 We all want to eat the kinds of foods that make us feel better and live longer. But there's so much conflicting information out there, so many nutrition opinions. Welcome to the Nutrition Facts podcast. I'm your host, Dr. Michael Greger. It's my job to give you the information you need to make the healthiest choices possible. Did you know that as we age, our telomeres shorten? Telomeres are a series of DNA sequences that protect the ends of our chromosomes from becoming frayed or tangled. As it turns out, a plant-based diet and lifestyle can effectively reverse their aging by elongating telomeres. Here's the story. Identifying simple strategies to prevent or delay age-related diseases is a major public health concern. But how could you measure the effects of such strategies? Telomere length is a reliable hallmark of biological aging and the risk of developing age-related chronic diseases. What is a telomere and why does it matter how long they are? Telomere comes from the Greek for end part of our chromosomes. Telomeres cap the ends of our chromosomes like shoelace tips to essentially keep our DNA from fraying. Telomere length is important since there's a minimum length required, but every time our cells divide, a bit of the telomere is lost. And once they get too short, the cell can die. That's why telomeres are sometimes called the molecular clock of cells. Every year they get shorter and shorter, kind of like life's fuse. But in some people, that fuse burns faster than in others. Accelerated telomeres shortening has been identified as a key biomarker for accelerated aging, disease risk, and diminished longevity. There's some good news. Telomere shortening can be counteracted by an enzyme in our cells called telomerase. Telomerase can replenish the lost bits and elongate our telomere. So how can we boost this enzyme to, in effect, reverse cellular aging? Exercise may help. Those with high levels of physical activity have longer telomeres, whereas obese individuals and smokers tend to have shorter telomeres, along with those getting inadequate sleep. But what about nutrition? Globally, we might expect that any antioxidant or anti-inflammatory diet could be protective for telomeres. So we're talking like a whole food plant-based diet was a reduced intake of meat and, in fact, swapping out animal protein in general in favor of plant-based proteins. Given that plant-based foods have well-known antioxidants and anti-inflammatory effects, there are fair grounds to believe that the consumption of plant-based foods can help that counteract telomere attrition. But you don't know if it actually would. Until you put it to the test. Dr. Dean Ornish, along with a Nobel laureate who co-discovered the telomerase enzyme, studied the effects of comprehensive lifestyle changes on telomerase activity and telomere length, using the same plant-based diet and lifestyle program shown to reverse the progression of heart disease and early stage prostate cancer, and maybe even early stage Alzheimer's, and telomere length shortened in the control group and they aged five years as expected, but didn't just not shorten as much or hold steady, but actually lengthened in the plant-based lifestyle group. Whereas in a similar study across a similar time frame, there was no difference in telomere length when just giving people the more typical low-fat dairy, skinless chicken breast, generic type healthier dietary advice. Antioxidant-rich plant foods help maintain telomere length. In contrast, total and saturated fat intake and consumption of refined flour grains, meat and meat products, and soda relate to shorter telomeres. People eating more anti-inflammatory diets tend to have longer telomeres. The greater the anti-inflammatory potential of the diet over time, the greater potential to significantly slow down the rate of telomere shortening. Those with the most pro-inflammatory diets had almost twice the risk of accelerated telomere shortening. The most pro-inflammatory food component is saturated fat found in meat, dairy, eggs, and junk, along with other pro-inflammatory food components like cholesterol and trans fat. Make it three, these tend to be anti-inflammatory, but when put to the test, fish oil supplements fail to have any significant telomere effects. The most anti-inflammatory food component is fiber. And indeed, if you look at dietary fiber and taking telomere length in a representative sampling of thousands of U.S. adults, even though nobody was eating enough, the more fiber people consumed the longer their telomere tended to be. Since there appeared to be a straight line increase, they could do the math and appeared that just a 10 gram increase in fiber per thousand calories would equate to four fewer years of biologic aging. Whereas, for example, the consumption of soda appeared to increase cell aging by almost two years per daily serving. Now, of course, diets high in fiber and diets with significant amounts of fruits, vegetables, and whole grains go hand in hand, so fiber may just be a marker for eating lots of whole healthy plant foods. But are there any specific plants associated with telomere lengthening? We'll find out next. Telomere length is considered a biomarker of aging. Shorter telomeres are associated with decreased life expectancy and increased rates of age-related chronic diseases. Telomere shortening has been shown to be accelerated by oxidative stress and inflammation, so since plant foods contain plenty of compounds with antioxidants and anti-inflammatory properties, it's plausible that their sustained consumption might help counteract telomere attrition. And indeed, if you pull all the best studies on the impact of nutrition on telomere length, the consumption of vegetables, fruits, beans, and nuts has been associated with positive effects on markers of inflammation and oxidative stress in parallel with longer telomeres. By contrast, processed meats, alcoholic and sugar sweetened beverages, and other foods rich in saturated fats, alcohol, and sugar are linked to an increase in inflammation and oxidative stress in parallel with shorter telomeres. Their randomized controlled trials, showing a whole-food plant-based diet and lifestyle program, could actually lengthen telomeres. Is it just because they cut out the junk? Those eating the most ultra-processed foods have been found to have almost twice the odds of having short telomeres. Maybe it's because they cut out the processed meat like Baking Ham Hot Dog's Lunch Meat Sausage, which had been associated with not only cancer and diabetes risk, but shorter telomeres as well, meaning accelerated cellular aging, though just having something like a steak was not similarly associated with telomere length. Processed meat, but not unprocessed red meat, is associated with shorter telomere length. This is perhaps due to the particularly high concentrations of glycotoxins, the advanced glycation end products, as well as carcinogenic nitrosamines in the processed meat that may promote inflammation and oxidative stress. The only unprocessed meat associated with shorter telomeres was poultry. For dairy, it appears to be the milk fat. A national survey of thousands of Americans found an association between increased biological aging and the consumption of high-fat milk. Even people just going up like 1% milk fat, from like 1% milk to 2% milk, low-fat milk to reduced fat milk, appeared to have more than four years of additional biological aging. Everything is because of the saturated fat, given that saturated fats trigger an inflammatory response. Not all plant foods are good for you, though. French fries and potato chip consumption is associated with shorter telomeres. Yes, fiber intake goes hand-in-hand with longer telomeres, as does higher vegetable and fruit consumption, but that may be trumped by a deep fryer. What about the consumption of a high-fat whole plant food, like nuts? We know higher telomere-building enzyme activities associated with a higher dietary antioxidant score, and botanically, seeds are packed with antioxidants, and by seeds they mean any food you can put in the ground and sprout a whole plant. Like whole grains, beans, chickpeas, lentils, nuts, they are naturally enriched in antioxidant compounds that protect the seed DNA from damage. Four weeks of navy beans didn't seem to affect telomere length, though. What about nuts? Well, based on how much your telomere is shortened every year, you can estimate the rate of aging. In other words, two people can have the same chronological age, same calendar age, but suffer more or less effective cellular aging. So, for example, if you smoke a pack a day for a decade, your cells may age about three years faster, or if you drink soda every day, it's like almost two years of additional aging. So, what about nuts? U.S. adults of the same age would experience almost two years less biologic aging per ounce of nuts and seeds consumed per day, the amount I recommend in my free Daily Dozen app. The estimated biologic aging advantage would be nearly one year for each 100 calories of nuts and seeds consumed every day. The researchers conclude that clearly consumption of nuts and seeds accounts for meaningful lower levels of biologic aging in U.S. men and women, but that's just an association you don't know if nuts can slow telomere shortening until you put it to the test. A randomized control trial investigating whether the inclusion of one or two ounces of walnuts a day for two years would help maintain telomere length, which normally shortens with age. In the control group, their telomere shortened as expected over those two years, whereas the walnut group telomeres maintain their length though the difference didn't reach statistical significance. Now that was measuring average telomere length, and it's probably more telling to look at how long the shortest telomeres are rather than the average. And if you do that, look at the percentage of telomeres that are particularly short, the walnut group does edge out over the control group. It's well established that the length of the shortest telomeres is the key biomarker on the onset of senescence. The researchers conclude that the inclusion of walnuts in the regular diet for two years tends to delay leukocyte telomere shortening in older individuals. A study on pistachio consumption two ounces a day for four months reduced signs of DNA damage, but did not significantly slow the rate of telomere shortening. And this study, which randomized people to eat more mixed in nuts, found a higher risk of telomere shortening in the nut group for which the researchers could offer no explanation, so it's not clear whether nuts help with telomeres or not. Most supplement intervention studies observed no effects on telomere length as well with the exception of green tea. 36 elderly women were randomly divided into two groups, exercise alone or exercise with green tea consumption for five months, and a significant boost in telomere length in the green tea group with no change from the placebo. Green tea is essentially a green leafy vegetable we dip in hot water. How about eating green leafy vegetables? In fact, the healthiest kind cruciferous vegetables like broccoli, cabbage, collards, and kale, they pitted a raw versus cooked and found that cooked was better than raw for reducing DNA damage from a carcinogen, but raw was more anti-inflammatory. Consequently, to fully exploit the complexity of the health-promoting potential of Ethiopian kale and, by extension, maybe other cruciferous, a mix of both raw and cooked vegetables should be part of the diet. Okay, but what about for boosting the telomere lengthening age reversal enzyme, raw or cooked? Which do you think? A short-term dietary intervention showed that cooked, but not raw, boosted telomerase activity, in as short as five days eating one and a quarter cups of this kale a day. It was thought that you'd need like four months of a change to affect telomeres, but this study provides for the first time evidence that telomerase activity can respond in a matter of days to a food intervention, but not just any food, but the healthiest food out there, cruciferous dark green leafy vegetables. Finally today, Dr. Dean Ornish showed that his plant-based diet exercise and stress management intervention could, in effect, reverse the aging of our DNA. What effect might the stress management component have had? In my research into reversing aging video, I highlighted Dean Ornish's landmark study showing that a low-fat, whole foods, plant-based diet, high in vegetables, fruits, whole grains, beans, along with walking, stress management support, could not only reverse heart disease, open up arteries without drugs and surgery, and potentially reverse the progression of early-stage prostate cancer, but was the first intervention ever shown to increase telomerase activity, the enzyme that builds and maintains these caps at the tips of our chromosomes called telomeres, which appear to slow the aging of our cells. Yes, this new finding was exciting and should encourage people to adopt a healthy lifestyle in order to avoid or combat cancer and age-related diseases, but was it the diet, the exercise, or the stress management? That's what researchers have been trying to tease out in the six years since the study was published. Let's look at stress first. In the film The Holiday, Cameron Diaz exclaimed, severe stress caused the DNA in our cells to shrink until they can no longer replicate. Did Hollywood get the science right? Do people who are stressed have shorter telomeres? To answer that question, researchers measured the telomere lengths in mothers of chronically ill children. What could be more stressful than that? The longer a woman had spent being the main carer of her ill child, the shorter were her telomeres. The extra telomere shortening in these stressed mothers was equivalent to that caused by at least a decade of aging. We see the same thing in caregivers of Alzheimer's patients, and those suffering severe work-related exhaustion. Even those abused as children may grow up with shorter telomeres. Not much we can do about our past, but if we manage our stress, can we grow some of our telomeres back? Well, if you go off to a meditation retreat and meditate for 500 hours, you can indeed boost your telomerase activity. 600 hours of meditation may be beneficial as well, but come on, it's gotta be a quicker fix, and this exciting new study delivered. Caregivers of family members with dementia randomized to just 12 minutes of daily meditation for 8 weeks, so just about 10 hours in total, experienced significant benefit. Better mental and psychological function accompanied by an increase in telomerase activity suggesting improvement in stress-induced cellular aging. We would love it if you could share with us your stories about reinventing your health through evidence-based nutrition. Go to nutritionfacts.org slash testimonials, which may be able to share it on social media to help inspire others. If you'd like to see any graphs, charts, graphics, images, or studies mentioned here, go to the Nutrition Facts Podcast landing page, there you'll find all the detailed information need, plus links to all the sources we cite for each of these topics. My last two books were How to Survive a Pandemic and My How Not to Diet Cookbook. Get ready this year for the launch of How Not to Age, and of course, all the proceeds for the sales of all my books goes directly to charity. NutritionFacts.org is a non-profit science-based public service where you can sign up for free daily updates on the latest in nutrition research with bite-sized videos and articles uploaded nearly every day. Everything on the website is free, there are no ads, no corporate sponsorships, no kickbacks, it's strictly non-commercial, not selling anything. I just put it up as a public service as a labor of love as a tribute to my grandmother, whose own life was saved with evidence-based nutrition.