Isn’t it crazy to think of all the different kinds of foods so many of us eat every day? Chips, cookies, burgers, fries. Our bodies dutifully process whatever it is we choose to swallow – regardless of whether or not what we eat could actually harm us or shorten our lives. Our bodies are amazing as they try and pull out nutrients while trying to protect us from all the garbage. So – maybe – just maybe – we should try and give our bodies a break.
I’m Dr. Michael Greger and you’re listening to the Nutrition Facts podcast. I’m here to tell you that nutrition matters. We could choose a diet proven to not only prevent and treat but reverse our #1 killer, heart disease, along with other deadly diseases such as type 2 diabetes and high blood pressure. But many of us – don’t make that choice.
Our goal today is to help you make that choice – and present you with the results of the latest in peer-reviewed nutrition and health research, presented in a way that’s easy to understand.
Today, back by popular demand, we present the Nutrition Facts grab bag with the latest news on a whole variety of topics. First up – how in certain medical conditions, probiotic supplements may actually make your health worse. Here’s the story.
When you make sauerkraut at home, you don’t have to add any kind of starter bacteria to get it to ferment, because the lactic acid-producing bacteria are already present on the cabbage leaves themselves, out in the field. This suggests raw fruits and vegetables may not only be a source of prebiotics—fiber—but also a source of novel probiotics.
Researchers have since worked on characterizing these bacterial communities, and found two interesting things. First, that “the communities on each produce type were significantly distinct from one another.” So, the tree fruits harbored different bacteria than veggies on the ground, and grapes and mushrooms seemed to be off in their own little world. So, if indeed these bugs turn out to be good for us, that would underscore the importance of eating not just a greater quantity, but greater variety, of fruits and veggies every day. And second, they found that there were “significant differences in [microbial] community composition between conventional and organic…produce.” “This highlights the potential for differences in the [bacteria] between conventionally and organically farmed produce items to impact human health.” But, we don’t know in what direction. They certainly found different bacteria on organic versus conventional, but we don’t know enough about fruit and veggie bugs to make a determination as to which bacterial communities are healthier.
What about probiotic supplements? I’ve talked about the potential benefits, but there appears to be publication bias in the scientific literature about probiotics. This is something you see a lot with drug companies, where the sponsor, the supplement company paying for their own probiotic research, may not report negative results—not publish it, as if the study never happened. And so, then, we doctors just see the positive studies.
Using fancy statistical techniques, they estimated that as many as 20 unflattering studies were simply MIA. And, even in the studies that were published, even when the authors were directly sponsored by like some yogurt company, the conflicts of interest were very commonly “not reported.”
There’s also been concerns about safety. A review for the government’s Agency for Healthcare Research and Quality concluded that there’s “a lack of assessment and systematic reporting of adverse events in probiotic intervention studies.” So, while “[t]he available evidence in [randomized, controlled trials] does not indicate an increased risk [for the general public],…the current literature is not well equipped to answer questions on the safety of probiotic[s]…with confidence.”
Acute pancreatitis—sudden inflammation of the pancreas—is on the rise, which can become life threatening in some cases, as bacteria break through our gut barrier, and infect our internal organs. Antibiotics don’t seem to work, so how about probiotics? Seemed to work on rats. If you cause inflammation by cutting them open and mechanically damaging their pancreas, not only do probiotics show “strong evidence for efficacy,” but there were “no indications [of] harmful effects.” So, half the people with pancreatitis got probiotics, half got sugar pills, and, within ten days, the mortality rates shot up in the probiotics group, compared to placebo. More than twice as many people died on the probiotics. Thus, probiotics for acute pancreatitis? Probably not a good idea. But, further, probiotics “can no longer be considered to be [completely] harmless.”
The researchers were criticized for not telling patients, not cautioning patients, about the risk before signing up for the study. (The study subjects were told probiotics had “a long history of [safe] use” with no known side effects). In response to the criticism, the researchers replied “‘There [were] no side effects,’ until [their] study.”
Our next story is about the tasty avocado. I’ve talked about avocado consumption improving artery function, but what effect might guacamole have on cancer risk?
In my last video about avocados, I described the anti-inflammatory effects and cholesterol- and triglyceride-lowering effects. But what about that video I did years ago about the chromosome-damaging effects in a Petri dish? That all goes back to 1975, when a pesticide naturally produced by the avocado tree was discovered—thought to explain why lactating livestock suffered mammary gland damage nibbling on the leaves. The toxin was named persin, also found to be damaging to the heart, which is why you should never feed avocado to your pet birds.
But hey, if it attacks mammary cells in animals, might it attack breast cancer cells in humans? It did seem to have the same kind of cell cytoskeleton-clumping effect in vitro that chemotherapy can have, demonstrating potent cell growth-stopping and -killing effects of the “novel plant toxin” among various lines of human breast cancer cells. So, they’re thinking about how it might one day be used as chemo itself. But, here I am thinking, “Holy guacamole, Batman; please tell me it doesn’t have toxic effects on normal cells, too.”
In 2010, we got an answer: an “Evaluation of [the] Genotoxicity,” the toxicity to our chromosomes, of avocado extracts on human white blood cells in a Petri dish. Normally, less than 10% of our dividing cells have any chromosome abnormalities, but drip some avocado fruit extracts on them, and up to half come out defective in some way. They conclude that there’s something in avocado fruit that “can potentially induce significant genomic instability and some genetic damage” in human white blood cells in a Petri dish. If the same effect occurs in actual people, it could, for example, result in transforming cells into cancer. That’s a big if, though.
These were blood cells. You don’t inject guac into the vein. For anything to get into our bloodstream, it first has to survive our stomach acid, get absorbed through our intestines, and then sneak past our liver’s detoxification enzymes. And indeed, persin may be affected, changed, by acidic conditions. So, given all the differences between what happens in a Petri dish and a person, “it is essential to carry out [further] studies…before making a final remark” about its toxicity. Okay, but what do you do before these studies come out? I was concerned enough I provisionally moved it from a stuff-your-face green-light food, to a moderate-your-intake yellow-light food, until we knew more, to err on the side of caution.
Even if persin was utterly destroyed by stomach acid, what about oral cancer? At high-enough concentrations, avocado extracts can harm the growth of the kinds of cells that line our mouths. Yeah, but this is in a Petri dish, where the avocado is coming in direct contact with the cells. But that’s kinda what happens in your mouth when you eat it. But, it harms oral cancer cells even more. But, since it does this more to cancerous than normal cells, they end up concluding avocados may end up preventing cancer.
What about the esophagus, which lies between the mouth and the stomach? They similarly found that an “avocado fruit extract [appeared to inhibit] cancer cell growth” more than normal cell growth, when it came to colon cancer cells, or esophageal cancer cells. But, rather than comparing the effects to normal colon and esophagus cells, they compared to a type of blood cell, which again is limited relevance in a Petri dish study of something you eat.
See, “fermentation of carbohydrates [in the colon, like fiber] is considered beneficial, whereas fermentation of [protein] [which is called] (putrefaction) is considered…detrimental.” So, you switch people to a high-protein diet, and within days, the excess protein putrefying in their gut leads to an increase in ammonia, as well as p-cresol—in fact, a doubling of levels within a week. But, might phytonutrient-rich plant foods, like “apples, cranberries, grapes, [or] avocados,…protect [the cells lining our colon] from the deleterious effects of p-cresol…in terms of cell viability, mitochondrial function, and epithelial integrity,” meaning like protection against gut leakiness? But, bottom line, avocados appear to have beneficial effects on colon-lining cells; so, that’s a good sign.
Okay, but enough of these in vitro studies, already. Yes, an avocado extract can inhibit cancer cell growth in a Petri dish, but unless you’re doing some unspeakable things to that avocado—like guacamole with benefits, there’s no way that the avocado is going to come in direct contact with your prostate cells. So, what does this study mean?
So, do avocado eaters have more cancer risk, or less cancer risk? We’ll find out…right now!
Men who ate the most avocado, more than about a third of an avocado a day, “reduced [their] risk of prostate cancer.” In fact, less than half the odds. So, with the data on improved artery function, lower cholesterol, and, if anything, an association with decreased cancer risk, I’d suggest moving it back into the green zone.
Here’s a fun fact. Did you know that lemon balm may beat out drugs for controlling the symptoms of severe dementia? Here’s the story.
Improving cognitive performance with aromatherapy in young healthy volunteers is one thing, but how about where it really matters? This group of Japanese researchers had this pie-in-the-sky notion that maybe certain smells could lead to “nerve rebirth” in Alzheimer’s patients. Twenty years ago, to even raise such a possibility as a hypothetical was heretical! Everybody knew that the loss of neurons is “irreversible.” In other words, “dead [nerve cells] are not replaced”—an important factor in neurodegenerative diseases. That’s what I was taught; that’s what everyone was taught, until 1998.
Patients with advanced cancer volunteered to be injected with a special dye that’s incorporated into the DNA of new cells. On autopsy, the researchers then went hunting for nerve cells in the brain that lit up. And, there they were, new nerve cells in the brain that didn’t exist just days or months before, demonstrating “that cell genesis occurs in human brains and [that] the human brain retains the potential for self-renewal throughout life.” Something we can take comfort in.
Still doesn’t mean smells can help, but an aromatherapy regimen of rosemary, lemon, lavender, and orange was attempted for a month and their cognitive function starting six weeks before the treatment, showing a rather steady decline until they reversed after the aromatherapy. The researchers conclude aromatherapy may be efficacious and “have some potential for improving cognitive function”—all, of course, without any apparent side effects.
What about severe dementia? We always hear about the cognitive deficits, but “more than [half] of patients with dementia experience behavioral or psychiatric symptoms.” Thorazine-type antipsychotic drugs are often prescribed, even though they appear to be particularly dangerous in the elderly. But hey, it’s easier to just prescribe a drug than offer “nonpharmacological alternatives,” such as aromatherapy—rubbing a lemon balm-infused lotion on their arms and face twice daily, compared to a lotion without the scent. Everybody got rubbed, but in the lemon balm group, “significant improvements…in…agitation…,…(shouting, screaming), and physical aggression.” And improved quality-of-life indicators—less socially withdrawn, more engagement in constructive activities. That’s important, because when you give the antipsychotics, patients become more withdrawn, less engaged; it’s like a chemical restraint. Yeah, the drugs can reduce agitation too, but that may just be because you’re effectively knocking the person out.
So, “aromatherapy with [lemon] balm…is safe, well tolerated,…highly efficacious, with additional benefits on key quality of life parameters. These findings clearly indicate the need for longer-term multicenter trials.” But we never had any, until—never. We still don’t have any. This study was back in 2002 and still nothing, but is that a surprise? Who’s going to fund such a study? Big Balm?
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 also check out my new How Not to Die Cookbook, beautifully designed, with more than 100 recipes for delicious, life-saving, plant-based meals, snacks, and beverages. And, like all my books, DVDs, and speaking engagements, all the proceeds I receive are donated to charity.
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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.