Natural Strategies to Reduce Stroke Risk
Conventional medications and surgeries used to prevent stoke and cerebrovascular disease are often associated with side effects and are limited in their ability to target the multiple factors that contribute to stroke. Life Extension emphasizes a global stroke prevention strategy. This strategy includes a series of preventive measures such as reducing chronic inflammation, maintaining healthy body weight, reducing cholesterol, suppressing homocysteine and fibrinogen levels, and lowering blood pressure (Houston 2010).
Mediterranean Diet. The traditional Mediterranean diet is rich in fruits, vegetables, whole grains, and fish, and low in red meat and sweets (Fung 2009). Adherence to a Mediterranean diet is associated with reduced all-cause mortality and lower incidence of several age-related diseases, including stroke (Mitrou 2007; Fung 2009). A 2011 study found that strict adherence to a Mediterranean diet decreased the likelihood of ischemic stroke irrespective of cholesterol levels, age, and gender (Kastorini 2011). In a separate population study, adherence to a Mediterranean diet significantly decreased the risk of ischemic stroke, heart attack, and vascular death (Gardener 2011). In a study surveying over 70 000 American women, a "prudent" diet of fruits, vegetables, fish and whole grains was associated with a lower risk of total and ischemic stroke compared to a "Western" diet high in processed meats, refined grains, and sweets (Ding 2006). Consuming a Mediterranean diet low in red meat and rich in fresh fruits and vegetables can also curtail excess homocysteine levels in people genetically prone to high homocysteine (Dedoussis 2004).
Targeted Nutritional Interventions
Olive leaf & olive oil. The Olea Europaea plant is an important constituent of the diet of Mediterranean cultures, and has anti-hypertensive and anti-atherosclerotic effects (El 2009). The leaves of the olive tree contain the active compounds oleuropein and oleacein. In a human trial, 1000 mg daily of olive leaf extract reduced blood pressure (Perrinjaquet-Moccetti 2008). Pretreatment with 100 mg/kg of olive leaf extract has also been shown to reduce brain damage in a rat model of ischemic stroke (Dekanski 2011). Olive oil also contains heart-healthy compounds. A French study showed that older subjects who consume olive oil in both cooking and in dressing have a 41% lower ischemic stroke risk compared with people who never use olive oil (Samieri 2011).
Nattokinase. A 2008 study demonstrated that nattokinase, an enzyme extracted from fermented soybeans, is helpful in reducing blood pressure in patients with hypertension (Kim 2008). The participants that received 2000 fibrinolytic units (FU) of nattokinase daily for 8 weeks had a reduction in systolic and diastolic pressure of almost 6 mmHg and 3 mmHg, respectively. Nattokinase breaks apart the protein fibrinogen, which contributes to blood viscosity and clotting. This reduction in blood viscosity may be one of the ways that nattokinase affects blood pressure. Nattokinase also inhibits the elevation of angiotensin II in the bloodstream (Fujita 2011).
L-carnitine, acetyl-L-carnitine, and propionyl-L-carnitine. L-carnitine is an essential co-factor in the metabolism of lipid molecules into cellular energy. L-carnitine has been shown to be neuroprotective in rat models of ischemic stroke (Wainwright 2003). Laboratory studies on human tissue specimens demonstrate that L-carnitine causes vasodilation. In one laboratory study, L-carnitine selectively inhibited a platelet-activating factor, demonstrating that L-carnitine has a protective effect against thrombosis in ischemic stroke. In a sample of 9 ischemic muscle specimens from 5 patients with vascular disease, L-carnitine levels were low, but were restored 2 days after a single injection followed by a 30-minute infusion of propionyl-L-carnitine (Andreozzi 2009). In an animal model of ischemic stroke, pre-treatment with acetyl-L-carnitine decreased brain damage (Zhang 2012).
Vinpocetine. Vinpocetine is derived from the chemical vincamine, which is an extract from the leaves of the lesser periwinkle plant. Since its synthesis in the 1960s, vinpocetine has shown both neuroprotective and cerebral blood-flow-enhancing properties. It is widely used in cerebrovascular disease in Japan, Hungary, Poland, Russia, and Germany (Patyar 2011).
Vinpocetine has neuroprotective effects due to its ability to block sodium channels and calcium channels in brain cells, preventing excitotoxicity and death of brain tissue (Bereczki 2008). Animal models reveal a role for vinpocetine in blocking inflammatory processes. This is significant because chronic inflammation leads to endothelial dysfunction and atherosclerosis, increasing the risk for stroke. In an animal model of ischemic stroke, damage to a brain area known as the hippocampus was reduced from 77% in untreated animals to 37% in animals treated with vinpocetine (Patyar 2011).
Vitamin D. Evidence from clinical trials suggests that vitamin D plays a modest role in blood pressure control (Witham 2009). Vitamin D regulates blood pressure by modulating calcium-phosphate metabolism, controlling endocrine glands, and improving endothelial function. Vitamin D deficiency appears to be an independent risk factor for stroke incidence in Japanese-American men (Kojima 2012) and Korean men (Park 2012). A recent study also showed that individuals whose vitamin D levels were greater than 30 ng/mL had the lowest incidence of heart attack and stroke (Park 2012). Vitamin D may also promote normal insulin metabolism (Houston 2010).
Vitamin B6, B12, and Folic Acid. B-vitamin therapy has been shown to lower homocysteine levels and independently reduce stroke risk (Saposnik 2009). Homocysteine levels can become elevated when serum B12 level are below 400 pmol/L (Spence 2011). Analysis of data on 5522 participants in a large trial to assess the role of B-vitamins in stroke risk reduction (the HOPE-2 trial) demonstrated that treatment with folic acid and vitamins B6 and B12 lowered plasma homocysteine levels and overall stroke incidence. In this study, the incidence of both ischemic and hemorrhagic stroke was lower in the vitamin group compared to the placebo group (Saposnik 2009). A 2012 review of 19 different studies found that B-vitamin supplementation reduces stroke risk by approximately 12% (Huang 2012a). Another 2012 study supported those findings by demonstrating that supplementation with folic acid can reduce stroke incidence by 8% (Huo 2012).
Omega-3 fatty acids. Omega-3 fatty acids are found in certain fat sources such as cold-water fish and flaxseed oil (Houston 2010). Studies have demonstrated that omega-3 fatty acids help regulate blood pressure and reduce platelet aggregation, inflammation, LDL-cholesterol, and other atherosclerosis risk factors (AHA 2010). A 2006 review article indicated that omega-3 fatty acids have a significant protective effect against cerebrovascular disease (Wang 2006). In a mouse model of ischemia, 3 months of treatment with docosahexaenoic acid (DHA) blunted inflammatory responses after an ischemic stroke and decreased brain damage (Lalancette-Hebert 2011).
Omega-3 intake may slow the progression of atherosclerosis by reducing plasma triglyceride levels (Mozaffarian 2011). In short-term clinical trials, consumption of omega-3 fatty acids stimulated nitric oxide production, which enhances the dilation of arteries and improves blood flow throughout the body. Omega-3 fatty acids have also been shown to improve endothelial function and prevent abnormal heart rhythms (arrhythmias) (Mozaffarian 2011; Reiffel 2006; Singer 2004). The American Heart Association suggests that some people may not get enough omega-3 fatty acids through diet alone and that these individuals should consider taking a dietary supplement (AHA 2010).
Garlic. Some clinical trials have found that increased consumption of garlic can lower blood pressure in hypertensive patients. Consumption of approximately 10 000 mcg of the active ingredient allicin, the amount contained in about four cloves of garlic, per day appears to be necessary to lower blood pressure (Houston 2010). A review of studies demonstrated that garlic consumption appears to lower systolic and diastolic blood pressure by an average of 16 and 9 mmHg, respectively (Reinhart 2008).
Dehydroepiandrosterone (DHEA). DHEA, an endogenous steroid hormone derived from cholesterol, is the most abundant circulating steroid in humans. DHEA improves arterial dilation and protects against endothelial dysfunction, a risk factor for stroke (Kawano 2003). In a study of over 300 postmenopausal women, higher levels of DHEA-s, a major metabolic derivative of DHEA, were associated with less severe stroke (Pappa 2012).
Vitamin C. Vitamin C, also known as ascorbic acid, is a water-soluble antioxidant that improves endothelial function. Numerous observational and clinical studies have documented that dietary intake of vitamin C can lower blood pressure and heart rate. Evaluation of published clinical trials has shown that intake of 250 mg vitamin C twice daily lowered systolic and diastolic blood pressure by about 7 mmHg and 4 mmHg, respectively. Vitamin C may lower blood pressure by reducing binding of angiotensin II to its receptor. Vitamin C also appears to enhance antihypertensive effects of some blood pressure medications (Houston 2010).
Flavonoids. Flavonoids are naturally occurring antioxidants found in fruits, vegetables, red wine, and tea (Houston 2010). A 2012 study showed that increased intake of flavonoids is associated with reduced risk of ischemic stroke in women, and that consumption of citrus fruits can reduce overall stroke risk (Cassidy 2012). An animal model showed that a single intravenous dose of the flavonoid resveratrol improved cerebral blood flow by 30% and protected against ischemia-induced brain damage (Lu 2006).
Rutin. Rutin is a flavonoid that occurs naturally in buckwheat and some fruits (eg, apples) (Kreft 2006; Lata 2009). Rutin inhibits an enzyme called protein disulfide isomerase (PDI), which participates in blood clot formation. Among nearly 5000 agents screened as potential PDI inhibitors in one study, rutin was one of the most potent (Jasuja 2012). An animal model showed that rutin inhibits the formation of blood clots (Jasuja 2012).