Rohan Arora, MD

Larsson SC. Dietary Approaches for Stroke Prevention. Stroke. 2017

This review by Susanna Larsson focuses on the current evidence from randomized controlled trials and prospective studies on dietary modifications that could help with stroke prevention.

The article is very important since diet is one of the modifiable factors that can help with reducing the risk of stroke and promote cardiovascular health. The stroke survivors or their family members are of utmost curiosity to change their diet after seeing a family member suffer from stroke.

The recommended DASH diets (Mediterranean and Dietary Approaches to Stop Hypertension) have been shown to be helpful in reducing 24-hour ambulatory blood pressure, total cholesterol and fasting blood glucose levels. Mediterranean-type diet emphasizes vegetables, fruits, and whole grains and includes low-fat dairy products, poultry, fish, legumes, olive oil, and nuts. It limits intake of sweets and red meats.

PREDIMED trial studied primary prevention of cardiovascular disease with a Mediterranean diet; participants assigned to a Mediterranean diet supplemented with mixed nuts had a 46% reduced risk of stroke (RR, 0.54; 95% CI, 0.35–0.84), compared with the control group (advised to reduce fat intake). Additionally, participants randomized to extra virgin olive oil experienced 33% reduced risk of stroke.

We most definitely encourage our patients to adhere to a diet plan, but with the help of this article, it’s important to explain the underlying mechanism in support of our recommendation. Fruits and vegetables are the predominant sources of vitamin C, which is an antioxidant that reduces oxidation of low-density lipoprotein cholesterol, decreases smooth muscle proliferation and eventually slows the progression of atherosclerosis. Fish consumption is weakly inversely associated with risk of stroke. Eggs are a rich source of protein but are also high in cholesterol. Dietary protein and certain amino acids, such as cysteine, which is found at high levels in eggs, might reduce blood pressure and have been associated with lower risk of ischemic and hemorrhagic stroke.

It is interesting to note that there is a dietary implication of coffee and tea, which is a beverage consumed by most people on a daily basis, and so a quite frequently encountered question to stroke neurologists. Studies have shown to decrease risk of stroke without clear causality. The potential mechanism is they enhance endothelial-dependent vasodilation. Meta-analysis from studies shows calcium supplements may increase risk of stroke by influencing vascular calcification. Sugar-sweetened beverages and artificial beverage consumption increase risk of stroke through hyperglycemia or by replacing healthier food options. It appears that the authors have discouraged consumption of processed meat as it contains high sodium, which raises blood pressure, the most commonly implicated risk factor for stroke in Americans.

Although we cannot deny that adherence to a Mediterranean or DASH dietary pattern reduces risk of stroke, the author does recognize the limitations of evidence available to make specific recommendations about dietary approach since most of the data has been collected from observational studies, making it difficult to prove causality. Since most studies reported results for all strokes combined, what continues to be an interesting area to research is dietary approaches according to stroke subtype, in particular, ischemic stroke subtypes, i.e. a different dietary approach may be indicated for cardio embolic stroke prevention as compared to Lacunar (small vessel disease).