The Foods to Avoid to Lower Stroke Risk

“Stroke remains one of the most devastating of all neurological diseases,” killing about 5 million people a year worldwide, and is “the leading cause of permanent disability in the USA.” But the good news is that about 80 percent of stroke risk may be due to basic lifestyle factors: primarily, improving our diet, stopping smoking, and getting regular exercise.

The best way to stop smoking, evidently, is to have a heart attack. Certainly, once dead, you can’t smoke. Of those who survive a heart attack, strong, repeated advice from their doctor may persuade up to two-thirds to quit and never smoke again in any form as long as they live. “Yes, quitting smoking is very difficult. It doesn’t matter; it has to be done. If you were walking along the lakeshore and one of your grandchildren is drowning, it doesn’t take will power to go into the lake; it just has to be done.” It’s like a healthy diet: Some things just have to be done. Getting up at night to feed a baby can be difficult, too, but it’s not a matter of having willpower—some things in life just have to be done. After all, what we regularly eat every day is indeed a matter of life and death.

For stroke prevention, that means eating a more plant-based diet, like a traditional Mediterranean diet centered around whole grains, fruits, vegetables, lentils, beans, and nuts, as I discuss in my video Best Foods to Reduce Stroke Risk. A vegetarian or vegan diet may also work, but it must be accompanied by a regular, reliable source of vitamin B12, meaning B12-fortified foods or supplements. “Unfortunately, recommending taking B12 supplements may meet opposition among vegetarians because misconceptions regarding this nutrient are prevalent. Many individuals still hold on to the old myth that deficiency of this vitamin is rare and occurs only in a small proportion of vegans…Future studies with vegetarians should focus on identifying ways of convincing vegetarians to routinely take vitamin B12 supplements in order to prevent a deficiency.” The research is clear on that.

What is it about plant-based diets that make them beneficial for stroke prevention? In my video How to Prevent a Stroke, I talked about the role of fiber, which potentially leads to about a 1 percent drop in risk for every 1 gram of fiber ingested per day. Or, even better: A 12 percent drop in risk is associated with every extra 10 grams of fiber a day. In fact, fiber from whole grains is associated with a lower chance of dying not only from heart attack and stroke, but also cancer, diabetes, and respiratory diseases, as well as a lower risk of dying from infections or other causes––in other words, a lower risk of dying prematurely from all causes combined. Why? Perhaps because of the anti-inflammatory effects of fiber, which could explain how it could help across the board. Or, it could be that eating fiber means eating fewer pro-inflammatory foods. Those who eat more whole plant foods, which are where fiber is found, may be eating less processed and animal foods. In fact, the study immediately preceding the meta-analysis of fiber was a meta-analysis on meat, which looked at red meat and processed meat, and found about a 10 percent increased risk for stroke associated with each three and a half ounce daily portion, which is about the size of a deck of playing cards, or about 10 percent increased risk for every “half-deck” of processed meat.

Perhaps this occurs because of the heme iron—the blood and muscle iron—in meat, or because of “its pro-oxidative properties.” (No association was found between stroke and non-heme iron, which is the type of iron that predominates in plants.) Or, perhaps it’s because of some of the toxic pollutants like PCBs that can build up in animal fats. We’ve known, for example, that living next to a toxic waste dump might increase stroke risk, but only recently have we realized that dietary exposure even at so-called safe levels might increase stroke risk—and increase it by as much as eight or nine times for those with the highest levels of these pollutants in their bloodstream.


For more on how to reduce stroke risk with diet, see:

What does vitamin B12 have to do with stroke? Watch my video Vitamin B12 Necessary for Arterial Health to find out.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

What Happens When Pregnant Women Eat More Animal Protein

Are high-protein diets during pregnancy healthful or harmful? That question was answered about 40 years ago in the infamous Harlem Trial of 1976: a “randomized controlled trial of nutritional supplementation pregnancy, in a poor black urban population in the United States.” The study, which I discuss in my video The Effect of Animal Protein on Stress Hormones, Testosterone, and Pregnancy, “was begun when protein was commonly assumed to be deficient in the diet of the poor.” Had researchers actually analyzed their diets before they started, they would have realized that this wasn’t true, but why let facts get in the way of assumptions? So, the researchers split poor black pregnant women into three groups, each receiving one of the following treatments: (1) an extra 40 grams of animal protein a day, which is essentially a couple cans of Ensure, (2) an extra 6 grams of animal protein, or (3) no extra protein. Then they sat back and watched what happened. The high-protein group suffered “an excess of very early premature births and associated neonatal [infant] deaths, and there was significant growth retardation” in the babies who survived. More protein meant more prematurity, more deaths, and more growth retardation, which you can see reflected in the chart at 1:00 in my video.

What’s more, animal protein intake during pregnancy has been associated with children becoming overweight later in life and getting high blood pressure. The “offspring of mothers who reported eating more meat and fish had higher systolic blood pressure” in adulthood. This was part of another failed dietary intervention trial in which mothers were advised to eat a pound of meat a day. The increased weight gain and high blood pressure may be due to the obesity-causing chemical pollutants in the meat supply, as I’ve discussed in my video Animal Protein, Pregnancy, and Childhood Obesity, or the animal protein-induced rise in the growth hormone IGF-1. Or, it could be due to a steroid stress hormone called cortisol.

As you can see in the chart at 2:01 in my video, a single meal high in animal protein can nearly double the level of the stress hormone in the blood within a half hour of consumption, much more than a meal closer to the recommended level of protein. When subjects are given a meal of crab, tuna fish, and cottage cheese, the stress hormone level shoots up. If they’re instead given some barley soup and a vegetable stir-fry on rice, the stress hormone level goes down after the meal, as you can see at 2:27 in my video. Imagine eating meat-fish-dairy meals day after day. Doing so “may chronically stimulate” our stress response axis “and increase the release of vasoactive hormones” that could increase our blood pressure. And, all that extra cortisol release has been linked to increased risk for elevated blood levels of insulin, triglycerides, and cholesterol.

When men on a high-protein diet, “such as meat, fish, poultry, egg white,” were switched to a high-carb diet of bread, vegetables, fruit, and sugary junk, their cortisol levels dropped about a quarter within 10 days. At the same time, their testosterone levels shot up by about the same amount, as you can see at 3:09 in my video. High-protein diets suppress testosterone. That is why, if men eating plant-based diets begin to eat meat every day, their testosterone levels go down and some estrogens actually go up, and that’s why bodybuilders can get such low testosterone levels. It’s not the steroids they’re taking. If you look at natural bodybuilders who don’t use steroids, there is a 75 percent drop in testosterone levels in the months leading up to a competition. Testosterone levels were cut by more than half, which is enough to drop a guy into an abnormally low range, as you can see at 3:47 in my video. It’s ironic that they’re eating protein to look manly on the outside, but it can make them less and less manly on the inside. And, from an obesity standpoint, in general, a drop in testosterone levels may increase the risk of gaining weight and body fat. What does cortisol have to do with weight?

There’s actually a disease caused by having too much cortisol, called Cushing’s syndrome, which can increase abdominal obesity. Even in normal women, though, chronic stress and chronic high cortisol levels can contribute to obesity. What’s more, if they’re pregnant, high-meat and low-carb diets may increase cortisol levels in the moms, which can lead to inappropriate fetal exposure to cortisol, which, in turn, can affect the developing fetus, resetting her or his whole stress response thermostat and leading to higher cortisol levels in later adult life. This can have serious, life-long health consequences. Every maternal daily portion of meat and fish was associated with 5 percent higher cortisol levels in their children as much as 30 years later, though green vegetable consumption was found to be protective. Higher meat consumption, such as three servings a day compared to one or two, was associated with significantly higher cortisol levels, but eating greens every day appeared to blunt some of that excess stress response, as you can see at 5:12 in my video.

As well, the adult children of mothers who ate a lot of meat during pregnancy don’t only have higher stress hormone levels, they also appear to react more negatively to whatever life throws at them. Researchers put them through the Trier Test, which involves public speaking in front of a panel of judges, following by a live math exercise. You can see in my video at 5:36 a chart comparing the stress hormone responses in those whose moms ate less than two servings of meat per day, about two servings a day, or about two to three servings a day. Note that before the test started, the cortisol levels of the two groups eating less meat started out about the same, but their exaggerated cortisol response was laid bare when exposed to a stressful situation. The real-world effects of this are that after that sort of test, when people are given their own private snack buffet with fruits and veggies versus fatty, sugary, comfort foods like chocolate cake, guess who may eat less of the fruits and veggies? Those who have high chronic stress levels. “Cortisol has been implicated as a factor in motivating food intake” even when we aren’t really hungry.

It’s no surprise then that a woman’s animal protein intake during pregnancy may lead to larger weight gain for her children later in life—and maybe even for her grandchildren. “Remarkably, recent evidence suggests that the long-term consequences of adverse conditions during early development may not be limited to one generation, but may lead to poor health in the generations to follow, even if these individuals develop in normal conditions themselves.” Indeed, the diet of a pregnant mother may affect the development and disease risk of her children and even her grandchildren. Ultimately, these findings may shed light on our rapidly expanding epidemics of diabetes, obesity, and heart disease.


Whoa, there was a lot to unpack! Rather than break it up, since so much of it was tied together, as you could see, I compiled everything into this one, heftier piece. You may want to read this a second time and watch the video to absorb it all.

For more on how a woman’s diet during pregnancy can affect her children, see Maternal Diet May Affect Stress Responses in Children and Animal Protein, Pregnancy, and Childhood Obesity.

Protein is such a misunderstood nutrient. For more information, check out:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

Proof that Lifelong Cholesterol Reduction Prevents Heart Disease

“It is well accepted that coronary atherosclerosis is a chronic progressive disease that begins early in life and slowly progresses over several decades” before symptoms arise. However, the average age in cholesterol-lowering drug trials is 63; therefore, people have already been exposed to a lifetime of circulating LDL cholesterol. It’s no wonder pharmaceutical therapies typically reduce cardiovascular disease risk by only 20 to 30 percent.

We know LDL, the so-called bad cholesterol, plays “a central role” in the “initiation, development, and progression” of our number-one killer. In fact, more than 100 prospective studies involving more than a million people have demonstrated that those with higher LDL levels are at higher risk.

“It seems reasonable to assume, therefore, that if lowering LCL-C [cholesterol] levels beginning later in life can slow the progression of advanced atherosclerotic plaques…then keeping LDL-C levels low, beginning much earlier in life” might prevent our arteries from getting clogged in the first place. A reasonable assumption, certainly—but let’s not just assume.

“It would be…unethical to set up a controlled clinical trial in which young adults with elevated serum cholesterol levels were treated or not treated over their lifetime”—just as we couldn’t ethically set up a study in which half the young adults are made to start smoking to see if smoking really does cause lung cancer. That’s where observational studies come in. We can follow people who already smoke and compare their disease rates to those who don’t.

It was aroud 40 years ago when the president of the American Heart Association tried to argue we should all stop smoking even though there were no randomized controlled trials. You can see a copy of the “Presidential Address” entitled “The Case for Prevention of Coronary Heart Disease” to the AHA’s 47th Scientific Sessions at 1:34 in my video. Those who smoke have a higher risk of heart attack, and the more we smoke the higher the risk. After we stop smoking, our risk drops. The same can be said for high cholesterol.

Young men 18 through 39 years of age were followed for up to 34 years, and their cholesterol levels, even when they were young, predicted long-term risk of heart disease and death. Men in their 20s and 30s who have a total cholesterol just under 200 have a “substantially longer estimated life expectancy”—around 4 to 9 years longer—than those with levels over 240.

“Evidence from observational studies, however, [is] vulnerable to confounding” factors. Eating a diet that is plant-based enough to lower cholesterol below average, for example, may add years to our lives regardless of what our cholesterol actually is. Ideally, we’d have a long-term, randomized, controlled trial.

Nature may have actually set one up for us. Each of us, at conception, gets a random assortment of genes from our mother and our father, and some of those genes may affect our cholesterol levels. Just like there are rare genetic mutations that result in unusually high cholesterol levels, there are rare genetic mutations that lead to unusually low cholesterol levels, “provid[ing] an ideal system in which to assess the consequences of low LDL cholesterol levels independently of other factors that may modify disease progression,” such as confounding diet and lifestyle factors.

Starting at 3:14 in my video, you can see what I mean. About 1 in 40 African Americans have a mutation that drops their LDL cholesterol from around 130 down toward more optimal levels. Now, this group didn’t eat healthy to get achieve that drop. It’s just in their genes. More than half had high blood pressure and there were a lot of smokers and diabetics in the group, yet those with genetically low LDL levels still had a significant reduction in the incidence of coronary heart disease even in the presence of all those other risk factors. How significant? How much less heart disease? A remarkable 88 percent of heart disease was simply gone.

The astounding finding was that the risk of heart disease in these individuals was reduced by more than 80 percent, whereas the same 20- to 40-point decrease in LDL from drugs only reduces risk around 30 percent. Makes sense, though, because the folks with the mutation had low levels their entire life. They didn’t simply start taking a pill when they were 60.

“The magnitude of the effect of long-term exposure to lower LDL-C [cholesterol] concentrations observed in each of these studies represents a threefold greater reduction in the risk of CHD,” or coronary heart disease, compared to drug treatment started later in life. (As an aside, for all of my fellow research nerds, check out that p value shown in my video at the 4:30 mark. You’d have to do arourd a quintillion studies to get that kind of result by chance!)

“Therefore, a primary prevention strategy that promotes keeping LDL [cholesterol] levels as low as possible, beginning as early in life as possible, and sustaining those low levels of LDL [cholesterol] throughout the whole of one’s lifetime has the potential to dramatically reduce the risk of CHD,” coronary heart disease.


If you don’t know your cholesterol level, you should get it checked—maybe even starting in childhood. See my video Should All Children Have Their Cholesterol Checked? to learn more.

What if you do get tested and your doctor tells you not to worry because your cholesterol’s “normal”? Having a “normal” cholesterol level in the society where it’s normal to drop dead of a heart attack (the number-one killer of men and women) is not really such a good thing. See my video When Low-Risk Means High-Risk.

Check out Optimal Cholesterol Level and What’s the Optimal Cholesterol Level? to find out where you should be.

What if your doctor tells you your LDL is large and fluffy? See my video Does Cholesterol Size Matter?.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations: