Heart Health

California walnuts are a great way to add flavor, crunch and nutritious goodness to all kinds of meals and snacks.

  • The only nut with an excellent source of omega-3 ALA (2.5g/oz)
  • Certified by the American Heart Association as a heart-healthy* food
  • Satisfying plant-based protein (4g/oz) and fiber (2g/oz)

What the Research Says

Since 1993, published research has been investigating how eating walnuts affects various heart health biomarkers and risk markers including:

  • LDL and HDL cholesterol
  • Apolipoprotein B and non-HDL cholesterol
  • Blood pressure
  • Inflammation
  • Endothelial function
  • Plaque formation

Due to the evidence supporting the cardiovascular benefits of walnuts, the U.S. Food and Drug Administration approved one of the first qualified health claims for a whole food in March of 2004: “Supportive but not conclusive research shows that eating 1.5 ounces of walnuts per day, as part of a low saturated fat and low cholesterol diet, and not resulting in increased caloric intake may reduce the risk of coronary heart disease.”1

Continue below for a scientific summary of the research to date.

American Heart Association Certified

A Heart-Healthy Food

Walnuts are certified by the American Heart Association® with the Heart-Check mark, per one ounce serving.

American Heart Association Heart-Check Certified Recipes

The possibilities are endless! Walnuts are so versatile and make an easy heart-healthy* snack to grab on the go or to incorporate into a heart-healthy* meal. Get inspired with these recipes.

Research Information

The research supporting the role that walnuts can play in heart health began with a Loma Linda University study, showing walnuts may lower total and LDL cholesterol in men by as much as 12 percent and 16 percent, respectively.2 In this eight-week randomized, crossover trial, 18 healthy men (ages 21-43) were assigned to a cholesterol-lowering diet that did not include nuts or a cholesterol-lowering diet that included walnuts. All food was provided by the researchers and the walnut diet contained three servings (equivalent to 3 ounces) of walnuts per day.

A clinical trial revealed there may be a connection between heart and gut health aided by consumption of walnuts.3 Findings showed that consuming walnuts enriched certain gut bacteria associated with improvements in blood pressure and cholesterol. Overweight and obese adults at risk for heart disease (42 total) followed a diet that replaced some saturated fat with either walnuts, a vegetable oil with the same fatty acids as walnuts (including omega-3 ALA, a type of polyunsaturated fat), or a vegetable oil higher in monounsaturated fat. Individuals who consumed walnuts and the vegetable oil with the same fatty acid profile as walnuts had favorable shifts in gut bacteria, suggesting a positive impact of omega-3 ALA. Those who followed the walnut diet had a unique enrichment of a particular species of bacteria – one that plays an important role in metabolizing ellagitannins, a bioactive component of walnuts that may be associated with cardiovascular benefits. The types of fatty acids in walnuts and vegetable oil may impact gut health, but this study also suggests there may be benefits to consuming whole walnuts.

A systematic review from the Harvard T.H. Chan School of Public Health examined 25 years of evidence for the role of walnut consumption on cardiovascular risk factors, including cholesterol, triglycerides, blood pressure, and weight.4

A meta-analysis was done on 26 randomized controlled trials representing 1059 individuals (ages 22-75), including those with a variety of conditions such as high cholesterol, type 2 diabetes, metabolic syndrome, overweight or obesity, as well as those that were healthy. When compared to control diets, including low-fat, Mediterranean, American or Japanese, a diet supplemented with walnuts in amounts varying from 5-24 percent of total calories per day (equivalent to 0.5-3.9 ounces per day) resulted in a significantly greater percent decrease in total cholesterol (3.25%), LDL cholesterol (3.73%), triglycerides (5.52%), and apolipoprotein B (4.19%). In addition, incorporating walnuts into the diet had no adverse effects on body weight or blood pressure, according to the studies included in the meta-analysis.

Research from the landmark PREvención con DIeta MEDiterránea (PREDIMED) study further demonstrated the potential heart health benefits of walnuts. The study was conducted among more than 7,000 Spanish individuals (ages 55-80) at high risk for cardiovascular disease and found that a Mediterranean diet supplemented with mixed tree nuts (primarily walnuts) was associated with a lower risk of cardiovascular events, including cardiovascular death, myocardial infarction (heart attack), and stroke, when compared to a low-fat control diet.5

Larger and longer-term studies, as well as studies in more diverse populations, are needed to clarify population-wide effects, especially in gut health studies since the microbiome can be highly variable among individuals.2,3,4,5 In some cases, the amount of walnuts consumed in these trials was relatively large and might be difficult to maintain in a non-research setting.2,3,5 A meta-analysis offers a comprehensive look at findings among patients of various backgrounds, however, it can be limited by the methods, reported outcomes and quality of the individual studies involved.4 In the PREDIMED study, it is difficult to precisely define what part of the Mediterranean diet was associated with cardiovascular benefits.5

View peer-reviewed publications supported by the California Walnut Commission.
Walnut Heart Health

1One ounce of walnuts provides 18g of total fat, 2.5g of monounsaturated fat, 13g of polyunsaturated fat, including 2.5g of alpha-linolenic acid, the plant-based omega-3.

2Sabaté J, Fraser GE, Burke K, et al. Effects of walnuts on serum lipid levels and blood pressure in normal men. N Engl J Med. 1993;328:603-607.

3Tindall AM, McLimans CJ, Petersen KS, et al. Walnuts and Vegetable Oils Containing Oleic Acid Differentially Affect the Gut Microbiota and Associations with Cardiovascular Risk Factors: Follow-up of a Randomized, Controlled, Feeding Trial in Adults at Risk for Cardiovascular Disease. J Nutr. 2019 Dec 18. pii: nxz289. doi: 10.1093/jn/nxz289. [Epub ahead of print]

4Guasch-Ferré M, Li J, Hu FB, et al. Effects of walnut consumption on blood lipids and other cardiovascular risk factors: an updated meta-analysis and systematic review of controlled trials. Am J Clin Nutr. 2018;108(1):174-187. doi: 10.1093/ajcn/nqy091.

5Estruch R, Ros E, Salas-Salvadó J, et al. Primary Prevention of Cardiovascular Disease with a Mediterranean Diet Supplemented with Extra-Virgin Olive Oil or Nuts. N Engl J Med. 2018;378(25):e34. doi: 10.1056/NEJMoa1800389.

Generated with Avocode.Generated with Avocode.