Not eating walnuts may double our risk of dying from heart disease (compared to at least one serving a week)—perhaps because nuts appear to improve endothelial function, allowing our arteries to better relax normally.
Walnuts and Artery Function
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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
Not eating walnuts may double our risk of dying from heart disease, compared to at least one serving a week. But, walnut consumption may only drop our cholesterol levels about 5%. How could we get a 50% drop in cardiac mortality from just a 5% drop in cholesterol? Walnuts must have some other heart-protecting benefits, besides just lowering cholesterol—such as improving arterial function.
This review found five clinical trials analyzing the effect of nut consumption on the ability of our arteries to relax and open normally—considered “an excellent ‘barometer’ of underlying vascular health.” Even after controlling for other risk factors, 80% of those with better-than-average arterial function survived cardiac event-free over the years, whereas 80% of those with below-average dilation didn’t.
And so, what effect do nuts have? All three studies on walnuts showed an improvement in endothelial function, arterial function—this so-called flow-mediated dilation measured in the arm. The one study on pistachios also found a positive effect, but the one study on hazelnuts was a wash. A subsequent study on hazelnuts, though, did find a significant improvement in arterial function, so the data on hazelnuts is mixed—whereas two subsequent walnut studies, however, confirmed walnuts’ benefits.
So, eight studies to date on nuts and brachial artery function, and seven out of eight showed a significant improvement in arterial function; one showed a negligible effect; and none found nuts made things worse. Half the studies, though, used the added walnuts to replace foods in the diet known to have a negative effect on endothelial function.
For example, in this study, walnuts replaced meat and dairy, which have been shown to be detrimental, so, no wonder arterial function got better. When you do a study like that, you can’t tell if the benefits you’re seeing is because you’re adding good stuff, or getting rid of the bad.
And, in three of the other studies, nuts replaced olive oil, which tends to lead to a worsening of endothelial function—thereby exaggerating the beneficial effects of the walnuts, from here to here.
But, the other four studies, like this one, that just added nuts “as a snack or with a meal,” without replacing any specific foods, found nuts “significantly improved [arterial] functioning.” And, given their association with longevity, I encourage everyone to eat an ounce of nuts a day—unless, of course, you’re allergic. Only about 1% of people report nut allergies, but still, that’s a significant “downside of [nut] consumption” for millions of Americans.
Please consider volunteering to help out on the site.
- M Guasch-Ferré, M Bulló, MÁ Martínez-González, E Ros, D Corella, R Estruch, M Fitó, F Arós, J Wärnberg, M Fiol, J Lapetra, E Vinyoles, RM Lamuela-Raventós, L Serra-Majem, X Pintó, V Ruiz-Gutiérrez, J Basora, J Salas-Salvadó. Frequency of nut consumption and mortality risk in the PREDIMED nutrition intervention trial. BMC Med. 2013 11:164.
- J Mukuddem-Petersen, W Oosthuizen, JC Jerling. A systematic review of the effects of nuts on blood lipid profiles in humans. J Nutr. 2005 135(9):2082 – 2089.
- M Shechter, A Shechter, N Koren-Morag, MS Feinberg, L Hiersch. Usefulness of brachial artery flow-mediated dilation to predict long-term cardiovascular events in subjects without heart disease. Am J Cardiol. 2014 113(1):162 – 167.
- DL Katz, A Davidhi, Y Ma, Y Kavak, L Bifulco, VY Njike. Effects of walnuts on endothelial function in overweight adults with visceral obesity: A randomized, controlled, crossover trial. J Am Coll Nutr. 2012 31(6):415 – 423.
- A Orem, FB Yucesan, C Orem, B Akcan, BV Kural, C Alasalvar, F Shahidi. Hazelnut-enriched diet improves cardiovascular risk biomarkers beyond a lipid-lowering effect in hypercholesterolemic subjects. J Clin Lipidol. 2013 7(2):123 - 131.
- B Cortés, I Nunez, M Cofan. R Gilabert, A Perez-Heras, E Casala, R Deulofeu, E Ros. Acute Effects of High-Fat MealsEnriched With Walnuts or Olive Oil on Postprandial Endothelial Function. J Am Coll Cardiol. 2006 48(8):1666-71.
- SG West, AL Krick, LC Klein, G Zhao, TF Wojtowicz, M McGuiness, DM Bagshaw, P Wagner, RM Ceballos, BJ Holub, PM Kris-Etherton. Effects of diets high in walnuts and flax oil on hemodynamic responses to stress and vascular endothelial function. J Am Coll Nutr. 2010 29(6):595 – 603.
- P Russo, A Siani. The role of nuts in the optimal diet: Time for a critical appraisal? Nutr Metab Cardiovasc Dis. 2012 22(12):1019-1023.
- SH Sicherer, A Munoz-Furlong, JH Godbold, HA Sampson. US prevalence of self-reported peanut, tree nut, and sesame allergy: 11-Year follow-up. J. Allergy Clin Immunol. 2010 125(6):1322 – 1326.
- P Casas-Agustench, P López-Uriarte, E Ros, M Bulló, J Salas-Salvadó. Nuts, hypertension and endothelial function. Nutr Metab Cardiovasc Dis. 2011 Jun;21 Suppl 1:S21-33.
Images thanks to Alex Ex and J.Dncsn via Wikimedia, and angels aguirre via flickr
Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
Not eating walnuts may double our risk of dying from heart disease, compared to at least one serving a week. But, walnut consumption may only drop our cholesterol levels about 5%. How could we get a 50% drop in cardiac mortality from just a 5% drop in cholesterol? Walnuts must have some other heart-protecting benefits, besides just lowering cholesterol—such as improving arterial function.
This review found five clinical trials analyzing the effect of nut consumption on the ability of our arteries to relax and open normally—considered “an excellent ‘barometer’ of underlying vascular health.” Even after controlling for other risk factors, 80% of those with better-than-average arterial function survived cardiac event-free over the years, whereas 80% of those with below-average dilation didn’t.
And so, what effect do nuts have? All three studies on walnuts showed an improvement in endothelial function, arterial function—this so-called flow-mediated dilation measured in the arm. The one study on pistachios also found a positive effect, but the one study on hazelnuts was a wash. A subsequent study on hazelnuts, though, did find a significant improvement in arterial function, so the data on hazelnuts is mixed—whereas two subsequent walnut studies, however, confirmed walnuts’ benefits.
So, eight studies to date on nuts and brachial artery function, and seven out of eight showed a significant improvement in arterial function; one showed a negligible effect; and none found nuts made things worse. Half the studies, though, used the added walnuts to replace foods in the diet known to have a negative effect on endothelial function.
For example, in this study, walnuts replaced meat and dairy, which have been shown to be detrimental, so, no wonder arterial function got better. When you do a study like that, you can’t tell if the benefits you’re seeing is because you’re adding good stuff, or getting rid of the bad.
And, in three of the other studies, nuts replaced olive oil, which tends to lead to a worsening of endothelial function—thereby exaggerating the beneficial effects of the walnuts, from here to here.
But, the other four studies, like this one, that just added nuts “as a snack or with a meal,” without replacing any specific foods, found nuts “significantly improved [arterial] functioning.” And, given their association with longevity, I encourage everyone to eat an ounce of nuts a day—unless, of course, you’re allergic. Only about 1% of people report nut allergies, but still, that’s a significant “downside of [nut] consumption” for millions of Americans.
Please consider volunteering to help out on the site.
- M Guasch-Ferré, M Bulló, MÁ Martínez-González, E Ros, D Corella, R Estruch, M Fitó, F Arós, J Wärnberg, M Fiol, J Lapetra, E Vinyoles, RM Lamuela-Raventós, L Serra-Majem, X Pintó, V Ruiz-Gutiérrez, J Basora, J Salas-Salvadó. Frequency of nut consumption and mortality risk in the PREDIMED nutrition intervention trial. BMC Med. 2013 11:164.
- J Mukuddem-Petersen, W Oosthuizen, JC Jerling. A systematic review of the effects of nuts on blood lipid profiles in humans. J Nutr. 2005 135(9):2082 – 2089.
- M Shechter, A Shechter, N Koren-Morag, MS Feinberg, L Hiersch. Usefulness of brachial artery flow-mediated dilation to predict long-term cardiovascular events in subjects without heart disease. Am J Cardiol. 2014 113(1):162 – 167.
- DL Katz, A Davidhi, Y Ma, Y Kavak, L Bifulco, VY Njike. Effects of walnuts on endothelial function in overweight adults with visceral obesity: A randomized, controlled, crossover trial. J Am Coll Nutr. 2012 31(6):415 – 423.
- A Orem, FB Yucesan, C Orem, B Akcan, BV Kural, C Alasalvar, F Shahidi. Hazelnut-enriched diet improves cardiovascular risk biomarkers beyond a lipid-lowering effect in hypercholesterolemic subjects. J Clin Lipidol. 2013 7(2):123 - 131.
- B Cortés, I Nunez, M Cofan. R Gilabert, A Perez-Heras, E Casala, R Deulofeu, E Ros. Acute Effects of High-Fat MealsEnriched With Walnuts or Olive Oil on Postprandial Endothelial Function. J Am Coll Cardiol. 2006 48(8):1666-71.
- SG West, AL Krick, LC Klein, G Zhao, TF Wojtowicz, M McGuiness, DM Bagshaw, P Wagner, RM Ceballos, BJ Holub, PM Kris-Etherton. Effects of diets high in walnuts and flax oil on hemodynamic responses to stress and vascular endothelial function. J Am Coll Nutr. 2010 29(6):595 – 603.
- P Russo, A Siani. The role of nuts in the optimal diet: Time for a critical appraisal? Nutr Metab Cardiovasc Dis. 2012 22(12):1019-1023.
- SH Sicherer, A Munoz-Furlong, JH Godbold, HA Sampson. US prevalence of self-reported peanut, tree nut, and sesame allergy: 11-Year follow-up. J. Allergy Clin Immunol. 2010 125(6):1322 – 1326.
- P Casas-Agustench, P López-Uriarte, E Ros, M Bulló, J Salas-Salvadó. Nuts, hypertension and endothelial function. Nutr Metab Cardiovasc Dis. 2011 Jun;21 Suppl 1:S21-33.
Images thanks to Alex Ex and J.Dncsn via Wikimedia, and angels aguirre via flickr
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Walnuts and Artery Function
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Content URLDoctor's Note
This helps explain why Nuts May Help Prevent Death.
What else can nuts do? See, for example:
- Fighting Inflammation in a Nut Shell
- Tree Nuts or Peanuts for Breast Cancer Prevention?
- Pistachio Nuts for Erectile Dysfunction
- Nuts & Bolts of Cholesterol Lowering
Don’t nuts make us fat, though? You may be surprised—see Nuts & Obesity: The Weight of Evidence.
Which type of walnut is better? See Black vs. English Walnuts.
Keep up with all of my newest videos about nuts on the topic page.
What about the phytates in nuts–do we need to soak or toast them? See:
- Phytates for the Prevention of Osteoporosis
- Phytates for the Prevention of Cancer
- Phytates for Rehabilitating Cancer Cells
- Phytates for the Treatment of Cancer
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