Coronary heart disease (CHD) remains one of the leading causes of death worldwide, but research suggests that dietary choices can significantly impact cardiovascular health. Among heart-healthy foods, walnuts stand out for their ability to reduce cholesterol, lower inflammation, and improve blood vessel function. We explore the scientific evidence supporting walnuts as a key dietary component in CHD prevention and management. 

Walnuts and Cholesterol Reduction 

One of the primary risk factors for CHD is high low-density lipoprotein (LDL) cholesterol, often called ‘bad’ cholesterol. Walnuts, rich in polyunsaturated fats—particularly alpha-linolenic acid (ALA), an omega-3 fatty acid—help lower LDL cholesterol and improve overall lipid profiles. A meta-analysis of 26 clinical trials found that walnut consumption significantly reduced total cholesterol, LDL cholesterol, and triglyceride levels while maintaining or slightly increasing high-density lipoprotein (HDL) cholesterol, the ‘good’ cholesterol (Banel & Hu, 2009). Another study published in Circulation demonstrated that replacing saturated fats with walnuts led to a 9-16% reduction in LDL cholesterol, similar to the effect of cholesterol-lowering medications (Kris-Etherton et al., 1999). 

Anti-Inflammatory and Antioxidant Effects 

Chronic inflammation is a key contributor to atherosclerosis, the process of plaque buildup in arteries that leads to CHD. Walnuts are packed with antioxidants, including polyphenols, vitamin E, and melatonin, which help combat oxidative stress and reduce inflammation. 

A study in the Journal of Nutrition found that individuals who consumed walnuts regularly had lower levels of C-reactive protein (CRP), a marker of inflammation strongly linked to heart disease risk (Ma et al., 2010). Additionally, walnuts contain ellagitannins, which are converted by gut bacteria into urolithins—compounds with potent anti-inflammatory properties that support heart health (Tomás-Barberán et al., 2014). 

Improved Blood Vessel Function and Blood Pressure Control Endothelial dysfunction, characterised by poor blood vessel function, is an early indicator of CHD. Walnuts help improve endothelial function by increasing nitric oxide production, which promotes vasodilation and enhances blood flow. 

A randomised controlled trial published in the American Journal of Clinical Nutrition found that participants who followed a walnut-enriched diet experienced significant improvements in endothelial function compared to those on a control diet (West et al., 2012). Furthermore, the magnesium and potassium in walnuts contribute to lower blood pressure, another critical factor in reducing CHD risk.

Reduced Risk of Heart Attacks and Strokes 

Long-term studies show that regular walnut consumption is associated with a lower risk of heart disease and cardiovascular-related mortality. A large prospective study from the New England Journal of Medicine found that individuals who consumed nuts, including walnuts, five or more times per week had a 29% lower risk of CHD compared to those who rarely ate nuts (Bao et al., 2013). Additionally, the PREDIMED study, which examined the benefits of the Mediterranean diet, found that participants who supplemented their diet with walnuts and other nuts had a 30% lower risk of major cardiovascular events such as heart attacks and strokes (Estruch et al., 2013). 

Conclusion 

The scientific evidence is clear: walnuts offer significant cardiovascular benefits, from lowering cholesterol and reducing inflammation to improving blood vessel function and lowering blood pressure. Incorporating a handful of walnuts (about 28 grams) into your daily diet can be a simple yet effective way to protect your heart and reduce the risk of CHD. 

Easy ways to add walnuts into your daily diet:

• Sprinkle a small handful into your breakfast bowl with your cereal, fruit or yoghurt.

• Enjoy a palm-sized portion as a mid-morning snack with an apple. 

• Crumble lightly toasted walnuts over a roasted vegetable salad 

• Make a delicious walnut pesto to top chicken breasts or stir through wholewheat pasta.

  
  

References 

• Banel, D. K., & Hu, F. B. (2009). Effects of walnut consumption on blood lipids and other cardiovascular risk factors: A meta-analysis and systematic review. American Journal of Clinical Nutrition, 90(1), 56-63. 

• Bao, Y., et al. (2013). Association of nut consumption with total and cause-specific mortality. New England Journal of Medicine, 369(21), 2001-2011. 

• Estruch, R., et al. (2013). Primary prevention of cardiovascular disease with a Mediterranean diet. New England Journal of Medicine, 368(14), 1279-1290. 

• Kris-Etherton, P. M., et al. (1999). High-monounsaturated fatty acid diets lower both plasma cholesterol and triacylglycerol concentrations. Circulation, 100(5), 511-518. 

• Ma, Y., et al. (2010). Effects of walnut consumption on endothelial function in type 2 diabetic subjects. Journal of Nutrition, 140(8), 1442-1447. 

• Tomás-Barberán, F. A., et al. (2014). Urolithins, the gut microbiota-derived metabolites of ellagitannins, are bioavailable in humans and have antioxidant and anti-inflammatory properties. Journal of Agricultural and Food Chemistry, 62(30), 6535-6545. 

• West, S. G., et al. (2012). Effects of diets high in walnuts and flax oil on hemodynamic responses to stress and vascular endothelial function. American Journal of Clinical Nutrition, 95(5), 1003-1007.