No aspect of walnuts has been better evaluated in the research than their benefits for the heart and circulatory system. Some review studies have emphasized the very favorable impact of walnuts on "vascular reactivity," namely, the ability of our blood vessels to respond to various stimuli in a healthy manner. In order to respond to different stimuli in a healthy way, many aspects of our cardiovascular system must be functioning optimally. These aspects include: ample presence of antioxidant and anti-inflammatory nutrients, proper blood composition, correct balance in inflammation-regulating molecules, and proper composition and flexibility in our blood vessel walls. Researchers have determined the ability of walnuts to have a favorable impact on all of these aspects. The chart below summarizes some key research findings about walnuts and heart health:
| Cardiovascular Aspect | Walnut Benefit |
|---|---|
| Blood Quality | decreased LDL cholesterol; decreased total cholesterol; increased gamma-tocopherol; increased omega-3 fatty acids in red blood cells (alpha-linolenic acid) |
| Vasomotor Tone | decreased aortic endothelin; improved endothelial cell function |
| Risk of Excessive Clotting | decreased maximum platelet aggregation rate; decreased platelet activation |
| Risk of Excessive Inflammation | decreased C reactive protein (CRP); decreased tumor necrosis factor alpha (TNF-a) |
Research on the blood pressure benefits of walnuts has been mixed. We suspect that these mixed results are related to the surprising differences in mineral composition amongst different varieties of walnuts. Researchers have long been aware of the relationship between healthy blood pressure and intake of specific minerals, including potassium, calcium, and magnesium. In multiple studies, these minerals have a much greater impact on blood pressure than the mineral sodium (familiar to most people in its sodium chloride form, i.e., everyday table salt). We've seen studies showing the following ranges for key blood pressure-regulating minerals in walnuts:
| Mineral | Natural Range Found Amongst Different Walnut Varieties (milligrams per 100 grams) |
|---|---|
| Potassium | 375-500 |
| Calcium | 13-91 |
| Magnesium | 189-278 |
Even though there are valuable amounts of these blood pressure-regulating minerals in virtually all varieties of walnuts, the ranges above may help explain why some studies have shown statistically significant benefits from walnuts on blood pressure while others have not.
Not in question with respect to walnuts and cardiovascular support is their reliable omega-3 content. Adequate intake of omega-3s, including the alpha-linolenic acid (ALA) present in walnuts, has repeatedly been shown to help improve a wide variety of cardiovascular functions, including blood pressure. In at least one research study, adults have been able to significantly increase their blood level of ALA with as few as 4 walnuts per day.
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