These 7 Foods Kill Inflammation and Help Your DNA Repair Itself

0:00 There's a reason two people the same age can feel a decade apart. For some, it could be belly fat that just will not go away or brain fog or achy joints. An explanation you always hear is that's just getting older, but it's not. Most of what we call aging is damage piling up in your cells faster than your body can repair it. And a lot of that damage lands on your DNA. Now, the genetic code that you were dealt, that part's fixed.

0:25 You can't change that. But the wear and tear on the DNA, that's happening every single day, and so is the repair. It's a constant tug of war between the two, and which side is winning is a big part of how fast you age. But the good news is you've got a repair crew built into every cell working around the clock. And the food on the plate either arms that crew or it gets in the way. And a heads up, you've probably eaten a few of these foods already this week. The name of the food was never the hard part. What actually decides whether it works for you is the form you eat it in and how much. That's where most of the benefit usually slips away. But if you get it right though, it will translate to steadier energy and less inflammation and easier weight loss. So in this video, I want to go over seven foods, all backed by human studies, that quiet inflammation and help that repair crew do its job. And one of those foods was shown to cut DNA damage by about 23% with the biggest effect in the people whose cells were under the most oxidative stress. And then another food that we'll cover goes even further. It doesn't just shield your DNA, it actually helps repair the damage that's already been done. And if you're new here, I'm Dr. Leana Kim. I'm a double board certified physician, and on this channel, I go over the science and the practical tools to not only live longer, but to feel better today. And as always, this information is educational only and not medical advice. So please talk to your doctor before making any changes to your health regimen. So really quickly, let me give you one framework that makes all seven of these foods tie together.

1:53 Think of it as a race that never stops. On one side, you have things chipping away at your DNA all day long. So be like chronic inflammation and blood sugar spikes and something called oxidative stress. And oxidative stress sounds complicated, but it's really not. Your cells naturally produce unstable molecules called free radicals. And normally antioxidants help keep them under control, but when you have more free radicals than your body can handle, well, that's when they can start damaging things around them including your DNA. And on the other side of the race is your repair team, real enzymes whose whole job is to find damage in your DNA and cut out those damaged pieces and help put clean ones back in.

2:34 Now you can't win this race by stopping all of the damage. That's just not possible. At the end of the day, we're all aging and we can't really stop the clock, but you can slow down aging by taking the work off the repair team and handing them the parts that they need so they finish faster than the damage piles up. And every food on this list does one of those two jobs. And the one I want to start with is the rare one that actually does both. So number one may be the most impressive food on this whole list and it's kiwi. Researchers ran a small crossover study where the same people ate kiwi for a stretch and then went without it. So everyone was basically their own comparison. And then researchers measured the DNA inside white blood cells using something called a comet assay, which is just a way to see how much damage is sitting in your cells' DNA. And after the kiwi weeks, the damage in the DNA came down. But here's what made the study different.

3:26 The researchers deliberately exposed those cells to extra oxidative stress. And after people had been eating kiwi fruit, their cells repaired the damage faster than before. So kiwi fruit wasn't just protecting DNA from new damage, it actually seemed to speed up the machinery that repairs the damage that was already there in the first place. And almost no food has been shown to do that in people. So ideally we want to eat one or two kiwis a day eaten whole and the skin is actually completely fine to eat. And that's where you can get even more fiber and vitamin C, so you can leave it on if the fuzz doesn't bother you. And I like to eat them at night closer to bedtime because there's studies that show that they can actually help you with sleep. Now, kiwi helps your cells repair the damage, but this next one that works more on the other side of the equation stopping some of that damage before it happens. And it's a green that's very easy to overlook, and I'm talking about watercress, those small, round, peppery leaves that you've probably seen in the produce section of your grocery store. And this is the food that I mentioned earlier, the one tied to that 23% reduction in DNA damage. So there was a randomized crossover study where researchers took 60 healthy adults. Half of them were smokers and had them eat about 85 g of watercress per day, which is two big handfuls. And after just eight weeks, the DNA damage in their blood cells had fallen by around 23%. And the fascinating part was the people who improved the most were smokers, the ones whose cells were under the heaviest oxidative stress to begin with. So how does a salad leaf pull that off?

4:54 Watercress belongs to the cruciferous family, the same family as broccoli and kale and cabbage and Brussels sprouts. And when you chew it, it releases a compound called phenethyl isothiocyanate. And that compound flips a switch inside your cells called NRF2, that master switch for your body's own antioxidant and detox system. So instead of just giving your body antioxidants from the outside, you're turning up the defenses you already have built in. But there is a catch with watercress and its heat. Cooking can destroy a lot of the compounds that we're after. So ideally, you want to eat this raw in a salad or in a sandwich or you can blend it into a smoothie. And if you can't find watercress or you hate that peppery taste, arugula is from the same family and it contains similar compounds. Now, the study was done on watercress specifically, but it's in the same neighborhood. Okay, the next food I want to talk about is actually a drink, and it's green tea. And if you've seen any of my other videos, you know I can't do a video without mentioning green tea at least once, but that's because the human data on this is so compelling. In one study, researchers followed heavy smokers for months, so people whose cells are under a lot of oxidative stress every single day. And they split them into three groups. One drank green tea, and then the other group drank black tea, and the third group just drank plain water. And by the end of the study, the green tea group had cut a marker of oxidative DNA damage by 31 percent, and the black tea and water groups barely changed. And what's doing the work here is a polyphenol in green tea called EGCG. It's a type of polyphenol that basically acts as a heavy-duty antioxidant. But just like with watercress, how you consume green tea matters quite a bit. The study used freshly brewed green tea, which is important because a lot of the bottled green teas can have much less EGCG by the time you drink them, and some of them are loaded with added sugar. So ideally, you brew the actual tea and just drink one or two cups per day. And one interesting part is that study used decaf green tea. So if caffeine makes you jittery or keeps you awake at night, you can still get the benefits. Now there's lots of variations of green tea, and I personally prefer matcha or sencha, and people often ask me what brand of green tea I like. Now it really doesn't have to be anything fancy, and I'm going to post a link to the green tea that I personally drink in the description below. That's just the best one that I found on Amazon that has the best combination of price and quality.

7:11 Now speaking of caffeine, the next one is something most of us probably already drink every morning, and that's coffee. And coffee is interesting because in a randomized controlled trial, researchers had people drink dark roast coffee every day for four weeks. And when they look at their blood cells afterwards, they found significantly fewer breaks in their DNA compared with the water group. And part of the reason may actually come from the roasting process itself, because roasting coffee beans creates a compound called NMP, which also activates NRF2, that same antioxidant defense which we talked about with watercress. But again, how you drink your dark roast coffee matters a lot.

7:47 The study used dark roast brewed coffee and close to black. What we don't want to do is load it with sugar or syrup or whipped cream, because at that point, you're probably giving a lot of that benefit right back. And drinking one or two cups per day is fine for most people, but we just want to be careful about drinking it too late in the day. Many people underestimate how long it takes to metabolize caffeine out of your system. And for most people, we need to stop drinking caffeine at least 10 to 12 hours before bedtime. So, if your typical bedtime is let's say 11 p.m., well, that means we shouldn't drink any more caffeinated beverages past noon.

8:21 And even if you fall asleep easily, late caffeine can still disrupt that restorative deep sleep later in the night. Now, number five is something that most of us probably already have sitting in the kitchen, but the bottle you have may be missing a lot of what makes it beneficial. And I'm talking about extra virgin olive oil because with olive oil, quality really, really matters. And it's easy to think that the benefit from olive oil comes from the healthy fats, and that's definitely part of it, but when it comes to protecting your cells, a lot of what makes extra virgin olive oil special actually comes from compounds called polyphenols. And there's a really interesting study that shows just how much this matters. So, in this study, researchers gave people olive oils that were basically the same except for one thing how many polyphenols they contained. And the people getting the high polyphenol olive oil ended up with less oxidative damage to their DNA. So, same fat, but different amounts of polyphenols, and you get very different results. And this is the main problem with olive oil. A lot of the bottles sitting on grocery store shelves may already be low in these polyphenols to begin with. And even if you buy a good one, those polyphenols are pretty fragile. They tend to break down over time, and their breakdown can speed up with heat and light. So, we want to treat extra virgin olive oil like fresh juice that's perishable as opposed to a pantry item that just sits in a bottle next to your stove for years. So, here's what you want to look for when you're looking for a good extra virgin olive oil. number one is you look for a harvest date, not a best used by date, but an actual harvest date. And ideally, we want early harvest olive oil and use it within 12 to 18 months of harvest. The fresher, the better. And number two is make sure the olive oil is in a dark bottle or container and never in a clear glass because light and especially UV light can break down those beneficial compounds. And three is a taste test. A good and high polyphenolic olive oil should have some bitterness and this peppery kick in the back of your throat, sometimes enough to actually make you cough. And part of the burning comes from oleocanthal, one of those anti-inflammatory polyphenols in olive oil. So if your oil is completely smooth and buttery with no bite at all, well, that's probably not the oil I'd choose.

10:30 Now number six is probably one of the easiest foods on this entire list to add to your regimen, and that's blueberries. And with blueberries, the first clue is actually their color. That deep blue purple color comes from compounds called anthocyanins. Those are the pigments that make blueberries blue, but they also act as powerful antioxidants and help turn down inflammation. In a one human randomized crossover trial, researchers had people eat a single serving of blueberries, and then they took their blood and exposed those cells to oxidative stress. And after just 300 g of blueberries, their cells were better able to resist DNA damage. And this one doesn't have to be complicated.

11:06 In the study, they used two servings of blueberries, but one cup a day is a great target. And fresh blueberries can get pretty expensive at times, so frozen blueberries are just as good. And I personally prefer them blended in a smoothie, but there's so many different ways you can eat them. And it doesn't always have to be blueberries, blackberries and dark cherries, pomegranate. In general, those deep red and blue and purple colors are a good clue that you're getting more anthocyanins and other polyphenols. So if you can, ideally you rotate through them just to get that rich biodiversity.

11:37 Now the last one is a little different because everything we talked about so far either helps prevent some of that damage or it helps your cells protect themselves when the damage happens. But there's one more thing that your DNA repair crew still needs to do its job and its energy. And that brings us to number seven, which is vitamin B3. And you may also hear different forms of it called niacin or nicotinamide. Now technically vitamin B3 isn't really a food, it's a water-soluble B vitamin found in a bunch of different foods. And it's very important because your body uses it to make molecules called NAD.

12:09 And NAD does a lot of things inside your cells, but the reason it matters here is that some of the enzymes that actually repair damaged DNA, well, they need NAD to work. Think of NAD like the battery pack for the DNA repair crew. The proper repair enzymes can all be there, but if the battery starts running low, they don't have the same energy to do their job. And this becomes even more important as we get older because NAD levels tend to naturally decline with age. And we actually have some interesting human data on this.

12:38 Nicotinamide has been shown to improve the repair of DNA damaged by UV light. In a one double-blind randomized control trial of nearly 400 people at high risk for skin cancer, taking nicotinamide cut the number of new non-melanoma skin cancers by about 23%. Now, this is where you'll hear a lot about NAD supplements and NAD boosters because remember, your own body can make NAD from vitamin B3. And as a general rule of thumb, I'm actually not a big fan of those. And you can get it from regular foods. Now, there's a lot more that we can get into as far as why I don't recommend this to my patients, but it probably deserves a whole dedicated video on this topic. So if you're interested, let me know in the comments. And if there's enough demand, I'll make a whole separate dedicated video on this. But overall, we just want to focus on getting enough natural B3 from foods. So this would be foods like salmon and turkey and chicken and sardines, avocados, and peanuts are also a very good source. All right, hope this was helpful. Stay healthy and I'll see you in the next one.