How can we explain the drop in stroke risk as the Japanese diet became Westernized by eating more meat and dairy?
Vegetarians and Stroke Risk Factors—Saturated Fat?
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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
As Japan westernized, their stroke rate plummeted. Stroke was the leading cause of death in Japan, but the mortality rate sharply decreased as they moved away from their traditional diets and started eating more like those in the west; so, maybe there was a protective effect of all the extra meat and dairy they started to eat. After all, their animal fat and animal protein intake were going up at the same time their stroke rates were going down.
“Protection from stroke by eating animal foods? Surely not!” commented a noted Loma Linda cardiology professor. “Many vegetarians, like myself have almost come to expect the data to indicate that they have an advantage, whatever the disease that’s being considered. Thus, it is disquieting to find evidence in a quite different direction for at least one subtype of stroke.”
Can dietary saturated fat, like that found in meat and dairy, be beneficial in the prevention of stroke risk? There appeared to be a protective association, but only in East Asian populations. High dietary saturated fat was found associated with a lower risk of stroke in Japanese but not in non-Japanese. So, what was it about the traditional Japanese diet where the Westernization of their diets made things better when it came to stroke risk? Well, at the same time their meat and dairy was going up, their salt intake was going down.
The traditional Japanese diet was packed with salt—in fact, they had some of the highest salt intakes in the world, like a dozen spoonfuls of salt a day. Before the widespread availability of refrigeration, they ate all sorts of salted, pickled, fermented foods from soy sauce to salted fish. And in the areas that had twice the salt intake, they had twice the stroke mortality, but when the salt intake dropped do did the stroke death rates, because when the salt came down their blood pressures came down, too. And high blood pressure is perhaps the single most important modifiable risk factor for stroke. So, it’s no big mystery why the westernization of the Japanese diet led to a drop in stroke risk.
When they abandoned their more traditional diets their obesity rates went up, their diabetes and coronary artery disease went up, but as they gave up the insanely high salt intake their insanely high stroke rates correspondingly fell. It’s like if you look at their stomach cancer rates, a cancer closely associated with excess salt intake. Their stomach cancer rates came down beautifully as they westernized their diets away from salt-preserved foods, but of course as they started eating more animal foods like dairy, their rates of fatal prostate cancer, for example, shot through the roof. Compared to Japan, not only does the U.S. have seven times more deaths from prostate cancer, but five times more deadly breast cancer, three times more colon cancer and lymphoma mortality, and six to twelve times the death rate from heart disease. Yes, Japanese stroke and stomach cancer rates were higher, but they were also eating up to a quarter cup of salt a day.
That would seem to be the most likely explanation, rather than some protective role of animal fat, as eventually acknowledged in the official Japanese guidelines for the prevention of cardiovascular disease.
Now, one of the Harvard cohorts found a protective association between both saturated fat and trans fat for hemorrhagic strokes, prompting a “sigh of relief throughout the cattle-producing Midwest,” even though the researchers clearly concluded that, of course, we all have to cut down on animal fat and trans fat for the heart disease benefit regardless, but looking at another major Harvard cohort they found no such protective association for any kind of stroke, and put all the studies together and zero protection across the board.
Observational studies have found that higher LDL cholesterol seems to be associated with lower risk of hemorrhagic stroke, raising the possibility that low cholesterol may be a double-edged sword, decreasing the risk of ischemic stroke but increasing the risk of hemorrhagic stroke. But low cholesterol levels in the aged may just be a surrogate for nutrient deficiencies, or a sign of debilitating diseases, or maybe they’re on a combo 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. Put together about two dozen randomized controlled trials, and the lower your cholesterol the better when it comes to overall stroke risk, with no significant increase in the risk of hemorrhagic stroke with lower achieved LDL cholesterol levels.
The genetic data appears mixed, with some suggesting a lifetime of elevated LDL would give you a higher hemorrhagic stroke risk, and other data suggesting more of a double-edged sword effect, but any possible excess of bleeding stroke with lower cholesterol is greatly outweighed by the protective effect against the much more common clotting stroke, not to mention heart disease, perhaps on the order of 18 fewer clotting strokes for every one extra bleeding stroke with cholesterol lowering.
How about this as a candidate to explain the increased stroke risk found among vegetarians? This is the type of stroke that appeared higher in vegetarians, but the cholesterol levels in vegans were even lower and, if anything, they had a trend towards a higher clotting stroke risk; so, that doesn’t really make sense. If there is some kind of protective factor in animal foods, it is to be hoped that a diet can be found that still protects against killer #1, heart disease, without increasing the risk of killer #5, stroke. But first, we have to figure out what that factor is, a hunt that will continue, next.
Please consider volunteering to help out on the site.
- Tong TYN, Appleby PN, Bradbury KE, et al. Risks of ischaemic heart disease and stroke in meat eaters, fish eaters, and vegetarians over 18 years of follow-up: results from the prospective EPIC-Oxford study. BMJ. 2019;366:l4897.
- Tong TYN, Appleby PN, Bradbury KE, et al. Risks of ischaemic heart disease and stroke in meat eaters, fish eaters, and vegetarians over 18 years of follow-up: results from the prospective EPIC-Oxford study. BMJ. 2019;366:l4897.
- Kinjo Y, Beral V, Akiba S, et al. Possible protective effect of milk, meat and fish for cerebrovascular disease mortality in Japan. J Epidemiol. 1999;9(4):268-74.
- Fraser G. Commentary: protection from stroke by eating animal foods? Surely not! Int J Epidemiol. 2003;32(4):543-5.
- Muto M, Ezaki O. High Dietary Saturated Fat is Associated with a Low Risk of Intracerebral Hemorrhage and Ischemic Stroke in Japanese but not in Non-Japanese: A Review and Meta-Analysis of Prospective Cohort Studies. J Atheroscler Thromb. 2018;25(5):375-392.
- Kinoshita M, Yokote K, Arai H, et al. Japan Atherosclerosis Society (JAS) Guidelines for Prevention of Atherosclerotic Cardiovascular Diseases 2017. J Atheroscler Thromb. 2018;25(9):846-984.
- Campbell T. A plant-based diet and stroke. J Geriatr Cardiol. 2017;14(5):321-326.
- Oiso T. Incidence of stomach cancer and its relation to dietary habits and nutrition in Japan between 1900 and 1975. Cancer Res. 1975;35(11 Pt. 2):3254-8.
- Cao J, Eshak ES, Liu K, Gero K, Liu Z, Yu C. Age-Period-Cohort Analysis of Stroke Mortality Attributable to High Sodium Intake in China and Japan. Stroke. 2019;50(7):1648-1654.
- Ando K, Kawarazaki H, Miura K, et al. [Scientific statement] Report of the Salt Reduction Committee of the Japanese Society of Hypertension(1) Role of salt in hypertension and cardiovascular diseases. Hypertens Res. 2013;36(12):1009-19.
- Shimamoto T, Komachi Y, Inada H, et al. Trends for coronary heart disease and stroke and their risk factors in Japan. Circulation. 1989;79(3):503-15.
- Tanaka M, Ma E, Tanaka H, Ioka A, Nakahara T, Takahashi H. Trends of stomach cancer mortality in Eastern Asia in 1950-2004: comparative study of Japan, Hong Kong and Singapore using age, period and cohort analysis. Int J Cancer. 2012;130(4):930-6.
- Athyros VG, Tziomalos K, Karagiannis A, Wierzbicki AS, Mikhailidis DP. Aggressive statin treatment, very low serum cholesterol levels and haemorrhagic stroke: is there an association?. Curr Opin Cardiol. 2010;25(4):406-10.
- Wang X, Dong Y, Qi X, Huang C, Hou L. Cholesterol levels and risk of hemorrhagic stroke: a systematic review and meta-analysis. Stroke. 2013;44(7):1833-9.
- De carvalho LSF. Total cholesterol and the risk of stroke: A double-edged sword or a blunt knife?. Atherosclerosis. 2018;270:191-192.
- Akoudad S, Ikram MA, Portegies ML, et al. Genetic loci for serum lipid fractions and intracerebral hemorrhage. Atherosclerosis. 2016;246:287-92.
- Judge C, Ruttledge S, Costello M, et al. Lipid Lowering Therapy, Low-Density Lipoprotein Level and Risk of Intracerebral Hemorrhage - A Meta-Analysis. J Stroke Cerebrovasc Dis. 2019;28(6):1703-1709.
- Sun L, Clarke R, Bennett D, et al. Causal associations of blood lipids with risk of ischemic stroke and intracerebral hemorrhage in Chinese adults. Nat Med. 2019;25(4):569-574.
- He K, Merchant A, Rimm EB, et al. Dietary fat intake and risk of stroke in male US healthcare professionals: 14 year prospective cohort study. BMJ. 2003;327(7418):777-82.
- Cheng P, Wang J, Shao W, Liu M, Zhang H. Can dietary saturated fat be beneficial in prevention of stroke risk? A meta-analysis. Neurol Sci. 2016;37(7):1089-98.
- Denke M. Dairy products and red meat: midwesterners always knew they were good for something. Circulation. 2001;103(6):784-6.
- Iso H, Stampfer MJ, Manson JE, et al. Prospective study of fat and protein intake and risk of intraparenchymal hemorrhage in women. Circulation. 2001;103(6):856-63.
- Pandian JD, Gall SL, Kate MP, et al. Prevention of stroke: a global perspective. Lancet. 2018;392(10154):1269-1278.
- Tsugane S, Sasazuki S, Kobayashi M, Sasaki S. Salt and salted food intake and subsequent risk of gastric cancer among middle-aged Japanese men and women. Br J Cancer. 2004;90(1):128-34.
- Ganmaa D, Li XM, Qin LQ, Wang PY, Takeda M, Sato A. The experience of Japan as a clue to the etiology of testicular and prostatic cancers. Med Hypotheses. 2003;60(5):724-30.
- Willcox BJ, Willcox DC, Todoriki H, et al. Caloric restriction, the traditional Okinawan diet, and healthy aging: the diet of the world's longest-lived people and its potential impact on morbidity and life span. Ann N Y Acad Sci. 2007;1114:434-55.
- Shin J, Chung JW, Jang HS, et al. Achieved low-density lipoprotein cholesterol level and stroke risk: A meta-analysis of 23 randomised trials. Eur J Prev Cardiol. 2019;:2047487319830503.
- Hooper L, Martin N, Abdelhamid A, Davey Smith G. Reduction in saturated fat intake for cardiovascular disease. Cochrane Database Syst Rev. 2015;(6):CD011737.
Video production by Glass Entertainment
Motion graphics by Avocado Video
- animal products
- brain health
- breast cancer
- cancer
- cardiovascular disease
- cholesterol
- dairy
- diabetes
- fat
- fermented foods
- fish
- Harvard
- heart disease
- heart health
- Japan
- LDL cholesterol
- meat
- men's health
- mortality
- Plant-Based Diets
- prostate cancer
- salt
- saturated fat
- soy sauce
- stomach cancer
- stroke
- trans fats
- vegans
- vegetarians
- women's health
Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
As Japan westernized, their stroke rate plummeted. Stroke was the leading cause of death in Japan, but the mortality rate sharply decreased as they moved away from their traditional diets and started eating more like those in the west; so, maybe there was a protective effect of all the extra meat and dairy they started to eat. After all, their animal fat and animal protein intake were going up at the same time their stroke rates were going down.
“Protection from stroke by eating animal foods? Surely not!” commented a noted Loma Linda cardiology professor. “Many vegetarians, like myself have almost come to expect the data to indicate that they have an advantage, whatever the disease that’s being considered. Thus, it is disquieting to find evidence in a quite different direction for at least one subtype of stroke.”
Can dietary saturated fat, like that found in meat and dairy, be beneficial in the prevention of stroke risk? There appeared to be a protective association, but only in East Asian populations. High dietary saturated fat was found associated with a lower risk of stroke in Japanese but not in non-Japanese. So, what was it about the traditional Japanese diet where the Westernization of their diets made things better when it came to stroke risk? Well, at the same time their meat and dairy was going up, their salt intake was going down.
The traditional Japanese diet was packed with salt—in fact, they had some of the highest salt intakes in the world, like a dozen spoonfuls of salt a day. Before the widespread availability of refrigeration, they ate all sorts of salted, pickled, fermented foods from soy sauce to salted fish. And in the areas that had twice the salt intake, they had twice the stroke mortality, but when the salt intake dropped do did the stroke death rates, because when the salt came down their blood pressures came down, too. And high blood pressure is perhaps the single most important modifiable risk factor for stroke. So, it’s no big mystery why the westernization of the Japanese diet led to a drop in stroke risk.
When they abandoned their more traditional diets their obesity rates went up, their diabetes and coronary artery disease went up, but as they gave up the insanely high salt intake their insanely high stroke rates correspondingly fell. It’s like if you look at their stomach cancer rates, a cancer closely associated with excess salt intake. Their stomach cancer rates came down beautifully as they westernized their diets away from salt-preserved foods, but of course as they started eating more animal foods like dairy, their rates of fatal prostate cancer, for example, shot through the roof. Compared to Japan, not only does the U.S. have seven times more deaths from prostate cancer, but five times more deadly breast cancer, three times more colon cancer and lymphoma mortality, and six to twelve times the death rate from heart disease. Yes, Japanese stroke and stomach cancer rates were higher, but they were also eating up to a quarter cup of salt a day.
That would seem to be the most likely explanation, rather than some protective role of animal fat, as eventually acknowledged in the official Japanese guidelines for the prevention of cardiovascular disease.
Now, one of the Harvard cohorts found a protective association between both saturated fat and trans fat for hemorrhagic strokes, prompting a “sigh of relief throughout the cattle-producing Midwest,” even though the researchers clearly concluded that, of course, we all have to cut down on animal fat and trans fat for the heart disease benefit regardless, but looking at another major Harvard cohort they found no such protective association for any kind of stroke, and put all the studies together and zero protection across the board.
Observational studies have found that higher LDL cholesterol seems to be associated with lower risk of hemorrhagic stroke, raising the possibility that low cholesterol may be a double-edged sword, decreasing the risk of ischemic stroke but increasing the risk of hemorrhagic stroke. But low cholesterol levels in the aged may just be a surrogate for nutrient deficiencies, or a sign of debilitating diseases, or maybe they’re on a combo 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. Put together about two dozen randomized controlled trials, and the lower your cholesterol the better when it comes to overall stroke risk, with no significant increase in the risk of hemorrhagic stroke with lower achieved LDL cholesterol levels.
The genetic data appears mixed, with some suggesting a lifetime of elevated LDL would give you a higher hemorrhagic stroke risk, and other data suggesting more of a double-edged sword effect, but any possible excess of bleeding stroke with lower cholesterol is greatly outweighed by the protective effect against the much more common clotting stroke, not to mention heart disease, perhaps on the order of 18 fewer clotting strokes for every one extra bleeding stroke with cholesterol lowering.
How about this as a candidate to explain the increased stroke risk found among vegetarians? This is the type of stroke that appeared higher in vegetarians, but the cholesterol levels in vegans were even lower and, if anything, they had a trend towards a higher clotting stroke risk; so, that doesn’t really make sense. If there is some kind of protective factor in animal foods, it is to be hoped that a diet can be found that still protects against killer #1, heart disease, without increasing the risk of killer #5, stroke. But first, we have to figure out what that factor is, a hunt that will continue, next.
Please consider volunteering to help out on the site.
- Tong TYN, Appleby PN, Bradbury KE, et al. Risks of ischaemic heart disease and stroke in meat eaters, fish eaters, and vegetarians over 18 years of follow-up: results from the prospective EPIC-Oxford study. BMJ. 2019;366:l4897.
- Tong TYN, Appleby PN, Bradbury KE, et al. Risks of ischaemic heart disease and stroke in meat eaters, fish eaters, and vegetarians over 18 years of follow-up: results from the prospective EPIC-Oxford study. BMJ. 2019;366:l4897.
- Kinjo Y, Beral V, Akiba S, et al. Possible protective effect of milk, meat and fish for cerebrovascular disease mortality in Japan. J Epidemiol. 1999;9(4):268-74.
- Fraser G. Commentary: protection from stroke by eating animal foods? Surely not! Int J Epidemiol. 2003;32(4):543-5.
- Muto M, Ezaki O. High Dietary Saturated Fat is Associated with a Low Risk of Intracerebral Hemorrhage and Ischemic Stroke in Japanese but not in Non-Japanese: A Review and Meta-Analysis of Prospective Cohort Studies. J Atheroscler Thromb. 2018;25(5):375-392.
- Kinoshita M, Yokote K, Arai H, et al. Japan Atherosclerosis Society (JAS) Guidelines for Prevention of Atherosclerotic Cardiovascular Diseases 2017. J Atheroscler Thromb. 2018;25(9):846-984.
- Campbell T. A plant-based diet and stroke. J Geriatr Cardiol. 2017;14(5):321-326.
- Oiso T. Incidence of stomach cancer and its relation to dietary habits and nutrition in Japan between 1900 and 1975. Cancer Res. 1975;35(11 Pt. 2):3254-8.
- Cao J, Eshak ES, Liu K, Gero K, Liu Z, Yu C. Age-Period-Cohort Analysis of Stroke Mortality Attributable to High Sodium Intake in China and Japan. Stroke. 2019;50(7):1648-1654.
- Ando K, Kawarazaki H, Miura K, et al. [Scientific statement] Report of the Salt Reduction Committee of the Japanese Society of Hypertension(1) Role of salt in hypertension and cardiovascular diseases. Hypertens Res. 2013;36(12):1009-19.
- Shimamoto T, Komachi Y, Inada H, et al. Trends for coronary heart disease and stroke and their risk factors in Japan. Circulation. 1989;79(3):503-15.
- Tanaka M, Ma E, Tanaka H, Ioka A, Nakahara T, Takahashi H. Trends of stomach cancer mortality in Eastern Asia in 1950-2004: comparative study of Japan, Hong Kong and Singapore using age, period and cohort analysis. Int J Cancer. 2012;130(4):930-6.
- Athyros VG, Tziomalos K, Karagiannis A, Wierzbicki AS, Mikhailidis DP. Aggressive statin treatment, very low serum cholesterol levels and haemorrhagic stroke: is there an association?. Curr Opin Cardiol. 2010;25(4):406-10.
- Wang X, Dong Y, Qi X, Huang C, Hou L. Cholesterol levels and risk of hemorrhagic stroke: a systematic review and meta-analysis. Stroke. 2013;44(7):1833-9.
- De carvalho LSF. Total cholesterol and the risk of stroke: A double-edged sword or a blunt knife?. Atherosclerosis. 2018;270:191-192.
- Akoudad S, Ikram MA, Portegies ML, et al. Genetic loci for serum lipid fractions and intracerebral hemorrhage. Atherosclerosis. 2016;246:287-92.
- Judge C, Ruttledge S, Costello M, et al. Lipid Lowering Therapy, Low-Density Lipoprotein Level and Risk of Intracerebral Hemorrhage - A Meta-Analysis. J Stroke Cerebrovasc Dis. 2019;28(6):1703-1709.
- Sun L, Clarke R, Bennett D, et al. Causal associations of blood lipids with risk of ischemic stroke and intracerebral hemorrhage in Chinese adults. Nat Med. 2019;25(4):569-574.
- He K, Merchant A, Rimm EB, et al. Dietary fat intake and risk of stroke in male US healthcare professionals: 14 year prospective cohort study. BMJ. 2003;327(7418):777-82.
- Cheng P, Wang J, Shao W, Liu M, Zhang H. Can dietary saturated fat be beneficial in prevention of stroke risk? A meta-analysis. Neurol Sci. 2016;37(7):1089-98.
- Denke M. Dairy products and red meat: midwesterners always knew they were good for something. Circulation. 2001;103(6):784-6.
- Iso H, Stampfer MJ, Manson JE, et al. Prospective study of fat and protein intake and risk of intraparenchymal hemorrhage in women. Circulation. 2001;103(6):856-63.
- Pandian JD, Gall SL, Kate MP, et al. Prevention of stroke: a global perspective. Lancet. 2018;392(10154):1269-1278.
- Tsugane S, Sasazuki S, Kobayashi M, Sasaki S. Salt and salted food intake and subsequent risk of gastric cancer among middle-aged Japanese men and women. Br J Cancer. 2004;90(1):128-34.
- Ganmaa D, Li XM, Qin LQ, Wang PY, Takeda M, Sato A. The experience of Japan as a clue to the etiology of testicular and prostatic cancers. Med Hypotheses. 2003;60(5):724-30.
- Willcox BJ, Willcox DC, Todoriki H, et al. Caloric restriction, the traditional Okinawan diet, and healthy aging: the diet of the world's longest-lived people and its potential impact on morbidity and life span. Ann N Y Acad Sci. 2007;1114:434-55.
- Shin J, Chung JW, Jang HS, et al. Achieved low-density lipoprotein cholesterol level and stroke risk: A meta-analysis of 23 randomised trials. Eur J Prev Cardiol. 2019;:2047487319830503.
- Hooper L, Martin N, Abdelhamid A, Davey Smith G. Reduction in saturated fat intake for cardiovascular disease. Cochrane Database Syst Rev. 2015;(6):CD011737.
Video production by Glass Entertainment
Motion graphics by Avocado Video
- animal products
- brain health
- breast cancer
- cancer
- cardiovascular disease
- cholesterol
- dairy
- diabetes
- fat
- fermented foods
- fish
- Harvard
- heart disease
- heart health
- Japan
- LDL cholesterol
- meat
- men's health
- mortality
- Plant-Based Diets
- prostate cancer
- salt
- saturated fat
- soy sauce
- stomach cancer
- stroke
- trans fats
- vegans
- vegetarians
- women's health
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Title
Vegetarians and Stroke Risk Factors—Saturated Fat?
LicenseCreative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
Content URLDoctor's Note
But wait, aren’t there studies suggesting saturated fat isn’t as bad as we used to think? Check out:
- The Saturated Fat Studies: Set Up to Fail
- The Saturated Fat Studies: Buttering Up the Public
- Is Butter Really Back? What the Science Says
Just like the traditional Japanese diet had lots of things going for it but had the high sodium as the fatal flaw, what might be the Achilles heel of plant-based diets when it comes to stroke risk?
This is the 7th video in this stroke series. So far we’ve covered:
- What to Eat for Stroke Prevention
- What Not to Eat for Stroke Prevention
- Do Vegetarians Really Have Higher Stroke Risk?
- Vegetarians and Stroke Risk Factors—Vitamin D?
- Vegetarians and Stroke Risk Factors—Omega 3s?
- Vegetarians and Stroke Risk Factors—Vegan Junk Food?
Stay tuned for:
- Vegetarians and Stroke Risk Factors—Animal Protein?
- How to Test for Functional Vitamin B12 Deficiency
- Should Vegetarians Take Creatine to Normalize Homocysteine?
- The Efficacy and Safety of Creatine for High Homocysteine
2023 Update: I recently put out a new video, Update on Vegetarian Stroke Risk.
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