I’m Dr. Michael Greger and this is Nutrition Facts.
There’s one thing we’ve been thinking about a lot lately, and that’s how to stay healthy in the middle of a global pandemic. Especially since we’ve learned that those with underlying health problems like obesity, hypertension, diabetes, and heart disease are more likely to have serious complications if they contract COVID-19. So what do we do? We try to stay healthy – with evidence-based nutrition.
Today, it’s all arterial health all the time. Starting with lowering our Lipoprotein a; otherwise known as Lp(a). Why, you may ask? Because high LP(a) can cause coronary artery disease. Here is our first study.
What could explain severe coronary disease in someone considered to be at low cardiovascular disease risk with a healthy lifestyle? A young man ends up in the ER with a heart attack; ultimately found to have severe coronary artery disease, yet given his age, blood pressure, and cholesterol, his 10-year risk of a heart attack should only be like 2 percent. But what he did have was a high lipoprotein(a) level, also known as Lp(a), markedly high at 80, which may help explain it. You can see the same thing with women. A 27-year old with a heart attack with a high Lp(a). What is this Lp(a), and what can we do about it?
Lp(a) is an underestimated cardiovascular risk factor. It causes coronary artery disease, heart attacks, strokes, peripheral arterial disease, calcified aortic valve disease, and heart failure. And these can occur even in people without high cholesterol, because it is cholesterol. It’s basically an LDL cholesterol molecule linked to another protein, which, like LDL, transfers cholesterol into the lining of our arteries, contributing to the inflammation in atherosclerotic plaques. But it has yet to gain recognition by practicing physicians.
The main reason for the limited clinical use of Lp(a) is the traditional lack of effective and specific therapies to lower it. Lp(a) concentrations are approximately 90 percent genetically determined, so the conventional thinking has been that look, you’re just kind of born with higher or lower levels, and there’s not much you can do about it. Even if that were the case, you still might want to know about it, since if it was high, that would be all the more reason to make sure all the other risk factors that you do have more control over are absolutely as good as possible––like you know, maybe help you quit smoking, and do everything you can do lower your LDL cholesterol as much as possible.
Lp(a) levels in the blood can vary a 1,000-fold between individuals (from less than 0.1 mg/dL to a hundred or more). So, if we’re like the 1 in 5 people with elevated levels, what can we do about it?
The way we know that Lp(a) causes atherosclerosis is that we can put it to the ultimate test. There’s something called apheresis, which is basically like a dialysis machine where they can take out your blood, wash out some of the Lp(a), and then give your blood back to you. And when you do that, you can reverse the progression of disease. Atherosclerosis continues to get worse in the control group, but better in the apheresis group. This is great for proving the role of Lp(a), but has limited clinical application, given the cost, accessibility, and the time commitment required for biweekly sessions of two to four hours each. It causes a big drop in blood levels, but they quickly creep back up, so you have to keep going in, costing more than $50,000 a year. There has to be a better way.
In our next story, we learn how lack of inadequate blood flow to the brain due to clogging of cerebral arteries may play a pivotal role in the development and progression of Alzheimer’s dementia.
In 1901, Auguste was taken to an insane asylum in Frankfurt, Germany by her husband. She was described as a delusional, forgetful, disoriented woman who “could no longer carry out her homemaking duties.” She was seen by a Dr. Alzheimer, and was to become the case that made his a household name.
On autopsy, he described the plaques and tangles in her brain that would go on to characterize the disease, but lost in the excitement of discovering a new entity, a clue may have been overlooked. He described arteriosclerotic changes—hardening of the arteries—within her brain.
We typically think of atherosclerosis in the heart, but atherosclerosis involves virtually the entire human organism—our entire vascular tree. And, one of the most poignant examples of this systemic nature is the link between coronary artery disease, degenerative brain disease, and dementia.
Back in the 70s, the concept of cardiogenic dementia was proposed: dementia generated from the cardiovascular system. Since the aging brain is highly sensitive to lack of oxygen, and since heart problems are so common, it was easy to imagine that’s how dementia could result.
And now, we have a substantial body of evidence that strongly associates atherosclerotic vascular disease with the #1 cause of dementia, Alzheimer’s disease. Autopsy studies, for example, have shown that individuals with AD have significantly more atherosclerotic narrowing of the arteries within their brain. What kind of brain arteries do you want in your head?
Normal resting cerebral blood flow, the amount of blood flow circulating within our brains, is about a quart a minute. But we lose about half a percent a year, so by age 65 we may be down 15% to 20%. But this doesn’t necessarily affect brain function, as we have a built-in buffer. However, this age-related decline in cerebral blood flow can become critical to brain cell survival if an additional burden further lowers the flow.
This reduction of blood flow can starve the brain of oxygen, cause silent little mini-strokes and brain atrophy—the cumulative effects of which appear to play a pivotal role in accelerating and augmenting the development and evolution of Alzheimer’s disease.
In light of such findings, some have even suggested the disease be reclassified as a vascular disorder.
This is good news, though, because atherosclerosis is potentially reversible. These findings were confirmed in two larger studies—over 1,000 autopsies each, which found the same thing. Atherosclerosis in the brain is significantly more frequent and severe in those with Alzheimer’s disease.
This suggests that strategies proven to delay the progression of artery disease, like plant-based diets, may be useful for preventing or treating Alzheimer’s disease.
Of course, autopsy studies are a little late for that; so, to assess the impact of intracranial arterial narrowing on the progression from mild cognitive impairment to Alzheimer’s disease, researchers followed 400 folks with cognitive impairment for four years using CT angiography, special CAT scans to evaluate the amount of brain artery blockage. The cognition of those with the least atherosclerosis in their heads remained pretty stable over the years. But those with more cholesterol buildup got worse, and those with the most blockage rapidly declined. And, the same with the ability to carry out the activities of daily living. And, it doubled the progression to Alzheimer’s disease. An inefficient blood supply to the brain has very grave consequences on brain function.
But does treatment of vascular risk factors, like high blood pressure and high cholesterol, actually make a difference? We didn’t know, until now. 300 patients with Alzheimer’s, and those with all their vascular risk factors treated showed significantly less decline, slower progression of their disease, than those who went untreated.
It is said that, “The goal of medicine is to provide patients with hope, and when there is no hope to offer understanding.” Well, for the first time in the history of this disorder, we have the chance to provide Alzheimer’s patients with hope.
Finally today, we look at what happens inside the arteries of those who add nuts or extra virgin olive oil to their diet.
The heart of a traditional Mediterranean diet is mainly vegetarian, much lower in meat and dairy, and uses fruit for dessert. So, no surprise those eating that way had very low heart disease rates compared to those eating standard Western diets. This landmark study, though, has been cited to suggest that all types of fat, animal or vegetable, are associated with the appearance of new atherosclerotic lesions in our coronary arteries, feeding our hearts.
About a hundred men were given angiograms at baseline and then two years later, looking for the development of lesions, before and after, all the while monitoring their diets every year. Only about 1 in 20 eating lower fat diets had new lesions, compared to about 8 in 20 on more typical American diets around 33% or more fat. But when they drilled down, though, only three types of fat appeared to significantly to increase the likelihood of the appearance of new, lesions: lauric, oleic, and linoleic. Lauric acid is a saturated fat, found in coconut oil, and palm kernel oil, which is found in junk food—whipped cream and candy bars. Oleic from the Latin word oleum for olive oil, but that’s not where these men were getting their oleic acid from. The top sources for Americans are basically cake, chicken, and pork, and linoleic comes mostly from chicken. So, the study really just showed that people eating lots of junk, chicken, and pork tended to close off their coronary arteries. To see if major sources of plant fats, like olive oil or nuts, help or hurt, ideally, we’d do multi-year randomized study where you take thousands of people and have a third eat more nuts, a third eat more olive oil, and a third do essentially nothing to see who does better.
And that’s exactly what was done. The PREDIMED study took thousands of people at high risk for heart disease in Spain, who were already eating a Mediterranean-ish diet, and randomized them into three groups for a couple years, one with added extra virgin olive oil, one with added nuts, and a third group that was told to cut down on fat, but they didn’t; so, basically ended up as a no dietary changes control group. What happened to the amount of plaque in their arteries over time?
Whereas there was significant worsening of carotid artery thickening and plaque in the no dietary change control group, those in the added nuts group showed a significant reversal in thickening, an arrest in plaque progression. There were no significant changes in the added olive oil group.
The richness of the plant-based Mediterranean diet in potentially beneficial foods, such as fruit, vegetables, beans, nuts, whole grains, and olive oil, is believed to explain its cardioprotective effects. However, these results suggest nuts are a preferable source of fat compared to olive oil, and may delay the progression of atherosclerosis, the harbinger of future cardiovascular events such as stroke. Adding nuts appeared to cut the risk of stroke in half.
Note, though, they were still having strokes. Half as many strokes; so, the nuts appeared to be helping, but they were still eating a diet conducive to strokes and heart attacks. All three groups had basically the same heart attack rates, the same overall death rates. That’s what Dr. Ornish noted when he wrote in: there was no significant reduction in the rates of heart attack, death from cardiovascular causes, or death from any cause, just that stroke benefit. But hey, that’s something. A Mediterranean diet is certainly better than what most people are consuming, but even better may be a diet based on whole plant foods, shown to reverse heart disease, not contribute to it. The authors of the study replied that they didn’t wish to detract from Ornish’s work, noting that Mediterranean and plant-based diets actually share a great number of foods in common. Yes, Ornish’s diet may reverse heart disease— but, the Mediterranean diet proponents argue, the major problem with Ornish’s diet is that it doesn’t taste good; so, hardly anyone sticks to it.
We would love it if you could share with us your stories about reinventing your health through evidence-based nutrition. Go to NutritionFacts.org/testimonials. We may share it on our social media to help inspire others.
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 of the sources we cite for each of these topics.
For recipes, check out my How Not to Die Cookbook. It’s beautifully designed, with more than 100 recipes for delicious and nutritious meals. Speaking of new books, I have a new book just out – How to Survive a Pandemic – now out in audiobook, read by me, and e-book with physical copies out in August. Pre-order the physical copy now or download the e-book and audiobook now as well.
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 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.
Thanks for listening to Nutrition Facts. I’m your host, Dr. Michael Greger.