If you're worried whether your largely vegan diet increases your stroke risk, check out the study, "GF-I activity may be a key determinant of stroke risk--a cautionary lesson for vegans." The author of that study is McCarty MF. The study's abstract notes that IGF-I acts on vascular endothelium to activate nitric oxide synthase, thereby promoting vascular health. There is reason to believe that this protection is especially crucial to the cerebral vasculature, helping to ward off thrombotic strokes. Readers want to know what foods protect IGF-I.
IGF-I may also promote the structural integrity of cerebral arteries, thereby offering protection from hemorrhagic stroke. These considerations may help to explain why tallness is associated with low stroke risk, whereas growth hormone deficiency increases stroke risk--and why age-adjusted stroke mortality has been exceptionally high in rural Asians eating quasi-vegan diets, but has been declining steadily in Asia as diets have become progressively higher in animal products.
Do low-fat vegan diets increase stroke risk? Can salt restriction help if one followed a vegan diet?
There is good reason to suspect that low-fat vegan diets tend to down-regulate systemic IGF-I activity. This effect would be expected to increase stroke risk in vegans. Furthermore, epidemiology suggests that low serum cholesterol, and possibly also a low dietary intake of saturated fat--both characteristic of those adopting low-fat vegan diets--may also increase stroke risk.
Vegans are thus well advised to adopt practical countermeasures to minimize stroke risk--the most definitive of which may be salt restriction. A high potassium intake, aerobic exercise training, whole grains, moderate alcohol consumption, low-dose aspirin, statin or policosanol therapy, green tea, and supplementation with fish oil, taurine, arginine, and B vitamins--as well as pharmacotherapy of hypertension if warranted--are other practical measures for lowering stroke risk.
Although low-fat vegan diets may markedly reduce risk for coronary disease, diabetes, and many common types of cancer, an increased risk for stroke may represent an 'Achilles heel'. Nonetheless, vegans have the potential to achieve a truly exceptional 'healthspan' if they face this problem forthrightly by restricting salt intake and taking other practical measures that promote cerebrovascular health.
The question readers would like to see answered by research is that if one is concerned about ischemic stroke risk caused by blood clots in the carotid artery, for example rather than a stroke caused by bleeding in the brain, would a vegan diet help or not help? And if one went back on a fish or meat diet, wouldn't the arteries fill up again with plaque?
The risk versus reward is of concern to people trying to maximize health benefits from nutrition. A balanced diet would help. But the important question is which diet, considered balanced will prevent against stroke and still work to reverse arteries clogged by soft plaque? Also see, Dietary sources of animal and plant protein intake among Flemish preschool children and the association with socio-economic and lifestyle-related factors, and check out the study, Resistance training with soy vs whey protein supplements in hyperlipidemic males. [J Int Soc Sports Nutr. 2009].
People in countries with a higher stroke risk and largely vegetarian diets also use lots of salt and often MSG
Under what conditions would excess amino acid intake be unhealthy? An unnecessarily high intake of essential amino acids--either in the absolute sense or relative to total dietary protein--may prove to be as grave a risk factor for 'Western' degenerative diseases as is excessive fat intake, say some researchers. Scientists in the past also have studied the high omega 3 fatty acid, high vitamin A, D and E fish and seafood diets of Arctic indigenous peoples on their native diets who may not use a lot of salt and found that they, too have a higher 'bleeding' type of stroke risk from all that fish oil, especially from cod liver oil in excess by eating the livers of fish and seals.
Is it the vegan diet, the high salt intake, or the vegan diets of peoples with higher bleeding type of stroke risks? And what about those with stroke risk from blood clots and thick rather than thin blood types? For example, the risk of many degenerative disorders may be decreased in vegans, although reduced growth factor activity may be responsible for an increased risk of hemorrhagic stroke. But readers are wondering what foods will not reduce "growth factor activity" and still give people the advantages of what health benefits a vegan diet can add.
The answer may be a balanced diet, depending on how an individual tailors that specific diet to the person's genes, blood type, body shape, metabolic and chemical response to the food or supplement, and what the readings on blood tests show as well as tests of what's being absorbed in the cells from foods or supplements.
What can a low-fat diet do for you? Recent studies have looked at using low-fat (about 10% daily fat) vegan diets to reverse the clog in arteries filled with soft plaque as well as reduce risk of further strokes in stroke-prone people with predispositions. And research has looked at vegan proteins to reduce the risk of cancer.
Vegan proteins may reduce risk of cancer, obesity, and cardiovascular disease by promoting increased glucagon activity
You may want to check out a study or its abstract "Vegan proteins may reduce risk of cancer, obesity, and cardiovascular disease by promoting increased glucagon activity" by McCarty MF. In the study's abstract, researchers found that diets featuring vegan proteins can be expected to lower elevated serum lipid levels, promote weight loss, and decrease circulating IGF-I activity. The latter effect should impede cancer induction (as is seen in animal studies with soy protein), lessen neutrophil-mediated inflammatory damage, and slow growth and maturation in children, according to the article, "Soy protein and cancer, obesity, and cardiovascular disease." Also check out his hypothesis from a study done in 1999.
What the soy protein study researched showed how amino acids affect (modulate) the secretion of both insulin and glucagon. The composition of dietary protein has the potential to influence the balance of glucagon and insulin activity.
Researchers looked at soy protein and other vegan proteins because they're higher in non-essential amino acids than animal protein
Low-fat vegan diets may be especially protective in regard to cancers linked to insulin resistance--namely, breast and colon cancer--as well as prostate cancer. Conversely, the high IGF-I activity associated with heavy ingestion of animal products may be largely responsible for the epidemic of 'Western' cancers in wealthy societies.
Increased phytochemical intake is also likely to contribute to the reduction of cancer risk in vegans. Regression of coronary stenoses has been documented during low-fat vegan diets coupled with exercise training; such regimens also tend to markedly improve diabetic control and lower elevated blood pressure. But another study reported that vegan diets raise the stroke risk for the 'bleeding' type of stroke. See the abstract of the study,"GF-I activity may be a key determinant of stroke risk--a cautionary lesson for vegans."
Non-essential amino acids health effects
Soy protein, as well as many other vegan proteins, are higher in non-essential amino acids than most animal-derived food proteins, and as a result should preferentially favor glucagon production. Scientists studied how glucagon, by acting on hepatocytes, promotes (and insulin inhibits) cAMP-dependent mechanisms that down-regulate lipogenic enzymes and cholesterol synthesis, while up-regulating hepatic LDL receptors and production of the IGF-I antagonist IGFBP-1.
The insulin-sensitizing properties of many vegan diets--high in fiber, low in saturated fat--should amplify these effects by down-regulating insulin secretion. Additionally, the relatively low essential amino acid content of some vegan diets may decrease hepatic IGF-I synthesis.
Research focused on the insulin-sensitizing properties of vegan diets high in fiber and low in saturated fat
Researchers found that diets featuring vegan proteins can be expected to lower elevated serum lipid levels, promote weight loss, and decrease circulating IGF-I activity. The latter effect should impede cancer induction (as is seen in animal studies with soy protein), lessen neutrophil-mediated inflammatory damage, and slow growth and maturation in children. In fact, vegans tend to have low serum lipids, lean physiques, shorter stature, later puberty, and decreased risk for certain prominent 'Western' cancers; a vegan diet has documented clinical efficacy in rheumatoid arthritis.
Risk of many other degenerative disorders may be decreased in vegans, although reduced growth factor activity may be responsible for an increased risk of hemorrhagic stroke. By altering the glucagon/insulin balance, it is conceivable that supplemental intakes of key non-essential amino acids could enable omnivores to enjoy some of the health advantages of a vegan diet.
An unnecessarily high intake of essential amino acids--either in the absolute sense or relative to total dietary protein--may prove to be as grave a risk factor for 'Western' degenerative diseases as is excessive fat intake. For further information, check out the studies or abstracts, "A low-fat, whole-food vegan diet, as well as other strategies that down-regulate IGF-I activity, may slow the human aging process. [Med Hypotheses. 2003]," and "IGF-I activity may be a key determinant of stroke risk--a cautionary lesson for vegans. [Med Hypotheses. 2003]."
· IGF-I activity may be a key determinant of stroke risk--a cautionary lesson for vegans. [Med Hypotheses. 2003]
· Review Dietary fat consumption and health. [Nutr Rev. 1998] Review Energy balance, physical activity, and cancer risk. [Methods Mol Biol. 2009]
· The origins of western obesity: a role for animal protein? [Med Hypotheses. 2000]
· Review Health effects of vegan diets. [Am J Clin Nutr. 2009]