance parameters. And as for black tea, there isn't really anything that hasn't been funded by industry looking at the effects of black tea on insulin sensitivity. And the main takeaways from the studies out there on tea are that green tea, in particular the catechins within green tea, have all sorts of benefits for health and weight loss, including improved insulin sensitivity, improved cholesterol, lowered blood pressure, weight loss, and predicts potentially reduced cancer risk and type 2 diabetes risk. And studies on catechin content suggest that you can get more from drinking matcha than from drinking standard green tea, but either one is going to be great for you. As for black tea, the story is a little more nuanced because almost all of the studies out there are industry funded, which kind of tells me like the combination of so few studies finding anything about black tea with the fact that most of the studies are industry funded tells me that black tea probably isn't doing much of anything either way or else there would be more non-funded researchers publishing on it like with green tea. And just so you have this information, the research that is funded by industry on black tea unsurprisingly finds that black tea is also very very good for everything I've talked about. So if you believe industry funded findings then they do suggest that black tea is also great for you and probably about equivalent to green tea. But if we just focus on unfunded findings it seems like black tea has much weaker effects than green tea in terms of benefiting our health and weight. And why is that? Well the main thing that is responsible for the health benefits of black tea and green tea is polyphenols, which includes catechins, and green tea is much higher in polyphenols that you absorb than black tea is. So that's probably the reason that green tea is found to be more beneficial in terms of effect sizes than black tea. And I'm going to add a little disclaimer because a lot of people seem to think that no matter what the video topic is I must be biased to be talking about that topic at all or I must be sponsored or something, which honestly is a fair assumption on YouTube because most people are so I totally get it. So I just want to be clear this is just my hobby, I do not accept any sponsorships, I am not an affiliate of anyone, and I have no personal interest in tea of any kind, I just drink coffee and black tea and green tea about equally depending on what sounds best in the moment and the time of year and whatnot. So I have zero position either way on tea versus coffee or black tea versus green tea, I'm just sharing what the studies say. And if you don't believe me, which really why should anyone believe a rando on YouTube, please check out the studies in the links below, they're all on tea in humans, none of the like weird abstract like here's a little pathway and some cell cultures that we're going to abstract to humans, these are all studies in humans. And speaking of coffee, in case you are curious about the effects of coffee, I already have videos here on YouTube looking at studies on the effects of coffee on health, as well as a more blood sugar and diabetes focused video on the effects of coffee on that. So if you're interested in that, check out those videos linked in the description below and up here. And if you are interested in a direct comparison of coffee to tea in terms of which one is better in studies directly comparing them, then let me know in the comments below if you'd like to see a video on that. And as a reminder, if you want to see more videos like this one, as well as get your questions directly answered by me, then head on over to the Patreon, which is linked in the description below. I want to say thank you to all our patrons. It's been so amazing watching the community grow and getting to chat with you all and answer some really interesting questions that have been very thought provoking and that I've been learning from too, as I do the research to answer them. So thank you very much for that. And if you like this video, please like and share it so that other people can learn the science on how tea affects us. And if you haven't already, be sure to hit the subscribe button and the notification bell below to stay up to date on all this science. Thank you so much for watching, and I will see you next time.