Chapter 88
Vegetarians’ Stroke Risk
We have also long known that ingested cholesterol contributes substantially to atherosclerosis. A meta-study published in 2020 of more than 50 randomized controlled trials found that eggs significantly raise cholesterol levels. Even studies funded by the egg industry show that eating eggs has this effect. As a result, people who eat more eggs have significantly higher calcium scores in their coronary arteries, a sign of atherosclerotic deposits in the blood vessels and, more importantly, a significantly higher risk of heart attack and death. In the United States, half a dozen population groups with tens of thousands of participants were followed for up to 30 years, and it turned out that each additional half an egg per day is associated with a significantly higher risk of cardiovascular and all-cause mortality. This increased risk of death persisted even when other lifestyle factors were taken into account, including diet quality. In other words, it wasn't just because the people who ate a lot of eggs were also consuming more bacon.
Despite pressure from the egg industry, the Dietary Guidelines for Americans from 2015 to 2020 explicitly advised to eat as little cholesterol as possible, as the Institute of Medicine had recommended, advice that was repeated in the 2020— 2025 guidelines: The National Academies recommend eating as little trans fat and cholesterol as possible, explaining that any intake greater than zero increases the concentration of LDL cholesterol in the blood and thereby increases the risk of our number-one cause of death.
J. David Spence, the director of the Stroke Prevention and Atherosclerosis Research Centre, wrote: After the conviction for misleading advertising that pretended eggs were harmless, the egg industry is spending hundreds of millions of dollars to convince the public, physicians, and policymakers that dietary cholesterol is not harmful. In fact, people living with the risk of cardiovascular disease should not eat eggs regularly, Dr. Spence wrote, which basically includes all North Americans who hope to live beyond middle age.
What about Lp(a)?
Lipoprotein(a), or Lp(a), is an underrecognized independent risk factor for cardiovascular disease. It contributes to coronary artery disease, heart attacks, strokes, peripheral arterial disease, aortic valve calcification, and heart failure. These can occur even in people without elevated cholesterol, because Lp(a) is cholesterol. It is nothing other than an LDL-cholesterol molecule linked to another protein, and like LDL cholesterol, it delivers cholesterol to the inner walls of arteries, where it contributes to inflammation in atherosclerotic deposits. If you would like to learn more about Lp(a) and possible countermeasures, see see.nf/lpa and see.nf/lpadiet. In short, the concentration of Lp(a) in the blood is primarily genetic, but it can be influenced through diet.
We have known for years that the trans fats in meat and dairy products are just as bad for raising LDL cholesterol as the industrially produced trans fats in partially hydrogenated oil in junk food. But when it comes to Lp(a), the trans fats in meat and dairy products appear to be even worse. It's not enough to just leave out meat and live ovo-lacto-vegetarian. There are some very specific plants that can help a little, such as ground flaxseed or amla (powder made from dried Indian gooseberries). When, in one study, participants were given a whole-food, plant-based diet with lots of fruits and vegetables, their Lp(a) levels fell by 16 percent in four weeks. In addition, the subjects lost an average of 15 pounds over those 28 days, though weight loss itself does not appear to have a positive effect on Lp(a) levels, so the researchers assumed it must have been the food. If you eat mostly plant-based for a month, it not only leads to weight loss, but blood pressure improves too—even when participants stopped taking their blood pressure medications. In addition, you can achieve a drop in LDL cholesterol of 25 points and a decline in C-reactive protein of 30 percent, as well as a significant reduction in other inflammation markers, for a systemic, cardioprotective effect.
Vegetarians' Stroke Risk
Healthy plant-based eating is associated with lower overall mortality, by up to 34 percent over an average of eight years. Eating a vegetarian diet even in adulthood means more than four additional years of life. A meta-analysis of twelve studies that prospectively followed more than half a million people for up to 25 years found something similar: significantly less heart disease and a lower overall mortality rate among participants who ate more plants. A systematic review concluded that this was no surprise given the evidence that plant-based lifestyle programs may have stabilized or even reversed coronary heart disease.
Those who eat plant-based are usually leaner and have significantly lower LDL cholesterol, triglyceride, blood sugar, and blood pressure levels, as well as less thickening of the carotid artery walls, and ultrasound measurements at the neck show less plaque formation. Risk factors can change quickly, as shown by the results of one- to three-week Kickstart programs in which people were allowed to eat as much plant-based food as they wanted. For example, the nonprofit Rochester Medicine Lifestyle Institute developed a 15-day at-home program called Jumpstart. Among the first few hundred participants eating a whole-food, plant-based diet, those with obesity lost an average of seven pounds without restricting portion sizes or counting calories, people with diabetes found their fasting blood sugar fell by 28 points, anyone with an LDL cholesterol level over 100 saw a drop of 33 points—equivalent to the effect of some statin medications—and those suffering from hypertension experienced their systolic value decline by 17 points, which is more than you can achieve with medications. And all of that through diet in just two weeks.
When the arterial function of those who do not eat meat is compared with that of meat eaters, the healthy ability of arteries to dilate normally to allow blood to flow is four times better among vegetarians, and it seems to be true: the longer, the better. The degree of superiority in arterial function was associated with the number of years during which no meat had been eaten. Arterial function not only did not worsen with increasing age; it kept getting better the longer participants ate healthfully.
Studies up to 35 years old show that people who eat primarily plant-based also have improved blood rheology —that is, the blood is less viscous and flows better—which may play a role in protecting their cardiovascular system. Subsequent intervention studies that tested these cross-sectional findings showed that rheology measures can be improved in as little as three to six weeks if you switch people to a plant-based diet. But does vegetarians' blood perhaps flow a little too well? A study of thousands of British vegetarians recorded an increased risk of hemorrhagic strokes (with bleeding in the brain), but the twelve-part video series that I produced in response to the study on vegetarians and their stroke risk (starting with see.nf/vegstroke) was for nothing, because as I explain in see.nf/strokeupdate, six follow-up studies found that, on the contrary, there is a lower stroke risk among those who eat more plant-based.