How can we explain the declining risk of stroke as the Japanese diet became westernized with more meat and dairy?
Like Japan westernizedThe country’s stroke rate plummeted, as you can see in the graph below and at 0:15 in my video. Vegetarians and stroke risk factors: Saturated fats?.
Strokes had been a leading cause of death in Japan, but the mortality rate dropped dramatically as they moved away from their traditional diets and began eating more like Westerners. Did consuming all that extra meat and dairy have a protective effect? After all, their intake of animal fat and animal protein was going at the same time as their stroke rates were dropping, as shown below and at 0:35 in my video.
Commented A prominent Loma Linda cardiology professor said: “Protection against stroke by consumption of animal foods? Surely not!… Many vegetarians, like myself, have almost come to expect that the data will indicate that they have an advantage, whatever disease is being considered. So it is disturbing to find evidence in a quite different direction for at least one subtype of stroke.”
Can Can dietary saturated fats, such as those found in meat and dairy products, be beneficial in preventing stroke risk? There seemed to be a protective association, but only in East Asian populations, as you can see below and at 1:11 in my video. video.
High dietary intake of saturated fat was found It was associated with a lower risk of stroke in Japanese, but not in non-Japanese. So what was it about the traditional Japanese diet that the Westernization of their eating habits made things better when it came to stroke risk? Well, at the same time, their consumption of meat and dairy products was going going up, and their salt intake was going down, as you can see see down already at 1:40.
The traditional Japanese diet was full With salt. They had one of the highest salt intakes in the world, about a dozen tablespoons of salt a day. Before refrigeration become widely available, they ate All kinds of salted, pickled and fermented foods, from soy sauce to salted fish. In areas with double the salt consumption, had Twice as much stroke mortality, but when salt intake decreased, so did stroke mortality rates, because when salt intake decreased, their blood pressure decreased as well. High blood pressure is It may be “the most important potentially modifiable risk factor for stroke,” so it’s no great mystery why the Westernization of the Japanese diet led to a decreased risk of stroke.
When they abandoned Because of their more traditional diets, their obesity rates increased, as did their diabetes and coronary artery disease, but as they gave up the incredibly high salt intake, their incredibly high stroke rates correspondingly decreased.
Stomach cancer is closely associated with excessive salt consumption. When looking at their stomach cancer rates, came The children’s diets shrank beautifully as they westernized their diets, moving away from salt-preserved foods, as can be seen in the graph below and at 2:50 in my video.
But of course, like them began By eating more animal foods like dairy, their rates of lethal prostate cancer, for example, skyrocketed. Compared to Japan, the United States has 7 times more deaths from prostate cancer, 5 times more fatal breast cancer, 3 times more mortality from colon cancer and lymphoma, and 6 to 12 times the mortality rate from heart disease, as you can see in the graph below and at 3:15 in my videoYes, the rates of stroke and stomach cancer in Japan were higher, but they were also eating up to a quarter cup of salt a day.
That would be it seem The most likely explanation is that animal fat has some protective role, and indeed it was eventually recognized in the official Japanese guidelines for the prevention of cardiovascular disease: “Refrain from consuming large amounts of fatty meat, animal fat, eggs and processed foods…”
Now one of Harvard’s cohorts found a protective association between hemorrhagic stroke and saturated fats and trans fats, incitement a “sigh of relief… heard across all cattle-producing Midwestern states,” even though researchers Completed that of course we all need to reduce our consumption of animal fats and trans fats to gain benefits in preventing heart disease. Looking However, in another large Harvard cohort, they found no similar protective association for any type of stroke, and when they pooled all the studies together, they found no protection at all. found In general, as you can see below and at 4:07 in my video.
Observational studies have found that a higher level of LDL cholesterol appears to be associated with a lower risk of hemorrhagic stroke, lifting The possibility that cholesterol is “a double-edged sword,” decreasing the risk of ischemic stroke but increasing the risk of hemorrhagic stroke. But low cholesterol levels in the elderly “may be an indicator of nutritional deficiencies … or a sign of debilitating diseases,” or perhaps individuals were taking a combination of cholesterol-lowering drugs and blood thinners, and that’s why we tend to see more brain bleeds in those with low cholesterol. You don’t know until you put it to the test.
Researchers put Together, about two dozen randomized controlled trials were conducted and found that the lower the cholesterol, the better when it came to overall stroke risk, with “no significant increase in the risk of hemorrhagic stroke with lower low-density lipoprotein levels achieved.” [LDL] “cholesterol levels”.
Genetic data appears mixedand some suggest that having elevated LDL throughout life would give you a higher risk of hemorrhagic stroke, while other data suggest More of that double-edged sword effect. However, with lower cholesterol, “any potential excess bleeding [bleeding] Stroke is very serious surpassed for its protective effect against ischemic stroke,” the much more common type of clotting stroke, not to mention heart disease. be on the order of 18 fewer strokes for each additional hemorrhagic stroke with cholesterol reduction.
Does this explain the increased risk of stroke found among vegetarians? Hemorrhagic stroke is The type of stroke that was seen most often in vegetarians, but cholesterol levels in vegans were even lower, and if anything, vegans tended to be at higher risk for clotting stroke, so it doesn’t make sense. If there is some protective factor in animal foods, then hopefully a diet can be found that still protects against the leading cause of death, heart disease, without increasing the risk of the leading cause of death, stroke. But first, we need to figure out what that factor is, and the search continues.
Aren’t there studies suggesting that saturated fats aren’t as bad as we used to think? Check them out:
Just as the traditional Japanese diet had many advantages despite having high sodium content as a fatal flaw, what could be the Achilles heel of plant-based diets when it comes to stroke risk?
This is the seventh video in this series on stroke. See the related posts below for the others.
