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:

How to Avoid Fatty Liver Disease

In the documentary Supersize Me, Morgan Spurlock eats exclusively at McDonald’s for a month and predictably his weight, blood pressure, and cholesterol go up, but so do his liver enzymes, a sign his liver cells are dying and spilling their contents into the bloodstream. His one-man experiment was actually formally replicated. A group of men and women agreed to eat two fast food meals a day for a month. Most of their liver values started out normal, but, within just one week, most were out of whack, a profound pathological elevation in liver damage.

What’s happening is non-alcoholic fatty liver disease (NAFLD), the next global epidemic, as I discuss in my video How to Prevent Non-Alcoholic Fatty Liver Disease. Fatty deposits in the liver result in a disease spectrum from asymptomatic fat buildup to non-alcoholic steatohepatitis (NASH), which can lead to liver scarring and cirrhosis, and may result in liver cancer, liver failure, and death.

NAFLD is now the most common cause of chronic liver disease in the United States, affecting 70 million Americans, nearly one in three adults. Fast food consumption is a great way to bring it on, since it’s associated with the intake of soft drinks and meat. Drinking one can of soda a day may raise the odds of NAFLD by 45 percent, and those eating the equivalent of 14 chicken nuggets’ worth of meat a day have nearly triple the rates of fatty liver compared to those eating 7 nuggets or less.

It’s been characterized as a tale of fat and sugar, but evidently not all types of fat are culpable. Those with fatty hepatitis were found to have eaten more animal fat and cholesterol, and less plant fat, fiber, and antioxidants. This may explain why adherence to a Mediterranean-style diet, characterized by high consumption of foods such as fruits, vegetables, whole grains, and beans, is associated with less severe non-alcoholic fatty liver disease. It could also be related to the presence of specific phytonutrients, like the purple, red, and blue anthocyanin pigments found in berries, grapes, plums, red cabbage, red onions, and radicchio. These anthocyanin-rich foods may be promising for the prevention of fatty liver, but that’s mostly based on petri dish experiments. There was one clinical trial that found that drinking a purple sweet potato beverage seemed to successfully dampen liver inflammation.

A more plant-based diet may also improve our microbiome, the good bacteria in our gut. “‘We are what we eat’ is the old adage but the modern version might be ‘we are what our bacteria eat.’” When we eat fat, we may facilitate the growth of bad bacteria, which can release inflammatory molecules that increase the leakiness of our gut and contribute to fatty liver disease.

Fatty liver disease can also be caused by cholesterol overload. The thought is that dietary cholesterol found in eggs, meat, and dairy oxidizes and then upregulates liver X receptor alpha, which can upregulate something else called SREBP, which can increase the level of fat in the liver. Cholesterol crystals alone cause human white blood cells to spill out inflammatory compounds, just like uric acid crystals in gout. That’s what may be triggering the progression of fatty liver into serious hepatitis: “the accumulation of sufficient concentrations of free cholesterol within steatotic hepatocytes [fatty liver cells] to cause crystallization of the cholesterol.” This is one of several recent lines of evidence suggesting that dietary cholesterol plays an important role in the development of fatty hepatitis—that is, fatty liver inflammation.

In a study of 9,000 American adults followed for 13 years, researchers found a strong association between dietary cholesterol intake and hospitalization and death from cirrhosis and liver cancer, as dietary cholesterol can oxidize and cause toxic and carcinogenic effects. To limit the toxicity of excess cholesterol derived from the diet, the liver tries to rid itself of cholesterol by dumping it into the bloodstream. So, by measuring the non-HDL cholesterol in the blood, one can predict the onset of fatty liver disease. If we subtract HDL from total cholesterol, none of the hundreds of subjects followed with a value under 130 developed the disease. Drug companies view non-alcoholic fatty liver disease as a bonanza, “as is the case of any disease of affluence…considering its already high and rising prevalence and…[its] needing continuous pharmacologic treatment,” but maybe avoiding it is as easy as changing our diet, avoiding sugary and cholesterol-laden foods.

“The unpalatable truth is that NAFLD could almost be considered the human equivalent of foie gras (loosely translated from French as ‘fat liver’). As we overeat and ‘force-feed’ ourselves foods that can result in serious health implications, however, having such a buttery texture in human livers is not a delicacy to be enjoyed by hepatologists [liver doctors] in clinical practice!”


Like my video Preventing Gout Attacks with Diet, How to Prevent Non-Alcoholic Fatty Liver Disease covers an important topic worth the extensive coverage the video provides.

For more on how bad added sugars are for us, see:

For more on how bad cholesterol can be, see:

In health,
Michael Greger, M.D.

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

Bell Peppers to Help Ward Off Parkinson’s

Parkinson’s disease is a movement disorder striking 1 percent of our older population and is the 14th leading cause of death in the United States. While we don’t really know what causes it, we do know that people with a smoking history only appear to have about half the risk. Of course, “[s]moking is hugely damaging to health; any benefit derived from a reduction in risk of Parkinson’s disease is outweighed by the increased risks of cancer and cardiovascular disease,” as well as lung disease, but this shouldn’t stop us from “evaluating tobacco components for possible neuroprotective effects.”

Nicotine may fit the bill. If nicotine is the agent responsible for the neuroprotective effects, is there any way to get the benefit without the risks? That’s the topic of my video Peppers and Parkinson’s: The Benefits of Smoking Without the Risks?.

After all, where does nicotine come from? The tobacco plant. Any other plants have nicotine? Well, tobacco is a nightshade plant, so it’s in the same family as tomatoes, potatoes, eggplants, and peppers. And guess what? They all contain nicotine as well.

That’s why you can’t tell if someone’s a smoker just by looking for the presence of nicotine in their toenail clippings, because non-smokers grow out some nicotine into their nails, as well. Nicotine is in our daily diet—but how much? The amount we average in our diet is hundreds of times less than we get from a single cigarette. So, though we’ve known for more than 15 years that there’s nicotine in ketchup, it was dismissed as insignificant. We then learned that even just one or two puffs of a cigarette could saturate half of our brain’s nicotine receptors, so it doesn’t take much. Then, we discovered that just exposure to second-hand smoke may lower the risk of Parkinson’s, and there’s not much nicotine in that. In fact, one would only be exposed to about three micrograms of nicotine working in a smoky restaurant, but that’s on the same order as what one might get eating the food at a non-smoking restaurant. So, the contribution of dietary nicotine intake from simply eating some healthy vegetables may be significant.

Looking at nightshade consumption, in general, researchers may have found a lower risk compared to other vegetables, but different nightshades have different amounts of nicotine. They found none in eggplant, only a little in potatoes, some in tomatoes, but the most in bell peppers. When that was taken into account, a much stronger picture emerged. The researchers found that more peppers meant more protection. And, as we might expect, the effects of eating nicotine-containing foods were mainly evident in nonsmokers, as the nicotine from smoke would presumably blot out any dietary effect.

This could explain why protective associations have been found for Parkinson’s and the consumption of tomatoes, potatoes, and a tomato- and pepper-rich Mediterranean diet. Might nightshade vegetables also help with treating Parkinson’s? Well, results from trials of nicotine gum and patches have been patchy. Perhaps nicotine only helps prevent it in the first place, or could it be that it isn’t the nicotine at all, but, instead, is some other phytochemical in tobacco and the pepper family?

Researchers conclude that their findings will be need to be reproduced to help establish cause and effect before considering dietary interventions to prevent Parkinson’s disease, but when the dietary intervention is to eat more delicious, healthy dishes like stuffed peppers with tomato sauce, I don’t see the reason we have to wait.


Benefits of smoking? See the tobacco industry gloat in my video Is Something in Tobacco Protective Against Parkinson’s Disease?.

Bell peppers may actually be healthiest raw, as I discuss in Best Cooking Method.

What about tomato products? Choose whole, crushed, or diced tomatoes instead of tomato sauce, purée, or paste. Why? See Inhibiting Platelet Activation with Tomato Seeds for the answer.

You may be interested in my in-depth video series on the Mediterranean Diet:

In health,
Michael Greger, M.D.

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