¿Te has preguntado si existe una manera natural de bajar tus niveles de presión arterial, protegerte contra el alzhéimer, perder peso y sentirte mejor? Resulta que sí la hay. El doctor Michael Greger (FACLM), fundador de NutritionFacts.org y autor del rotundo éxito de ventas del New York Times "How Not to Die" (Comer para no morir), nos presenta la nutrición basada en la evidencia para añadir años a nuestra vida y vida a nuestros años.

Welcome to Nutrition Facts.  I’m your host, Dr. Michael Greger, and I’m here to ask you, what is the most important decision you’ll make today, is it how you’ll get to work, who you’ll set up a meeting with, what friend you’ll call for lunch?  Well, as it turns out, probably the most important decision you’ll make today is what to eat.  What we eat on a day-to-day basis is the number one determinant of our health and longevity—literally.  Most premature deaths in the United States are preventable and related to nutrition.  So, we’re going to explore some smart nutrition choices based, naturally, on facts.  Here, we refer to the science, the research, the available data published in the peer-reviewed medical literature right now.  That’s why I wrote my book, “How Not to Die”, and why I created my nonprofit site NutritionFacts.org and, now, this podcast.

Today, we get a bit nervy and take a close look at how to maintain the health of our nerves.  Because the alternative doesn’t sound like a lot of fun.  Poor nerve health can result in pain and/or loss of muscle control and, naturally, what we eat can be a factor in our nervous system health.

First up:  Is atherosclerotic plaque clogging the arteries feeding our spine leading to low back pain, disc degeneration, and sciatic nerve irritation?  Here’s the study. 

Low back pain became one of the biggest problems for public health systems in the Western world during the second half of the 20th century.  The lifetime prevalence of low back pain is reported to be as high as 84%, and chronic low back pain currently affects about 1 in 5, with 1 in 10 being disabled.  It’s an epidemic.  Are people just lifting more heavy stuff?  No.  Mechanical factors, such as lifting and carrying, probably do not play a major role in the disease.  Well then, what causes it?  I’ve touched on it before; atherosclerosis can obstruct the arteries that feed the spine and this diminished blood flow can result in various back problems.  This can be seen on angiography, showing normal arteries on the left and clogged on the right, or on autopsy, where you can see the openings to the spinal arteries can get squeezed shut by these cholesterol-filled plaques.

Autopsy, because back pain may predict fatal heart disease, just like clogs in the penile arteries (erectile dysfunction) can precede heart attacks, because it’s the same disease; clogged, crippled arteries throughout our body.

Now, we have MRI imaging that can show the occlusion of spinal arteries in people with back pain, and the degeneration of their discs, normal blood flow in someone without back pain, versus constricted blood flow in someone with.  They showed that patients with long-term lower back pain had these kinds of arterial clogs, and those with high cholesterol appeared to suffer more severe symptoms. Those with narrowed arteries appear about eight and a half times more likely to have suffered from chronic back pain.

This makes sense.  The discs in our lower back are the largest avascular tissue in the body, meaning our discs don’t have any blood vessels.  Thus, its nutrition just kind of diffuses in from the margins, making it especially vulnerable to deprivation.  Using MRIs you can measure the effects of impaired blood flow on that diffusion.  Although disc degeneration has multiple causal factors, with genetic, occupational, and mechanical influences, alteration in nutrition has been proposed as the final common pathway.  By age 49, 97% of the discs of those eating the standard American diet show at least grade 2 degradation.

Cholesterol plaques in the walls of the aorta can obliterate the orifices, the lumbar and middle sacral arteries, and may decrease blood flow of the lumbar spine and surrounding structures.  Structures with precarious nutrient supply, such as the intervertebral discs, may suffer and gradually degenerate from this lack of blood flow, as well as herniate.  Not only is there a link between cholesterol levels and disc degeneration, there’s an association between cholesterol levels and disc herniation as well.

This compromised blood flow may also damage the nerve roots that come off the spine, causing sciatica.  Sciatica is back pain that radiates down the legs, causing additional pain, numbness or weakness, and prolonged disability and may affect as many as 1 in 20 people and, independent of weight, some other factors, clinical sciatica may be associated with cholesterol as well.  See, the nerve roots, which are most commonly associated with sciatic pain, are supplied by some of the arteries most vulnerable to atherosclerotic plaque formation.  Obliteration of these arteries by cholesterol buildup results in compromised nutrient supply to the nerve itself and that lack of oxygen to the nerve may be playing a role in sciatica pain.

Reduced blood flow also hampers the removal of waste products, such as lactic acid, which can, in turn, irritate the nerve endings, causing pain and deterioration.

Because of this vulnerability, discs degenerate far earlier than do other musculoskeletal tissues.  The first unequivocal findings of degeneration in the discs of the lower spines can be seen starting around age 11.  By the early teen years you can already see the discs starting to degenerate.  This makes sense.  As I’ve talked about before, nearly all kids have the beginnings of atherosclerosis by age 10 and, sadly, low back pain is now common in children and adolescents as well.  It is becoming a real public health concern and it’s getting worse.  It’s like kids now getting disorders like adult-onset diabetes.  Teenagers starting their lives out with a chronic disease. That’s why it’s never too early to start eating healthier.

It appears that berries counteract the neurotoxic, nerve-damaging effects of pesticides in vitro, potentially explaining why berry consumption is associated with lower risk of developing Parkinson’s disease.

In the original description of Parkinson’s disease, by none other than Dr. James Parkinson himself, he described a characteristic feature of the disease, constipation—torpid or lethargic bowels, which may precede the diagnosis by many years.  In fact, bowel movement frequency may be predictive.  Men with less than daily bowel movements were four times more likely to develop Parkinson’s an average of 12 years later.  Now, this could just be a really early symptom of the disease, tied to decreased water intake.  Many Parkinson’s patients report never really feeling very thirsty; maybe that led to the constipation or, alternately, the constipation may have increased the risk of Parkinson’s disease, as constipation results in a longer stay of the waste in the bowel and, thus, more absorption of potential neurotoxicants—neurotoxins from the diet.

Yes, there are two studies suggesting an association between constipation and Parkinson’s, but at the same time, there are 38 studies linking the disease to pesticide exposure and, by now, more than a hundred studies linking pesticides to an increased risk of up to 80%.

Now, many of these studies are on occupational exposure—like farmworkers, who may reduce their risk of Parkinson’s by wearing gloves and washing their clothes.  But Parkinson’s has also been linked to ambient exposure.  Approximately a billion pounds of pesticides are applied annually in the U.S., and just living or working in high-spray areas may increase Parkinson’s risk.  And the same with using pesticides in the home.  I didn’t realize how common household pesticide use was, but this study out of UCLA suggests it might not be such a good idea.

Pesticides may cause DNA mutations that increase susceptibility for the disease, or play a more direct role.  See, many neurodegenerative diseases appear to be caused by the buildup of misfolded proteins.  In Alzheimer’s, it’s the protein amyloid beta; in Creutzfeldt–Jakob and mad cow disease, it’s prions; in Huntington’s, it’s a different protein; and in Parkinson’s disease, it is a protein called alpha-synuclein.  In a variety of pesticides, 8 out of the 12 they tested, were able to trigger synuclein accumulation in human nerve cells, at least in a Petri dish.

The buildup of synuclein may play a role in killing off specialized nerve cells in the brain—70% of which are gone by the time the first symptoms arise.  Pesticides are so good at killing these neurons that pesticides are used to try to recreate Parkinson’s disease in lab animals.  

Is there any way to stop the process?  Well, there’s no drugs yet that can prevent this protein aggregation.  What about flavonoid phytonutrients and natural compounds found in certain fruits and vegetables?  They can cross the blood-brain barrier and may have neuroprotective effects.  So, they tested 48 different plant compounds to see if any could stop the clumping of synuclein proteins into the little fibers that clog up the cell and they found a variety of flavonoids that can not only inhibit the spider web-like formation of synuclein fibers, but some could even break them up.  Turns out flavonoids may actually bind to synuclein proteins and stabilize them.  So this implies that flavonoids in our diet may be combating Parkinson’s disease as we speak and healthy diets may be effective in preventing and even “curing the disorder” but these were all Petri dish experiments in a laboratory.  Is there any evidence that people eating berries are protected from Parkinson’s?  There was this study, published forever ago, that suggested the consumption of blueberries and strawberries was protective.  But this was a tiny study, and the results were not statistically significant—which is why I never brought up the study before.  But that was the best we had, until now.

Those eating a variety of phytonutrients were less likely to develop Parkinson’s disease–specifically, higher intake of berries was associated with significantly lower risk.  The accompanying editorial, “An Apple a Day to Prevent Parkinson’s Disease,” concluded that more research is necessary, but until then, an apple a day might be a good idea.  Of course, this is coming from a man.  Apples appeared to be protective against Parkinson’s for men, but not women; however, everyone appeared to benefit from the berries.  We just may not want to have our berries with cream, as the milk supply may be contaminated with the same kind of neurotoxic pesticide residues found in the brains of Parkinson’s disease victims.

Studies indicate that a more plant-based diet may not only be the safest treatment for multiple sclerosis, it may also be the most effective.

Multiple sclerosis is an unpredictable and frightening degenerative autoimmune inflammatory disease of the central nervous system in which our body attacks our own nerves.  It often strikes in the prime of life, and can cause symptoms in the brain—cognitive impairment, in the eye—painful loss of vision, tremor, weakness, loss of bladder control, pain, and fatigue.

The most frequently prescribed drug for multiple sclerosis is beta interferon, which can make you feel lousy, and cost $30,000 a year, but hey—it might be worthwhile, if it actually worked.  We learned last year that it doesn’t seem to prevent or delay long-term disability.

That leaves chemo drugs, like mitoxantrone, that causes irreversible heart damage in one out of every eight people who go on the drug, and treatment-related acute leukemia.  It causes leukemia in nearly 1% of people who take it.  But hey, MS is no walk in the park.  If only there was a cheap, simple, safe, side-effect-free solution that also just so happened to be the most effective treatment for MS ever described.

Dr. Roy Swank, whom we lost at age 99, was a distinguished neurologist whose research culminated in over 170 scientific papers.  As far back as 1950, we knew that there were areas in the world that had a lot of MS (North America, Europe), and other places (Africa and Asia) that hardly had any.  And now, we have all these migration studies showing that if you move from a high-risk area to a low-risk area, your risk drops, and vice versa.  So, it seemed less genetics, and more lifestyle.

Dr. Swank had an idea, as he recounts in an interview with Dr. John McDougall, at the ripe young age of 84:  “It seems possible to me that this could be a matter of food, because the further north you go the less vegetarian a life is led, and the more people are carnivores, you might say; they spend a lot more time eating meat.”

After looking at the multiple sclerosis data from World War II in occupied countries where meat and dairy were rationed, and his famous study in ’52 finding “the frequency of MS directly related to the amount of saturated animal fat consumed daily in different areas of Norway”, he concluded it might be the animal fat.  So, he decided to put it to the test, by restricting people’s intake of saturated animal fat.  Normally, you’re lucky if you get people to stick to a diet for six months and, so, that’s why most dietary trials last a year, at the most.  This is reporting results from the first three-and-a-half years.  Then came the five-and-a-half year follow-up; he adds another hundred patients. Then, the seven-year follow-up, published in the Annals of Internal Medicine. Then, the 20-year follow-up; the 34-year follow-up.

How did they do?  If you can get people early in their disease, when they’re only mildly disabled, and restrict their saturated fat intake, Dr. Swank showed he could stop their disease, in 95% of cases—no further disability, 34 years later.  But, if they started slacking on their diet—even years in, their disease could become reactivated.  They felt so great they were like, hey, I can cheat a little bit; I got this disease under control.  But, eating just eight grams of saturated fat more a day was accompanied by a striking increase in disability, and nearly tripling the death rate.

How about a 50-year follow-up?  They were able to track down 15 of the original patients that stuck to the diet (now in their 70s and 80s) with multiple sclerosis for over 50 years, and 13 out of 15 were walking around normal in all respects.  They were active and, evidently, unusually youthful-looking.  Conclusion:  “This study indicated that, in all probability, MS is caused largely by consumption of saturated animal fat.”

He thought it was the sludging of the blood, caused by even a single meal of saturated fats, that can clog tiny capillaries that feed our nervous system.  See, diets rich in saturated fat and cholesterol can thicken the blood, and make our red cells sticky.  A single meal of sausage and eggs can stick our blood cells together like rolls of quarters.  And, this kind of hyperaggregation can lead to a reduction in blood flow and oxygenation of our tissues.

If you put someone’s blood through a machine that sucks out about 90% of the cholesterol in their blood, you can demonstrate an immediate improvement in microcirculation in the heart muscle. But, what about the brain?

Eyes are the windows to your brain.  You can visualize, in real-time, changes in blood vessel function in the retina at the back of the eye—which gives you a sense of what’s happening further back in the brain.  And, if you lower the cholesterol level in the blood, you can immediately get a significant improvement in vasodilation; the little veins open wider and let the blood flow.

So, yes, it could be the saturated fat leading to clogging of our capillaries.  But, now we know animal fats can have all sorts of other deleterious effects, such as inflammation.  So, who knows what the actual mechanism may be by which cutting animal fat can cut MS progression.  Regardless, patients with MS that follow a diet with no more than 10 or 15 grams of saturated fat can expect to survive and thrive to a ripe old age.  Of course, cutting out saturated fat completely might be better, given that, you know, heart disease is our #1 killer.

The bottom line is that the results Dr. Swank published “remain the most effective treatment of multiple sclerosis ever reported in the peer reviewed medical literature.  In patients with early stage MS, 95% were without progression of their disease 34 years later after adopting his low-saturated-fat dietary program.  Even patients with initially advanced disease showed significant benefit. To date, no medication or invasive procedure has ever even come close to demonstrating such success.”  Doesn’t cost $30,000 dollars; doesn’t give you leukemia—and, works, better!

Of course, this all begs one big, obvious question.  If Dr. Swank’s results are so stunningly impressive, why haven’t other physicians, neurologists, or centers adopted this method of treatment?  Good question.  One reason may be that MRI machines weren’t invented until the 1970s.  MRIs are how we track the progress of MS today.  We don’t have to rely on patients’ subjective reports, or doctors’ clinical judgments.  We can see the disease get better or worse, right there in black and white.

It’s like in the 1970s, when Nathan Pritikin appeared to reverse heart disease by the thousands, but no one took him seriously, until angiography was invented, and the likes of Ornish and Esselstyn could hold up images like this—proving conclusively that a plant-based diet could literally open up arteries, right there in black and white.

So, what we need is someone to repeat Swank’s experiments today, with MRI scans every step of the way and, I’m happy to report that exact experiment was just completed, by Dr. John McDougall.  Dr. Swank was one of Dr. McDougall’s medical mentors, and Dr. McDougall is one of mine.  Study enrollment was completed last year, and we should have the results sometime soon.

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.

NutritionFacts.org is a nonprofit, science-based, public service, where you can sign up for free daily updates on the latest in nutrition research via bite-sized videos and articles.

Everything on the website is free.  There’s no ads, no corporate sponsorship.  It’s strictly non-commercial.  I’m not selling anything.  I 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.

Thanks for listening to Nutrition Facts.  I’m Dr. Michael Greger.

This is an approximation of the audio content, contributed by Allyson Burnett.

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