Hello and welcome to the Nutrition Facts podcast. I’m your host, Dr. Michael Greger.
Now, I know I’m known for explaining how not to do certain things (just look at my books, How Not to Die, the one I’m working on right now–How Not to Diet), but what I actually have to share with you is quite positive and boils down to this: What’s the best way to live a healthy life? Here, are some answers.
It’s time for the Nutrition Facts grab bag, where we look at the latest science on a whole variety of topics. Our first story, just in time for that sunburn you just got at the beach, looks at the risks and benefits of Aloe vera.
“Aloe vera is one of the most popular home remedies in use today, yet most physicians know little about it. In fact, most dismiss it as useless, while their patients firmly believe in its healing properties.” “The usual tendency of most [doctors] is to dismiss as useless any popular remedy that can be purchased without a prescription. However, the Aloe plant deserves a closer look, because, surprising as it may seem, there may be a scientific basis for some of its uses.” It has, after all, been used medicinally for thousands of years by a number of ancient civilizations. Only recently, though, has it been put it to the test.
But, the tests have been like finding out if you can use Aloe to ameliorate the damage of albino rat testicles, or affecting the cholesterol and estrogen responses in juvenile goldfish.
Yes, if you inject Aloe in the bloodstream of rats, their blood pressure drops. But, if you feed it to people, it doesn’t appear to have any blood pressure-lowering effect. In rats, drinking Aloe causes colorectal tumors to form, whereas it appears to have anti-inflammatory effects on human intestinal lining—in a Petri dish. But, when put it to the test for irritable bowel syndrome, no benefit was found for improving symptoms or quality of life in IBS patients. What about IBD—inflammatory bowel disease? No benefit found there, either.
What about the beneficial effects of Aloe in wound healing? Evidently, “so miraculous as to seem more like myth than fact.” Works when you slice open guinea pigs, or when you try to frostbite off ears of bunny rabbits. But, in people, may make things worse, Aloe causing “a delay in wound healing.” Twenty-one women were studied who had wound complications after having a Caesarean or other abdominal surgery, healing on their own in an average of 53 days, whereas the wounds treated with Aloe vera gel required 83 days—50% longer. They thought it would help, based on the animal research, but when put to the test in people, it failed.
At this point in my research, it was looking like the only benefit to Aloe was to improve the quality of cheap beef burgers. But what about burns? Aloe has been used to treat burns since antiquity, but, in their ageless wisdom, they were also applying excrement to burns. So, I wouldn’t put too much faith in ancient medical traditions.
That’s why we have science. What is the effectiveness of Aloe vera gel compared with silver sulfadiazine as burn wound dressings in second-degree burns? “The introduction of topical antimicrobial agents has resulted in a significant reduction in burn mortality,” and the most commonly used is the silver sulfadiazine. Unfortunately, it may delay wound healing, and become toxic to the kidneys and bone marrow. So, they tried it head-to-head against topical Aloe gel, and the Aloe burns healed 50% faster, and the pain went away about 30% quicker. The researchers concluded that Aloe has “remarkable efficacy” in the treatment of burn injuries. Anyone see the flaw in that logic, though? What was this study missing? Right, a placebo control group. Why? Because I just told you that one of the side effects of the drug is delayed wound healing. So, maybe the Aloe worked better just because it wasn’t delaying healing, but wouldn’t have worked better than just nothing.
When put to the test against nothing, Aloe vera in Vaseline versus the Vaseline alone, the Aloe really did seem to help—speeding healing by about a third. And, indeed, put all the studies together, and Aloe does appear to significantly speed up the healing of second-degree burns. Okay, but blistering burns are thankfully less common than just like sunburns, where your skin just turns red. What is the efficacy of Aloe vera in the prevention and treatment of sunburn? “The Aloe vera cream was applied…30 minutes before, immediately after, or both before and after” burning people with a UV lamp. And, surprisingly, the Aloe appeared to offer “no sunburn…protection and [had] no efficacy in sunburn treatment when compared to placebo.”
But, hey, at least it worked for blistering burns. So, should we keep some Aloe vera gel in the medicine cabinet? The problem is that Aloe vera at the store may have no Aloe vera at all. Oh, they say they have Aloe vera as the first or second ingredient, but are apparently lying. See, “There’s no watchdog assuring that Aloe products are what they say they are.” “That means suppliers are on an honor system,” and when health and nutrition are mixed with profit, honor, too often, goes out the window.
In our next story, dinosaur kale and red cabbage are put to the test.
LDL “bad” cholesterol is bad, but oxidized LDL may be worse. What role might our diet play? “Increased fruit and vegetable consumption has been reported to reduce the risk of developing [cardiovascular disease, heart attacks, and strokes].” Well, maybe it’s in part because of all the antioxidants in healthy plant foods preventing the oxidation of LDL cholesterol. And, indeed: “The LDL oxidation resistance was [found to be] greatest” among those eating more plant-based. So, that would be “in addition to the decreased blood pressure” and lower LDL overall in terms of “beneficial effect[s].” But, you don’t know if it’s cause and effect, until you put it to the test. Put people on a whole-food plant-based diet for just three weeks, and rates and extent of LDL oxidation drop.
“The effects of kale” on LDL oxidation were put to the test. Kale is a best-of-all-worlds food, low in calories, packed to the hilt with nutrition—vitamins, minerals, anti-inflammatory compounds, antioxidant phytonutrients—you name it! No surprise, then, given its “high antioxidant capacity… kale showed a protective effect on the oxidation of [LDL] even at low concentrations.” But, this was in vitro, in a test tube. Kale was also put to the test in mice. But, what about people?
I did a video on how “kale juice improves coronary artery disease risk factors in men with high cholesterol.” Extraordinary results: a 20% drop in LDL among the nonsmokers. But, they were drinking the equivalent of about 10 cups of kale a day. Still, the fact that they were able to see an improvement, even though nearly all the fiber was removed, because it was just juice, shows there does seem to be something special in the plant. But, can you get the benefit just eating the stuff? Let’s find out.
“The effect of black and red cabbage on…oxidized [LDL].” And by black cabbage, they mean lacinato kale, also known as dinosaur or Tuscan kale. They had people eat a bag of frozen kale and cabbage a day for just two weeks—which is great because you can just keep it in the freezer, pre-washed, pre-chopped, just throw it into any meal you are making—and got “significant reductions” of total cholesterol, LDL cholesterol, and even blood sugar levels. And, the antioxidant capacity of their blood went up. And, so, no surprise, they demonstrated “a significant decrease” in oxidized LDL, too.
Would it have been better to take that red cabbage and ferment it into sauerkraut? Red or purple cabbage, one of my favorite vegetables—packed with antioxidants, yet dirt cheap, and seems to last forever in the fridge and it’s pretty, juicy, tasty. I try to slice shreds off into any meal I’m making. But, when you ferment it, not only do you add way too much salt, but you end up wiping out some of the nutrition. Does cabbage have to be raw, though? No. Some “[c]ooking techniques may improve the…antioxidant activity in kale and red cabbage.” “The effects of the cooking process can be positive, since cooking softens the vegetable tissues,” helping your body extract the active compounds. “However, cooking can also be negative, because heat treatment can degrade [some of the] compounds. They looked at a variety of different cooking methods, and concluded “steaming [may] be considered to be the best home cooking technique to prepare kale and red cabbage.” But with foods that healthy, the truly best way to prepare them is whatever way will get you to eat the most of them.
Are the health benefits associated with apple consumption just due to other healthy behaviors among apple eaters? Here are some answers.
Regular apple intake is associated with all sorts of good things, like living longer—particularly a lower risk of dying from cancer. Yeah, but maybe people who eat apples every day just happen to practice other healthy behaviors, like exercising more, or not smoking, and that’s really why they’re living longer. Well, they controlled for most of that—obesity, smoking status, poverty, diseases, exercise—so as to compare apples to apples (so to speak!). But, what they didn’t control for was an otherwise healthier diet. Studies show that those who regularly eat apples have higher intakes of not just nutrients like fiber, found in the apples, but they’re eating less added sugar, less saturated fat—in other words, they’re eating overall healthier diets and, so, no wonder apple eaters live longer. But, is apple eating just a marker for healthy eating, or is there something about the apples themselves that’s beneficial? You don’t know…until you put it to the test.
There are all sorts of fun studies, where subjects were randomly assigned in the morning to nothing, a caffeinated energy drink, black coffee, or an apple—given that athletes use a variety of common strategies to stimulate arousal, cognition, and performance before their morning training. Did the apple hold its weight? Yes, appearing to work just as well as the caffeinated beverages. The problem with these kinds of studies, though, is they’re not blinded. Those in the apple group knew they were eating an apple; and, so, there may have been an expectation bias, placebo effect, that made them unconsciously give that extra bit of effort in the testing, and skew the results. You just can’t stuff a whole apple into a pill.
That’s why researchers, instead, test specific extracted apple components. So, they can perform a double-blind, placebo-controlled study, where half get the fruit elements, half get a sugar pill, and you don’t know until the end who got which. The problem there, though, is that you’re no longer dealing with a whole food—removing the symphony of interactions between the thousands of phytonutrients in the whole apple.
Most of those special nutrients are concentrated in the peel, though. Instead of just dumping millions of pounds of nutrition in the trash, why couldn’t researchers just dry and powder the peels into opaque capsules to disguise them, and then run blinded studies with that? Even just “[a] small amount could greatly increase…phytochemical content and antioxidant activity…”
The meat industry got the memo: “Dried apple peel powder decreases microbial expansion in [meat] and protects against carcinogen production…” when you cook it. And, “[o]ne of the carcinogens formed during [the] grilling of meat is [a] beta-carboline” alkaloid, a neurotoxin, which may be contributing to the development of neurological diseases, like Parkinson’s. I did a video about it a while ago. Uncooked meat doesn’t have any; the neurotoxin is formed when you cook it. But, you can cut the levels in half by first marinating the meat with dried apple peel powder.
And, it also cuts down on the amount of fecal contamination bacteria in the meat. Apple peels can also inhibit the formation of genotoxic, DNA-damaging, heterocyclic amines, cutting the effects of these cooked meat carcinogens by up to more than half. “In view of the risks associated with consuming [these cancer-causing compounds in meat], there is a need to reduce exposure by blocking HCA formation such as by adding [apple peel powder] during the cooking of meats to [help] prevent their production.” I mean I can’t think of any other way to reduce exposure.
What about consuming apple peels directly? Dried apple peel powder was found to exhibit “powerful anti-inflammatory and antioxidant action.” But, this was in mice. Does it have anti-inflammatory properties in people? You don’t know…until you put it to the test.
A dozen folks “with moderate loss of joint [range of motion] and associated chronic pain” were given a spoonful of dried apple peels a day for 12 weeks, and pain scores dropped month after month, and the range of motion improved in their neck, shoulders, back, and hips. Conclusion: “Consumption of dried apple peel powder was associated with improved joint function and…pain reduction.” Why just “associated”? Because there was no control group; so, they might have all been just getting better on their own, or it could have been a placebo effect. But hey, why not give apple peels a try by eating more apples?
To see any graphs, charts, graphics, images or studies mentioned here, please go to the Nutrition Facts podcast landing page. There, you’ll find all the detailed information you need – plus links to all the sources we cite for each of these topics.
Be sure to check out my new How Not to Die Cookbook. It’s beautifully designed, with more than 120 recipes for delicious, plant-based meals, snacks and beverages. All the proceeds from the sales of all my books all go to charity. I just want you to be healthier.
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Thanks for listening to Nutrition Facts. I’m Dr. Michael Greger.
This is just an approximation of the audio content, contributed by Allyson Burnett.