Harvard research links eating walnuts to lower risk of type 2 diabetes and cardiovascular disease

 Research carried out by machine learning revealed eating walnuts is associated with 19 different metabolites, linked with lower risk of both diseases

Researchers from the Harvard T.H. Chan School of Public Health used machine learning, a subset of artificial intelligence, to identify more precisely the components in walnuts that may be responsible for potentially reducing the risk of type 2 diabetes and cardiovascular diseases. In the UK, more people than ever before have diabetes[1] and there are around 7.4 million people living with heart and circulatory disease[2].

This study, supported by the California Walnut Commission and published in The Journal of Nutrition, used a novel approach, agnostic machine-learning, to identify 19 metabolites that were associated with walnut consumption. The body forms specific metabolites based on what food is consumed. The walnut metabolite profile was associated with a 17% lower risk of type 2 diabetes and 29% lower risk of cardiovascular disease. This is the first study to examine the association between walnut metabolites and the risk of cardiometabolic diseases, contributing to the three decades of existing research on walnuts and heart health.

“With data-driven technologies, we are able to enhance our understanding of the relationship between diet and disease and take a personalized approach to nutrition which will lead to better prevention and management of various health conditions,” says Dr. Marta Guasch-Ferré a Research Scientist at the Department of Nutrition at Harvard T.H. Chan School of Public Health, Instructor in Medicine at Harvard Medical School and Brigham and Women’s Hospital, and lead investigator of this research.

“In this study, we revealed the unique metabolomic signature of walnuts, which brings us one step closer to understanding “how” walnuts are good for our health. These cutting-edge technologies are shaping the future of nutrition recommendations,” says Guasch-Ferré.

Researchers examined data from 1,833 participants of the PREvención con DIeta MEDiterránea (PREDIMED) study, a large-scale, multi-year study that took place in Spain and looked at the effects of a Mediterranean diet in the prevention of cardiovascular disease among people at high risk for heart disease. Participants were aged 55-80 and followed one of three diets: 1) Mediterranean diet supplemented with mixed nuts (50% walnuts, 25% almonds, and 25% hazelnuts); 2) Mediterranean diet supplemented with extra-virgin olive oil; or 3) low-fat diet.  The metabolites in walnuts form the walnut metabolite profile associated with a reduction in type 2 diabetes and cardiovascular disease.

These findings further emphasise the connection between walnut consumption as part of a healthy diet and cardiometabolic health. New tools as used in this epidemiological study will help identify links between diet and disease. However, the results do not prove cause and effect. More research is needed in other populations since this study was focused on older Spanish adults only. In addition, given the field of metabolomics is rapidly evolving, future studies will be needed to identify additional biomarkers of walnut intake that were not pursued in this study as well as to understand individual metabolic responses after consuming walnuts.


[1] https://www.diabetes.org.uk/resources-s3/2019-02/1362B_Facts%20and%20stats%20Update%20Jan%202019_LOW%20RES_EXTERNAL.pdf
[2] https://www.bhf.org.uk/what-we-do/news-from-the-bhf/contact-the-press-office/facts-and-figures#:~:text=There%20are%20around%207.4%20million,of%20heart%20and%20circulatory%20disease.